Design and Prototype Build of the Interfaces of a Steer-By-Wire Assembly

Javier Angulo

Alan Benedict, Team Leader

Amber Russell, Team Manager

Kurush Savabi

Dr. Sohel Anwar, Faculty Advisor & Sponsor

Dr. Hazim El-Mounayri, Course Instructor

Overview

• Purpose & Objective

• Requirements & Targets

• Concept Generation & Evaluation

• Product Generation & Evaluation

• Conclusions & Recommendations

Introduction

Overall Purpose:

Create a steer-by-wire system parallel to that of an automobile for use in laboratory

Introduction (continued)

Driver Interface Sub-System

Microcontroller Sub-System

Rack-and-Pinion Sub-System

Overall Steer-By-Wire System

Objectives of Design

Objectives: Design of an interface between a standard automotive

rack-and-pinion steering assembly and electric motors.

Design of an interface between the same rack-and-pinion steering assembly and angle position sensors

Design of a stand to support the entire system and provide reaction forces to rack

Requirements and Targets

Functionality and safety Benchmark Visteon-GM Sequel

Requirements and Targets (continued)

Concept Development & Evaluation

Development ProcessDevelopment Process Functional Decomposition Function Concept-Mapping

Evaluation ProcessEvaluation Process Feasibility Testing Go/No-Go Screening Decision Matrices Failure Mode Effects Analysis (FMEA)

Final Concept

Motor to Rack-and-Pinion Interface Gear Train

Motor to Motor Interface Gear Train

Sensor to Sensor Interface Stackable Sensors / Shaft

Sensor to Rack and Pinion Interface Direct Shaft

Metal Stand Position Sensors

Stacked / Shaft

Rack

Motor

Motor Controllers

Gear Train

Motor

Pinion 1 Pinion 2

Product Generation & Evaluation

Motors Requirements Torque of 52 Nm at 67 rpm Torque of 20.8 Nm at 133 rpm Input voltage of <60 VDC

Selected Motor Specifications Torque of 52 Nm at 67 rpm Torque of 20.8 Nm at 127.4 rpm Input voltage of 75 VDC

Product Generation & Evaluation

Motor Interfaces Enables redundancy Allows for maintenance

Product Generation & Evaluation

Stand RequirementsMax deflection of 12.7mm

Max stress of 450MPa

Stand Analysis ResultsMax deflection of 1.83E-4mm

Max stress of 89.1MPa (Dynamic)

FOS 3 to 5 (267.3MPa to 445.5MPa)

Product Generation & Evaluation

Springs Spring Requirements of 102 kN/m Selected Spring Specifications of 83 kN/m Force of 6876 N (to simulate dynamic loading)

Maximum Stress = 104.6 MPa Yield Strength of Plate = 250 MPa

Product Generation & Evaluation

SensorsHollow-angle sensors Ease of interface Zero backlash Lack of availability Lower accuracy Requires less space

Conventional Potentiometers Meet accuracy requirement Readily available Cost efficient Requires gear train interface (backlash)

Final Design

Final Design (continued)

Engineering Requirements

Questions

For further questions, please feel free to ask the design team or refer to the project report. Thank you.

References

Cesiel, Daugherty, Gaunt, “Development of a Steer-by-Wire System for the GM Sequel”, SAE Technical Paper Series, 2006-01-1173.

David G. Ullman, “The mechanical design process”, Third edition, McGrawHill, 2003, USA.

“Delphi Non-Contact Multi-Turn Rotary Position Sensor”, Delphi, www.delphi.com.

“Electric Power Assisted Steering”, Visteon, 2005.

Matweb, www.matweb.com. March 2007.

Miller, Duane K., P.E., Use “Undermatching Weld Metal Where Advantageous: Practical Ideas for the Design Professional”, Welding Innovation, Vol. XIV, No. 1, 1997.

Parker Motion, www.parkermotion.com. April 2007.

Roy Mech, www.roymech.co.uk/useful_tables/form/weld_strength

“Sensors for Position Measurement: Single-turn/Multi-turn Steering-angle Sensor”, Hella International, www.hella.com.