Preliminary System Design & Project Plan
October 12, 2011
Michael Gorman
Prosper Majyambere
Ivan Michelli
Mark Moore
Trevor Pringle

M A T T | 1
System Design .............................................................................................................................................. 3
Background ............................................................................................................................................... 3
System Overview ....................................................................................................................................... 3
Block Diagrams .......................................................................................................................................... 4
MATT – Level 0 ................................................................................................................................. 4
MATT – Level 1 ................................................................................................................................. 5
Power Source System – Level 2 ...................................................................................................... 6
Control and Interface System – Level 2 .......................................................................................... 7
Launching System – Level 2 ............................................................................................................. 8
Mobility System – Level 2 ................................................................................................................ 9
Functional Description of Blocks ............................................................................................................. 10
Designs and Justifications ....................................................................................................................... 16
Project Plan ................................................................................................................................................. 24
Organization and Management .............................................................................................................. 24
Fall Work Breakdown Structure .............................................................................................................. 25
Spring Work Breakdown Structure ......................................................................................................... 28
Budget ..................................................................................................................................................... 32
Fall Project Plan (Gantt Chart) ................................................................................................................ 34
Spring Project Plan (Gantt Chart) ............................................................................................................ 35

M A T T | 2
Fall Network Diagram ............................................................................................................................. 37
Spring Network Diagram ......................................................................................................................... 39
Appendices ................................................................................................................................................. 42
Appendix A .............................................................................................................................................. 42
Requirements Specification ........................................................................................................... 42
Appendix B .............................................................................................................................................. 51
Possible Components ..................................................................................................................... 51

M A T T | 3
System Design
Background
There is a wide range of products currently available on the market to help tennis players improve their skills or to provide an enjoyable practice session. One such product is the tennis ball launching machine, of which many different types and variations are available, each with its own advantages and disadvantages. The main problem with such tennis ball machines is the fact that they are stationary. With a stationary platform, the tennis balls are shot to the player from the same location every time, decreasing the realism of the practice session. In a game or match, the shots would be hit to the player from a variety of different locations and angles on the tennis court. The goal of the Mobile
Automatic Tennis Trainer (MATT) is to provide a competitive alternative to the standard stationary tennis ball machine design. MATT will add a new element to the tennis ball machine market by being the first tennis ball machine that moves itself. The machine will change its position on the tennis court, thereby providing a wider variety of shots to the player. MATT will also include many of the same features that the typical tennis ball machines exhibit. Some of these features include variation of speeds, and variation of horizontal and vertical angles. All of these features will enable MATT to provide a more realistic training experience than a stationary tennis ball machine, while having a cost that is competitive with similar products.
System Overview
The MATT prototype will provide a more realistic practice experience to tennis players of any skill level with its very own unique mobility feature. MATT will be programmed to move itself laterally, parallel from the net, and remain within 6.0 ± 0.5 meters from the center of the court at all times.
While moving, MATT will launch tennis balls with varying initial speeds between 4 and 45 meters per second. MATT will also provide a wide range of different angles for shots. The range of horizontal angles will be from 40° to 140° and the range of vertical angles will be from 0° to 50°. MATT will be operational anywhere from 10.0 ± 0.5 to 12.0 ± 0.5 meters from the net and will travel the entire width of the tennis court in less than 20.0 ± 1.0 seconds. The maximum time the prototype will take to adjust its aim through the widest range of horizontal or vertical angles is 3.0 ± 1.0 seconds. MATT will have adjustable settings which a user can control through a user interface system. MATT will be able to hold a minimum of 150 tennis balls, which will be launched at a maximum feed rate of one tennis ball per two seconds, allowing a continual practice of a minimum of five minutes.

Block Diagrams
MATT – Level 0
M A T T | 4

Power Input
12-15V
0-55A
Tennis Balls
1-150
Remote
Start/Stop
Pulse
User Interface
Court Position
M A T T | 5
MATT – Level 1
Power Source
Electrical
Power
12-15V
0-25A
Mobility System
Movement
Control
Signal
Electrical
Power
3-5V
0-300mA
Electrical
Power
12-15V
0-25A
Launching
System
Interface/
Controls
System
Launching
Control
Signal
“Recharge Battery”
LED
Machine Mobility
0.5 m/s
Shot Speed
4-45 m/s
Shot Directions
40⁰-140⁰ Horizontally
0⁰-50⁰ Vertically
Tennis Balls
1-150
Ball Feed Rate
≥1ball/3s

Power Input
12-15V
0-55A
Power Source System – Level 2
Source
(Batteries)
Power Input
12-15V
0-55A
Power Input
12-15V
Power
Splitter
Low Battery
Indecator
M A T T | 6
Electrical
Power
12-15V
0-25A
Electrical
Power
12-15V
0-25A
Electrical
Power
3-5V
0-300mA
“Recharge Battery”
LED

M A T T | 7
Control and Interface System – Level 2
Electrical
Power
3-5V
0-300mA
Start/Stop
Pulse
Practice
Mode
(Analog)
Court Position
Power
Splitter
3-5V
0-150mA
3-5V
0-50mA
Remote
Receiver
Start/Stop
Signal
3-5V
0-50mA
User
Interface
Practice
Mode
(Digital)
3-5V
0-50mA
Court
Positioning
System
Court
Position
2-16 bit
Coordinates
Control
Process
Movement
Control
Signal
Launching
Control
Signal

Launching System – Level 2
Tennis Balls
1-150
Electrical
Power
12-15V
0-25A
Hopper
Tennis Ball
1-150
12-15V
0-5A
Feeder Tennis Ball
1-150
Power
Spliter
12-15V
0-20A
Launch
Signal
Launch
Speed
3-5V
0-100mA
Launching
Control
Board
Launch
Angle
Launching
System
Angle
Change
Targeting
System
12-15V
0-5A
Launching
Control
Signal
M A T T | 8
Ball Feed Rate
≥1ball/3s
Shot Speed
4-45 m/s
Tennis Balls
1-150
Shot Direction
40⁰-140⁰Horizontal
0⁰-50⁰ Vertical

M A T T | 9
Mobility System – Level 2
Electrical
Power
12-15V
0-25A
Movement
Control
Signal
Power
Splitter
12-15V
0-25A
Movement
(Speed/Direction)
Movement
Motors
3-5V
0-100mA
Mobility
Control
Board
Brake
Signal Brake
System
Machine Mobility
0.5 m/s

M A T T | 10
Functional Description of Blocks
Power Source
Description: The power supply will consist of 12 VDC or 24 VDC (0 – 55 A) from batteries, or some combination thereof. The power will then be reduced to the correct voltage and current needed by each of the other systems on the machine. There will be a low voltage indicator to indicate if the voltage drops below a certain level. There will also be a master power switch that will turn the machine on or off, which will be independent of the remote.
Inputs:

Power: 12 VDC or 24 VDC from batteries

Current: 0 – 55 A
Outputs:

Control and Interface System: 3 – 5 VDC (300 mA)

Launching System: 12 – 15 VDC (0 – 25 A)

Mobility System: 12 – 15 VDC (0 – 25 A)
Subsystems of Power Source:
Low Voltage Indicator
Description: The low voltage indicator is a circuit that will light an LED once the voltage of the batteries drops below a certain level.
Inputs:

Power Source: Electrical power greater than or equal 11 VDC (0 – 10 mA)
Outputs:

LED 5VDC (0-10mA)
Power Splitter
Description: The power splitter will distribute the required amount of voltage and current to all the various subsystems of the machine.
Inputs:

Power Source: 12 VDC or 24 VDC from batteries at 0 – 55 A
Outputs:

Control and Interface System: 3 – 5 VDC (300 mA)

Launching System: 12 – 15 VDC (0 – 25 A)

Mobility System: 12 – 15 VDC (0 – 25 A)
Interface and Control System
Description: The interface and control system receive information from the user via the user interface, the remote control, and all other external sensors. The microprocessor will process the information to determine the targeting controls, movement instructions, launching signals and parameters, and then distribute the necessary information and instructions to all of the various subsystems.
Inputs:

User Commands: Instructions for operation

Power Source: Electrical power at 3 – 5 VDC (300mA)

External Information: o Current Court Position: Analog Coordinates

Launching System:

M A T T | 11 o Current Horizontal Angle: 0 – 5 VDC (0 – 50 mA) o Current Vertical Angle: 0 – 5 VDC (0 – 50 mA)
Outputs:

