Hyperstatic analysis of a fully pre-stressed six-axis force/torque sensor

This study proposes a fully pre-stressed dual-layer six-axis force/torque sensor based on a modified Stewart platform architecture, and discusses the hyperstatic analysis of the sensor. First of all, the number of measuring limbs is determined and the structure characteristics are introduced. Force distribution analysis of the sensor is conducted based on the mathematical model and force mapping matrix. Secondly, the forces on the measuring limbs are decomposed into particular solution (reacting force) and homogeneous solution (pre-tightening force). The stiffness weighted norm and weighted Moore–Penrose inverse of measuring limbs are defined, and their physical meanings are revealed. Then, a linear transformation method to determine the pre-tightening force is presented in order to ensure that the limbs be compressed. Finally, the numerical example and experimental result are performed, which demonstrate the correctness of the theoretical analysis. The results of the paper are useful for the further research and application of the fully pre-stressed six-axis force/torque sensor.

► A fully pre-stressed dual-layer six-axis force/torque sensor is proposed. ► Stiffness weighted norm and weighted Moore–Penrose inverse of limbs are defined. ► The pre-tightening force is determined by linear transformation method. ► The experimental result is consistent with the numerical analysis.