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Int. J. Mech. Eng. & Rob. Res. 2014 Dilip S Choudhari, 2014

FOUR WHEEL STEERING SYSTEM FOR FUTURE

Dilip S Choudhari1*

*Corresponding Author: Dilip S Choudhari,ds_choudhari@rediffmail.com

A Four Wheel steering (4WS) System is also known as “Quadra Steering System”. In thispaper, both front as well as rear wheels can be steered according to speed of the vehicle andspace available for turning. Quadra steer is system that gives full size vehicles greater easewhile driving at low speed, and improves stability, handling and control at higher speed. Quadrasteering system works in following three phases Negative phase, Neutral phase, Positive phase.It enables the car to be steered into tighter parking spaces. It makes the car more stable atspeed (less body roll). It makes the car more efficient and stable on cornering, easier and saferlanes change when on motorways. The steering system allows the driver to guide the movingvehicle on the road and turn it right or left as desired. The main aim is that turning of the vehicleshould not require greater efforts on the part of the driver. The Quadra steer steering systemoffers a 21% reduction in turning radius. So if a vehicle is capable of making a U-turn in a 25-footspace, Quadra steer allows the driver to do it in about 20 feet.

Keywords: Quadra, Negative phase, Neutral phase, Positive phase

INTRODUCTIONThe steering system allows the driver to guidethe moving vehicle on the road and turn it rightor left as desired. Further such turning of thevehicle should not require greater efforts onthe part of the driver there are mainly two typesof steering system:

Conventional Steering SystemUsually during the steering of the vehicle, onlythe front wheels are steered towards right orleft according to the requirement and the rear

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Int. J. Mech. Eng. & Rob. Res. 2014

1 Department of Mechanical Engineering, Pad. Dr. D.Y. Patil Institute of Engg.and Technology, Pimpri, Pune 411018, MaharashtraState, India.

wheels are mere followers of the front wheelsin this system.

Four Wheel Steering SystemThe direction of steering the rear wheelsrelative to the front wheels depends on theoperating conditions. At low-speed wheelmovement is pronounced, so that rear wheelsare steered in the opposite direction to that offront wheels. This also simplifies the positioningof the car in situations such as parking in aconfined space. Since the rear wheels are

Research Paper

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Int. J. Mech. Eng. & Rob. Res. 2014 Dilip S Choudhari, 2014

made to follow the path on the road taken bythe front wheels, the rear of a 4WS car doesnot turn in the normal way. Therefore the riskof hitting an obstacle is greatly reduced.

At high speed, when steering adjustmentsare subtle, the front wheels and rear wheels turnin the same direction (Jack Erjavee, 2009). Asa result, the car moves in a crab-like mannerrather than in a curved path. This action isadvantageous to the car while changing laneson a high-speed road. The elimination of thecentrifugal effect and, in consequence thereduction of body roll and cornering force onthe tyre, improves the stability of the car so thatcontrol becomes easier and safer. In a 4WSsystem, the control of drive angle at front andrear wheels is most essential.

pitman arms would not be suitable for thismode, since the two front wheels are steeredin opposite directions. The Hurricane jeep ishaving the four wheels Steering System(Thomas Birch, 1987). Steer-by-wire systemswould work fine, however, since independentcontrol can be achieved.

PHASES OF QUADRASTEERING SYSTEMIn this type of steering system, we can steer afront wheel, as well as the rear wheel of thevehicles simultaneously. This steering mainlyincludes two types of steering:

Front wheels and rear wheels are steeredin the same direction and are parallel to eachother. This type of system is very useful duringlane changing. Front wheels are steered in thedirection opposite to that of the rear wheel. Thissteering system reduces the space requiredby the vehicle during turning as compared tothat of the two wheel steering system.

Quadra Steer is the system that gives fullsize vehicles greater ease or maneuverabilitywhile driving or tugging trailer at low speed,

Figure 1: A Model of Four Wheel SteeringSystem

The four wheels have fully independentsteering and need to turn in an unconventionaldirection to ensure that the vehicle turns aroundon its own axis. Such a system requiresprecise calculation from a servo motor withreal-time feedback to make certain that allthree steering modes function perfectly. Theonly major problem posed by this layout is thata conventional rack-and-pinion steering with

Figure 2: Jeep Hurricane

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Int. J. Mech. Eng. & Rob. Res. 2014 Dilip S Choudhari, 2014

and improves stability, handling and control athigher speed. The present “Four WheelSteering” works mechanically with help oflinkages. The system utilizes a manualmanipulator to control and direct thearticulation (left and right turning) of rearwheels.

The system operates in three phases:Negative, Neutral and Positive.

At lower speeds, rear wheel turns inopposite direction from the front wheel. Thisis negative phase.At moderate speed, the rearwheel remains straight or neutral.