Launching System Control Signals o Horizontal Angle: 0 – 5 VDC (0 – 50 mA) o Vertical Angle: 0 – 5 VDC (0 – 50 mA) o Launching Speed: 0 – 5 VDC (0 – 50 mA) o Launch Signal: 0 – 5 VDC (0 – 50 mA)

Mobility Control Signals o Movement Speed: 0 – 5VDC (0 – 50 mA) o Movement Direction: 0 – 5VDC (0 – 50 mA) o Brake Signal: 0 – 5VDC (0 – 50 mA)
Subsystems of Interface and Control System:
User Interface
Description: The user interface will provide a method for the entry of user instructions and will allow the user to determine the effective skill level of the machine. The interface will be easy to understand and use, as well as providing user control over the following factors: target distribution, speed range, height range, and launching rate.
Inputs:

User Commands: Instructions for operation

Power Source: 3 – 5 VDC (0 – 50 mA)
Outputs:

Microprocessor o Target Distribution: Six 16-bit or 32-bit percentage values (Summing to 100%) o Launching Speed Range: Two 16-bit or 32-bit speed values o Height Range: Two 16-bit or 32-bit angle values o Firing Rate: 16-bit or 32-bit frequency o Movement Speed: 16-bit or 32-bit speed values
Remote Control Transmitter
Description: The remote control transmitter is a remote that the player can carry with them to signal
MATT once they are ready for it to start launching the tennis balls. The remote will also be used to signal MATT to stop launching if the machine needs to be turned off quickly.
Inputs:

User Commands: Instructions for operation
Outputs:

Remote Receiver o Start: RF Signal o Stop: RF Signal
Remote Control Receiver
Description: The remote control receiver subsystem receives the signal from the remote control transmitter and translates it to the start or stop instruction for the microprocessor.
Inputs:

Remote Transmitter o Start: RF Signal

M A T T | 12 o Stop: RF Signal

Power Source: 3 – 5 VDC ( 0 – 50 mA)
Outputs:

Microprocessor o Start Signal: 5 V Pulse o Stop Signal: 5 V Pulse
Sensors
Description: The sensor subsystem determines the location of the machine relative to the court, and the current targeting values. It then sends this information to the microprocessor for calculations.
Inputs:

External Information: o Current Court Position: Analog Coordinates

Launching System: o Current Horizontal Angle: 0 – 5 VDC (0 – 50 mA) o Current Vertical Angle: 0 – 5 VDC (0 – 50 mA)

Power Source: 3 – 5 VDC ( 0 – 50 mA)
Outputs:

Microprocessor o Current Court Position: 32-bit coordinate values o Current Horizontal Angle: 16-bit or 32-bit angle values o Current Vertical Angle: 16-bit or 32-bit angle values
Microprocessor
Description: The microprocessor subsystem receives data for the practice specifications, current machine conditions, and remote control signals. The microprocessor then processes the information, making the decisions and calculations necessary to set up next shot and keep the machine from leaving the court. It translates this information into signals to send to the appropriate systems.
Inputs:

Remote Receiver o Start Signal: 5 V Pulse o Stop Signal: 5 V Pulse

User Interface o Target Distribution: Six 16-bit or 32-bit percentage values (Summing to 100%) o Launching Speed Range: Two 16-bit or 32-bit speed values o Height Range: Two 16-bit or 32-bit angle values o Firing Rate: 16-bit or 32-bit frequency o Movement Speed: 16-bit or 32-bit speed values

Sensors o Current Court Position: 32-bit coordinate values o Current Horizontal Angle: 16-bit or 32-bit angle values o Current Vertical Angle: 16-bit or 32-bit angle values

Power Source: 3 – 5 VDC ( 0 – 50 mA)
Outputs:

Launching System Control Signals o Horizontal Angle: 0 – 5 VDC (0 – 50 mA)

M A T T | 13 o Vertical Angle: 0 – 5 VDC (0 – 50 mA) o Launching Speed: 0 – 5 VDC (0 – 50 mA) o Launch Signal: 0 – 5 VDC (0 – 50 mA)

Mobility Control Signals o Movement Speed: 0 – 5VDC (0 – 50 mA) o Movement Direction: 0 – 5VDC (0 – 50 mA) o Brake Signal: 0 – 5VDC (0 – 50 mA)
Launching System
Description: The launching system will consist of a launching mechanism, an aiming mechanism, a tennis ball feeding mechanism, and a motor assembly for each mechanism. The launching mechanism will launch tennis balls at speeds between 4 m/s and 45 m/s, and is likely to be done using counterrotating wheels. The aiming mechanism will consist of both a vertical adjustment and a horizontal adjustment to provide for the specified angle ranges. The feeding mechanism will keep a steady flow of tennis balls to the launcher, depending on the selected setting. This system will be powered from the power source, and controlled via instructions from the microprocessor and motor controllers, based on sensor input information.
Inputs:

Power: 3 - 5VDC at (0 - 25 A)

Launching Control Signals (Digital – from Microprocessor and Motor Controller): o Horizontal Angle Position: 0 – 5 VDC at (0 – 50 mA) o Vertical Angle Position: 0 – 5 VDC at (0 – 50 mA) o Launching Speed: 0 – 5 VDC at (0 – 50 mA) o Launch Signal: 0 – 5 VDC at (0 – 50 mA)

Tennis Ball Feed Rate: Delivery from hopper and feeder system at a rate less than or equal to 1 tennis ball every 2 seconds
Outputs:

Shot Speed: 4 – 45 m/s

Shot Direction: 0° - 50° vertical displacement, 40° - 140° horizontal displacement

Shot Feed Rate: Less than or equal to 1 tennis ball every 2 seconds

Tennis Balls: Wide variety of shots to player
Subsystems of Launching System:
Launching Mechanism
Description: The launching mechanism will provide a means of launching the tennis ball from MATT at variable speeds. The launching mechanism will most likely consist of counter-rotating wheels, attached to a single chain and a single motor, allowing both of the wheels to rotate at the same speed.
Inputs:

Power Source: 3 - 5VDC at (0 - 25 A)

Launching Control Signals (Digital – from Microprocessor and Motor Controller): o Launching Speed: 0 – 5 VDC at (0 – 50 mA) o Launch Signal: 0 – 5 VDC at (0 – 50 mA)

M A T T | 14
Outputs:

Tennis Balls: Launched at speeds ranging from 4 m/s to 45 m/s

Current Conditions: o Launching Speed: 16-bit or 32-bit speed values
Targeting System
Description: The targeting system will control the aiming of the tennis ball launching mechanism.
This system will consist of two major components, the horizontal angle adjustment mechanism and the vertical angle adjustment mechanism. The horizontal angle adjustment will provide horizontal angles from 40° to 140°, and the vertical angle adjustment will provide vertical angles from 0° - 50°.
Both of these aiming mechanisms will be powered by their own motor assembly.
Inputs:

Power Source: 3 - 5VDC at (0 - 25 A)

Launching Control Signals (Digital – from Microprocessor and Motor Controller): o Horizontal Angle Position: 0 – 5 VDC at (0 – 50 mA) o Vertical Angle Position: 0 – 5 VDC at (0 – 50 mA)
Outputs:

Tennis Balls: Launched at speeds ranging from 4 m/s to 45 m/s

Current Conditions: o Current Horizontal Angle: 16-bit or 32-bit angle values o Current Vertical Angle: 16-bit or 32-bit angle values
Hopper and Feeder System
Description: The hopper will store at least 150 tennis balls in the machine when loaded to capacity.
The hopper will be designed to prevent the tennis balls from spilling out during motion of the machine. The feeder will supply a steady flow of tennis balls to the launching mechanism as long as there are still tennis balls in the hopper. The feed rate will be adjustable and determined by the microprocessor and motor controller based on movement, launching, and user inputs.
Inputs:

Power Source: 3 - 5VDC at (0 - 25 A)

Tennis Ball Feed Rate (Microprocessor and Motor Controller Signals): Delivery from hopper and feeder system at a rate less than or equal to 1 tennis ball every 2 seconds
Outputs:

