subject of the research and development in last decades. The reason is commercial as well as being scientific. The main aim of the commercial activity is the desire of the automotive manufacturers to improve the performance and quality of their products. On the other hand, researchers and control system designers have claimed that the active control of the vehicle suspension system is possible when the developments in actuators, sensors and electronics have been considered. In the last twenty years, many studies have been published on activeandsemi-activesuspensionsystems.
All the systems in vehicle have the own functions including the suspension system. One from the function is to supports the weight of the frame, body, engine, transmission, drive train and passengers. For the passengers, the suspension system will provides a smooth, comfortable ride by allowing the wheels and tires to move up and down with minimum movement of the vehicle. Sometimes, the vehicle will become the body roll when the rapid cornering. Body roll is a vehicle leans to one side. The suspension system will allows rapid cornering without extreme body roll.
The suspension of a car is actually part of the chassis, which comprises all of the important systems located beneath the car's body. Traditional vehicle suspension consists of combinations of springs and dampers. The roll trade-off of suspensionsystems has been a long standing challenge for vehicle dynamicists. Achieving better ride performance almost invariably leads to increased roll of the vehicle. To the car engineer this roll leads to
In general, an activesuspension is widely used in automation system as it is an important part for safety purpose. Balancing the tradeoff between ride quality and road handling performance is a purposed of the suspension system . This performance can be achieved by maintaining the relative position and movement between the vehicle body and wheels. Hence, the effects of vibrations will be reduced for particular road profile. The performance of the handling requires a stiff suspension because the system becomes stable when the tire contact keeping with the road. Suspension can be categorized as a dangerous and safe condition. The dangerous suspension is referring the road irregularities which can allow the body, resulting in poor ride comfort performance.
A car suspension is comprises with several of components and provides all the solution for car stabilization. Tan Wei Teck, 2001  explain in his thesis about spring element in car suspension. The springs play an important part in handling of the suspension system. Springing action should be as soft as possible for the best ride comfort. Road shocks should be swallowed and not transmitted to the vehicle. Springing action should also be progressive, taking a bump in the roadway softly at first and gradually hardening towards the end of the deflection. Springing action should assure evenness of ride regardless of vehicle load.
The concept of AGCS is intelligent and it overcomes many negative points of conventional activesuspensionsystems. AGCS has simple control logic and hardware component. Moreover, if energy supply goes off in conventional system the performance becomes failure mode but in AGCS, vehicle performance will be equal to passive suspension. (Lee,S. 2005)
intelligent activesuspensionsystems are proposed for complicated models with no negligibly strong non-linearity and uncertainty. Numerical and experimental results showed that such activesuspensionsystems give relatively more satisfactory performance, but need more increasing loads to achieve active control, compared with the linear activesuspensionsystems [25 - 29]. In this study a pneumatically actuated activesuspension (PAAS) for reducing unwanted vehicle motion in longitudinal direction is proposed. The proposed PAAS system is used to minimize the effects of unwanted pitch and vertical body motions of the vehicle in the presence of braking or throttle input from the driver. The aims of using activesuspension system are to improve stability, maneuverability and passenger comfort, the activesuspension system is the system in which the passive suspension system is augmented by pneumatic actuators that supply additional external forces. The necessary forces for the four unit pneumatic system are determined by a controller using the data from the sensors attached to the vehicle.
This report presents the developing a mathematical modelling for full vehicle dynamics study specifically for the vehicle braking and cornering condition. The derivation of 7 DOF vehicle ride model are presented. Vehicle ride model includes the degree of freedom for pitch, roll, and vertical motion of the sprung mass and also vertical motion of each unsprung mass. The 7 DOF full vehicle mathematical equation are been derive and was simulate in Matlab Simulink. Additional simulation programming such as CarSimEd is combined and validated to the 7 DOF ride model to study and control the performance of activesuspension. The performance comparison due to rolling and pitching of the vehicle between passive suspensions with activesuspension will also be discussed
This second chapter discusses the background of study related to the project. This chapter consists of the evidence with the broad (e.g. books, internet, lecture notes etc) and focus (previous PSM, thesis, journal papers etc) areas of the study. In this chapter, the trend, direction and research issues are also identified. It can be said that this chapter is more on the evidence of not repeating what others have done.
SemiBactive suspensions on the other hand are less complex, more reliable and commercially available. SemiBactive suspension system is quite similar with the conventional suspension system. This kind of suspension has a spring and controllable damper in which the spring element is used to store the energy meanwhile the controllable damper is used to dissipate the energy. Some of the semiBactive suspensionsystems use the passive damper and the controllable spring. The controllable damper usually acts with limited capability to produce a controlled force when dissipating energy . Figure 2.2 shows the schematic diagram of semiBactive system with passive spring and controllable damper as a component of suspension.
