Out of Date

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System Level
Total Costs
• 3 fully powered and steering, 4 idler modules
• Prototyping Costs (1 fully powered and steering, tested
on bench):
–
–
–
–
Power Electronics = 183.50
Control System = 279.19
Mechanical = 221.90
TOTAL = 684.59
• Production Costs:
–
–
–
–
–
Power Electronics = 382.34
Control System = 128.59
Mechanical = 657.04
PCB Setup Cost = 200.00
TOTAL = 1367.97
• TOTAL = $2052.56
Mechanical
High Performance Motor Module
High Performance Motor Module
Low Performance Motor Module
http://robots.mit.edu/publications/papers/2000_09_Yu,_Dub_Skw.pdf
Airtrax.com
http://robots.mit.edu/publications/papers/2000_09_Yu,_Dub_Skw.pdf
100 kg Stress Study
Out of Date
Out of Date
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RE-30
Maxonmotorusa.com
www.superdroidrobots.com
www.superdroidrobots.com
Power Electronics
Knowing the requirements for the motor from the mechanical subsystem such as required torque
and motor speed, a compatible motor is the Maxon RE-30 60 Watt DC Motor (310007).
Out of Date
Datasheet for Maxon RE-30
http://www.maxonmotorusa.com/files/catalog/2005/pdf/05_080_e.pdf
Out of Date
Operating Voltage = 24V
Max Continuous Current = 3.81 A
Terminal Resistance = .611 Ohms
Terminal Inductance = .00012 H
Speed Constant = 369 rpm/V
Using the formula from “Robot DNA Series - Building Robot Drive Trains” by Dennis Clark and Michael Owings to determine PWM frequency for this motor,
2f L  R
Where >> is a factor of at least 10.
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10 R
2L
10(.611)

2 (.00012)
 8.1kHz
f PW M 
f PW M
f PW M
Using a formula from Maxon Precision Motors Inc. to calculate the current ripple seen on the DC bus:
Out of Date
Ipp 
U  EMF
2 f PW M L
Where U is the supply voltage and the EMF is the speed constant divided by the speed.
Ipp 
24  ( RPM / 369)
2(10,000)(.00012)
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The motor will have the feature of a power-off electronic brake through the use of a DPDT relay.
U1A
1
2
7404
Motor
H-Bridge
Diagram of Motor with
Safety Relay
DC-DC
When power is applied the relay will allow the motor to be powered by the H-Bridge. Without power the relay contacts will be
wired such that the motor terminals are shorted.
Battery
Title
<Title>
Size
A
Date:
Document Number
<Doc>
Tuesday , October 10, 2006
Rev
<Rev Code>
Sheet
1
of
1
Omron G2R Relay example:
Contact specifications on Omron G2R DPDT Relay
http://www.components.omron.com
$5-$10 depending on mounting and options (LEDs)
Coil Specification on Omron G2R DPDT Relay
21.8 mA @ 24 VDC Current Draw
http://www.components.omron.com
H-Bridge frequency needs to be at least 8 kHz, however higher frequencies help reduce current ripple and increase efficiency.
Examples of compatible H-Bridges:
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Freescale Semiconductor H-Bridge
Section of Datasheet, page 1/32
http://www.freescale.com/files/analog/doc/data_sheet/MC33887.pdf
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STMicroelectronics Dual Full Bridge Driver
Section of datasheet, page 1/13
http://www.st.com/stonline/products/literature/ds/1773.pdf
STMicroelectronics Dual Full Bridge Driver
Section of datasheet, page 7/13
http://www.st.com/stonline/products/literature/ds/1773.pdf
National Semiconductor LMD18200
Section of datasheet, page 1/14
http://cache.national.com/ds/LM/LMD18200.pdf
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Allegro Full-Bridge Power MOSFET Controller
http://www.allegromicro.com/sf/3940/
Available from Digikey; <$5
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Infineon N-Channel MOSFET
http://rocky.digikey.com/WebLib/Infineon/Web%20Data/IPP14N03LA_Rev1.2.pdf
Available from Digikey; ~$1
Estimated Power Systems Loads
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Potential Deep Cycle Batteries; PVX-340T costs $105.
http://store.solar-electric.com/cosuagmba.html
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Potential battery datasheet giving 1 hour rate of discharge
13.2 Ah at 1 hour
http://www.vision-batt.com/newpdf/D/CP12180D.pdf
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Table from datasheet (page 2/2) giving voltage sag levels at different drain currents
http://www.vision-batt.com/newpdf/D/CP12180D.pdf
Control Power Distribution Board Functional Decomposition
Amp DUAC Connector
http://catalog.tycoelectronics.com/TE/bin/TE.Connect?C=1&PN=794657-4&M=BYPN&LG=1&I=13
<$1
9A Current (MAX)
Parvus PC104 Power Supply
http://www.parvus.com/products/Transportation/Board-LevelOEM/PRV-0617/
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Tenergy Sc 3500 mAh high capacity High Drain (10C) NiMH Rechargeable batteries
“Up to 35 Amps 10C high drain current rate”
~$5.00 per cell
http://www.all-battery.com/
To power some of the feedback devices a voltage other than the control voltage may be needed.