Tennis Balls: Launched at speeds ranging from 4 m/s to 45 m/s

Shot Feed Rate: Less than or equal to 1 tennis ball every 2 seconds
Mobility System
Description: The mobility system will consist of a motor assembly that will power wheels, and therefore allowing the lateral movement of the device, generally parallel to the net. The machine will be able to traverse the court in a maximum of 20 seconds. The machine will have a brake system, which will be able to slow or stop the machine when a command to do so is provided by the microprocessor automatically, depending on sensor inputs, or by the user via the remote control. Most likely the braking will be performed by the motor controller, without having an actual mechanical brake system. The entire system will be powered from the power source, and controlled via instructions from the microprocessor using motor controllers. The mobility system will also have an encasement to prevent

M A T T | 15 tennis balls from causing damage or prohibiting proper operation of the machine.
Inputs:

Power Source: 12 -15 VDC at (0 - 25 A)

Mobility Control Signals (Digital – From Microprocessor and Motor Controller): o Movement Speed: 0 – 5 VDC at (0 – 50 mA) o Movement Direction: 0 – 5 VDC at (0 – 50 mA) o Brake Signal: 0 – 5 VDC at (0 – 50 mA)
Outputs:

Lateral Motion (Parallel to the net): 0.55 – 2.2 m/s
Subsystems of Mobility System:
Drive System
Description: The drive system of the mobility system will consist of a motor assembly, driving the wheels of the machine. The motor assembly will have a torque reducing gearing system to reduce the size of the motor required to move the machine under the worst case scenario, which would be at a maximum mass of 70 kg. The motor assembly will most likely consist of two separate motors that can be controlled individually by the motor controllers, to adjust the movement direction of the machine if necessary.
Inputs:

Power Source: 12 -15 VDC at (0 - 25 A)

Mobility Control Signals o Movement Speed: 0 – 5VDC (0 – 50 mA) o Movement Direction: 0 – 5VDC (0 – 50 mA)
Outputs:

Lateral Motion (Parallel to the net): 0.55 – 2.2 m/s
Braking System
Description: The braking system will be system to brake and slow the machine automatically on command. The braking system will most likely be controlled electronically by reversing or slowing the drive motors.
Inputs:

Power Source: 12 -15 VDC at (0 - 25 A)

Mobility Control Signals o Brake Signal: 0 – 5 VDC at (0 – 50 mA)
Outputs:

The machine can stop itself once in motion

M A T T | 16
Designs and Justifications
Mobility System
The mobility system is the system that will make MATT a unique product. Though there will be nothing revolutionary about the design of the mobility system itself, the concept of a moving tennis ball machine is new and innovative. The design team has looked through many different patents and resources and has not yet found another tennis ball launching machine that moves to provide variability of shot origin to the player. Some preliminary calculations were performed to find a minimum torque value that would need to be provided by the motors to move the machine at the speed specified. To do this the machine was a assumed to have a mass of 70 kg, which is just above the maximum specified mass of the machine with the addition of the mass of at least 150 tennis balls. This value was used as an upper range for the amount of torque that would be required. From this information the maximum torque was determined to be approximately 55 N·m. As this is a very high torque value for electric motors, it has been determined by the design team that a torque reduction gearing or chain system will be required so that the power and cost of the necessary motors can be greatly reduced.
Hopper and Feeder System
The hopper and feeder system of MATT will store the required minimum of 150 tennis balls, while ensuring that they are not spilled during machine movement, as well as ensuring that tennis balls are fed to the launching system at a constant feed rate. The most likely design concept for this subsystem is a rather simple one. Essentially there will be a rotor in the bottom of the hopper that will rotate at a constant rate and feed balls into a tube or chute. The feed rate of the rotor will be adjusted by the microprocessor and motor controllers, depending upon user inputs, machine movement, and launching signals. The tube or chute will operate entirely by a gravity feed system where once the tennis balls are in it, they will move directly to the launching system, only under the influence of gravity, where they will automatically launch.
Launching System
The launching system will consists of two vertical wheels, a motor, and an idler pulley all fixed in a platform. These components are linked by means of chains or belts. Calculations were performed for motor specifications, which to launch a tennis ball at 45 m/s, our maximum shot speed, the required angular speed on 7.62 cm (6 in) wheels was found to be approximately 5700 rpm, and a torque of approximately 26 mN·m. The motor will then need approximately a 0.021 hp to launch tennis balls every two seconds. The launching system is illustrated in Fig. 1.

M A T T | 17
Figure 1: Launching system
Power System
A variety of different methods were discussed for the power system and supply method for
MATT. The best options were assembled into a decision matrix to allow aid in selecting the best method.
The actual decision matrix for the power system is shown below in Table 1. Each category was assigned a weighting percentage, and then each criterion for potential methods was rated on a three point rating system and multiplied by the weight. The votes were 1 being good, 5 being better and 9 being best.
Table 1: Decision Matrix for Power System Selection
Criterion
Longevity
Weight/Size
Cost
Ease of Use
Limitations
Power
Efficiency
Safety
Implementation
Difficulty
Totals:
Batteries
Weight Vote
15 1
10
15
9
5
10
15
10
9
9
9
10
15
100
9
9
AC Power
Weight Vote
15 9
90
75
9
9
90
135
90
5
5
5
90
135
5
1
50
15
Gasoline Engine
Weight Vote
135 5
90
135
1
1
50
75
50
5
5
5
1
1
10
15
Solar Panel
Weight Vote
75 5
10
15
1
1
50
75
50
9
1
1
1
5
Weight
75
10
15
90
15
10
10
75
Standard Weighted Standard Weighted Standard Weighted Standard Weighted
60 720 48 600 24 300 24 300

M A T T | 18
As can be seen in Table 1, the option with the best resultant score was a battery power system.
The team opted to pursue this method unless the power requirements of the mechanical components for some reason require much more than batteries could supply. The expected voltage requirements based on preliminary torque calculations and product research is between 12 VDC and 15 VDC.
Currently, the team plans to provide this voltage with one or two 12 VDC batteries.
Horizontal Angle Adjustment
The horizontal angle range was specified to be between 40° and 140°, measured from a line parallel to the net on the tennis court and rotating counter clockwise. The widest horizontal angle range of similar products on the market was a total of 50°, with the range being from 65° to 115°. The wider horizontal angle range for MATT was needed because, unlike other tennis ball launching machines,
MATT will move laterally on the court; therefore it will need a much larger range of horizontal angles to provide a comparable set of angles from varying launch positions. The operating range of the machine was determined mainly based upon the horizontal angles required. The determined operating range can be seen in Fig. 2.
12.0 ± 0.5
10.0 ± 0.5
6.0 ± 0.5 m
Figure 2: Operating range of MATT in regards to the tennis court.
The widest range of horizontal angles required was calculated based on this operating range and the worst case scenario for shot placement. This worst case scenario would be when the machine was as close to the net as allowed, as far as possible from the center of the court and placing the shot on the opposite sideline directly behind the net. From this information, the maximum angle needed was calculated. Figure 3 shows the dimensions used to calculate the maximum angle of 50°.

M A T T | 19
Figure 3: Dimensions for horizontal angle calculations
A few different design concepts have been considered to provide the mechanical horizontal angle adjustment. The main methods have consisted of some sort of lever system, or a rotating platform on which the launching system would rest. The lever system would be implemented with either pneumatic or hydraulic pistons or actuators, which would require a large expensive component such as an air compressor or a hydraulic pump. Due to the simplicity of the design, the rotating platform for the launching system was selected. A motor would rotate the platform through the required angular displacement. A rough diagram of this system design is shown in Fig. 4.
Launching Mechanism
Rotating Platform
Horizontal Adjustment Motor
Figure 4: Horizontal angle adjustment design concept drawing
Vertical Angle Adjustment
The vertical angle range was defined to be between 0° and 50°, measured from an axis parallel to the surface of the tennis court. Three major designs were analyzed for vertical aiming. The first one

M A T T | 20 consists of a platform that holds the launching system, which is hinged at the launching system center of mass to another platform that has a rack and pinion system attached to it. The first design is illustrated in Fig. 5. This design was considered simpler, although it has a major problem, a high cost for the rack, which needs to be relatively large and have high yield strength. The average cost of the rack and pinion system was $100 for steel. Preliminary calculations were performed to predict the torque needed in motor 3 to raise and keep platform 1 in place, although they are meaningless since the rack does not fit our budget.
Rotating
Wheels
Motor 1
1111
Platform 1
Idler Pulley
Platform 2
Motor 3
Motor 2
Rack
Pinion
Figure 5: Rack and pinion aiming system design
The second design consists of a motor pulling a sprocket pivoted at the center of the bottom rotating wheel, which is connected to the top wheel by a shaft. The vertical aiming changes as the top wheel rotates about the bottom wheel. The major problem with this design is that it has many moving parts, which basically makes it harder to build, and easier to break. As of now, no calculations have been performed for this design. An illustration for this rotating shaft aiming system design is shown in Fig. 6, and was considered better than the first one mainly because it is affordable, even though it is more complex.

