Device for compensating for deflection in a pliable positioning apparatus

摘要

A working structure having a support and an arm assembly pivotally connected to the support. The arm assembly includes at least two arm members pivotally connected to each other and each pivotally moved by a respective actuator. The second arm member has an external load applied to its front end or working point. The apparatus includes angle sensors for sensing pivoting angles of the respective arm members, load sensors for sensing the external load, target position indication device for indicating the coordinate target position of the working point, and a control unit including a deflection calculation section responsive to signals produced by the angle sensor means and load sensor means for calculating a deflection of the arm assembly at the working point, pivoting angle calculation section responsive to signals produced by the target position indication device for calculating provisional pivoting angles for the arm members corresponding to the target position when the arm assembly is assumed to produce no deflection, and correcting angle calculation section responsive to signals produced by the deflection calculation section and pivoting angle calculation sections for calculating, as correcting angles, the pivoting angles for the respective arm members corresponding to the deflection in the position of the provisional pivoting angles such that the first and second actuators are actuated based on the signals from the pivoting angle calculation and correcting angle calculation sections to pivotally move the first and second arm members to correct any error caused by the deflection of the arm assembly.