Fig. 1 Schematic construction of a PWS vehicle Fig. 2 Main power circuit of an inverter system for two motors drive

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ようたながだき
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1 An Application of Multiple Induction Motor Control with a Single Inverter to an Unmanned Vehicle Propulsion Akira KUMAMOTO* and Yoshihisa HIRANE* 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. Key Words: vehicle, inverter, induction motor, motor control

2 Fig. 1 Schematic construction of a PWS vehicle Fig. 2 Main power circuit of an inverter system for two motors drive

3 Table 1 Test vehicle specification Fig. 3 Driving and control circuit assembly of two motors for a PWS vehicle

5 Fig. 4 General flow-chart of speed control in case of either straight or curved course running (a) Without guidance (a) V=10m/min (b) V=40m/min (c) V=25m/min 10m/min Fig. 5 Experimental results of straight course running for various vehicle velocity commands (horizontal axis 1s/div) (b) With self guidance Fig. 6 Effect of self guidance in case of straight course running (vehicle velocity command V=30m/min) - 89-

6 (a) R=0.5m, (b) R=1.35m, V=10m/min V=10m/min Fig. 8 Experimental traces of tread center in case of curved course running (a) Vlimit=5m/min (b) Vlimit=l5m/min Fig. 9 Experimental traces of tread center in case of spin-turn (a) V=10m/min, R=0.5m (b) V=10m/min, R=1.5m (c) V=20m/min, R=1.0m Fig. 7 Experimental results of curved course running for various course patterns (horizontal axis 1s/div)

7 6) J. Okabe, A. Kumamoto, Y. Hirane and H. Tanaka: Independent Closed-Loop Control of Two Induction Motors Paralleled to a Single Inverter and its Application to an Automatically Guided Ground Vehicle, Proceedings of IECON '84, 180/185 (1984) -91-

On the Wireless Beam of Short Electric Waves. (VII) (A New Electric Wave Projector.) By S. UDA, Member (Tohoku Imperial University.) Abstract. A new e

On the Wireless Beam of Short Electric Waves. (VII) (A New Electric Wave Projector.) By S. UDA, Member (Tohoku Imperial University.) Abstract. A new electric wave projector is proposed in this paper. The