M A T T | 21
Rotating
Wheels
Idler Pulley Shaft
Sprocket
Motor 1
Platform
Motor 3
Motor 2
Figure 6: Rotating shaft aiming system design
The third design, shown in Fig. 7, is similar to the first one, with the exception of having a fourbar linkage system instead of a rack and pinion. Shafts 1 and 2 are hinged at platforms 2 and 1 respectively, and are themselves hinged. Motor 3 rotates shaft 1 by means of a sprocket, which consequently rotates shaft 2, making platform 1 go up and down. This idea was just proposed, so no calculations have been performed yet, although it appeals to be our best design since it is cheaper than the rack and pinion, and simpler than the rotating shaft.
Rotating
Wheels
Motor 1
Platform 1
Platform 2
Motor 2
Idler Pulley
Shaft 1
Sprocket
Figure 7: Four-bar linkage aiming system design
Shaft 2
Motor 3

M A T T | 22
User Interface
Several concepts for user controls and user interface options were discussed and placed in a decision matrix to aid in selection. The process was the same as that described in the power system section. The decision matrix for the user interface is shown in Table 2.
Table 2: Decision Matrix for User Interface
Criterion Difficulty Setting Keypad Input Scanner/USB Balance Dial
Weight Vote
Ease of Use 0.25 9
Flexibility 0.25
Cost to Make 0.25
Ease of
Construction
0.25
Totals: 1
1
9
9
Standard
28
Weight
2.25
0.25
2.25
2.25
Weighted
7
Vote
5
9
1
5
Standard
20
Weight
1.25
2.25
0.25
1.25
Weighted
5
Vote
1
9
5
5
Standard
20
Weight
0.25
2.25
1.25
1.25
Weighted
5
Vote
9
5
9
9
Standard
32
Weight
2.25
1.25
2.25
2.25
Weighted
8
The two prevailing design concepts for the user interface controls were the balanced dial method which would consist of adjustable ranges for launch parameters, such as speed, height, width, and shot rate. The difficulty setting method would consist of a variety of preset difficulty settings on the user interface. The user would be able to select a preset value and start the machine using those programmed settings. The design team opted to use a combination of preset difficulty settings and the customizable balance dials to provide the functionality desired. It was determined by the computer engineer that the integration of both systems would be plausible.
Criterion
Name
Ease of Setup
Accuracy
Portability
Price
Power
Court Positioning Sensor System
The sensor court positioning system is a component that is crucial to the accurate operation of
MATT. Many different court positioning systems have been considered, and the decision matrix in Table
3 outlines the most plausible options considered by the design team.
Table 3: Court Positioning Sensor System
Laser Cross
Triangulation
Weight Vote
10 1
25
10
15
10
9
5
5
5
Patterned Tape
Weight Vote
10 5
225
50
75
50
5
9
5
9
Line Following with
Accelerometer
Weight Vote
50 9
125
90
75
90
5
9
5
9
Weight
90
125
90
75
90
Track System
Vote
5
5
1
5
9
Weight
50
125
10
75
90

M A T T | 23
Ease of
Design/Construction and impact on other systems
Flexible Court
Placement
Totals :
20
10
100
1
9
20
90
5
9
100
90
5
5
100
50
9
9
180
90
Standard Weighted Standard Weighted Standard Weighted Standard Weighted
35 520 47 620 47 620 43 620
As noted in Table 3, three of the top four ideas presented came out essentially equal when the votes were tallied. After much deliberation, the track system was eliminated, because such a system would be extremely inconvenient from a portability standpoint. The team opted to select a combination of a line following system and some sort of patterned tape that the machine would read and gather information needed for proper operation. The idea behind this system would be some sort of sensor array system that would follow the white baseline on the tennis court and allow adjustment if it got off track. The patterned tape would be placed on or near the baseline and provide position information such as the approximate location of the machine on the tennis court. This method should allow for accurate court positioning as well as consistent operation of the machine.

M A T T | 24
MATT’s design team consists of two mechanical engineering students, two electrical engineering students, and one computer engineering student. Design tasks and project management responsibilities will be distributed equally among the team members. Each team member will be in charge of a major subsystem of the device, with two other team members supporting him. There will be one project manager over the entire project.

Mark Moore (Mechanical Engineer) o Mark is the project manager and is responsible for organizing the activities and tasks of the design team. He will ensure that the required documents, design work, and presentations will be completed on schedule. He will also be the primary engineer responsible for the design and construction of the mobility system and the ball feeding mechanism. He will be a secondary engineer for the both the launching system design, and the power source design.

Michael Gorman (Computer Engineer) o Michael is the primary engineer responsible for the design and construction of the microprocessor, the programming, and the user interface of MATT. He will also be a secondary engineer for both the mobility system and the control and sensor systems.

Ivan Michelli (Mechanical Engineer) o Ivan is the primary engineer responsible for the design and construction of the tennis ball launching system. He will also be a secondary engineer for both the mobility system and the control and sensor systems.

Prosper Majyambere (Electrical Engineer) o Prosper is the primary engineer responsible for the design and construction of the power source for the entire machine. He will also be a secondary engineer for both the microprocessor and interface system and the launching system.

Trevor Pringle (Electrical Engineer) o Trevor is the primary engineer responsible for the design and construction of the control and sensor systems on MATT. This system will consist of the all motor controls, any positioning or data input sensors, and the remote control. He will also be a secondary engineer for both the microprocessor and interface system, and the power source system.
Each of the team members will ultimately be responsible for the task, of which he is the primary engineer. Each team member will also be expected to be familiar with all other systems on the machine, keeping in mind the total integration of all these systems in the final product at all phases in the design process. It is also important to note that though each major subsystem has a primary engineer and two secondary support engineers, the work done on each subsystem is not limited to these three team members.

M A T T | 25
Task ID Task Name Description Deliverables
F 1.0 Project Management Ensure that the project team is on schedule and meets
F 2.0 Documentation budget constraints
Records of all documents, tests,
F 3.0 Project Selection calculations, design work, etc.
Project ideas discussed and actual project selected
F 4.0 Project Specification Technical requirements and
Budget statements, schedule
Design reports, schematic, flow-charts, models, etc.
Verbal confirmation of project idea
Project Launch
Document
F M.1
Review
F 5.0 System Design &
F M.2
F 6.0
F 6.1.2
F 6.1.3
F 6.1.4
F 6.2
F 6.2.1
Project Launch
Project Plan
Preliminary Design
Review
Component Design
Power Distribution &
Regulation
Low Voltage
Indicator
Power Switch
Control & Interface
Design
Microprocessor design criteria specified
Project Launch
Review presentation
Design concepts selected, preliminary calculations and analysis performed, project plan constructed work assignments given
Preliminary Design
Review presentation
Detailed design of individual subsystems and components
F 6.1 Power Source Design Design of the power
F 6.1.1 Power Source
Selection source
Power source design and specific
Project Launch
Presentation
Preliminary System
Design & Project Plan
Document
Preliminary Design
Presentation
Schematics of each subsystem, part specifications, test and calculation results and analysis
Schematics, MultiSim models
Schematics, MultiSim models components selected
Power regulation and design of distribution for various subsystems
Low voltage indicator for power source
Schematics, MultiSim models
Controller and system interface designs
Schematics, MultiSim models warnings
Power switch design Schematics, MultiSim models
Microprocessor schematics, datasheets, code, LabView interfaces
Microprocessor and Datasheets
Duration Engineer(s)*
Aug. 25 th –
Dec. 8 th
M
Aug. 25 th –
Dec. 8 th
Aug. 25 th –
Sep. 6 th
Sep. 6 th
Sep. 27
Sep. 24
Oct. 13
Oct. 17 th
Nov. 17
Oct. 17
Nov. 11
Oct. 24
Oct. 26
Nov. 9
Oct. 24
Oct. 26
Oct. 17
– th th th th th th th
Oct. 19
Oct. 13 th
Nov. 11 th
– th
–
– th
– th
– th
–
– th
Sep. 27 th –
Oct. 13 th
Oct. 13
Oct. 13 th th th
–
I,M,Mi,P,T
I,M,Mi,P,T
I,M,Mi,P,T
I,M,Mi,P,T
I,M,Mi,P,T
I,M,Mi,P,T
I,M,Mi,P,T
M,P,T
P
M,P,T
T
P
Mi,P,T
Mi

