Semi-active suspension design for vehicle tire force control

This thesis is concerned with design of semi-active suspensions to reduce dynamic tire force including the development and application of observers for bilinear systems with unknown disturbances. The objectives of this study are to design advanced suspensions, i.e., "semi-active" suspensions, for application to heavy vehicles in order to reduce pavement damage, to investigate the implementation of semi-active control laws to reduce pavement damage and to perform an investigation of their impact on the response of flexible pavement.; Semi-active control laws to reduce dynamic tire forces for leaf spring tandem heavy vehicle suspensions are investigated and a bilinear observer structure for bilinear systems with unknown disturbances is formulated such that the estimation error is independent of the unknown external disturbances and the error dynamics are stable for bounded input.; A semi-active suspension for heavy vehicles to reduce pavement damage due to vehicle dynamics is described. The peak dynamic tire forces, which are greatly in excess of static tire forces, are highly dependent on the dynamic characteristics of vehicle suspensions and this study shows that the dynamic tire force can be reduced by the use of semi-active suspensions.; The disturbance decoupled bilinear observer developed is applied to the dynamic tire force estimation of semi-active suspensions. The bilinear observer for dynamic tire force estimation is designed using sprung and unsprung mass acceleration measurements. The performance of the proposed bilinear observer is examined via both computer simulation and experiment using a laboratory half car test rig.; In addition to the simulation study, an experimental study on the performance of a semi-active suspension to reduce the dynamic tire forces is made via a laboratory vehicle test rig. The clipped optimal semi-active control laws to reduce dynamic tire force are implemented by the use of a semi-active damper with twenty states, sensors such as accelerometers and a load cell, and a personal computer. The proposed disturbance decoupled bilinear observer is applied to estimate dynamic tire force in a semi-active suspension implemented on a test rig. Experimental studies using the laboratory test rig show that the performance of the semi-active suspension is close to that of the best passive suspension for all frequency ranges in the sense of minimizing the dynamic tire force and the dynamic tire force can be replaced by the estimated one. (Abstract shortened by UMI.)...