An autonomous surface following control of robot manipulators using an ultrasonic proximity sensor and a vision sensor

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One of the practical problems of the autonomous surface following control system based on the sensory feedback is reliability of the proximity sensors. When the sensory information is decreased at discontinuous part of the surface, such as corners and edges, autonomous task also has to be discontinuous. In order to solve the problem, this research discusses a method to supplement the proximity sensor with a simple vision system.Results of the research are summarized as follows :1 An ultrasonic proximity sensor using a commercial ultrasonic range sensor and an ultrasonic orientation sensor was constructed.2. A gimbal mechanism was designed and fabricated to keep the sensor direction to the normal direction of an objective surface.3. An active antenna arm was developed, which is installed at the hand of a manipulator and searches the objective surface prior to the following task. The arm is moved on the bases of the feedback control of the ultrasonic proximity sensor installed at the tip.4. A simple and compact vision sensor was developed to investigate the surface conditions. The sensor detects a slit pattern projected on the surface and measure the shape of the surface. The sensor is installed at the tip of the antenna arm and detects the corners and edges of the surface.5. An algorithm was developed to avoid the edge or corner of the surface based on the vision information.6. The developed system was applied to the surface following tasks of robot manipulator and several experiments showed that the system can avoid the discontinuous part of the surface automatically and continue the autonomous surface following control.The results suggest that the developed system can be applied to the practical surface following tasks of robot manipulators.