milestone 2: project proposal e.e advisor : dr. li m.e. advisor : dr. shih team members: tomas bacci...
TRANSCRIPT
Milestone 2: Project Proposal
E.E Advisor : Dr. Li M.E. Advisor : Dr. Shih
Team Members: Tomas BacciDanny Covyeau Scott HillStephen KempinskiGeorge NimickSam Risberg
Proposed Design
OverviewElectric Category Mechanical – braking, chassis, suspension and
steering Electrical – motor design and battery management
Direction Feasibility, tangibility, and budget
Constraints Budget, rules
University of Texas, ArlingtonNearly every vehicle from 1984 - 2008
Project Management
ME Systems ME Leader – George
Nimick
Chassis – George Nimick and Sam Risberg
Braking – Sam Risberg
FEA – George Nimick and Tomas Bacci
Steering and Suspension – Stephen Kempinski and Tomas Bacci
EE Systems EE Leader – Scott Hill
Motor Control and Design – Danny Covyeau
Battery Management and Accumulator Design - Scott Hill
EE Top-Level Diagram
Propulsion/Motor Design
Propulsion 4 electric motors, one on each wheel.
Mounted onboard the vehicle (i.e. not ‘in-wheel’ or ‘hub’ motors) Each motor will have its own gear reduction so as to limit the top speed
of the vehicle as well as increase the mechanical torque.
2 motor controllers, 2 motors per controller 1 controller for two front motors 1 controller for two rear motors Motors will be wired in a series configuration
2 HV battery packs, 1 per controller Will help distribute the weight evenly between the front and rear of the
vehicle.
Why AWD? Traction at all four wheels Cornering Stability Load Transfer
Deceleration Regenerative Braking Advantage
Acceleration AWD biased towards the
rear wheels
Formula SAE Dynamic Events Autocross
Average Speed: 25 – 30 mph
Endurance Average Speed: 29.8 – 35.4 mph
For more information see: http://autopedia.com/stuttgart-west/Physics/StuttPhysics01.html
http://www.motortrend.com/roadtests/sedans/112_0506_front_rear_allwheel_drive/viewall.html
Electric Drive
The electric motors must work with one another in such a way to safely, efficiently and quickly propel the vehicle.
The motors should all be the same make and model to simplify the design.
Item Cost Quantity Shipping Total
Motor $ 1595.00 3 $ 130.00 $ 4915.00
Electric Motors
Robotmarketplace.com
Agni 95-R Permanent Magnet 72 VDC 400 Amp peak 93% Peak Efficiency 30 peak horsepower Only 24 lbs 6000 rpm max
rotational speed
Motor Controllers The motor controllers should be able to
control two motors in series simultaneously Regenerative Braking built-in The motor controller selected should be
specifically built for the type of motor chosen (i.e. ac induction, series dc, etc).
It should be able to handle at least twice the rated voltage of the motor and the same maximum current of the motor.
Cloudelectric.com
Item Cost Quantity Shipping Total
Controller $ 1300.00 2 $ 60.00 $ 2660.00
Motor Control System The motor control system will consist of two permanent magnet motor
controllers. One will control the front motors while the other will control the rear motors. The motors in the front/back will be connected in a series configuration such
that a single controller can operate both motors simultaneously. This will not only simplify the design but will also create somewhat of a differential-like
effect for the front and rear.
Separate battery packs One in the front and one in the rear to help create a better weight balance
between the front and rear. These packs will be wired in parallel with one another to maintain a constant
potential difference between the front and rear controllers and so that there is a common ground.
Throttle Control The throttle should directly affect the vehicles speed
and/or torque. Theory:
Accelerator pedal called a pot box or potentiometer box.
Sends an analog signal to the ECU. The ECU will then plug this signal, along with signals
from each motors RPM sensor, the brake pedal, and other sensors into an algorithm that will determine what analog values to send to both the front and rear motor controllers.
The front and rear controllers will receive different signals depending on the
amount of torque desired
at either end.
