Transcript Systems Design Review Presentation

MSD P15280
RIT HOT WHEELZ
TEST BENCH
AGENDA
❖Review Problem Definition Material
❖System Level Design Review
▪Functional Decomposition
▪Morphological Chart & Pugh Chart
▪Benchmarking
▪Concept Selection & Systems Architecture
▪Feasibility Analysis
▪Risk Assessment
▪Further Engineering Analysis Needed
PROJECT BACKGROUND
❖ The RIT Hot Wheelz Electric Vehicle Team is a group of
all female undergraduate engineers who come together to
form a team of innovative and creative race enthusiasts.
❖ The team seeks to enter the 2016 Formula Hybrid
competition in the Electric-only class.
❖ A test bench is needed to test the drivetrain of the vehicle
and ensure timely completion of the vehicle.
CUSTOMER REQUIREMENTS
PROJECT PLANNING
OPEN ITEMS FROM LAST REVIEW
❖ No existing design for Hot Wheelz electromechanical
drive system
➢ Working closely with Hot Wheelz team to understand
needs
❖ "Surrogate" customer
➢ Working well for us
❖ Interdependence between MSD team and Hot Wheelz
➢ Resolving issues as they arise and planning for future
conflicts
❖ Budget unclear
➢ Working with customer
to finalize budget
Estimated Budget
Labview Software
$3,000.00
Electrical Components
$3,000.00
Motor
$2,000.00
Powertrain Test Bench
Bench Components
$700.00
Mounting Hardware
$500.00
Powertrain to Bench Connection
$300.00
TOTAL
9,500.00
Functional Decomposition
Pugh Chart
PUGH CHART
BENCHMARKING- Dyno Visit
❖ Visit provided insight into loading mechanisms
➢ Eddy Current Brake
➢ Generator - Resistor Bank
❖ Sample GUI
➢ Easy to view dials
➢ Large window to view results
❖ Example of safety precautions
➢ Straps, fans, ventilation
❖ Output data as Excel file
BENCHMARKING- Example Test Benches
❖ Speed Control Test Bench (Left)
➢ Allows the study of the operation of a servodrive
when a variety of loads are applied to the motor.
➢ Powder Brake to vary motor load
➢ Main Components:
■ Motor Voltage
■ Motor Temperature
■ Load amount and type
❖ Motor Test Bench (Below)
➢ Robust, multi-compatible
➢ Flexibility through modular design
➢ Motor Torque, Power & Efficiency
SELECTED CONCEPT- MECHANICAL
❖ Two mechanical
structures
➢ Mobile Cart to mimic Hot
Wheelz Chassis
➢ Enclosed T-framed
structure to house motors
and moving parts
➢ UI will be located on top
of the T-framed
enclosure.
➢ All pieces are portable
and compact
Above: Preliminary CAD model of a 36in by 30in T-slot
aluminum framing enclosure with two removable
plexiglass panels for access and electrical attachment.
Selected Concept - Electrical
User Interface
MCU
Sensors
Loading Mechanism
Hot Wheelz System
ELECTRICAL FEASIBILITY ANALYSIS
❖ How often will the tach counter need to be polled to avoid aliasing?
➢ max speed=4,500 rpm=75 rev/sec = Nyquist Rate of 150 Hz
➢ microcontroller will need to handle a count rate of 150 counts/second
➢ tach counter will need to be polled at a frequency greater than 150 Hz
➢ A frequency of 150 Hz should be no problem considering MCU can run up
to 15MHz
❖ How close to real time can the data from the sensors be displayed on
screen?
