Method for calibrating parallel kinematic mechanism

摘要

A calibration method for calibrating a parallel kinematic mechanism which is provided with an end effecter, a plurality of driver shafts connecting the base and the end effecter via a plurality of joints provided in the base and the end effecter, respectively, and a numerical control device for controlling the posture of the end effecter by manipulating coordinates of each driver shaft using the kinematics or the inverse kinematics, the calibration method comprising: setting an adjustment tool attached to the end effecter in a specified number of different predetermined postures in a reference coordinate system provided outside the parallel kinematic mechanism to define a reference coordinate system of the parallel kinematic mechanism, an axis of the adjustment tool being in agreement with an axis of the end effecter; a taking step of taking coordinates of the posture of the adjustment tool each time the adjustment tool is placed in the posture; recording coordinates of each driver shaft manipulated by the numerical control device in accordance with the inverse kinematics each time the adjustment tool is placed in the posture; and calculating kinematic parameters necessary for the kinematics of the parallel kinematic mechanism based on the taken coordinates of the postures of the driver shafts and the recorded coordinates of the driver shafts. Accordingly, it is possible to obtain accurate posture information of the end effecter and relative coordinates of the driver shafts.