Selection
F 6.2.2 Microprocessor
Interface required circuitry selected
Microprocessor interface with subsystems designed
F 6.2.3 Programming Outline Programming structure outlined and developed
F 6.2.4 Initial Programming Initial programming, simulations of how
F 6.2.5 Remote Control
Transmitter machine will behave
Remote control transmitter design and schematics
F 6.2.6 Remote Control
Receiver
F 6.2.7 User Interface
Remote control receiver design and schematics
Design of user interface controls and programming
F 6.2.8 Sensor Systems
F 6.2.9
F 6.3
F 6.3.1
Motor Control
Interfaces
Launching System
Design
Launching
Mechanism
Sensor system designs for each input and controller
Design motor controller system for various subsystems
Design method of launching tennis balls, consistently according to the requirements
Launching mechanism method and controller, and ball
F 6.3.2
F 6.3.3
F 6.3.4
Targeting System
Hopper Design
Feeder Mechanism feeding mechanism, major components selected
Design of both horizontal and vertical aiming mechanisms, major components selected
Design of hopper size and shape to work with overall design, and feeder mechanism
Design of mechanism to feed tennis balls from hopper to launcher
F 6.3.5 Launching Controller Design controller interface for entire
Schematics, code, flow charts
Outline and/or flow charts of programming concepts
Code printouts, simulation results
Schematics, datasheets
Schematics, datasheets
Schematics, MultiSim,
LabView, input controls
Sensor datasheets, schematics, MultiSim,
LabView
Schematics,
Schematics, SolidWorks models
Schematics, SolidWorks models, datasheets
Schematics, SolidWorks models, datasheets
SolidWorks models, miscellaneous diagrams
SolidWorks models, diagrams, and schematics
Schematics, datasheets
Oct. 13 th –
Oct. 25 th
Oct. 13 th –
Oct. 30 th
Oct. 25 th –
Nov. 2 nd
Nov. 2 nd –
Nov. 11 th
Oct. 30 th –
Nov. 17 th
Oct. 18 th
Oct. 18 th –
Nov. 2 nd
Oct. 13 th –
Oct. 17 th
Oct. 18 th –
Oct. 28 th
Oct. 20 th –
Oct. 23 rd
Oct. 23 rd –
Oct. 27 th
Oct. 18 th –
Nov. 2 nd
Oct. 21 st –
Nov. 6 th
Oct. 24 th –
Nov. 11 th
Oct. 13 th –
Nov. 17 th
M A T T | 26
Mi,P,T
Mi,P,T
Mi
T
T
Mi
Mi,P,T
I,Mi,T
I,M,P
I,M
I,M
M
I,M
I,M,P

F 6.4 Mobility System
Design
F 6.4.1 Drive System
F 6.4.2 Braking System
F 6.4.3 Mobility Controller
F 7.0 System Design &
Analysis
F 8.0 Final Design
F M.3 Interim Design
Review launching system
Design system to move the entire machine consistently
Power source, motor system and gearing to drive the machine
System to brake the moving machine
Interface to control mobility instructions
Final system and subsystem design, calculations, models, and testing
Final detailed system and subsystem design
Interim Design
Review presentation
SolidWorks models, schematics
SolidWorks models, schematics
SolidWorks models, schematics
SolidWorks models, schematics, MultiSim models
Preliminary Interim
Design Document, test results, MultiSim,
LabView, SolidWorks schematics and drawings
Interim Design
Document
Interim Design Review
Presentation
Oct. 13 th –
Nov. 7th
Oct. 13 th –
Oct. 23 rd
Oct. 18 th –
Oct. 28 th
Oct. 28 th –
Nov. 7th
Nov. 17 th –
Nov. 27th
Nov. 27 th –
Dec. 7th
Dec. 8 th
*I = Ivan, M = Mark, Mi = Michael, P = Prosper, T = Trevor
M A T T | 27
I,M,Mi
I,M
I,M
Mi
I,M,Mi,P,T
I,M,Mi,P,T
I,M,Mi,P,T

M A T T | 28
Task ID Task Name Description Deliverables
S 1.0 Project Management Ensure that the project team is on schedule and meets
S 2.0
S 3.0
Documentation
Component Build budget constraints
Records of all documents, tests, design work, etc.
Complete assembly of subsystems
S 3.1
S 3.1.1
Power System Build
Power Source
Implementation and testing of the power subsystems
Test the power capabilities of the power source
Budget Statements, schedule
Design reports, schematics, flow-charts
Subsystems are built as designed
Working subsystem that provides the correct voltage and current values
Functioning Power
Source that meets or exceeds necessary power ratings
Working prototype of the low voltage indication system
S 3.1.2 Low Voltage Indicator Build the low voltage
S 3.1.3 Power Distribution &
Regulation indication system on a breadboard and test the precision of the system
Assemble the power regulation
S 3.1.4 Power Switch components on a breadboard and test power distribution methods at maximum power ratings
Test the power switch at the system's
S 3.1.5
S 3.1.6
PCB Design of Power
System
PCB Build of Power
System maximum power ratings
Design the PCB for the power system components
Populate the power system PCB and test the subsystems
Working prototype of regulation system and distribution methods
Suitable primary power switch for the overall system
Accurate PCB design of the power system
Functioning PCB of power system components, Test Data
S 3.2 Control and Interface
Build
S 3.2.1 User Interface
Components
Implementation and testing of the control and interface subsystems
Assemble and connect the user interface components on a breadboard
Working control and interface subsystems
Functioning user interface system on a breadboard
Duration Engineer(s)*
Jan. 9 th –
Apr. 29 th
M
Jan. 9 th –
Apr. 29 th
Jan. 9 th –
Mar. 1 st
Jan. 9 th –
Feb. 24 th
Jan. 9 th –
Jan. 19 th
Jan. 20 th –
Jan. 25 th
Jan. 20 th –
Jan. 30 th
Feb. 5 th –
Feb. 14 th
Feb. 17 th –
Feb. 24 th
Jan. 9 th –
Feb. 15 th
Jan. 9 th –
Jan. 17 th
I,M,Mi,P,T
I,M,Mi,P,T
M,P,T
P
T
P
Jan. 31 st –
Feb. 4 th
P
P
P
Mi,P,T
Mi,P

M A T T | 29
S 3.2.2
S 3.2.3
S 3.2.4
S 3.2.5
S 3.2.6
S 3.2.7
S 3.2.8
S 3.2.9
S 3.2.10
Microprocessor and
User Interface
Integration
Motor Controllers
Microprocessor and
Motor Controller
Integration
Sensor Systems
Microprocessor and
Sensor System
Integration
Remote Control
Transmitter
Remote Control
Receiver
Remote Control
Operation
Microprocessor and
Remote Control
Receiver Integration
S 3.2.11 PCB Design of Control and Interface System
S 3.2.12
S 3.3
S 3.3.1
PCB Design of
Remote Control
Transmitter
Launching System
Build
Launching
Mechanism
Program the
Microprocessor to interact with the user interface
Build and test the launching mechanism
Functional programmed microprocessor and user interface interaction on a breadboard
Functioning control of motors, Test Data
Assemble and test the motor controllers on a breadboard
Program the
Microprocessor to interact with the motor controllers
Functional programmed microprocessor and motor controller interaction on a breadboard
Functioning sensor system, Test Data
Assemble and test the sensor systems on a breadboard
Program the
Microprocessor to interact with the sensor systems
Assemble and test the remote control transmitter system on a breadboard
Assemble the test remote control receiver system on a breadboard
Test the remote control transmit and receive systems
Program the
Microprocessor to interact with receiver of the remote control
Design the PCB for the control and interface system
Design the PCB for the Remote Control
Transmitter System and populate the PCB
Assemble and test the launching system
Functional programmed microprocessor and sensor interaction on a breadboard
Properly configured remote control transmitter system,
Test Data
Properly configured remote control receiver system, Test Data
Functioning remote control system, Test
Data
Functional programmed microprocessor and remote control receiver interaction on a breadboard
Accurate PCB design of the control and interface system
Accurate PCB design of the remote control transmitter
Functioning launching system assembly, Test
Data
Working launching mechanism, Test Data
Jan. 18 th –
Jan. 27 th
Jan. 9 th –
Jan. 19 th
Jan. 20 th –
Feb. 19 th
Jan. 16 th –
Jan. 24 th
Jan. 25 th –
Feb. 3 rd
Jan. 9 th –
Jan. 16 th
Jan. 9 th –
Jan. 16 th
Jan. 16 th –
Jan. 22 nd
Jan. 28 th –
Feb. 5 th
Jan. 22 nd –
Jan. 28 th
Feb. 6 th –
Feb. 15 th
Jan. 9 th –
Mar. 1 st
Jan. 9 th –
Jan. 27 th
Mi
T
Mi
T
Mi
T
T
T
Mi
Mi,P,T
T
I,M,P,T
I,M

