Closed-form force sensing of a 6-axis force transducer based on the Stewart platform

The 6-axis force transducers based on the Stewart platform require the solution of forward kinematics of the Stewart platform in order to obtain force and torque acting on the upper plate from given six leg forces. However, the solution of forward kinematics is not known in a closed form. In this paper, a closed-form solution of the forward kinematics is derived by means of linearization of the inverse kinematics equations, and the derived solution is applied to the calculation of force and torque acting on the transducer. In order to investigate the validity of the proposed method, a prototype of the transducer based on the Stewart platform is developed and force analysis is conducted. Moreover, the gravity compensation algorithm is proposed to reduce the weight effects of the transducer. (C) 2001 Elsevier Science B.V. All rights reserved.