Project Description
Strategy & Approach
Project Background:
Assumptions & Constraints:
The objective of this project is to design and build a test
stand that will validate the quality of electronic power
steering units for Maval Manufacturing. In 2007 Maval
Manufacturing launched its Wicked Bilt brand focusing on
steering solutions, including electronic power steering
(EPS) for UTVs. The Senior Design team is tasked with
designing and constructing a test stand for the EPS units.
Having a functional steering system is a major aspect of
customer safety so it is important to test all units. As
requested by Maval, we will be running several tests based
on input and output torque relationships. The units will be
serialized and the data will be recorded to a database. If
problems arise in the future, Maval needs to be able to
bring up the test data for any particular unit that has left the
building.
1.
Issues & Risks:




Problem Statement:
Validate the quality of electronic power steering units by
creating a test stand to test performance criteria of all
electronic power steering units from Maval Manufacturing.
Objectives/Scope:
1.
2.
3.
4.
Torsion bar integrity
Steering current draw
Torque input and output
Steering symmetry
Record all data
Create an easy to use interface
Ensure safety of operator
Deliverables:


Fully functioning test stand
User manual documentation
Expected Project Benefits:


More robust test method of steering units
Ability to store data for manufacturer
Core Team Members:







Validate quality by testing:
1.1.
1.2.
1.3.
1.4.
Travis Blais – Team Leader
Evan Lumby – Manufacturing Leader
Jordan Shields – Project Leader
Samuel Slezak – Software Leader
Accommodate power steering casting and splines



