1. Field of the Invention
This invention relates to a control device for a driven member and more particularly to a control device utilized for controlling a drive member of a controlled device, such as for example, a constant speed control device for vehicles.
2. Statement of Prior Art
As disclosed in a Japanese patent application published as 55-68627 in 1980, a constant speed control device includes a throttle opening degree control mechanism which is actuated by an actuator to adjust the opening degree of the throttle valve in accordance with the load conditions of a vehicle. Thus, the vehicle can be operated to run at a set speed without depressing the acceleration pedal.
Further, it is possible to change the opening degree of the throttle even under the constant speed operation if the operator of the vehicle wishes to change the present speed to a higher speed by depressing the acceleration pedal. However, when the vehicle is running on a slippery road under a constant speed running, even if the operator of the vehicle depress the acceleration pedal to increase the opening degree of the throttle, it is wise to reduce or keep low of the engine output to avoid the vehicle skidding conditions.