抄録
This paper is concerned with a new scheme of independent control of two induction motors which are connected in parallel to a single inverter. This method is developed as an AC motor alternative of a currently-used DC motor propulsion system for an unmanned ground carrier vehicle, which is equipped with a pair of identical motor-wheel driving mechanisms at right and left sides of the body. This type of the ground vehicle, named as a Powered Wheel Steering (PWS) Vehicle, because it can be steered by appropriately controlling the speed difference of each motor together with attaining the propulsion force by adjusting the average speed of the two motors, is playing an important role in the recent factory automation as a flexible carrier vehicle.
The paper firstly investigates the required basic running functions of a PWS vehicle and the proposed hardware to realize these functions is described. Followed with the above discussions, the speed control strategy to achieve the independent control of the two motors, under the limitation of the proposed single inverter utilization, is presented. The closed loop speed control program of motors is developed based on this control strategy. The experimental run of the test vehicle, with the specification which is almost the same as a currently-adopted 100kg load-weight carrier vehicle, is executed to examine the effectiveness of the proposed propulsion method.
The results, obtained for three running functions for a straight course, a curved course with a fixed radius of rotation and a spinturn which is defined as a turn of the vehicle arround the tread center, indicate that the presented method of induction motor propulsion assures a satisfactory operation for the vehicle control.
Furthermore, a self-sustained steering control, where the vehicle itself estimates the present position and generates the steering command so that the vehicle follows the pre-determined course on the floor, is tried for the straight course running. The result demonstrates the possibility that the vehicle will be well controlled under the presence of the guidance commands.