Cloudelectric.com
Battery Management/Accumulators
Accumulator
Lithium Polymer Batteries Voltage Per Cell : 3.7V
Desired Pack Configuration: 3S String with 11.1V per pack Chosen because desired voltage for each motor controller is
144V and in series it takes almost exactly 13 batteries to achieve this voltage
Due to competition rules (fusing parallel connections) the team cannot easily use packs that are internally wired in parallel. Therefore packs such as 3s2p that would achieve higher than 8Ah per pack cannot be used.
Picture Courtesy Danny Covyeau
Hobbyking.com
Battery Characteristics Maximum Capacity : 5,400 Wh
With a voltage of 144V current capacity of 37.5Ah is required to be at the maximum
This is before efficiency is taken into account though so a current capacity of 40Ah will be used.
With a current capacity of 40Ah our vehicle will require a total of 8 parallel strings if 5Ah batteries are used.
If 5.8Ah batteries are used the we could get away with 7 parallel strings, This would save us 13 batteries!
Battery Capacity 5 Ah 5.8Ah
Cost Each* ~$28.08 ~$36.97
Total Batteries Needed
104 91
Total Cost of Batteries
~$2920.32 ~$3364.27*Prices based off of hobby kingRetail website
Battery Discharge Simulation
Simulation Schematic 13s8p configuration(actually 39s8p configuration with 3s packs)
Battery DischargeSimulation (Cont).Simulation with a 5Ω Resistive Load Without SOC Measurement
Voltage Reading Current Reading
Operating Region
Capacitors
Capacitors are being considered for the vehicle in order to take advantage of regenerative braking function included in the controller Danny talked about previously.
According to the Formula Hybrid SAE 2012 Competition Rules “Endurance courses will be configured, where possible, in a manner which maximizes the advantage of regenerative braking.”
Picture Courtesy Danny Covyeau
Battery Management System
The 2009-2010 teams car used a e-lithion Lithiumate pro BMS.
To our knowledge the BMS is working and will be used in the 2011 car for purposes of budget
More research needs to be done on the on the Cell boards
BMS Master
Cell Board
Elithion.comPicture taken from 2009-2010 Car
Battery Charging System The battery charging system for this years team will
need to be much larger than last years since the vehicle is fully electric
The proposed charger is the “Battery Charger HWC4 Series Charger High Output 144V/15A 220VAC Input”
This charger also has a variable charge mode if battery configuration needs to be changed in the case of a large failure in the accumulator system
Cloudelectric.com
PLCcenter.com
Accumulator Enclosure A clear polycarbonate insulating material will be
used to construct the accumulator enclosure This material will allow for easy inspection at the
competition This material allows proper insulation of the HV
accumulator and the frame of the vehicle
TapPlastics.comNewegg.com
Accumulator System Budget
Item Quantity Price Per
Shipping
Total Cost
Batteries 108 $28.08 ~$100 $3124.40
BMS Master 1* $413 ~$25 $428
BMS Cell Board**
TBD TBD TBD >$500
Battery Charger
1 $700 ~$25 $725
Accumulator Enclosure
1 $75 ~$20 $95
Total >$4872
*Already Have 1 BMSmaster from 2009-2010 Team (Need 2 total)
** Company Needs to be contacted for pricing
TimelineNov 1 Dec
1 Jan 1
Feb 1
Mar 1
ME Top-Level Diagram
Chassis
Constructing the chassis
Strong Enclosure and component platform
The chassis will house the driver and a strong enclosure is required to ensure safety
The chassis will not only need to be aerodynamics, but should have a ideal weight distribution and center of gravity
Perform FEA
Chassis Ergonomics Mounting for:
Brakes Suspension Motors Driver accommodations Safety equipment mounting Steering Body panels Batteries
Chassis Budget
Part Name: Cost Quantity Shipping Total
Sheet metal (Al) $ 284.80 3.00
$ 25.00
$ 879.40
Structural tubing $ 53.11 25.00
$ 50.00
$ 1377.75
Conduit $ 3.00 100.00
$ 40.00
$ 340.00
Honeycomb (Al) $ 250.00 2.00
$ 15.00
$ 515.00
Total: $ 3112.15
Chassis Timeline
Steering
speedwaymotors.com
SteeringGoal
Control direction
Selection Mechanical (Rules) Less than 7 degrees
of free play Choices: rack and
pinion, recirculating ball, worm and sector, articulated steering and four wheel steering
Constraints Effectiveness Practicality Cost
Choice: Rack and Pinion
Installation Non-binding Driver operation Steering shaft
Steering Timeline
Estimated Budget for Steering
Item Cost Qty.