➢ Assuming uC clock runs at 15MHz -> 66.6ns/cycle
➢ Assuming max sample rate of 10us/sample
➢ Max clock cycles to obtain sample = less than 100
➢ Max clock cycles to send data to computer = less than 100
➢ Assuming baud rate of 115,200 bits/second
➢ Assumption that computer side delay is negligible
➢ Total time = (2x100x66.6x10^-9)+(12bits)(1/115200)+(10x10^-6) = 127us
delay
❖
MECHANICAL FEASIBILITY ANALYSIS- Load
Determine Track RequirementsCalculations
(New Hampshire Motor Speedway)
➢ Longest Straightaway 77m
➢ Hairpin Turn- Minimum 9m Diameter
➢ Constant Turn- Minimum Diameter 30m
➢ Drag Race- 75m
❖ Determine Approximate Speeds and Acceleration Rates
➢ Max Endurance/Autocross Speed of 65-70MPH
➢ Hairpin Turns 10-15MPH (~1G)
➢ Constant Turns 25-30MPH(~1G)
➢ Drag Race 75MPH (~1.5G)
❖ Estimated Vehicle Parameters
➢ Mass = 340kg
➢ Wheel Diameter = 23 inches = 0.5842m
➢ Friction Coefficient = 0.90
➢ Drag Coefficient =0.95
➢ Grade Angle = 4 degrees
MECHANICAL FEASIBILITY ANALYSIS- Load
Calculations
MECHANICAL FEASIBILITY ANALYSIS
❖ Potential Hot Wheelz Motor Specs
➢ 250 Nm → 2500 RPM
❖ Proposed Test Bench Load Varying Motor
➢ 125 Nm → 5000 RPM
❖ 2:1 Gear Ratio Between Test Bench and Hot
Wheelz Motor
Test Bench:
2 X RPM
½ X Torque
Hot Wheelz Motor:
½ X RPM
2 X Torque
MECHANICAL FEASIBILITY ANALYSIS
❖ Hot Wheelz Motor ~ $11,000
❖ Proposed Test Bench Motor $ 2,500 → Within Test Bench Budget
❖ Will be able to vary loads similar to:
➢ Endurance Race Conditions
➢ Long Runs
➢ Most Autocross Race Conditions
❖ Will not be able to vary loads similar to:
➢ Drag Race
➢ Max Acceleration
❖ Still allows for testing most scenarios, check for safety, tune and debugging
Golisano Institute of Sustainability (GIS)
Dynamometer vs. Hot Wheelz Test Bench
Using the Existing GIS Dyno
Pros:
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Cons:
Capabilities: the machine already exists and has the
capabilities that we need.
Cost: we would not need to build a load varying system
at all.
Complexity: ensures project will be completed in one
senior design session.
Testing/Calibrating: decrease in magnitude of systems
to test and calibrate.
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Availability of the Dyno: we would have to work by the
schedule of the dyno to run testing and to work out
integration issues.
Location: drive system would have to be transported to
dyno to run testing.
Interface with dyno: concrete existing hardware and
software, no flexibility; also would have to create partial
chassis to allow testing.
Using a Test Bench of Our Own Design and Construction
Pros:
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Cons:
Convenience: custom tailored to our specific need
Expandability: bench would be an investment for future
HW team vehicles.
Availability: ability to use the device when needed
without prior scheduling and arranging
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Cost: expensive to source a load varying device
Timeframe: difficulty in adhering to strict schedule if
problems arise
Testing/Calibrating: increase in magnitude of systems to
test and calibrate.
GIS Dynamometer vs. Hot Wheelz Test Bench
❖ Compromise between budget and load variance
❖ Test bench will have limited capabilities
❖ Max Load Testing will be done at GIS Dyno
RISK ASSESSMENT
Scale: 1 - 3 - 9
RISK ASSESSMENT
Scale: 1 - 3 - 9
ENGINEERING ANALYSIS NEEDED
❖ Mechanical
➢ Safety Calculations
■ Moving Objects
➢ Connection of Test Bench Motor to Vehicle Motor
➢ Structural Integrity Analysis
➢ Cooling Solutions for Motor
■ Make vs. Buy Cost Analysis
❖ Electrical
➢ Control power dissipation method
➢ System Integration - Whether the test bench will communicate with Hot
Wheelz electrical system to obtain results from its sensors
QUESTIONS?
FEEDBACK?