Formula Society of Automotive Engineers University of Delaware FSAE

Team Driver Controls

BACKGROUND INFORMATION Sponsor Background: The student chapter of the Society of Automotive Engineers was established at the University of Delaware with the intent of competing in annual Formula SAE events nationwide. The expectation of each student team is to design, build and test a prototype based on a series of rules, whose purpose is both ensuring on-track safety and promoting clever problem solving. In recent years, the University of Delaware FSAE team has not succeeded in building a car that passed all prerequisite safety and performance tests. As a result, the Mechanical Engineering Department has integrated the FSAE club into Senior Design in order to invest more resources and time into the program.

Project Goal and Scope: The primary goal of the Driver Controls Team is to develop, design and fabricate all of the necessary control and input systems required to safely and effectively operate the Formula car successfully in all of the driven events while meeting the criteria for safety, cost and ease of operation. In particular, the subsystems involved in this project are: 1. Steering Assembly 2. Pedal Box Assembly – includes adjustable pedal cluster and remotely adjustable brake bias 3. Shifting Assembly 4. Data Acquisition System – existing system will be used and will therefore not need to be designed. Instead it will need to

be understood and used to collect accurate information

Ryan Derrig, Michael Hospod, Michael Incontrera, Michael Williams

DESIGN JUSTIFICATION Each subsystem within the given scope met or surpassed every target value for each metric, as well as successfully proved to be the optimal design based on the allotted time and resources. This project will help the UD SAE team build a competitive car for the 2011 FSAE national event and hopefully provide the backbone for future competitions.

System Cost Steering $317.95

Shifting $476.12 Pedal Box $151.24 Data Acquisition $ -

TOTAL PROJECT COST: $945.31

PROJECT COST

SYSTEM VALIDATION

Testing the steering system is a very

basic, but accurate procedure. In order to test the steering wheel travel angle, the driver sat in the driver seat and measured, with a protractor, how far the steering wheel turned before the wheels responded To test the force to turn the steering wheel, a simple spring scale was used to measure the force it takes to pull the wheel straight down for a quarter of a turn in both directions. Finally, to measure the weight of the system, the system was simply placed on a scale to make sure it remained under the given metric.

SYSTEM VALIDATION In order to ensure the shifting system is safe and successful, it must be tested against its given metrics. A test was run in which the system was shifted 5,000 times to ensure it can withstand its target value before failing. Furthermore, the total area of the paddles was calculated to confirm that it was at least 2 in2 and the system was weighed to be under 6 lbs.

Metric Target Value Actual

Stiffness Total deflection < .125” < .125”

Range of Motion

9-12° on clutch 8-10° on brake

20-25° on accelerator

12° 10° 25°

Overall Adjustability > 6” 5”

Precision of Adjustability > ½” increments Unlimited

Weight 6 lbs. 5.9 lbs.

Pedal Height > 5” 7”

Cost < $175.00 $151.24

PEDAL BOX PERFORMANCE METRICS

Metric Target Value Actual

Angle of

Travel

< 7° (total) 2°

Force to Turn < ½ lbs. .45 lbs.

Weight < 8lbs. 7.5 lbs.

Cost < $325.00 $317.95

STEERING PERFORMANCE METRICS

Element Description Advantage

Steering Rack

Woodhaven Industries 12:1

Steering Rack

Significantly reduces slop, or the freedom of play in the system, and aids to driver ergonomics

Universal Joint Forged U-Joint Results in a low-slop, highly responsive system

Lower Mount Steel Tube welded to floor support at 45° angle

Prevents the rack from wear and locking up

KEY COMPONENTS The steering system consists of multiple components that all affect the driver’s ability to control the car.

Metric Target Value Actual

Reliability > 5000 shifts 5000

Interface Area > 2 in2/hand 3 in2

Weight < 6 lbs. 5.8 lbs.

Cost < $500.00 $476.12

SHIFTING PERFORMANCE METRICS

Element Description Advantage

Electric Actuator

Pingel Actuator capable of 30lbs. of

force

Unlimited number of allowed shifts Simple Connection

Rotary Switches

Sprint Return Momentary Switches

Allows actuator to extend or retract

Controller

Pingel Controller two MOSFET transistors

Prevents driver from shifting more than once per second

Paddles 6061 Aluminum Plates

Ergonomically sound technique of shifting

KEY COMPONENTS The shifting system benefits driver ergonomics and increases the overall performance of the car.

SYSTEM VALIDATION To test the overall deflection two people applied as much force as they could to the pedal frame if any noticeable deflection was detected visually the system would have been considered to fail. This test procedure was recommended by an FSAE design judge. The range of motion of the pedals were measured using a protractor to obtain optimum driver comfort. Overall adjustability was measured simply using a ruler, and the final weight of the system was calculated using a scale.

KEY COMPONENTS The data acquisition system contains many components that aid to driver ergonomics and safety.

Element Description Advantage

Brake

Pressure Sensors

Records magnitude

and speed of the brake pressure change

Records pressure required to lock the brakes

Steering

Angle Sensor

Determines how the driver is

handling the car

Determines if car is being understeered or oversteered

PEDAL BOX ASSEMBLY STEERING ASSEMBLY SHIFTING ASSEMBLY

DATA ACQUISITION SYSTEM

KEY COMPONENTS The pedal box system contains many components that aid to driver ergonomics and safety.

Element Description Advantage

Lead Screw System

Steel Threaded Rod

Firmly hold pedal box rigid and allow for adjustability

Brake Bias

Remotely Adjustable

Allows driver to adjust front and rear brake bias from seat

Frame 6061 Aluminum Square Tubing

Extremely stiff framework resulting in minimal system deflection

SYSTEM VALIDATION The data acquisition system will be considered successful if it is both positioned correctly according to a 95th percentile male and records correct, accurate values for the team to analyze.

Yield Strength 6.2053e+007 N/m2

Tensile Strength 1.25e+008 N/m2

Factor of Safety 1.7