P16221 – FSAE Shock DynamometerSystem Level Design Review

September 29, 2015

• Aung Toe – EE• Jim Holmes – EE– Project Manager

• Sal Fava – ME– Chief Engineer

• Chris Batorski – ME– Facilitator

• Andrew Dodd – ISE

P16221 – MSD Team

• Background (5 min)• System Analysis (10 min)• Concept and Architecture Development (5 min)• System Level Proposal (10 min)• Engineering Analysis (15 min)• Risk Assessment (5 min)• Test Plan(how we will meet the specs) (5 min)• Updated Project Plan (5 min)• Question and Answer (15 min)

Agenda

• A shock dynamometer is a measurement device • supply an input displacement vs time profile • measure the response (both displacement and force)

of a damper. • Overall: a tool used by engineers to tune the

suspension and ride quality of a vehicle in any application

Background:What is a Shock Dynamometer?

• The goal of this project – Design a device to characterize dampers – Capable of supplying a displacement input profile in time

and measuring force, displacement, and temperature responses of a damper

– Existing machines will be analyzed for compatibility. If there are no existing machines that will support the damper dyno integration, a new machine will be developed

Background:Problem Statement

1. Cost less than $3,0002. Able to be moved in the shop easily3. Reproduce damper displacements from track data4. Measure damper forces5. Measure damper shaft position6. Measure damper temperature during test7. Save and recall test data for post processing8. Maximum footprint of 4’ x 4’9. Accommodate wide range of damper sizes

Background:Customer Requirements

Background:Engineering Requirements

Predicted Costs

Predicted Costs

925.48; 51%

390; 21%

500; 28%

Predicted Costs

Controls and Electronics Mechanical: HardwareMechanical: Raw Materials

House of QualityOverall Picture

1 2

3

4

5

House of Quality1. Customer Reqs

House of Quality2. Functional Reqs

House of Quality3. Inter-relationships

House of Quality4. Roof

House of Quality5. Targets

Functional DecompositionDamper Characterization

Accessing Damper/Prep Test Running Test Data Collection User Safety/Results Output

Functional DecompositionAccessing Damper/Test Prep

Functional DecompositionRunning Test

Functional DecompositionData Collection

Functional DecompositionUser Safety/Result Output

System Level DesignConcept

Data

Test Commands

Post Processed

Results

System Level DesignFlowchart

Morph Chart

Morph Chart Cont.

Ball Screw Actuation• Capable of track data input profile– >10 in/s shaft speed– >1500 lbf input force

System Level Proposal

• Cam/Rotary type motor sizing• Memory Requirements• Microprocessor Read Speed Testing• Serial Speed Analysis• Load Cell Analysis

Engineering Analysis

• Determine a power requirement– Inputs

• 10 in/s shaft speed• 1500 lbf load capability

– Output• 2.72 Hp

– Conclusion• Need a 3-5 Hp motor

Cam/Rotary motor

• Calculate memory requirements for data acquisition– Inputs

• Track data sampled at 500 Hz (0.002 seconds between samples)• Data consists of a pair of numbers (time, displacement)

– Outputs• 1,800,001 samples• 13.74 MB requirement

– Conclusion• Eliminate time and send measurements at a constant 0.002• Record 1-5 minutes of data and send to PC in chunks

Memory

• Read Speed Test– Simulated series of analog input reads– ATmega328P-XMINI– Results

• Mean 339.3 us• Min 332 us• Max 432 us

– Conclusion• Should have plenty of time to control actuator at 125Hzcontrol

speed• 5 variables in sketch took 16% of available stack space

Microprocessor

• Serial Speed Analysis– Inputs

• Memory Requirements (64 bits of data in 0.002s)

– Output• 32,000 bits/s

– Conclusion- feasible baud rates:• 28400• 57600• 115200

RS-232

• Source a load cell that meets required specifications– Inputs

• 1500 lbf @ 500 Hz• No measurement phase lag• (+) and (-) force measurement capabilities• < $1000

– Output• PCB 1403-14A/084A100

– Conclusion• Exceeds all physical requirements• Need a discount or sponsor (> $1000)

Load Cell

Risk Assessment

• Emergency circuit breakers– Open enclosure door, verify the system stopped– Press emergency switch, verify the system stopped

• Sensor measurements – Force (give a known weight – get the reading) – Temperature (measure room temperature)– Position (command to move to a known distance –

measure)– Verify the measurements are within acceptable range

Test Plan

• Data collection speed (~250 Hz – 4ms period)– Collect data from the sensors and time taken

• Track frequency (~125 Hz – 8ms period)– Command the controller to move a period within 8 ms– Verify the frequency from sensor data

• Variable stroke range– Command the controller to vary the stroke range – Verify with the reading from linear potentiometer

• Data format– Verify .csv format in file system

Test Plan

• Replay track data– Use the data from .csv and produce graphs

• Sturdy base and mounting to withstand vibrations– Apply 100 lbs to top, measure deflection (<0.005in)

• Eye-to-eye distance/ overall footprint– Tape measurements

• Mobility– Customer judgement: 1 (zero mobility) – 10 (excellent

mobility)

Test Plan

Updated Project Plan

Questions?