P13226: Power Steering Test Stand November 14, 2012

Detailed Design Review

Project Description

Project Background:

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.

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. Validate quality by testing:

1.1. Torsion bar integrity

1.2. Steering current draw

1.3. Torque input and output 1.4. Steering symmetry

2. Record all data

3. Create an easy to use interface

4. 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: Travis Blais – Team Leader

Evan Lumby – Manufacturing Leader

Jordan Shields – Project Leader

Samuel Slezak – Software Leader

Strategy & Approach

Assumptions & Constraints: 1. Accommodate power steering casting and splines

Issues & Risks: 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

# Specific Customer Needs

Ensure Safety

S1 E-stop

S2 Safe to use

S3 Secure EPS

Validate

Quality

Q1 Repeatable Measurements

Q2 Display Errors

Q3 Measure/Apply Torque In

Q4 Measure Torque Out

Q5 Measure Supplied Current

Q6 Check sensor calibration

Q7 Password protect specifications

Q8 Two test fixutres

Easy to use

E1 Red/Green light for fail/pass

E2 Failure criteria clearly expressed to user

E3 User friendly interface

E4 Automated test

E5 Tool-less to secure EPS

E6 Easily adjustable specifications

E7 Low skill level to use

E8 Easy to replace high wear parts

Record Data

R1 Record Torque In

R2 Record Torque Out

R3 Record Current

R4 Record Errors

R5 Keep database of all test data

R6 Record Max torque

R7 Record Calibration

R8 Record operator ID

Serialize Parts P1 Assign new internal serial number

P2 Record internal/external serial number with test data

Engineering Specifications:

Engineering

Specification

Number

Engineering Specification Description Units of

Measure

Preferred

Direction

Nominal

Value

Method of

Validation

Customer

Need

S1 Button to turn off power to actuation device and EPS yes/no - yes - S1,S2

S2 EPS Current limit Amperes Range 30-40 Fuse/device limits S2

S3 Area of exposed wire/connections m2 Exact 0 - S2

S4 Maximum applied torque in Nm Increase 9 motor capability Q3, R6

S5 Maximum measurable torque out Nm Increase 67.5 sensor capability Q4, R2, R6

S6 Maximum measureable torque in Nm Increase 9 sensor capability Q3, R1

S7 Voltage supplied to EPS control unit V Range 12-13.5 measure E4

S8 Max measureable current Amperes Increase 30 sensor capability Q5, R3

S9 Allowable EPS movement during test degrees Decrease 5 measure S3

S10 Number of test fixutres Exact - 2 - Q8

S11 Accuracy of measured torque % Decrease 5 sensor capability Q1

S12 Calibration Accuracy Nm Decrease 1 measure Q1, Q6, R7

S13 Tolerance on current measurement % Decrease 5 sensor capability Q1

S14 Time to secure minutes Decrease 1 survey E5

S15 Number of steps to start test stand from off # Less 5 - E7

S16 Use tools to secure yes/no - no - E5

S17 Display errors on screen yes/no - yes - E2, E3

S18 Illuminates green/red light for pass/fail yes/no - yes - E1, E3

S19 Time to remove spline connection Minutes Decrease 5 - E8

S20 Steps to run test # Decrease 7 - E4, E7

S21 Password Protected yes/no - yes - Q7, E3

S22 Display modifiable specifications yes/no - yes - E3, E6

S23 Min number of tests stored # Increase 30000 - R1-7

S24 Minimum DAQ sample rate Samples/sec Increase 50 sensor capability Q1,3,4,5

S25 Storable alphanuemeric characters for serialization # Increase 20 - P1,P2

S26 Storable digits for operator ID # Increase 10 - 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.

After our detailed design review, we decided to move the free spce and the locker to the left side

of the stand to better accomodate parts moving in and out of the stand. This is based on the location that

the stand will be placed in the warehouse as well as the majority of people being right handed. Also, we

discovered that we would need to consider any misalighnment that would be seen in the splines as E.P.S.

Units are installed. To accomodate for this, we added hand wheels to allow for the operator to spin the

servo shaft as well as the E.P.S. motor shaft by hand so the splines can be properly aligned.

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

r = 11mm

t = 8mm

u = 4mm

h = 7mm

L = 40mm

T = 9Nm

Shear Failure:

Resist “crushing”:

u

F

F h

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-9263 4-Channel Analog Output Module:

Features:

- ± 10v Output

- 1mA/ch current drive

- 100kS/s

- 0.11V Accuracy

Signals:

(1) Speed Reference (-10V to 10V)

(2) Torque Reference (-10V to 10V)

(3) Speed Reference (-10V to 10V)

(4) Torque Reference (-10V to 10V)

NI-9472 8-Channel 24V Digital Output Module:

Features:

- 6 to 30V sourcing digital output

- 100 μs delay

Signals: (All signals duplicated for total of 8 channels)

(1) EPS Remote

(2) EPS Main Power Relay

(3) Servo Remote Relay

(4) Error Read Relay

FUTEK FSH00648 Reaction Torque Sensor:

Features:

- 1300 in-lb (147Nm) rated load

- 1 to 18V Excitation

- 2mV/V Max output

- 150% Safe overload

Graphical Interface Concept:

