Abstract: A PDC/PHS phone has both PDC communication function and PHS communication function. The PDC/PHS phone switches its communication mode from a PDC communication to a PHS communication which is less power consuming than the PDC communication, when its built-in battery runs down to a reference level in the course of communication with another phone. The PDC/PHS phone switches its communication mode back to the PDC communication again, when the battery is recharged enough.

Abstract: A method of and system for controlling the speed of a motor vehicle based on a control characteristic so that the speed of the vehicle follows a target speed. The system estimates a dynamic characteristic of the motor vehicle to adjust the control characteristic when the motor vehicle is under a cruising control. The system includes a sensor for detecting a speed of the motor vehicle and a sensor for detecting an operating position of an actuator which adjusts a travelling speed of the motor vehicle. In the system, the detected vehicle speed and actuator operating position are converted into data in terms of an imaginary operating point. The imaginary operating point remains constant because it is not affected by variations of a static characteristic of the motor vehicle. The dynamic characteristic of the motor vehicle is estimated on the basis of the conversion data. This arrangement can accurately estimate the dynamic characteristic of the motor vehicle.

Abstract: An automotive cruise control system equipped with an actuator to regulate the state of an automobile in accordance with a control signal indicative of an actuator control amount so that the vehicle maintains a target speed, the actuator control amount being determined on the basis of the speed of the vehicle and the operation state of the actuator. The automotive cruise control system is arranged so as to divide the vehicle into first and second systems: the first system on-line-identifies a model corresponding to the state of the vehicle; the second system on-line-identifies a model corresponding to the actuator used in the vehicle. The actuator control amount is calculated on the basis of the first and second system models to produce the actuator control signal in correspondence with these models.

Abstract: Disclosed is a vehicle speed control system for controlling the intake air amount introduced into an engine of a vehicle in order to allow the vehicle to travel at a target speed. The intake air amount is controlled in accordance with the integration value of deviation of the vehicle speed from the target speed. The integration value is rest when the vehicle acceleration is terminated and the reset integration value is derived on the basis of the vehicle speed and throttle valve opening degree. The vehicle speed control system includes an integral-added optimal regulator which determines the feedback amount on the basis of an optimal feedback gain predetermined in accordance with a dynamic model of the system relating to the constant travelling speed of the vehicle.