Shipping
Total
Steering Wheel $192.02
1 $15.00 $207.02
Steering Quick Release
$129.99
1 $4.00 $133.99
Rack and Pinion $96.95 1 $8.00 $104.95
U-Joints $28.00 2 $5.00 $61.00
Rod Ends $12.14 4 $8.00 $56.56
Tubing $27.83 1 $8.00 $35.83
Hex Stock $17.95 1 $2.00 $19.95
Total: $619.30
Braking
Braking system
Single control to ensure safe stop on four wheels -We will have one pedal acting on four wheels -A master cylinder will multiply the pedal force into a
hydraulic force
Two independent hydraulic circuits One circuit will control the rear wheel braking the other
the front This will ensure if one circuit fail another will be in place Safety will be the main concern for this system
Braking Continued
Brake line Durability We won’t be using a factory rubber brake line Stainless Steel braided line will prove more durable for
racing situations and heat produced from the extreme conditions
Testing the brakes To test the systems we will apply maximum pressure to
the brake pedal at a high speed and ensure all four wheels lock up as stated in the FSAE Hybrid rules.
Braking System Budget
Part Name: Cost Quantity Shipping Total
Brake Lines (Steel Braided) $ 52.32 6.00 $ 5.00
$ 318.92
Brake Fluid $ 19.99 1.00 $ -
$ 19.99
Brake Caliper $ 37.94 4.00 $ 10.00
$ 161.76
Brake Rotor and pads $ 215.68 4.00 $ 10.00
$ 872.72
Total: $1373.39
Braking timeline
Suspension
Competition Constraints 3.2.1 Suspension fully operational suspension system with shock
absorbers, front and rear usable wheel travel of at least 50.8 mm (2 inches),
25.4 mm (1 inch) jounce and 25.4 mm (1 inch) rebound, with driver seated.
3.2.2 Ground Clearance with the driver aboard there must be a minimum of
25.4 mm (1 inch) of static ground clearance under the complete car at all times.
Competition Constraints
Continued… 3.2.3 Wheels and Tires 3.2.3.1 Wheels The wheels of the car must be 203.2 mm (8.0 inches) or
more in diameter. 3.2.3.2 Tires Vehicles may have two types of tires as follows: Dry Tires – The tires on the vehicle when it is presented
for technical inspection are defined as its “Dry Tires”. The dry tires may be any size or type. They may be slicks or treaded.
Rain Tires – Rain tires may be any size or type of treaded or grooved tire provided:
Understanding Vehicle Dynamics Weight transfer – actual movement of the vehicle CoM relative to the wheel
axes due to displacement of the chassis as the suspension complies.
Downforce - downwards thrust created by the aerodynamic characteristics of a car.
Roll center - the notional point at which the cornering forces in the suspension are reacted to the vehicle chassis/body.
Camber – angle of the wheel relative to vertical.
Caster – angle to which the steering pivot axis is tilted forward or rearward from vertical
Toe – angle that each wheel makes with the longitudinal axis of the vehicle
Pitch - front and rear of the chassis go in opposite directions.
Yaw - rotation of the car in a horizontal plane around a vertical axis.
