| AWID/AWIS high-speed and high-maneuver platform is a new wheeled mobile robot platform with all wheels independent driving and independent steering function. It has more features, more flexible combination of driving and steering, and can provide more sport modes (such as lateral movement, pivot turn and other sport mode).Through this platform we can study the speed and maneuverability in small area. It is the development tendency of vehicle, such as the advanced civil vehicle, military vehicle, unmanned vehicle and wheel mobile robots with high speed ability in the future. This paper puts forward the typical 4WIS/4WID mobile robot as the research target and mainly studies the Steer Control System. The robot has 4 integrated wheels with inside 90°, outside 45°limited angle, controlled by electronic controller with lateral movement, pivot turn and other 4 sport modes. No mechanical connection is existing between wheels and handwheel, therefore it belongs to Steer-By-Wire system.The paper deals with the steer technology at the beginning, which is the basis of the stable and effective operation. With the overall goals of AWID/AWIS, we construct the distributed control network, and the implementation of distributed network is given in detail. Also, the capacity of load and reload of network is analysed carefully in the next. To improve direct feeling of road and resistance, we analyse the cause of lateral force and give a formula to evaluate it. From kinematics stability perspective, we study the regularity for Steering Ratio with change of yaw velocity and introduce an ideal steer radio model.This paper presents software design and hardware design of wheel-controller. Angle velocity, current and position need to be collected realtime, thus digital and analog process circuits are essential in steer-controller. In addition, the driver circuit is also the critical component for motor control. To improve the reliability, redundancy idea is adopted, such as CAN redundancy and interface redundancy.Operational stability is the important guideline for checking and balancing the platform performance when steering. From the kinematics perspective, we summarize 6 sport modes and study the relevances between steer radius and steer angle for research the operational stability. Further more, turning center is given in a limited area. Besides, we analyse the yaw velocity, lateral acceleration, slip angle as steering and give the domain response and steady-state gain, which lays the foundation for following research of stability control.Finally, we conclude this paper and give suggestions for future research. |
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