The integration of data acquisition software and hardware
will be the biggest challenge for our senior design team.
o To ensure success we plan on starting creation of
software early in the process as well as seek advice
from experts in the field.
Error codes occurring too often may cause operator to alter
software to prevent warnings (has happened on other tests at
shop)
o Password Protection of Software
o Proper Tolerances to ensure unit quality while also
minimizing error warnings
Spline wear deteriorating piece
o Proper material Selection
High Cost of Parts necessary for Testing
o Reasonable budget , cost assessment, price comparison
Lead time on manufactured parts
o Requests parts and notify shop on time
Designing Intuitive Interface
o Physical visit to Maval to speak with operator and
observe process in action and receive feedback
Repeatability of test results due to insufficient strain gauge
life.
o Research and Benchmarking Strain Gauge Fatigue Life
and Cost comparison to torque sensors available in
market
Inability to read Error Signals
o Conduct research with signals expert along with
detailed research of signals processing, including Morse
Code
Creating accurate torque sample range to be read while
maintaining an elastic torque region.
o Thorough analysis of connections as well as torque
sensor capability and signal generation.
Inability to find testing area that supplies 3-phase power
supply.
o Option 1:
 The Senior Design Facilities will be wired for the
capability of supporting 220V, 3-Phase power. The
Cost will be covered as a Facilities fee by RIT. The
testing of the stand will be completed in the Senior
Design Meeting Room.
o Option 2:
 The Test Stand will have castors attached to the
structure, regardless of the availability of power,
for the assembly and testing process. These castors
will most likely be removed once the stand is
delivered to Maval. This will provide portability of
the test stand and allow the team to transport it to
the second floor engineering machine shop, which
has 3-phase power available. Due to space
limitations, the stand cannot remain in the machine
shop, and must be returned to the Senior Design
Meeting Room.
Customer Needs:
Primary
Customer
Need
Ensure Safety
Validate
Quality
Easy to use
Record Data
Serialize Parts
#
Specific Customer Needs
S1
S2
E-stop
Safe to use
S3
Q1
Q2
Q3
Q4
Q5
Q6
Q7
Secure EPS
Repeatable Measurements
Display Errors
Measure/Apply Torque In
Measure Torque Out
Measure Supplied Current
Check sensor calibration
Password protect specifications
Q8
E1
E2
E3
E4
E5
E6
E7
E8
R1
R2
R3
R4
R5
R6
R7
R8
P1
Two test fixutres
Red/Green light for fail/pass
Failure criteria clearly expressed to user
User friendly interface
Automated test
Tool-less to secure EPS
Easily adjustable specifications
Low skill level to use
Easy to replace high wear parts
Record Torque In
Record Torque Out
Record Current
Record Errors
Keep database of all test data
Record Max torque
Record Calibration
Record operator ID
Assign new internal serial number
P2
Record internal/external serial number with test data
Engineering Specifications:
Engineering
Specification
Number
Engineering Specification Description
S1
S2
Button to turn off power to actuation device and EPS
EPS Current limit
S3
S4
S5
S6
S7
S8
S9
S10
S11
S12
S13
S14
S15
S16
S17
S18
S19
S20
S21
S22
S23
S24
S25
S26
Area of exposed wire/connections
Maximum applied torque in
Maximum measurable torque out
Maximum measureable torque in
Voltage supplied to EPS control unit
Max measureable current
Allowable EPS movement during test
Number of test fixutres
Accuracy of measured torque
Calibration Accuracy
Tolerance on current measurement
Time to secure
Number of steps to start test stand from off
Use tools to secure
Display errors on screen
Illuminates green/red light for pass/fail
Time to remove spline connection
Steps to run test
Password Protected
Display modifiable specifications
Min number of tests stored
Minimum DAQ sample rate
Storable alphanuemeric characters for serialization
Storable digits for operator ID
Units of
Measure
Preferred
Direction
Nominal
Value
Method of
Validation
Customer
Need
yes/no
Amperes
Range
yes
30-40
Fuse/device limits
S1,S2
S2
m2
Nm
Nm
Nm
V
Amperes
degrees
Exact
%
Nm
%
minutes
#
yes/no
yes/no
yes/no
Minutes
#
yes/no
yes/no
#
Samples/sec
#
#
Exact
Increase
Increase
Increase
Range
Increase
Decrease
Decrease
Decrease
Decrease
Decrease
Less
Decrease
Decrease
Increase
Increase
Increase
Increase
0
9
67.5
9
12-13.5
30
5
2
5
1
5
1
5
no
yes
yes
5
7
yes
yes
30000
50
20
10
motor capability
sensor capability
sensor capability
measure
sensor capability
measure
sensor capability
measure
sensor capability
survey
sensor capability
-
S2
Q3, R6
Q4, R2, R6
Q3, R1
E4
Q5, R3
S3
Q8
Q1
Q1, Q6, R7
Q1
E5
E7
E5
E2, E3
E1, E3
E8
E4, E7
Q7, E3
E3, E6
R1-7
Q1,3,4,5
P1,P2
R8
Test Bench Concept Selection:
The above images show our initial concepts that we used for conversation as a group to pick apart
the aspects we did and did not like to we could approach our customer with our best concept for the
layout of the test stand. As a group we decided the picture shown to the right would be the best to take to
Maval along with the other concepts.
When meeting with Maval we improved on the concept yet
again by following their suggestions.
o
Minimize horizontal surface to discourage clutter