This can be obtained by common DC-DC converters which regulate the voltage to a desired level.
Example Control Power Battery
http://rocky.digikey.com/WebLib/B&B%20Battery/Web%20Data/BP7-12.pdf
Typically used in UPS applications, $16 from Digikey
Page 1 of datasheet
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DC-DC Converter capable of 3.3V, 5V, and 12V outputs from a wide input voltage range
Section of datasheet, page 1/12
http://cache.national.com/ds/LM/LM2825.pdf
For speed feedback an encoder with quadrature output is needed for accurate speed and direction signals.
US Digital Encoder with Quadrature output, 5V input
400-1200 pulses per revolution, ~30$
Lower cost versions available ($20) via “Low cost push-on hub”
http://www.usdigital.com/data-sheets/E4%20Data%20Sheet.pdf
With a resolution of 400 pulses per revolution, the maximum error in position feedback will be:
1
(360)
400
 .9
 error 
 error
Increasing the number of pulses to 1200 decreases the error by a factor of 3.
On a 7” diameter wheel, that corresponds to .055” of accuracy
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Potential RTD: Honeywell HRTS-5760-B-T-0-12
Section of datasheet, page 1/3
http://catalog.micro.honeywell.com/AUTHOR/images/honeywell/temp/HRTS.pdf
Control System
Comm Protocol Pugh Chart
Controls Subsystem
Microchip PIC 18F2431
Microprocessor
Motor Control Graphical User Interface
The MC-GUI graphical user interface allows users to configure the motor and a wide range of
system parameters for a selected motor type, including speed, rotation direction, current,
heatsink temperature, fault status and much more. Available at no cost, this Windows® based
software program supports Microchip’s motor control demonstration boards to provide a
complete solution that helps reduce design time.
Data Monitor and Control Interface Software
A
(Baseline)
Microcontroller
BASIC
Stamp II
B
C
D
E
Atmel
AVR
(ATmega
8)
Motorola
Coldfire
MCF5307
89C4051
(8051
Architectur
e)
PIC18F2
431
Clock Speed
0
-1
1
1
1
PWM capabilities
0
1
1
1
1
Cost
0
0
-1
-1
1
Power Consumption
0
1
1
1
-1
I/O Ports
0
1
1
1
1
Flash Memory
0
1
0
1
1
I2C capability
0
0
1
0
1
H-Bridge Technology
0
0
0
0
1
Ease of Programability
0
1
1
1
1
Commercial Portability
0
1
1
0
1
Sum
0
5
6
5
8
Rank
5
3
2
3
1
Figure – Control Subsystem Concept Screening
A
(Baseline
)
B
C
D
E
Weight
BASIC
Stamp II
Atmel
AVR
(ATmega
8)
Motorola
Coldfire
MCF530
7
89C4051
(8051
Architectur
e)
PIC18F2431
Clock Speed
0.05
3
2
4
4
4
PWM
capabilities
0.15
3
4
4
4
4
0.2
3
3
2
2
2
0.05
3
4
4
4
4
0.1
3
4
4
4
4
Flash Memory
0.05
3
4
3
4
4
I2C capability
0.15
3
3
4
3
4
H-Bridge
Technology
0.15
3
3
3
3
4
Ease of
Programability
0.05
3
4
4
4
4
Commercial
Portability
0.05
3
4
4
3
4
Total
3
3.4
3.4
3.25
3.6
Rank
5
2
2
4
1
Microcontroller
Cost
Power
Consumption
I/O Ports
Continue?
No
No
No
No
Yes
Figure – Control Subsystem Concept Selection
Figure – Microcontroller Comparison Chart
R
Resistance
V
1/L
d/dt(i)
K
Inductance
Add
Ke
K
d2/dt2(theta)
1/J
Kt
Add1
Inertia
1
s
i
Integrator
1
s
d/dt(theta)
Integrator1
b
damping
Figure – PM DC Motor Simulation
Scope
Figure – Open Loop Response of the Simulated PM DC Motor
X axis = time (s)
Y axis = voltage (V)
Resources
http://www.microchip.com/ParamChartSearch/chart.aspx?branchID=55&mid=10&la
ng=en&pageId=74
http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1
335&dDocName=en010271
http://ww1.microchip.com/downloads/en/DeviceDoc/39616b.pdf (Datasheet)
Safety
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