Speed-Up of Robot-Manipulators Using Sliding Mode Control

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In this research, a servo-system using sliding mode and its application to robot manipulators is investigated. Results are as follows:(1) A method for generating the sliding mode by a relay with a small step is proposed in order to aboid the affection of chattering. The relay generates stepwise torque around the "equivalent control" to cover a wide range of output torques. The proposed method is used with the continuous control method of sliding mode in the boundary layer.(2) An algorithm for motor control to determine the control mode and the duty rate of PWM by taking the effect of the voltage generated by motor rotation into consideration is proposed. The energy consumption of the motor is saved by the algorithm.(3) A method to adjust the acceleration and the velocity of the desired hand position so as to keep the maximum duty rate within a range and to protect the sliding mode from its deviation.(4) The proposed methods are applied to a manipulator with two joints and investigated by computer simulation. It is verified by this simulation that the path accuracy is significantly improved, the system is robust against the change of the mass of the hand, the acceleration and deceleration control work well and are effective for the improvement of the computing time.(5) Methods to decrease the computing time for robot control using a multi-microprocessor are shown. The multiprocessor is applied to the inverse kinematics problem of a six-joint manipulator. The division of the inverse kinematics calculation into scalar level tasks and the re-combination of the tasks are discussed. It is verified by experiments that the computing time of the inverse kinematics of the elbow manipulator is decreased from 19.57 ms for one CPU to 3.07 ms with the proposed multi-microprocessor. The sliding mode control using the solution of the inverse kinematics is performed on the six-joint manipulator. It is shown that the sliding mode control is available for the six-joint manipulators.