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 DesignOverview

Electric 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 TotalMotor $ 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 TotalController $ 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 desiredat 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 5.8AhCost 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 $3124.40BMS 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 BudgetPart 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 directionSelection

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 $104.95U-Joints $28.00 2 $5.00 $61.00Rod Ends $12.14 4 $8.00 $56.56Tubing $27.83 1 $8.00 $35.83Hex 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 $372.20springs $45 4 10 $190shocks $675 4 20 $2720Wheel 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 DateResearch In ProgressPreliminary Design November 14, 2011Model November 30, 2011Determining final geometry December 7, 2011Connection to sprung mass December 14,2011Wheel Hub/spindle design December 20, 2011CAD compile January 15th 2011Final 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