Robust vehicle suspension system by converting active and passive control of a vehicle to semi-active control ystem analytically

This research article deals with a simplified translational model of an automotive suspension system which is constructed by considering the translation motion of one wheel of a car. Passive Vehicle Suspension System is converted into Semi Active Vehicle System. Major advantage achieved by this system is that it adjusts the damping of the suspension system without the application of any actuator by using MATLAB® simulations. The semi-active control is found to control the vibration of suspension system very well

Design of Robust Digital Pole Placer for Car Active Suspension with Input Constraint

This chapter deals with the problem of state feedback control for an active quarter-car suspension system with control input constraint. The dynamics of the suspension system is first formed in terms of the control objectives: ride comfort, suspension deflection, and maximum actuator control force. The control task is formulated as robustly placing the closed poles in a desired region against different passenger load. Since digital computers are widely used in the vehicle industry, a new saturated controller design method is presented for regional pole-placement of uncertain discrete time systems. The constraint of control input saturation is considered in the design phase. The desired dynamic performance for uncertain discrete-time systems is represented by the settling time and damping ratio. A sufficient condition is derived to place the poles in a desired region. The design is formulated in terms of linear matrix inequality optimization. The effectiveness of the proposed design is illustrated by applying it to a quarter?car active suspension system. Different road tests for the proposed controller are carried out: step and bump disturbances. The proposed design achieves the desired oscillation damping due to road disturbances in addition to passenger comfort. The results are compared with the passive suspension system

Model reaching adaptive-robust control law for vibration isolation systems with parametric uncertainty

Adaptive control has been used for active vibration isolation and vehicle suspensions systems. A model reference adaptive control law is used for the plant to track the ideal reference model. In a model reaching adaptive control approach, the ideal of a skyhook target without using a reference model is achieved. In this paper, a novel approach, a model reaching adaptive-robust control law is studied for active vibration isolation systems. A dynamic manifold for ideal system is defined using the ideal of a skyhook target model system parameters. First, a new Lyapunov function is defined. Based on the Lyapunov stability theory, a model reaching adaptive and a robust control laws are derived for the uncertain system to reach the ideal manifold. Parameters and upper bounding functions are estimated as a trigonometric function depending on the relative displacements, velocities and the defined manifold. The developed adaptive and the robust compensators are combined and this combination is proposed as an adaptive-robust control law. After that, the controller is applied to a vehicle suspension system and the ideal of a skyhook target without using a reference model is achieved. The results also show that the proposed robust control law can increase the comfort of the vehicle active suspension systems and the ride comfort is remarkably increased

Dynamic Understeer Control Using Active Rear Toe

This thesis was conducted to show the ability of Active Rear Toe to control the understeer characteristics of a vehicle. Active rear toe is the ability to control the angle of the rear wheels around the vertical axis, allowing the car’s turning radius to change. By changing this radius, the lateral acceleration can be controlled, therefore the understeer of the vehicle can be controlled. The controls scheme is a sliding mode control, specifically a hyperbolic tangent boundary layer and a type 1 zeno controller. The system shows effectiveness to control the understeer of the vehicle up until limit grip on the tire. Once this level is achieved, lateral acceleration can only be removed, not added. It is recommended that ART should supplement controls through the brakes of the car, allowing for the car to be controlled over a larger range of performance

Magnetic bearings-state of the art

Magnetic bearings have existed for many years, at least in theory. Earnshaw's theorem, formulated in 1842, concerns stability of magnetic suspensions, and states that not all axes of a bearing can be stable without some means of active control. In Beam's widely referenced experiments, a tiny (1/64 in diameter) rotor was rotated to the astonishing speed of 800,000 rps while it was suspended in a magnetic field. Despite a long history, magnetic bearings have only begun to see practical application since about 1980. The development that finally made magnetic bearings practical was solid state electronics, enabling power supplies and controls to be reduced in size to where they are now comparable in volume to the bearings themselves. An attempt is made to document the current (1991) state of the art of magnetic bearings. The referenced papers are large drawn from two conferences publications published in 1988 and 1990 respectively

Fault Tolerant Control in a Semi-active Suspension

6 pagesInternational audienceA Fault Tolerant Control System (FTCS) in a Quarter of Vehicle (QoV ) model is proposed. The control law is time-varying using a Linear Parameter-Varying (LPV ) based controller, which includes two scheduling parameters. One parameter for monitoring the nonlinear behavior of the damper, and another for fault accommodation using a reference model obtained by a state observer of the normal operating regime. The QoV model represents a semi-active suspension, including an experimental magneto-rheological damper model. The FTCS is analyzed when the velocity sensor fails abruptly and the QoV model is susceptible to disturbances in the road pro le. Simulation results show the e ectiveness of the FTCS in terms of vehicle comfort, suspension detection and road holding in comparison with a conventional LPV based control system. In the FTCS, the comfort index based on the power spectral density is within the desirable bound (1.8) in all range of frequencies, once the sensor fault has occurred; while, the conventional control system deteriorates the comfort 54 %, specially at low frequencies (0-4 Hz). Additionally, the FTCS improves the road holding and suspension de ection indexes, 33% and 39% respectively, when the fault accommodation is considered

Investigation on semi-active control of vehicle suspension using adaptive inerter

The analysis of passive control with inerter in suspension system has been well studied in previous work by employing different configurations and optimizing the spring stiffness, damping coefficient and inertance simultaneously. In this paper, we study the suspension performance with semi-active control under the assumption that the inertance may be adjusted in real-time. The suspension system is designed to attenuate the vertical acceleration of the sprung mass. A quarter-car model is considered, and the inerter is installed parallel to the spring and damper. First, an analysis is provided on the influence of a fixed inerter to a given suspension system. Then, a state-feedback H2 controller for active suspension system is designed. The active force is approximated by an inerter with adaptive inertance. Simulation results show that comparing with the passive suspension with a fixed inerter, the designedH2 controller realized by adaptive inerter can achieve good improvement of ride comfort at the sprung mass natural frequency at the expense of a relatively small deterioration at the unsprung mass natural frequency. Copyright © (2014) by the International Institute of Acoustics & Vibration All rights reserved.postprin