Theoretical analysis and experiment research of a statically indeterminate pre-stressed six-axis force sensor

This paper presents the theoretical analysis and experiment research of a novel statically indeterminate six-axis force sensor based on a modified Stewart platform architecture. The characteristic of the pre-stressed structure is analyzed in comparison with the traditional Stewart platform-based force sensor. The force-distribution problem of the seven-limb statically indeterminate structure is solved by considering the stiffness properties and compatibility in deformations, and the sensor's force mapping matrix including the effect of the seventh limb is obtained. The isotropy performance of the sensor is studied, and the analytic relations of key structural parameters leading to isotropic configuration are obtained. The pre-tightening force is determined by solving the conditional extremum of the Lagrange function. The sensor prototype and the calibration device are manufactured, and the experiment results prove the superiority of the structure and the correctness of the theoretical analysis.