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A robust control method applied to a DC-motor the actuator of a steering system installed on a radio-controlled multiloader truck is developed Requirements for the control system are robustness and stability against disturbances and change in plant characteristics, and rapid and accurate response to steering commands To comply with these requirements, we applied a robust model matching (RMM) control method to the steering actuator Results of simulation analyses and a hardware-in-the-loop simulation show the effectiveness of this control method

This study establishes the feasibility of improving the motion characteristics of commercial vehicles by applying rear axle steering. A model-matching control algorithm for rear axle steering was used to achieve the desired yaw rate response to steering action. Simulations with a two-degree-of-freedom model evaluated the effectiveness of the control method. Results of vehicle tests on an experimental medium-duty truck with rear axle steering proved that this control method can improve vehicle yaw response. However, the simulation results did not well represent the vehicle test results, because the simulation model was too simple. Adding the roll effect to the model reduced the discrepancy between the simulation and vehicle test results.

To improve the low-speed followability of semi-trailers, a control method has been developed for trailer-wheel steering. The basic concept of the control method is to steer the wheels so that the trailer rear end follows the tractor front end. Computational simulation results show that the control method minimizes the swept path of the tractor and trailer combination without causing any rear end overhang swing problems. To evaluate the effectiveness of the control method, the approximately one twelfth scale model vehicles of the tractor and semitrailer were produced. Tests on the articulated model vehicles show that better low speed follwabilty improvement is expected with path-following control compared with other trailer wheel steering control methods.

A rear-steering control method for a four-wheel steering truck has been developed. The purpose of this investigation is to develop a control method to minimize the turning radius without the excursion of the vehicle rear end toward the outside of the turn. The basic control concept is to steer the rear wheels so that the vehicle rear end follows the path of the front end. The control method was applied to an experimental medium-duty truck with four-wheel steering system. The simulation and vehicle test results showed the control method to be effective in minimizing the turning radius without causing the excursion of the vehicle rear end toward the outside in short turns.

This Paper describes a computer-controlled power steering system that has been developed and applied to production vehicles. The system provides full power assist at parking speeds, and gradually decreases assistance with increasing vehicle speed to give a normal unassisted “road feel” at highway speeds. The system enables a driver to choose one assistance characteristic among three choices at the flick of a switch, according to the driver's preference and road conditions. A solenoid-operated bypass valve is used to reduce the hydraulic fluid supply to the steering gear, which results in a heavier steering effort. The most suitable valve characteristic curve which corresponds to the increased pressure in the system due to the applied torque is discussed in this study. It is shown that detection of the velocity of steering wheel rotation and extension of the range of characteristics possible are effective ways to ensure good control over the power assistance.