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In a master--slave system, improving the positioning performance and the stability is needed in the case of remote control. However, if there exists time delay, the system destabilizes the performance. Furthermore, it is important to maintain the stability of not only the system but also the controlled object. This paper describes a strategy to improve these problems. This strategy enables operators to get a degree of time delay and instability by keeping the motion performance and the stability. The unstable response with a time delay is restrained by adjusting PD controller gains based on the velocity error of master--slave. Furthermore, switching bilateral control and autonomous control of slave without falling into unstable state is constructed when that cannot be restrained because of long time delay or unexpected disturbances of slave motion. The validity of the proposed strategy is confirmed by experiments stabilizing an unstable component, i.e., an inverted pendulum of slave system. Index Terms--Bilateral control, inverted pendulum, manipulator, stabilizing control, time delay.

This paper describes an adaptive control to realize the desired steering characteristics on a vehicle. As is well known, the steering characteristics indicate handling performance on a vehicle and are important for safe driving. In this paper, a strategy to adjust it to a driver's preference easily using a Steer-by-Wire system is proposed. The control system including the proposed method intervenes only when the front tire cornering stiffness undergoes many changes. Then, the estimated self-aligning torque is fed back to the steering wheel so that a driver can feel reaction torque from the road. This is one of the remarkable features in the proposed Steer-by-Wire system. Numerical simulation and experiment are carried out to show the validity of the proposed method. Index Terms--Parameter identification, steer-by-wire system, steering characteristics, steering control, vehicle state estimation.

The development of automatic control for driving a bicycle is a challenging theme and is expected to be a human assist system. Previously, an acceleration-based method for stabilizing bicycle posture was proposed by the authors. In the experiments with this controller, the posture of the bicycle might be stabilized, but it is impossible to run on the desired trajectory, because there is no consideration with respect to a trajectory control. For the sake of expanding this system into more sophisticated equipment, a realization of the trajectory control for the bicycle is important. From the viewpoint of an assist system for human motion, a unified control of posture and trajectory brings a sophisticated function to a bicycle, and a high-performance bicycle is expected to be a convenient vehicle, similar to a small car. This paper proposes two strategies to stabilize bicycle posture and trajectory control that realizes a straight-line tracking: one is a lateral velocity controller, and the other is a steering function controller. The validity of the proposed approaches is evaluated by simulations and experiments. Index Terms--Bicycle, inverted pendulum, line tracking control, posture control.