Four Wheel Steering Systems (4WS)

Four Wheel Steering Systems (4WS)

M.Viswanatp , S Richard Tharma2, M Vetrivelchozhan2 , J Hamton Raj2

1-Associate Professor, 2-UG Scholar Department of Mechanical Engineering,

Hindusthan Institute of Technology, Coimbatore-32

Abstract:- This paper is all about 4-wheel steering system rather than 2-wheel steering as in conventionalvehicles running in INDIA. A 4-wheel steering is completely different from a 4-wheel drive (in which each wheel is given power rather than to 2 wheels). A 4-wheel steering system is superior to a 2- wheel steering system. It reduces the turning radius as well as the space required for turning. It also enables to change road lane while driving even at high speed. This paper is under research in a university of Egypt. In this project we want to develop an electric carwith the wheelrotation up to 90º for the cause the parking problem faced in metro cities. This car will be a special utility vehicle which can run on 2-wheel steering as well as on 4-wheel steering.

1. INTRODUCTION

   Four-wheel steering (or all wheel steering) is a system employed by some vehicles to improve steering response, increase vehicle stability while maneuvering at high speed, orto decrease turning radius at low speed.

   In most active four-wheel steering systems, the rear wheels are steered by a computer and actuators. The rear wheels generally cannot turn as far as the front wheels. Some systems, including Delphis Quadra steer and the systemin Hondas Prelude line, allow for the rear wheelsto be steered in the opposite direction as the front wheels duringlowspeeds.

   Thisallowsthe

   vehicle to turn in a significantly smaller radius, sometimes critical for large trucks or vehicles with trailers. An electronic four-wheel steer system is an option available on the JCB Fastrac.

2. HISTORY

Four wheel steering is a system that allows the rear wheels to turn for maneuvering, ratherthan just follow the front wheels. 4WS isnt new;you might remember it as an option on HondaPreludes in the late1980s and early 1990s.

FEATURES OF THE FOUR WHEEL STEERING SYSTEM

The Four Wheel steering system offers a 21% reduction in turning radius. So if a vehicle is is capable of making a U- turn in a 25-foot space. space. It allows the driver to do it in about 20 feet. A front wheel active steering function was added to Rear Active Steer adopted on the Fuga. By controlling the steering angle of all four wheels, this active steering system helps improve stability and response at high speed and helps reduce drivers steering workload at low speed. To achieve precise vehicle.

Medium speed

(40 km/h to 80 km/h) Driving in urban areas and on major roads

Vehicle moves stably in the desired direction and turning is smooth, as the front wheels movewith less steering wheel motion, and the back wheels turn in the same direction

High speed

(over 80 km/h) Express- ways, etc.

As the speed of the ve- hicle increases, the turning angle of the front wheels decreases, and the back wheels turn in the same direction as the front, enabling the vehicle to be driven stably even when changinglanes.

Low speed

(10 km/h to 40 km/h) Turning in resi- dential and parking areas

Turning is easier, as the front wheels move with less steering wheel motion.

RECENT APPLICATION

Four-wheel steering found its most widespread use in monster trucks, where maneuverability in small arenas is critical, and it is also popular in large farm vehicles and trucks.

General Motors offers Delphis Quadra steer in their consumer Silverado/Sierra and Suburban/Yukon. However, only 16,500 vehicles have been sold with this system since its introduction in 2002 through 2004. Due to this low demand, GM will not offer the technology on the 2007 update to these vehicles.

Previously, Honda had four-wheel steering as an option in their 1987-2000 Prelude, and Mazda also offered four- wheel steering on the 626 and MX6 in 1988.

A new Active Drive system is introduced on the 2008 version of the Renault Laguna line. It was designed as one of several measures to increase security and stability. The Active Drive should lower the effects of under steer and decrease the chances of spinning by diverting part of the G- forces generated in a turn from the front to the rear tires. At low speeds the turning circle can be tightened so parking and maneuvering is easier.

NEW ACTIVE DRIVE WITH FOUR-WHEEL STEERING FOR NEW RENAULT LAGUNA GT AT GENEVA MOTOR SHOW:

• New high-performance GT versions of New Laguna Hatch and Sport Tourer available to order in the UK from 9 May 2008

• Featuring innovative Active Drive chassis with four- wheel steering for the ultimate in handling and response

• Exclusively available with 205hp two-litre turbo petrol engine or 180hp two-litre turbo diesel both making their debut in New Laguna

FOUR WHEEL STEERING ARRANGEMENT

Steering input is fed into the system through the steering wheel.

Steering gear multiplies the steering effort applied to the steering wheel by the driver. It also converts the turning motion of the steering wheel into a linear motion.

REFERENCES:

[1] Alter David Law (1989), Alex. Transient Steady State Performance Comparison of Two-Wheel Steering and Four- Wheel Steering Vehicles,Quadra steer 2.0. MazdaTetraCOM.

[2] At Geneva Motor Show, New Active Drive with Four-Wheel Steering for New Renault Laguna GT, 12:45 PM on Fri Feb. 22, 2008

[3] Brabec P, Maly M and Vozenílek R (2004), Control system of Vehicle model with four wheel steering (4WS), An International Journal, 04. 06.10.2004.

[4] Gene Liao Y and Isaac Du H (2003), Modeling and analysis of electric powersteering system and its effect on vehicle dynamic behavior, International Journal of Vehicle Autonomous Systems, Vol. 1, No. 2/2003, pp. 153-166.

[5] http://mazda.tetracom.net/4ws.htm

[6] http://www.pickuptruck.com/html/stori es/qs420/page1.html Mark Denny (2005), The dynamics of antilockbrakesystems, Print publication: Issue 6 (November 2005), Received 4 April 2005, in final form 8 June2005, Published 8August 2005.

[7] Masao Nagai (1991), Stability of 4ws Vehicle Based on Side Slip Zeroing Control: Influence of Steering System Dynamics, Document Number: 912564, Date Published: November 1991.

[8] Three dimensional modeling and dynamic analysis of four- wheel- steering vehicles, Journal Acta Mechenica Sinica, Publisher: Springer Berlin / Heidelberg, Issue, pp. 79-88, Vol. 19, No. 1, February 2003.

[9] Wellstead P E and Pettit N B O L (1994- 2006), Analysis and redesign of an antilock brake system controller, Journal Title- IEE proceedings. Control theory and applications ISSN 1350- 2379, Institution of Electrical Engineers, Steven age, ROYAUME-UNI (1994 -2006 ) (Revue).

[10] www.engr.uvic.ca/~forum/2004/abstra cts/ David%20Cruz%20Dec%202004.pdf.