This paper aims to design a controller for a vehicle active suspension system of an automobile. The vehicle cab motion is limited to heave in the y-direction and a small amount of pitch u of the vehicle’s longitudinal axis. The tires are assumed to remain in contact with the road surface at all times. Vehicle is subjected to random excitation due to road unevenness and variable velocity and sometimes due to speed bumps. The system has three translational degree of freedom. Based on the degree of freedom, from a rider’s comfort point of view the damping parameters and spring stiffness are adjusted to fit the criteria of a less bumpy ride. For controlling the vehicles degree of movement, the controller is designed based on Proportional controller, PID Controller, and pole placement. For the purpose of analysis, this paper only deals with the linear part of the system and excludes non-linear portion from the equation. The result shows that the response of the controlled suspension system can trace the input signal that is the PID controller is successfully able to control the variable shock absorber in order to eliminate the road surface disturbances effect to the car body.
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A vehicle suspension has a great impact on ride produced. Suspension system suspends the body on the shock absorbing system and the same time maintains contact patches of four tires in effective contact with the road surface. There are few major functions of vehicle suspension system. It separates the chassis from the road by allowing vertical compliance for the wheel to follow uneven road. It can maintain proper steer and chamber angles to road, it reacts to all forces produced by the tires resist roll of the chassis and keep the vehicle tires in contact with the road. Suspension can be classified in to two types: active and passive suspension system. These systems can compromise the ride comfort for vehicle load carrying, and vice versa. Passive suspension consists of elements that can only store energy in their spring and dissipate energy through shock absorber. There is no external energy supplied to a passive suspension system. Active suspension however adds energy to the suspension using actuator to produce desired force in the suspension system.
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The main objective of the suspension system is to provide optimum isolation between the driver and the ground. Suspension System of an All-Terrain Vehicles is mainly distinguished from an On-Road Commercial Vehicles in terms of its all-terrain capability due to its large travel and Ride Quality; also it has to face various ground conditions such as mud, ice, rocks, bumpy tracks etc. Hence it needs to be Robust enough to sustain in such frequently occurring undulations. Suspension systems of commercial vehicles are designed considering normal road conditions. While designing suspension system of an ATV, various terrain conditions have to take into consideration. It must also keep the tires in contact with the road, regardless of road surface. The suspension system comprises of two components viz. linkages and shock absorber. The linkages define the path traced by wheel with respect to chassis, during its travel on irregular surfaces. The shock absorber as the name suggests damps the impact of shocks and vibration transmitted through ground surface which in-turn prevent discomfort to the driver and passenger. There are many different approaches towards suspension design and deciding the working parameters. For this project we selected the top down approach i.e. starting from the driver and moving towards the wheels. This approach has predictable results and the results obtained after manufacturing can be validated easily. In this approach parameters like ride rate of the vehicle and its distribution over the front and rear ends is decided directly by the driver. These values are then converted into spring rates, wheel rates other motion ratios using 3D geometry and software like LOTUS Shark Suspension Simulation. 2.1 Front suspension design Once the wheel size and the rims are selected based on the traction force calculations and vehicle dimension regulations specified by ISNEE quad TORC 2016 rule book, we proceed
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The automotive industry experiences increasing competition in its market and requires alternative strategies to advance its products. To meet this objective, one of the investments auto companies have been exploring into is new and improved suspension systems. Suspension systems not only improve comfort for the driver and performance of the vehicle, but also slows down the wear of the car. This paper discusses the conventional suspension system arrangement involving a static spring and its effects on a vehicle traveling over a bump with given parameters. The study will be further expanded to analyze the appropriate spring and damper constants and relate the effects of the suspension system has on a traveling vehicle.
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IOP Conference Series: Materials Science and Engineering