S 3.3.2 Hopper System Build and test the hopper and feeding mechanism
S 3.3.3 Targeting System Build and test the horizontal and vertical components of the launching system
Mount the sensors to S 3.3.4 Sensor Integration the launching system and calibrate if necessary
S 3.3.5 Launching Controller Interface the motor
S 3.3.6 Launching System
Operation controller for the launching system to the motors
Test the launching system to confirm that it will meet required specifications and modify the system if necessary
S 3.4 Mobility System Build Assemble and test the mobility system
S 3.4.1 Drive System Build and test the drive system
S 3.4.2
S 3.4.3
S 3.4.4
Braking System
Sensor Integration
Mobility Controller
Test the braking method and provide alternative braking methods if necessary
Mount the sensors to the mobility system and calibrate if necessary
Interface the motor controller for the mobility system to the motors
S 3.4.5 Mobility System
Operation
Test the mobility system to confirm that it will meet required specifications and modify the system if necessary
S M.1 Final Design Review Present the final design to the faculty
Hopper that can hold required tennis balls and a functioning feeding mechanism,
Test Data
Working horizontal and vertical components of the launching system,
Test Data
Functioning launching system sensors, Test
Data
Functioning control of launching system motors, Test Data
Functioning launching system, Test Data
Functioning mobility system, Test Data
Working drive system,
Test Data
Working braking method, Test Data
Functioning mobility sensors, Test Data
Functioning control of mobility system motors,
Test Data
Functioning mobility system, Test Data
Presentation, demonstration of functioning subsystems
Jan. 13 th –
Jan. 28 th
Jan. 16 th –
Feb. 3 rd
Jan. 28 th –
Feb. 3 rd
Feb. 3 rd –
Feb. 21 st
Feb. 21 st –
Mar. 1 st
Jan. 9 th –
Feb. 24 th
Jan. 9 th –
Jan. 31 st
Jan. 31 st –
Feb. 5 th
Jan.22
nd –
Feb. 1 st
Feb. 3 rd –
Feb. 12 th
Feb. 13 th –
Feb. 24 th
Mar. 1 st
M A T T | 30
I,M
I,M
P,T
P,T
I,M,P
I,M,Mi,T
I,M
I,M,T
Mi, T
Mi,T
I,M,Mi
I,M,Mi,P,T

M A T T | 31
S 4.0 System Integration
S 5.0 Encasement
S 6.0 System Testing
S M.2 Acceptance Tests
Complete
S 7.0 User's Manual
S 8.0 Product Readiness
Report
S M.3 Product Readiness
Review
S M.4 Engineering
Showcase
Integrate the subsystems together
Construct encasement with any necessary modifications to meet acceptance tests
Ensure that the device is able to complete the required specifications and modify the system if necessary
Complete testing of system
Instructions to the user on how to operate the product
Final detailed report of the product's functionality
Present product to faculty
Functioning system
Protective encasement attached to the device
Functioning system that meets required specifications
Document
Document
Presentation and demonstration of functioning system
Mar. 1
Apr. 6 th
Apr. 9
Apr. 24
Apr. 2
Apr. 26
Apr. 26 st
Mar. 20
Mar. 4
Mar. 17
Mar. 20 th th nd th th
– th th th
Fully functional device Apr. 19 th
– th
–
–
–
Public product presentation
Complete functioning system
Apr. 27 th
*I = Ivan, M = Mark, Mi = Michael, P = Prosper, T = Trevor
I,M,Mi,P,T
I,M
I,M,Mi,P,T
I,M,Mi,P,T
I,M,Mi,P,T
I,M,Mi,P,T
I,M,Mi,P,T
I,M,Mi,P,T

M A T T | 32
Item References
Launching System
Launching Motor
Motor Controller
Horizontal Motor
Motor Controller
Vertical Motor
Motor Controller
Hopper Motor www.banebots.com
Half H-Bridge High Current www.jameco.com
Low Current Motor Controller www.banebots.com
Full H-Bridge High Current www.jameco.com
Motor Controller Low Current Motor Controller
Launching Wheels www.robotmarketplace.com
Sprockets
Mobility System
Casters www.mcmaster.com
Wheels with sprockets
Motor www.banebots.com
Motor 64:1 Gearbox www.banebots.com
Motor Controller
Sensor System
Full H-Bridge High Current
Phototransistor
LED IR Emitter
Potentiometer
Quadrature Encoder www.search.digikey.com www.search.digikey.com
Accelerometer www.parts.digikey.com
User Interface System
Knob
Potentiometer
Button
LED Indicator
Remote Control
Components
Microprocessor
System
Microprocessor
Printed Circuit Board www.4pcb.com
Power Supply System
Power Source
Price
$12.75
$15.17
$6.25
$10.00
$28.00
$24.90
$23.95
$6.25
$32.00
$20.00
$14.95
$47.00
Quantity
2
2
1
1
1
1
2
6
1
1
1
1
Quantity
From Lab
0
0
1
0
1
1
0
0
1
1
0
2
Extended
Price
$12.75
$15.17
$0.00
$0.00
$0.00
$24.90
$0.00
$0.00
$64.00
$120.00
$29.90
$0.00
$7.25
$52.89
$24.90
$0.345
$0.398
$0.65
$3.00
$39.56
$2.34
$0.65
$0.50
$0.09
$17.00
$10.00
$33.00
$139.95
10
10
2
6
1
2
2
2
5
5
5
10
1
1
1
1
0
0
0
0
1
2
0
1
0
0
0
0
0
0
0
0
$7.25
$0.00
$49.80
$3.45
$3.98
$1.30
$18.00
$0.00
$11.70
$3.25
$2.50
$0.90
$17.00
$10.00
$33.00
$139.95

M A T T | 33
Power Regulators
Low Voltage
Indicator
Encasement
Plywood
Amount Remaining for Miscellaneous
Charges, Shipping, and Tax
Percent of Budget Set
Aside www.lowes.com
$400.49
38.88%
$0.71
$2.00
2
1
2
0
$0.00
$2.00
$19.57 3 0 $58.71
Total: $629.51
Percentage of
Budget:
61.12%
Total Excluding Free
Parts:
$951.97

M A T T | 34

M A T T | 35

M A T T | 36

M A T T | 37

M A T T | 38

M A T T | 39

M A T T | 40

M A T T | 41

MATT – MOBILE AUTOMATIC TENNIS TRAINER
M A T T | 42
September 27, 2011
Michael Gorman
Prosper Majyambere
Ivan Michelli
Mark Moore
Trevor Pringle

M A T T | 43
Overview
There is a wide range of products currently available on the market to help tennis players improve their skills or to provide an enjoyable practice session. One such product is the tennis ball launching machine, of which many different types and variations are available, each with its own advantages and disadvantages. The main problem with such tennis ball machines is the fact that they are stationary. With a stationary platform, the tennis balls are shot to the player from the same location every time, decreasing the realism of the practice session. In a game or match, the shots would be hit to the player from a variety of different locations and angles on the tennis court. The goal of the Mobile Automatic Tennis Trainer (MATT) is to provide a competitive alternative to the standard stationary tennis ball machine design. MATT will add a new element to the tennis ball machine market by being the first tennis ball machine that moves itself. The machine will change its position on the tennis court, therefore providing a wider variety of shots to the player. MATT will also include many of the same features that the typical tennis ball machines exhibit. MATT will provide a more realistic training experience than a stationary tennis ball machine, while having a cost that is competitive with similar products.
Customer Needs
Several tennis players and their coaches were interviewed to determine what features are most desired or needed in a tennis ball machine. They all stated that they wanted a tennis ball machine that would behave more like a real opponent. A tennis player moves on the court and provides a wide variety of speeds and directions on shots to their opponent. The most desired features by these potential customers were variability of shot origin (the shot does not come from the same position every time), speed, angle, and height on the tennis ball. A large tennis ball capacity, a remote control, and a high percentage of shots landing within the court boundaries were also stated as customer needs. Customer needs determined by the design team were safety, ease of use, and randomization of shots. These needs were translated into seven concise customer need statements, shown here:
1.
The machine itself can move and provide shots from varying locations.
2.
The machine can vary speed and direction of shots.
3.
The machine can launch a high percentage of shots over the net and within bounds.
4.
The machine can be easily operated by either the player or coach.
5.
The machine can operate for a reasonable period of time without damage or resetting.
6.
The machine is safe.
7.
The machine is portable.
Each of these needs was broken down into sub-categories that were related to the actual technical specifications. The needs-metrics matrix shown in Fig. 1 in Appendix A shows these relationships.