Bill of Materials:

Product Number Vendor Product Descriptions Sub-System Quantity Price/Unit Row Total

N82E16824016172 Newegg Monitor Computer 1 $126.00 $126.00

Vostro Small Form Factor Dell Computer Computer 1 $469.00 $469.00

- Estimate Scanner Computer 1 $300.00 $300.00

- Estimate Printer Computer 1 $100.00 $100.00

LabVIEW Full ViewPoint Systems LabVIEW Full Data Acquisition 1 $2,699.00 $2,699.00

NI 9219 ViewPoint Systems DAQ Input Module Data Acquisition 1 $1,029.00 $1,029.00

NI 9263 ViewPoint Systems DAQ Analog Output Module Data Acquisition 1 $390.00 $390.00

NI 9472 ViewPoint Systems DAQ Digital Output Module Data Acquisition 1 $99.00 $99.00

cDAQ 9174 ViewPoint Systems DAQ Chassis Data Acquisition 1 $699.00 $699.00

T9YB656290 Global Industrial Electronic Equipment Cabinet Physical Structure 1 $102.95 $102.95

4854 Monoprice Monitor Adjustment Physical Structure 1 $19.73 $19.73

- Estimate Table Materials Physical Structure 1 $350.00 $350.00

Tripp Lite 40A Amazon AC to DC Convertor Power Supply & Distribution 1 $198.99 $198.99

V2025-ND Digi-Key Circuit Board Power Supply & Distribution 1 $6.26 $6.26

306-1064 Digi-Key Relay Power Supply & Distribution 4 $1.08 $4.32

1N4151VSTR-ND Digi-Key Rectifier Diode Power Supply & Distribution 2 $0.02 $0.04

1N5240BVSCT-ND Digi-Key Zener Diode Power Supply & Distribution 2 $0.42 $0.84

3482K-ND Digi-Key Standoff Power Supply & Distribution 4 $0.69 $2.76

PPC590YCT-ND Digi-Key Resistor Power Supply & Distribution 10 $0.18 $1.80

160-1067-ND Digi-Key LED Array Power Supply & Distribution 1 $1.26 $1.26

TGHGCR0010FE-ND Digi-Key Current Measurement Resistor Power Supply & Distribution 1 $30.07 $30.07

302-1239-ND Digi-Key Circuit Breaker Power Supply & Distribution 1 $7.00 $7.00

302-1330-ND Digi-Key Circuit Breaker Holder Power Supply & Distribution 3 $7.39 $22.17

7460K37 McMaster-Carr 1A Fuses (pack of 5) Power Supply & Distribution 1 $3.28 $3.28

PB679-ND Digi-Key Main Power Relay (30A) Power Supply & Distribution 2 $3.19 $6.38

PB714-ND Digi-Key Main Power Relay Holder Power Supply & Distribution 2 $6.58 $13.16

PB785CT-ND Digi-Key Terminals Power Supply & Distribution 10 $0.34 $3.40

PB786CT-ND Digi-Key Terminals Power Supply & Distribution 10 $0.34 $3.40

15N7086 Newark E-Stop Power Supply & Distribution 1 $23.86 $23.86

7587K921 McMaster-Carr 10 AWG (25ft) Power Supply & Distribution 1 $19.25 $19.25

7587K258 McMaster-Carr 24 AWG (100ft) Power Supply & Distribution 2 $9.29 $18.58

091-1152 Parts Express Wire binding post Power Supply & Distribution 10 $6.87 $68.70

75065K38 McMaster-Carr Power distribution enclosure (10x10x6in) Power Supply & Distribution 1 $29.18 $29.18

7561K321 McMaster-Carr Enclosure panel Power Supply & Distribution 1 $7.86 $7.86

7527K84 McMaster-Carr 30A Terminal Block Power Supply & Distribution 1 $5.03 $5.03

7527K41 McMaster-Carr 20A Terminal Block Power Supply & Distribution 2 $7.10 $14.20

7527K59 McMaster-Carr Terminal Block Jumpers Power Supply & Distribution 1 $4.34 $4.34

7113K265 McMaster-Carr Ring Terminals (#6 24AWG 25 Pack) Power Supply & Distribution 3 $8.61 $25.83

9983K24 McMaster-Carr Ring Terminals (#6 10AWG 10 Pack) Power Supply & Distribution 1 $9.60 $9.60

9983K25 McMaster-Carr Ring Terminals (#8 10AWG 10 Pack) Power Supply & Distribution 1 $9.60 $9.60

PKG-EMG10-EDB10-CBLS Anaheim Automation Servo, Drive, and Cables Torque Application 2 $1,053.00 $2,106.00

FSH00648 Futek Torque Sensor Torque Measurement 2 $495.00 $990.00

FSH00037 Futek Torque sensor cable Torque Measurement 1 $30.00 $30.00

8515k42 McMaster-Carr Handwheel Physical Structure 2 $46.55 $93.10

27075T71 McMaster-Carr Casters Physical Structure 2 $14.27 $28.54

27075T72 McMaster-Carr Casters Physical Structure 2 $23.59 $47.18

$10,219.66