To get a compliant active exoskeleton controller, the force interaction controllers are mostly used in form of either the impedance or admittance controllers. The impedance or admittance controllers can only work if they are followed by either the force or the position controller respectively. These combinations place the impedance or admittance controller as high-level controller while the force or position controller as low-level controller. From the application point of view, the exoskeleton controllers are equipped by task controllers that can be formed in several ways depend on the aims. This paper presents the review of the control systems in the existing active exoskeleton in the last decade. The exoskeleton control system can be categorized according to the model system, the physical parameters, the hierarchy and the usage. These considerations give different control schemes. The main consideration of exoskeleton control design is how to achieve the best control performances. However, stability and safety are other important issues that have to be considered.
Passive suspension has limitations due to the fixed suspension parameters. Low spring stiffness leads to good ride performance but sacrifices the vehicle handling whereas high spring stiffness causes poor ride performance but provides better vehicle handling. Therefore, in automotive industry, there is compromise between ride and handling performance. To provide one of the possible solutions to this problem, a hydraulic actuated activesuspension using active force control is proposed. The proposed activesuspension will be able to enhance the ride performance of the passenger vehicle.
The AMB technology has been briefly reviewed including its advantages, components, working principles, cost and performance. Some design and implementation issues have been also discussed. The authors believe that AMB systems are still relatively more expensive than conventional mechanical bearings; therefore the massive used of AMB in industries is still prohibitive despite of the many benefits offered. The AMB will still not completely replace conventional bearings in rotating machineries in the near future. However, AMB can find its place well in a limited volumes of high performance rotating machines.
The second persons are all Master Student under Dr. khisbullah Hudha (Mr. Fauzi, Mr. Zul, Mr. Fitrian, and Mr. Alif) which helps me throughout the project which consist of experiments and guided me through everything. Also, those fellow friend under Dr.Khisbullah Hudha (Mr. Zubir, Mr. Zulazrin, Mr. Ahmad Zaifazlin, Mr. Hanif, and Mr. Khairul Azri) for the time, their valuable advice and guidance when solving problems.
An ideal suspension system should isolate the car body from road disturbances and inertial disturbances associated with cornering and braking or acceleration . Furthermore, the suspension must able to minimize the vertical force transmitted to the passengers for passengers comfort. These can be achieved by minimizing the vertical body acceleration. An excessive wheel travel will result in non-optimum attitude of tyre relative to the road that will cause poor handling and adhesion. To maintain good handling characteristic, the optimum tyre-to-road contact must be maintained on four wheels .
Meanwhile, I would like to offer heartfelt thanks to my course mate in Bachelor of Mechanical Engineering (Automotive) programme who has been helpful. They also give professional guidance, constructive comments and ideas to me during finishing this PSM.
The first way to prevent body roll is to eliminate its source, roll moment. By increasing the roll center heights of the front and rear suspensions, this moment can be reduced. But, this will cause considerable lateral wheel displacements during bump and rebound with track variations during operation. Another negative effect is the higher camber angle change. Another method for preventing excessive body roll is to use stiffer suspension springs, thus making it harder for the suspensions to move in opposite directions at the same time. This, however, reduces the ride comfort. A compromise solution is to use softer suspension springs to provide ride comfort, lower roll centers to avoid lateral wheel displacement and anti-roll bar to reduce body roll.
5 The suspension system provides a vertical counterforce to compensate the forces experienced by the wheels due to the uneven road terrain, in order to isolate vibrations the vehicles chassis. The suspension also helps to well maintain the steer and the camber settings of the wheels to the road profile. The suspension responds to the control forces that are produced by the tires longitudinal forces due to acceleration and braking, lateral forces due to cornering and driving torques. The suspension of the vehicle also functions to resist the roll moment of the car due to cornering, and maintaining the wheels contact to the ground at all times (Gillespie 1992).
modeling an activesuspension system for a half-car model in state space form and develop a robust control strategy in controlling the activesuspension system. Fuzzy logic is used to control the system. Velocity and displacement of front wheels are taken as input variables of the fuzzy logic controller. Active forces improving vehicle driving, ride comfort and handling properties are considered to be the controller outputs. The controller design is proposed to minimize chassis and wheels deflection when uneven road surfaces, pavement points, etc. are acting on the tires of running cars. Comparison of performance of activesuspension fuzzy control system with passive suspension system is shown using Matlab/Simulink simulation. From the result, it shows that activesuspension system has better performance than the passive suspension system.
M. Z. Sariman , M. Hafiz Harun, A. K. Mat Yamin, F. Ahmad, M. R. Yunos, Magnetorheological Fluid Engine Mounts: A Review on Structure Design of Semi-Active Engine Mounting, International Journal of Materials, ISSN: 2313-0555, Volume 2, 2015, pg. 6-16.