抄録
Recently, sensory organs of industrial robots have become of general interest. Among them, the tactile sensor has indispensably the primary role for material handling, and when this is used to sense the environment around the robot, it will give the robot flexibility and also adaptivity.
In this paper, we propose a PID force sense feedback method which can give clever grasping motions to the robot by simple preprocessing of the raw force sense and its feedback. That is, the grasping force is detected by the strain gauge and fed back to the finger driving circuit after proportional, integral and differential, i.e. PID operation of it. Then the robot can grasp thee given object with one of several touching and grasping modes predetermined by the amounts and mixing ratios of the PID feedback signals mentioned above. For an example, feedback of appropriate P and D signals can realize the soft touching and soft grasping actions.
Results of some experiments and analog simulation are shown to confirm the proposed method. And we prepare a design chart to show the relation between each PID parameter and the grasping force response, settling time and force overshoot. Using this chart, one can determine easily the value of PID parameters for action of the robot's fingers suitable to the object for which the physical characteristics are given.