M A T T | 44
Technical Requirements Specification

Mobility o The machine will be programmed to move itself laterally and remain within 6.0 ±
0.5 meters from the center of the court at all times. This range of lateral movement will cover the entire width of the doubles lines on the tennis court. The machine will be able to operate anywhere from 10.0 ± 0.5 meters to 12.0 ± 0.5 meters from the net, with the motion of the machine intended to be parallel with the net. This range of motion can be seen in Appendix C.

Diversity o The machine will launch tennis balls at an initial speed between 4 and 45 meters per second. It will launch tennis balls at vertical angles between 0º and 50º, and horizontal angles with a range from 40º to 140º. (The horizontal angles will be measured from a line parallel to the net, where rotating counter-clockwise yields positive angles.) The maximum time the machine takes to adjust its aim through the widest range of horizontal or vertical angles is 3.0 ± 1.0 seconds. The machine will travel the entire width of the court in less than 20.0 ± 1.0 seconds.
Randomization of shots will be provided within user set limits, meaning that the amount of randomization will be related to what difficulty setting the user chooses.

Precision o At least 90% of the tennis balls launched will go over the net and land within the tennis court boundaries, with the constraint that wind speeds are no greater than 5 meters per second. The tennis court will be divided into a grid of six sections for

Safety testing purposes as seen in Fig. 2 in Appendix B.
o The majority of moving parts of the machine will be in an encasement to protect against user injury. Moving parts such as the launch mechanism and the ball feeder may not be completely enclosed and warnings about such hazards will be posted on the machine. All electrical components will be properly covered and insulated to prevent electrocution.

Durability o The machine will be constructed to withstand tennis ball strikes without damage.
The encasement will protect tennis balls from getting under the machine and prohibiting proper operation. The machine will also resist light rain for at least 3 minutes.

Ease of Use o Machine controls will be readable and accessible to, but not limited to, a standing user. Operational instructions will be labeled clearly on the machine. The machine can be started and stopped remotely from up to 30 meters away.

M A T T | 45

Operational Time o The machine will operate continuously for at least 60 minutes, with the constraint that a constant supply of tennis balls is provided. The maximum storage capacity of the machine will be a minimum of 150 tennis balls. The machine will have a maximum ball feed of one tennis ball per 2 seconds. With this ball capacity and feed rate, the machine will be able continuously launch tennis balls for approximately 5 minutes before it must be refilled. Also, the machine will still operate with as few as one tennis ball in the hopper.

Portability o The machine will weigh less than 60 kilograms, excluding tennis balls, and can be set up and operational within 10.0 ± 0.5 minutes. The machine will roll easily, without being turned on, for ease of transport.
Operational Description
The user will set up the tennis ball machine by first activating its power source, which could be a battery, extension cord, gasoline engine, or some other suitable power source. The user will turn on the machine and will input the desired settings. Then the device will idle on one side of the tennis court while the user goes to the other side. Upon receiving the signal to start, the machine will move, if desired, and launch tennis balls to the user’s side of the court. The movement will be entirely lateral, moving no more than 6.0 ± 0.5 meters from the center line of the court, and remaining anywhere from 10.0 ± 0.5 meters to 12.0 ± 0.5 meters from the net, with the motion of the machine generally parallel with the net.
Design Deliverables

Moving tennis ball launching machine

User manual

Testing and capabilities specification report

Final system design report
Not Included:

Tennis balls

Tennis court

Tennis racquet
Preliminary Test Plan

A radar gun will be used to test tennis ball launch speed.

The difference between the widest angled launch paths will be measured using a measuring tape and trigonometry.

M A T T | 46

The time to switch between the widest range of launch angles will be timed with a stopwatch to determine if it is less than 3.0 ± 1.0 seconds.

The time it takes the machine to traverse the entire width of the court will be measured with a stopwatch to determine if it is less than 20.0 ± 1.0 seconds.

A randomly selected group of five tennis players will be asked to set up the machine, turn it on, and start it while being timed with a stopwatch to determine if it takes the user less than 10.0 ± 0.5 minutes to have the machine set up and operational. The selected group will be surveyed about the ease of use and convenience of controls to determine if at least
90% find them satisfactory.

The remote will be tested at increasing distances to determine if its maximum range is greater than 30 meters.

The machine will operate for a set period of time while someone records the number of shots in bounds and the total number of shots.

The machine will operate for a set period of time and the overall distribution of the shots will be measured using the grid shown in Fig. 2 in Appendix B. The percent distribution of the ball placement will be: 20% for sections 1 and 3, 25% for section 2, 15% for section 5, and 10% for sections 4 and 6. The margin of error will be ± 3% for all sections.

The maximum number of tennis balls that can be placed in the hopper will be counted.

The machine will be operated while tennis balls are allowed to strike the machine to test its durability. Using a pitching machine, 100 tennis balls will be launched at the machine with initial speed of 30 meters per second, measured by a radar gun. This test will be performed only on the front section of the machine.

The machine will be weighed on a simple scale.

The machine will be visually inspected to determine if all moving parts are properly encased or noted with proper warnings. All electrical components will be inspected in a similar matter to determine if they are properly covered and insulated.

The machine will be sprinkled with water for a period of 3 minutes.
Implementation Considerations

Service
The user will be able to transport the machine to the tennis court by rolling it. The user will power up the machine, and turn it on, either locally or remotely. The machine will then move sideways along the opposite backside (relative to the player) of the tennis court launching tennis balls to the player. All movement of the machine will be lateral, moving no more than 6.0
± 0.5 meters from the center line of the court, and remaining anywhere from 10.0 ± 0.5 meters to
12.0 ± 0.5 meters from the net, with the motion of the machine intended to be parallel with the net.

Maintenance

M A T T | 47
The unit will not be serviceable by customer and must be sent in to manufacturer for repairs and maintenance.

Manufacturability
The machine will be manufactured mainly of pre-fabricated purchased parts for most internal mechanical and electric components. Any custom molded parts that will be needed will be produced via manufacturing options such as the 3-D printer, or the CNC machine. The frame of the machine will be constructed to custom fit the design using standard fastening methods such as glue, screws, bolts, and in some cases possibly welding. The entire design should able to be manufactured with the equipment at Harding University, except for the ordering of specific parts.
Relevant Codes and Standards
The rules and regulations of tennis can be found at
Appendices www.ITFTennis.com
.
Appendix A
5
6
7
1
2
3
4
Need
Mobility X
Various Launch
Factors
X X X X
Precision X
Ease of
Operation
X X X
Long Operation
Time
Safety
X
X
X
X
X
X
X
Portability
X
X
X X
X

M A T T | 48
Figure 1: Customer Needs-Metrics Matrix
The needs listed above in Fig. 1 correspond to the seven needs listed in the Customer
Needs section. The metrics are further described as following:
1.
The device will not move further than 6.0 ± 0.5 meters from the center line of the court to avoid running away from the court or into another court.
2.
The launching speed can vary, depending on the user input, from 4 m/s to 45 m/s.
3.
The horizontal angle can vary from 40º to 140 º in order to account for movement of the machine, while still making accurate shots.
4.
The vertical angle can vary up to 50º to produce longer distance shots with slower speeds as well as add more variety to the shots.
5.
The machine can vary its angle from one extreme to the other within 3.0 ± 1.0 seconds.
6.
The machine can consistently hit the player’s court without hitting the net at least 90% of the time
7.
The controls for the machine are within standing reach of an average player.
8.
The labels for the controls are readable for an average player.
9.
The device can be started remotely from at least 30 meters away.
10.
The device has enough power to run for at least 1 hour.
11.
The machine can withstand being hit on over 100 returns at an initial speed of 30 meters per second.
12.
The machine can hold at least 150 tennis balls.
13.
The machine can shoot with only one ball left.
14.
The machine can operate with the maximum capacity of tennis balls.
15.
The moving parts of the machine are encased. The majority of moving parts will not be accessible without modifying the device.
16.
The device will weigh less than 60 kilograms for portability.
17.
The machine will resist light rain for a minimum time of 3 minutes.
Appendix B
Figure 2 shows a diagram of the dimensions of a tennis court and the sections that will be used for testing purposes. The percent distributions of shot placements, corresponding to the grid is described in the Preliminary Test Plans section.

