Shankapal2, M. Monish Gowda3 1- M. Ramaiah School of Advanced Studies, Bangalore — Abstract Production cars are designed to understeer and rarely do they oversteer. Four-wheel steering is a serious effort on the part of automotive design engineers to provide near-neutral steering. Hence there is a requirement of a mechanism which result in less turning radius and it can be achieved by implementing four wheel steering mechanism instead of regular two wheel steering.
In this project Maruti Suzuki is considered as a benchmark vehicle. The main aim of this project is to turn the rear wheels out of phase to the front wheels.
A physical prototype was realised. Nomenclature By changing the direction of the rear wheels there is reduction in turning radius of the vehicle which is L Wheelbase mm efficient in parking, low speed cornering and high speed R Turning radius mm lane change. Usually customers pick the vehicle R1 Distance between instantaneous centre and with higher wheelbase and track width for their comfort the axis of the vehicle mm and face these problems, so to overcome this problem a Wf Load on front axle kg concept of four wheel steering can be adopted in the W Total weight of car kg vehicle.
Four wheel steering reduces the turning radius C1 Distance of instantaneous centre from front of the vehicle which is effective in confined space, in axle axis mm this project four wheel steering is adopted for the C2 Distance of instantaneous centre from rear existing vehicle and turning radius is reduced without axle axis mm changing the dimension of the vehicle.
Normally this vehicle and to increase the manuverbility. In a typical system is not been the preferred choice due to front wheel steering system the rear wheels do not turn complexity of conventional mechanical four wheel in the direction of the curve and thus curb on the steering systems.
However, a few cars like the Honda efficiency of the steering. In four wheel steering the rear Prelude, Nissan Skyline GT-R have been available with wheels turn with the front wheels thus increasing the four wheel steering systems, where the rear wheels turn efficiency of the vehicle. The direction of steering the by an angle to aid the front wheels in steering.
At low speed wheel movement is only 2 or 3 degrees, as their main aim was to assist the pronounced, so that rear wheels are steered in the front wheels rather than steer by themselves.
At high With advances in technology, modern four wheel speed, when steering adjustments are subtle, the front steering systems boast of fully electronic steer-by-wire wheels and the rear wheels turn in the same direction. Therefore the steer angles in real time. Although such a complex the risk of hitting an obstacle is greatly reduced. As a result the vehicle moves in a crab like manner rather than in a curved path.
This action is Compared with a conventional two wheel steering advantageous to the vehicle while changing lanes on a system, the advantages offered by a four wheel steering high speed road. The elimination of the centrifugal system include: effect and in consequence the reduction of body roll and cornering force on the tire, improves the stability of the 1. Superior cornering stability. Improved steering responsiveness and precision. High speed straight line stability. Notable improvement in rapid lane changing maneuvers.
Parallel parking 5. Smaller turning radius and tight space Zero steer can significantly ease the parking maneuverability at low speed. Relative wheel angles and their control. This is exemplified by the parallel parking scenario Usually in vehicles during turning, the tires are which is common in foreign countries and is pretty subject to the forces of grip, momentum, and steering relevant to our cities.
Here a car has to park itself input when making a movement other than straight- between the two other cars parked on the service lane. These forces compete with each other This maneuver requires a three way movement of the during steering manoeuvres.
With a front-steered vehicle and consequently heavy steering inputs. More vehicle, the rear end is always trying to catch up to the over to successfully park the vehicle without incurring directional changes of the front wheels.
This causes the any damage at least 1. When turning, the driver is putting into must be available for parking a two wheeled steer car. Each of these must As can be seen clearly the car requires just about be balanced against the others. The tires are subjected to the same length as itself to park in the spot. Also since road grip and slip angle.
The car touching the steering wheel. All he has to do give momentarily resists the turning motion, causing a tire throttle and brake inputs and even they can be slip angle to form. Once the vehicle begins to respond automated in modern cars. Hence such a system can to the steering input, cornering forces are generated.
This is referred to as rear-end lag because there is a time delay between steering input and vehicle reaction. When the front wheels are turned back to a straight-ahead position, the vehicle must again try to adjust by reversing the same forces developed by the turn.
As the steering is turned, the vehicle body sways as the rear wheels again try to keep up with the cornering forces generated by the front wheels. The idea behind four-wheel steering is that a vehicle requires less driver input for any steering maneuver if all four wheels are steering the vehicle. As with two- Fig. However, when the driver turns the wheel slightly, all four wheels react to the steering input, Another driving maneuver that frequently becomes causing slip angles to form at all four wheels.
The entire cumbersome and even dangerous is changing lanes at vehicle moves in one direction rather than the rear half fairly high speed. Although this is less steering sensitive attempting to catch up to the front.
There is also less this does require a lot of concentration from the driver sway when the wheels are turned back to a straight- since he has to judge the space and vehicles behind ahead position.
The vehicle responds more quickly to them. The vehicle with arrows is the model under study. The direction of steering the rear wheels relative to As can be seen from the figure the vehicle can turn with the front wheels depends on the operating conditions. This also simplifies the positioning of inexperienced drivers make quick lane changes even at the car in situations such as parking in a confined space.
That is, the considering same stub axle for front and rear. This means maneuverability of the model. The observed Calculation for steering angles for the turning radius of effect while driving might be best imagined as a 4. We know that angles. At percent rear steer angle, a 50 percent reduction So from equation 2 and 1 in turn radius occurs. The primary advantage of 4WS is derived from the To find steering angles; better control of transient behaviour in cornering.
The input is given at the steering considering turning radius as mm. The rear steering column is attached with the intermediate shaft also rotates as per the shaft such that the rear wheels attached to the rear steering column rotates as per the rear steering column, so the rear wheels rotates in opposite direction to the driver input to the steering wheel.
The values of C1 and C2 changes gradually, in figure 3 the value of C1 is greater and the value of C2 is lesser but in Figure 4 as the turning radius changes the values of C1 becomes lesser and the value Fig.
The joint given for radius. From change in instantaneous centre and front steering is replicated at the rear steering, there is calculations we conclude that for same wheelbase and bevel gear joint provided between steering column and track width there is change in turning radius from 4.
Enter the email address you signed up with and we'll email you a reset link. Need an account? Click here to sign up. Download Free PDF. Ijesrt Journal. A short summary of this paper. DOI: Here both front wheel and rear wheel can be steered according to space available.
Four wheel steering systems is a great effort in the field of automotive design to provide near-neutral steering. As we know in conventional steering system uses either Ackerman or Davis steering systems.
The main disadvantage associated with these systems is the minimum turning radius that is required for the steering action is more. To overcome the difficulty that is associated with the conventional methods of steering can be eliminated by employing a four wheel steering system. The most conventional steering arrangement is to turn the front wheels using a hand—operated steering wheel which is positioned in front of the driver, via the steering column. At high speed the turning radius of the front wheel decrease and the rear wheel turn in same direction as front, this arrangement of the wheel enable the vehicle to change lane smoothly.
Sakai, T. Matsuo, S. Murayama, H.
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