At higher speed, the rear wheel are in thepositive phase turning in the same directionas the front wheels.

Negative PhaseIn this drive the axles both the front and therear move in opposite direction relative to eachother. This drive is mainly used during parkingof the vehicle. As both the axle move in differentdirections the radius of curvature while turningreduces (Tim Gilles, 2014). This means thevehicle will require less space for parking and

this will be helpful in places where traffic andparking is a major problem.

Neutral PhaseIn this drive only the front axle moves either inclockwise or anticlockwise direction and therear wheel being unmoved. This is the drivethat we see in day to day life in all the fourwheelers (http://www.howstuffworks.com). It isgenerally used at moderate speed.

Figure 3: Negative Phase

Figure 4: Neutral Phase

Figure 5: Positive Phase

Positive PhaseAs the name suggest, in this drive both the axleviz. front and rear move in same directionrelative to the each other. This motion of both

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Int. J. Mech. Eng. & Rob. Res. 2014 Dilip S Choudhari, 2014

the front and the rear axle helps Quadrasteering system enabled vehicle to change thelane during highway driving (http://trucks.about.com/cs/4ws/a/4wheel_steering.htm). Itis generally applied at higher speed.

COMPARED OF 4WS SYSTEMWITH 2WS CONVENTIONALSYSTEM• Car more efficient and stable on cornering.

• Improved steering responsiveness andprecision (http://www.projecttopics.info/Mechanical/Mechanical-Four-Wheels-Steering.php).

• High speed straight line stability.

• Notable improvement in rapid, easier, saferlane changing maneuvers.

• Smaller turning radius and tight spacemaneuverability at low speed.

• Relative Wheel Angles and their Control.

• Risk of hitting an obstacle is greatlyreduced.

successful implementation will allow for thedevelopment of a four-wheel, steeredpower base with maximum maneuverability,uncompromised static stability, front- andrear-wheel tracking, and optimum obstacleclimbing capability.

The advanced system of “Four wheelsteering” will work electronically with the helpor microprocessors.

The system will utilize an onboard computerto control and direct the turning left and right ofthe rear wheels.

CONCLUSIONThus, the four wheel steering system has gotcornering capability, steering response,straight-line stability, lane changing and lowspeed maneuverability. Even though it isadvantageous over the convectional two wheelsteering system, four wheel steering is acomplex and expensive. Currently the cost ofa vehicle with four wheel steering is more thanthat of the convectional two wheel steering ofvehicle. Four wheel steering is growing inpopularity and it is likely to come in more andmore new vehicles. As the system becomemore common place, the cost of four wheelsteering system will drop down.

REFERENCES1. Brabec P, Maly M and Vpzenilek R

(2004), “Control System of Vehicle Modelwith Four Wheel Steering”, InternationalScientific Meeting Motor Vehicles &Engines, Kragujevac.

2. Jack Erjavee (2009), “AutomotiveTechnology–A System Approach”,Cengage Learning, 5th Edition.

Figure 6: Comparison of the AvoidanceManoeuvre with a Vehicle with 2WS

Conventional Steering

FUTURE ASPECTSAn innovative feature of this steering linkagedesign is its ability to drive all four Wheelsusing a single steering actuator. Its

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Int. J. Mech. Eng. & Rob. Res. 2014 Dilip S Choudhari, 2014

3. Johnson Erik (2007), “2008 Infiniti G37Sport Coupe-Suspension, Handling andFour-Wheel Steering”.

4. Kirpal Singh (2011), AutomobileEngineering, 12th Edition, pp. 207-229,Standard Publication Distributors.

5. Shibahata Y, Irie N, Itoh H and NakamuraK (1986), “The Development of anExperimental Four-Wheel–SteeringVehicle”, SAE 860623.

6. Thomas W Birch (1987), “AutomotiveSuspension and Steering System”.

7. Tim Gilles (2014), “Automotive Service-Inspection, Maintenance, Repair”.

8. Tom Murphy and Brian Corbett (2005),“Quadra Steer Off Course”

9. Vlk F (2001), “Dynamika MotorovýchVozidel”, Nakladatelství a zasilatelstvíVLK, Brno.

WEBSITES1. http://seminarprojects.com/Thread-four-

wheel-steering-system-full-report—6172#ixzz1tn3wSWNO.

2. http://seminarprojects.com/Thread-four-wheel-steering-system-full-report—26172#ixzz1tn3wSWNO.

3. http:// trucks.about.com/cs/4ws/a/4wheel_steering.htm

4. http://www.delphiauto.com

5. http://www.howhurricaneworks.com

6. http://www.howstuffworks.com

7. http://www.projecttopics.info/Mechanical/Mechanical-Four-Wheels-Steering.php

8. http://www.theautochannel.com

9. http://www.thecarconnection.com