o
Remove additional components
o
Start/Stop buttons
o
Indicator light
o
Reverse torque application so servos will be located
under the work surface
o
Create storage area to accommodate for computer and
hardware
o
Mount screen elsewhere, not sitting on a surface.
o
Open up work area so it is easier to move parts in and
out of the fixture
Once these considerations were gathered, a much better concept was generated that can be met
with further approval from our customer.
After continued discussion and consideration for space to allow the user to sit comfortably at the
test stand, we decided to make the stand 12 inches wider to allow us to fit all of our electronics inside of
one locker that can be bought and attached to the underside of the stand. This extra table space will also
accommodate the label printer. We believe this will be our last major change to the layout.
Torque Application:
Servo: Anaheim Automation EMG-10:
-
Rated torque of 677 oz-in (4.78Nm) continuous
Repeatable 2031 oz-in (14.34Nm)
Compatible with Anaheim Automation drives
Servo Drive: Anaheim Automation EDB-10AMA
-
Torque control
Speed Reference
Torque Sensor Fatigue and Max Stress Capability:
Torque Sensor Free Body Diagram
. Below are the calculations used to find the estimated expected stress.
Based on the Equations and coefficients in above from Futek, the 1300 in-lb Torque Sensor
selected for this project is limited to 15,000 psi for Maximum Stress. These calculations imply
that for the worst case scenario estimated for this application, the torque sensor chosen should
theoretically support infinite fatigue life for fully reversing loads, while including a factor of
safety of greater than 2.
Slip Shaft Design:
Outline of Slip Shaft
Solid Model of Slip Shaft
Using ANSYS APDL Software, The Slip Shaft was designed based on a 3/4in DD Steering Shaft
and Tube combination. Both the Tube (OD 1in) and the shaft (OD .75in) were 6 inches long,
with a 3 inch overlap.
Results
The Slip Shaft experiences less than 12000 psi maximum stress under the max specified torque
of 67.5 N-m
The Maximum Stress occurs on the DD Shaft, pictured above.
An end view detailing the radial stress experienced by the Slip Shaft.
Using the Maximum Yield Stress of 1016 cold drawn Steel, the Shaft has an ultimate yield
strength of 50800 psi, providing an approximate factor of safety of 4.2.
Servo Key Analysis:
Shigley’s Mechanical Engineering Design, Ninth Edition, by Richard G. Budynas and J. Keith Nisbett
F
h
r = 11mm
u
F
t = 8mm
u = 4mm
h = 7mm
L = 40mm
T = 9Nm
𝐹=
𝑇
𝑟
9𝑁𝑚
= 0.011𝑚 = 818.18𝑁
𝑆𝑠𝑦 = 0.577𝑆𝑦 = 0.577 ∗ 415𝑀𝑃𝑎 = 239.5𝑀𝑃𝑎
Shear Failure:
𝑆𝑠𝑦
𝑛
=
𝑛=
𝐹
𝑡𝐿
𝑆𝑠𝑦 ∗𝑡∗𝐿
𝑇
=
239.5𝑀𝑃𝑎∗0.008𝑚∗0.04𝑚
818.18𝑁
= 93.7
Resist “crushing”:
𝑆𝑦
𝑛
𝐹
= 𝑡𝑙/2
𝑛=
𝑆𝑦 ∗𝑡∗𝐿
2𝐹
=
415𝑀𝑃𝑎∗0.008𝑚∗0.04𝑚
2∗818.18𝑁
= 81.16
Data Acquisition:
cDAQ-9174 Chassis:
Features:
-
USB Interface
-
4-Slot Chassis
-
Compatible with over 50 modules
NI–9219 Universal Analog Input:
Features:
-
4 Channel Input module
-
Built in quarter, half, and full bridge support
-
Built in voltage and current excitation
-
250 Vrms channel to channel isolation
-
100 S/s/ch
Signals:
(1) Torque Sensor (2mV/V Excitation)
(2) Torque Sensor (2mV/V Excitation)
(3) EPS Error Signal (0-12V Pulse)
(4) Current Measurement (0-60mV)
NI-9264 16-Channel Analog Output Module:
Features:
-
± 10v Output
-
4mA/ch, 16mA total Current drive
-
25kS/s
-
0.01V Accuracy
Signals:
Signals duplicated on each side for a total of 10 used output channels, one side is listed:
(1) EPS Remote
(0-10V, < 0.01A)
(2) EPS Main Power Relay
(0-10V, 1.6mA)
(3) Speed Reference
(-10V to 10V)
(4) Torque Reference
(-10V to 10V)
(5) Servo Remote
(0-5V, 2.2mA)
FUTEK FSH00648 Reaction Torque Sensor:
Features:
-
1300 in-lb (147Nm) rated load
-
1 to 18V Excitation
-
2mV/V Max output
-
150% Safe overload
Bill of Materials:
Product Number
Vendor
Product Descriptions
Quantity
Price/Unit
Row Total
LabVIEW Full
ViewPoint Systems
LabVIEW Full
1
$2,699.00
$2,699.00
PKG-EMG10-EDB10-CBLS
Anaheim Automation
Servo, Drive, and Cables
2
$1,053.00
$2,106.00
NI 9219
ViewPoint Systems
DAQ Input Module
1
$1,059.00
$1,059.00
FSH00648
Futek
Torque Sensor
2
$495.00
$990.00
NI 9264
ViewPoint Systems
DAQ Output Module
1
$926.00
$926.00
cDAQ 9174
ViewPoint Systems
DAQ Chassis
1
$699.00
$699.00
Tripp Lite 40A
Amazon
AC to DC Convertor
1
$198.99
$198.99
CC1039-ND
Digi-Key
EPS Main Power Relay
2
$77.32
$154.64
N82E16824016172
Newegg
Monitor
1
$126.00
$126.00
T9YB656290
Global Industrial
Electronic Equipment Cabinet
1
$102.95
$102.95
CC1126-ND
Digi-Key
Servo alarm and remote relay
4
$18.73
$74.92
SPLT-RB
Parts Expressed
Wire quick connectors
10
$6.87
$68.70
4514k2
McMaster-Carr
Circuit breaker
1
$58.74
$58.74
55C4473
Newark
E-Stop button
2
$27.53
$55.06
4854
Monoprice
Monitor Adjustment
1
$19.73
$19.73
TGHGCR0020FE-ND
Digi-Key
Current measurement resistor
1
$30.07
$30.07
FSH00037
Futek
Torque sensor cable
1
$30.00
$30.00
NI 9904
ViewPoint Systems
DAQ Mounting
1
$30.00
$30.00
HS172
Digi-Key
EPS Main Power Relay Heat Sink
1
$17.64
$17.64
7587K921
McMaster-Carr
10 AWG Wire
1
$19.25
$19.25
7587K258
McMaster-Carr
24 AWG Wire
2
$9.29
$18.58
Vostro Small Form Factor
Dell
Computer
1
$469.00
$469.00
-
Estimate
Scanner
1
$300.00
$300.00
-
Estimate
Printer
1
$100.00
$100.00
-
Estimate
Table Materials
1
$350.00
$350.00
$10,703.27