Abstract
The vehicle suspension isolates the chassis from road irregularities, reacting to forces produced by the tires and the braking torques, always keeping the road tire contact, providing stability and safety. Stability and safety are two antagonistic characteristics in suspension design, when improving one the other is impaired and vice versa. The semi-active suspension is a type of vehicle suspension that can change its stiffness and/or damping in real time depending on the vehicle response to the actual road profile. The On-Off semi-active suspension changes its damping coefficient between two fixed limit values. This work proposes an On-Off semi-active suspension model, in which the damping coefficient changes its values considering the road profile function frequency. A control strategy is proposed in a way to improve performance keeping the same simplicity, without any structural change of the semi-active suspension. On the proposed control strategy one of the damping coefficients is obtained through the linear quadratic regulator (LQR) algorithm, with the aim to set the coefficient from the gain matrix associated to the velocity of the suspended mass. This model is compared to anothers found in literature.
Highlights
The vehicle suspension is intended to support the weight of the vehicle over its axles, keep the wheels in proper steering and angulation, react to external excitations produced by the tires, braking and acceleration torques, lateral loads, attenuating vibrations from the excitation of the course and ensuring the contact of the tires with the ground
Rao [7] investigates the performance of a quarter-car semiautomatic suspension system using the Proportional Integral Derivative (PID) controller under the MATLAB Simulink model
The 1/4 vehicle model was chosen for its simplicity and its commitment to accurately describe the dynamic behaviour of the suspension [1]
Summary
The vehicle suspension is intended to support the weight of the vehicle over its axles, keep the wheels in proper steering and angulation, react to external excitations produced by the tires, braking and acceleration torques, lateral loads, attenuating vibrations from the excitation of the course and ensuring the contact of the tires with the ground. Its practical application presents a number of disadvantages due to the complexity of the system, which makes its acquisition and maintenance costly Another factor that avoids its use in commercial automobiles is the need to supply energy from an external source, associated with the great weight of the system, active suspension increases fuel consumption considerably [2]. It uses less components when compared to the active suspensions, being more robust It works even off, acting as a passive suspension, this makes this type of suspension more applicable and more reliable [3]. Rao [7] investigates the performance of a quarter-car semiautomatic suspension system using the PID controller under the MATLAB Simulink model In this work it is presented a comparison between semiautomatic and passive suspension system and its dynamic characteristics. While maintaining the same simplicity of the traditional On-Off semi-active model, no changes are required in the physical structure of the suspension for its implementation in a real vehicle
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