Patent ID: 7148646

Claim:
A method for controlling a parallel kinematic mechanism machine, wherein the parallel kinematic mechanism machine comprises a base fixed outside, a plurality of struts connected to the base through a first universal joint, an actuator for driving each strut, an end effector connected to each strut through a second universal joint, and a control device for controlling the actuator by giving an actuator command thereto, the method comprising: a first step of obtaining each actuator command corresponding to position and posture commands of the end effector on the basis of predetermined kinematic parameters in the parallel kinematic mechanism machine; a second step of obtaining a load exerted by weight of at least any of the struts, actuators, first universal joints, second universal joints, and end effector; a third step of obtaining a load in the direction of axis of each strut and each actuator from the load obtained at the second step, kinematic parameters, and the position and posture commands of the end effector; a fourth step of decomposing the loads in the direction of axis of each strut obtained at the third step into each direction of axis of each universal joint defining an axial coordinate that contains the same axis in direction as any of rotation axes of the components of each first universal joint and/or each second universal joint; a fifth step of obtaining the amount of elastic deformation of at least any of the struts, actuators, or end effector from the loads in the direction of axis of each strut and each actuator obtained at the third step and from compliances of at least any of the strut, actuators, or end effector in each direction, and obtaining each first amount of elastic deformation and/or each second amount of elastic deformation that are amounts of elastic deformation of each first universal joint and/or each second universal joint respectively from compliances in each direction of axis of each universal joint and the loads in the direction of axis of each strut decomposed at the fourth step; a sixth step of converting each amount of elastic deformation, and each first amount of elastic deformation and/or each second amount of elastic deformation obtained at the fifth step into the direction of axis of each actuator in consideration of angles in the direction of axis of each actuator and each strut, and a seventh step of renewing actuator commands obtained at the first step in consideration of the converted each amount of elastic deformation, and converted each first amount of elastic deformation and/or converted each second amount of elastic deformation obtained respectively at the sixth step.