IJIRST –International Journal for Innovative Research in Science & Technology| Volume 2 | Issue 12 | May 2016 ISSN (online): 2349-6010 All rights reserved by www.ijirst.org 81 Dual Mode Four Wheel Steering System Sanu Adolphus Sooraj Abraham UG Student UG Student Department of Mechanical Engineering Department of Mechanical Engineering Saintgits College of Engineering, Kottayam, Kerala Saintgits College of Engineering, Kottayam, Kerala Justin T Martin Nikhil Sasikumaran Nair UG Student UG Student Department of Mechanical Engineering Department of Mechanical Engineering Saintgits College of Engineering, Kottayam, Kerala Saintgits College of Engineering, Kottayam, Kerala Liju Mathew Alexander Assistant.Professor Department of Mechanical Engineering Saintgits College of Engineering, Kottayam, Kerala Abstract Two wheel steering mechanism used in common vehicles are having a high turning radius and also difficult in high speed maneuvering. This results in low stability. The four wheel steering mechanism currently used in heavy vehicles, which drives the rear wheels at a same angle as that of the front wheels may result in over steer. So this cannot be implemented in light vehicles. An innovative four wheel steering mechanism which rectifies the above mentioned drawbacks are proposed which serves as our project work. In this steering mechanism the rear wheels are not actually following the front wheels, but turns at a specific ratio. There are two modes of steering mechanism that is for low speed and high speed. At slow speeds, the rear wheels turn in opposite direction of the front wheels. At faster speeds, the rear wheels turn in the same direction as that of front wheels. This steering mechanism improves steering response, increase vehicle stability, improves control etc. In situations like low speed cornering, vehicle parking and driving in city conditions with heavy traffic in tight spaces becomes easy, this is because of rear wheel turn in opposite direction to front wheel. At high speed it increases vehicle stability while maneuvering at and lane changing. Keywords: Steering Mechanism, Wheel Steering Mechanism, Turning Radius, Vehicle Stability _______________________________________________________________________________________________________ I. INTRODUCTION Four Wheel Steering System is employed in vehicles to achieve better maneuverability at high speeds, reducing the turning circle radius of the car and to reduce the driver’s steering effort. In most active 4 wheel steering system, the guiding computer or electronic equipment play a major role, in our project we have tried to keep the mechanism as much economical as possible. This project focuses on a mechanically feasible and innovative design involving an arduino circuit board and quadra coupler. Quadra coupler attached to steering column to sense the rotation of steering and given to arduino circuit board, the output from arduino circuit board is given to a dc motor with 2 reduction . The dc motor direct the rear wheel, by a simple chain drive. At slow speeds rear wheels turn in direction opposite to that of front wheels. This mode is used for navigating through hilly areas and in congested city where better cornering is required for U turn and tight streets with low turning circle which can be reduced . Also more capable for parking .At High Speeds, turning the rear wheels through an angle opposite to front wheels might lead to vehicle instability and is thus unsuitable. Hence the rear wheels are turned in the same direction of front wheels in four- wheel steering systems. Four Wheel Steering System Four-wheel steering, 4WS, also called rear-wheel steering or all-wheel steering, provides a means to actively steer the rear wheels during turning maneuvers. It should not be confused with four-wheel drive in which all four wheels of a vehicle are powered. It improves handling and helps the vehicle make tighter turns. Production-built cars tend to under steer or, in few instances, over steer. If a car could automatically compensate for an under steer over steer problem, the driver would enjoy nearly neutral steering under varying conditions. 4WS is a serious effort on the part of automotive design engineers to provide near-neutral steering. The front wheels do most of the steering. Rear wheel turning is generally limited to half during an opposite direction turn. When both the front and rear wheels steer toward the same direction, they are said to be in phase and this produces a kind of sideways movement of the car at low speeds. When the front and rear wheels are steered in opposite direction, this is called anti- phase, counter-phase or opposite-phase and it produces a sharper, tighter turn. This project aims at developing a 4 Wheel Steering