Heave - movement of the diagonally opposed wheels in opposite directions
Set up accuracy
Dependent on: Springs Shocks Camber Caster Toe Tire pressure Ride height Wings
Independent Suspension
Better ride quality Improved handling fully adjustable
SLA Double Wishbone
Short Long Arm Suspension
Lower A-Arm is longer than the Upper A-Arm
Reduced changes in camber angles
Reduces tire wear Increases contact patch
for improved traction
Connection to Sprung Mass
Predetermined geometry points
Chassis may be modified to accommodate
Mounting brackets welded to chassis
Connection to un-sprung mass
Spindle design Regenerative Brake
assembly Steering connection Wheel hub and
bearing Wheels/Tires
Connection to un-sprung mass
Continued
Push rod, spring, damper
A push rod will transfer suspension forces to coil-overs mounted to the chassis-Reduces amount of un-sprung weight
as the springs and shocks move in-board
-Spring compression rate can be controlled with a bell crank
-Increased aerodynamics for open wheel application
Linkage will be set up so as wheel travel increases, the rod will come closer to a 90 degree angle with the shock absorbers, increasing the efficiency of the shocks- Suspension stiffens with wheel travel
A bell crank can allow you to place shocks horizontally if needed
Push rod, spring, damper Continued
Test Plan
Observe Measure Analyze Simulation Predict changes Improve performance
Suspension - BudgetPart cost quantit
yshipping total
Aluminum Block
$324.85 1 20 $344.85
Rod ends $12.14 32 8 $372.20
springs $45 4 10 $190
shocks $675 4 20 $2720
Wheel Hub
34.99 4 15 154.96
Aluminum Block
$323.85 1 20 $343.85
4130-steel tubing
53.11 10 25 $556.10
Total $4671.96
Suspension-time lineObjective Completion Date
Research In Progress
Preliminary Design November 14, 2011
Model November 30, 2011
Determining final geometry December 7, 2011
Connection to sprung mass December 14,2011
Wheel Hub/spindle design December 20, 2011
CAD compile January 15th 2011
Final Product Build March 15st 2012
Risk Assessment
Risks associated with our design include: Individual Component Failure Unresolved Options in Design Sick Team Member(s) 2012 Formula Hybrid Rules Document Non-compliance Budget Miscalculation
Important Project DeadlinesSenior Design
Milestone 3: Conceptual Design Review 11/14/11
Competition Registration Deadline (completed) 10/04/11 Competition forms
Structural Equivalency Form 01/30/12Impact Attenuator Data 02/27/12Design Report & Spec Sheet s 04/09/12
The 2012 Formula Hybrid Competition begins April 30th 2012.
Date due
EE Budget
Proposal
ME Budget ProposalPart Name: Cost Quantity Shipping Total
Penske Shocks $ 675.00 4.00
$ 20.00
$ 2,720.00
Suspension springs $ 45.00 4.00
$ 10.00
$ 190.00
Hoosier Tires (Dry) $ 208.00 5.00
$ 35.00
$ 1,075.00
Hoosier Tires (Wet) $ 213.00 5.00
$ 35.00
$ 1,100.00
Rims $ 113.00 10.00
$ 70.00
$ 1,200.00
Rod Ends $ 12.14 30.00
$ 8.00
$ 372.20
Brake Lines (Steel Braided) $ 52.32 6.00
$ 5.00
$ 318.92
Brake Fluid $ 19.99 1.00
$ -
$ 19.99
Brake Caliper $ 37.94 4.00
$ 10.00
$ 161.76
Brake Rotor and pads $ 215.68 4.00
$ 10.00
$ 872.72
Wheel Hubs $ 34.99 4.00
$ 15.00
$ 154.96
Rack and pinion $ 96.95 1.00
$ 8.00
$ 104.95
Steering wheel $ 192.02 1.00
$ 15.00
$ 207.02
Steering wheel quick release
$ 129.99 1.00
$ 4.00
$ 133.99
Block of Aluminum $ 323.85 1.00
$ 20.00
$ 343.85
Sheet metal (Al) $ 284.80 3.00
$ 25.00
$ 879.40
CV Axle $ 72.78 4.00
$ 15.00
$ 306.12
Sheet metal seat $ 115.95 1.00
$ 15.00
$ 130.95
Total: $10,291.83
Joint Budget Proposal
**The Total Direct Costs is the actual cost of the project since expenses such as personnel and fringe benefit costs are not actually being paid.
References http://www.carbibles.com/suspension_bible.html http://cmrr.ucsd.edu/people/talke/documents/
Fornace_Thesis_8_31_06.pdf http://formula-hybrid.org/pdf/Formula-Hybrid-2012-
Rules.pdf http://www.m3post.com/forums/showthread.php?t=346660 http://robotmarketplace.com http://cloudelectric.com http://hobbyking.com http://elithion.com http://plccenter.com http://newegg.com http://tapplastic.com http://speedwaymotors.com