This paper presents the gravity compensation and kinematic calibration considering gravity for parallel mechanisms, which reduce position errors caused by elastic deformations of machine parts due to gravity. The influence on the elastic deformations to the positioning accuracy is analyzed using the model of force balance between gravity and the motor power. Then the inverse kinematics solution with gravity compensation is proposed, in which the kinematic parameters are updated gradually according to the traveling plate pose. This provides us a real time motion control with compensation not requiring extra compensation values. The kinematic calibration considering gravity is also proposed to identify kinamatic parameters with no load. In order to improve the positioning accuracy, the identified parameters are used with gravity compensation. These methods are applied on the parallel mechanism based milling machine, named HexaM, and the validity is verified by simulations and experiments.
|ジャーナル||Seimitsu Kogaku Kaishi/Journal of the Japan Society for Precision Engineering|
|出版ステータス||Published - 2001|
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