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Sport Utility Vehicles (SUV) and light duty trucks have gained in popularity for the last several years and the demand for more car-like behavior has increased, accordingly. Two areas for potential improvement are vehicle stability and maneuverability while parking. 4WS (4 wheel steering system) is known as an effective solution to stability and low speed maneuverability. In this paper, we identify a new systematic design method of two degree of freedom vehicle state feedback control algorithm that can improve vehicle stability, and show its control effects for a SUV with trailer towing. Low speed maneuvering is improved when the rear tires are steered in negative phase relative to the front tires. However with a large rear steer angle at low speed, the vehicle's rear overhang tracks a wider swing-out path than a 2WS vehicle. For this concern, we propose a new swing-out reduction control algorithm.

For active front steering control systems that intervene in driver's operation to assist in the control of the vehicle's motion, the effect of the man-machine interface is much larger than for other conventional control systems. This paper focuses on human factors. The results of analysis regarding control effects and system design concerns are also described. The user benefits of this control system are improved vehicle stability and reduced driving workload. Both theoretical and experimental evaluations are described. Regarding the man-machine interface, the influence of the oversteer characteristic when braking and turning on driver's steering operation, the influence of driver reaction in system failure and steering wheel reaction torque when driving with the actuator are also analyzed.

The objective of this research is to create a new brake system with fewer mechanical parts, higher performance, greater flexibility for adaptation to new functions, and lower cost. A simple/series electro-hydrostatic brake system is investigated as an inexpensive, reliable, and redundant integrated brake system that can include the functions; Boost, ABS, TCS, VDC, etc. Production issues are considered. The required motor power is the most critical and is estimated by simulation based on data from experiments. To reduce this power a flow boost self-energizing mechanism with computer control is explored, and it is found that the effect is significant. Robustness of the control for pad friction fluctuation is also analyzed, and the limitation is estimated. The result of analysis shows that a competitive commercial product can be developed.