M A T T | 49
Figure 2: A diagram of the dimensions of the tennis court and the grid sections labeled
1 through 6 for testing the precision of the machine.

M A T T | 50
Appendix C
12.0 ± 0.5 m
6.0 ± 0.5 m
10.0 ± 0.5 m
Figure 3: Diagram showing dimensions and location of acceptable area for range of motion.

Launching Motor:
Model: M5-RS775-12
Operating Voltage: 6V – 18 V
RPM – Peak Eff.: 7300
Torque – Peak Eff.: 0.0826 N-m
Current – Peak Eff.: 5.7A
Weight: 352 g
Horizontal Motor and Hopper Motor:
Model: HN-GH12-1634T-R
Operating Voltage: 4.5V – 12 V
RPM – Peak Eff.: 293
Torque – Peak Eff.: 0.0834 N-m
Current – Peak Eff.: 0.293 A
Vertical Motor:
Model: M4-R0062-12
Operating Voltage: 6V – 12 V
RPM – Peak Eff.: 4614
Torque – Peak Eff.: 0.3178 N-m
Current – Peak Eff.: 19.8 A
Weight: 1.304 kg
M A T T | 51

Launching Wheels:
Model: NPC-PT316
Bore: 1/2"
Key: 1/8"
Diameter: 6" diameter
Weight: 680.4 g
Mobility Motor:
Model: M5-RS550-12
Operating Voltage: 6V – 14.4 V
RPM – Peak Eff.: 17000
Torque – Peak Eff.: 0.0624 N-m
Current – Peak Eff.: 10.9 A
Weight: 218 g
Mobility Motor Gearbox:
Model: P60K-444-0004
Type: Planetary
Reduction: 64:1
Stages: 3 - 4:1, 4:1, 4:1
Weight: 273 g
M A T T | 52

Phototransistor:
Model: QSC113
Wavelength: 880 nm
Viewing Angle: 8

Power – Max: 100 mW
Lens Size: 3.5 mm
LED IR Emitter:
Accelerometer:
Model: QEC122
Wavelength: 880 nm
Viewing Angle: 8

Lens Size: 3.5 mm
Current – DC Forward: 50 mA
Voltage – Forward: 1.7 V
Model: ADXL203EB
Sensor Type: 2-Axis
Sensing Range: + or – 1.7g
Sensitivity: 1000 mV/g
Interface: Analog
Voltage: 3 – 6 V
M A T T | 53

Power Source:
M A T T | 54
Model: LA-12V70AH(D)
Type: Sealed Lead Acid Battery
Nominal Voltage: 12.0V
Nominal Capacity: 20 hr at 3.5 A = 70 Ah
Actual Capacity: 1hr at 42 A = 42 Ah
Weight: 23.0 kg

M A T T | 55
Preliminary design of Half H-Bridge High Current Motor Controller:
V_Motor
U3
50_AMP
EN 1
V+
2 Input
U1
Gate
5
4 GND Source 3
MIC5014
S1
MOTOR
Q1
IRF1324
R3
1kΩ
LED1
D2
1N4001
C1
10µF
D1
1N5353B
16V
PWM
R1
10kΩ
Q3
IRF1324
Preliminary Bill of Materials for Half H-Bridge High Current Motor Controller:
Manufacturer
Part #
Manufacturer
MIC5014YN Micrel Inc.
Description Price Quantity Extended
Price
$2.23 1 $2.23
IRF1324PBF-
ND
1N5353BG
International
Rectifier
ON
Semiconductor
IC Driver MOSFET HI/LO Side 8-
Dip
MOSFET N-CH 24V 195A
TO220AB 1.5mOhm
16V Zener Diode 5W
Miscellaneous
$3.75
$0.44
$5.00
2
1
1
Total:
$7.50
$0.44
$5.00
$15.17

M A T T | 56
Preliminary design of Full H-Bridge High Current Motor Controller:
V_Motor
U3
50_AMP
C1
10µF
D1
1N5353B
16V
CW_EN 1 V+
2 Input
U1
Gate 5
4
GND Source
3
MIC5014
CCW_PWM
R1
10kΩ
Q1
IRF1324
Q2
IRF1324
R3
1kΩ
Q3
IRF1324
S1
M
MOTOR
CW
LED1
LED2
CCW
Q4
IRF1324
C2
10µF
5 Gate
3
Source
U2
V+ 1
Input 2
GND
4
MIC5014
CCW_EN
CW_PWM
R2
10kΩ
Preliminary Bill of Materials for Full H-Bridge High Current Motor Controller:
Manufacturer
Part #
MIC5014YN
Manufacturer
Micrel Inc.
Description Price Quantity Extended
Price
$2.23 2 $4.46
IRF1324PBF-
ND
1N5353BG
International
Rectifier
ON
Semiconductor
IC Driver MOSFET HI/LO Side 8-
Dip
MOSFET N-CH 24V 195A
TO220AB 1.5mOhm
16V Zener Diode 5W
Miscellaneous
$3.75 4
$0.44 1
$5.00 1
Total:
$15.00
$0.44
$5.00
$24.90

M A T T | 57
Preliminary Bill of Materials for Low Current Motor Controller:
Manufacturer
Part #
SN7404N
DM7408
754410NE
Manufacturer Description Price Qty
Texas Instruments IC HEX INVERTER 14-DIP $1.86 1
Fairchild
Semiconductor
IC Quad 2-Input AND Gate 14-
DIP
$2.25 1
Texas Instruments IC Half-H Driver Quad 16-DIP $2.14 1
Extended
Price
$1.86
$2.25
$2.14
Total: 6.25
Preliminary design of 5V Regulation Circuit:
V_Battery
C1
0.33µF
U1
LM7805CT
LINE
VOLTAGE
VREG
COMMON
C2
0.1µF
5V
5V Regulator:
Model: LM7805CT
Voltage Input: 7 – 35 V
Voltage Output: 5 V
Current Max: 1 A

M A T T | 58
Preliminary design of Low Battery Indicator:
5V
V_Battery
R1
13kΩ
R2
10kΩ
3
2
7 1 5
741
U1
6
R3
330Ω
Low Battery LED
LED1
4
Preliminary Bill of Materials of Remote Control
Distributor Part # Distributor Description
WRL-08945
WRL-10533
563-HH-3505
Sparkfun RF Link Transmitter - 315MHz
Sparkfun RF Link Receiver - 4800bps
(315MHz)
Mouser Handheld Remote With 5
Buttons
Mouser Low Power PIC24 MCU 595-
MSP430G2211IN1
4
614-HU2032-LF Mouser Through Hole CR2032 Battery
Holder
CR2032 Battery 225mAh 614-CR2032-MFR Mouser
Remote Control Transmitter:
Frequency: 315 MHz
Range Max: 500 ft
Data Rate Max: 4800 bps
Voltage Input: 5V
1
1
1
1
Quantity Price Extended
Price
1 $1.95 $1.95
1 $4.95 $4.95
$5.30
$1.76
$5.30
$1.76
$0.82 $0.82
$0.82 $0.82
Total: $15.60

Remote Control Receiver:
Frequency: 315 MHz
Range Max: 500 ft
Data Rate Max: 4800 bps
Voltage Input: 5V
Remote Control Enclosure:
Buttons: 5
Form Factor: Key Fob
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