Improving the coupling errors of a Maltese cross-beams type six-axis force/moment sensor using numerical shape-optimization technique

In this paper, the optimal design of the elastic structure of a mechanically decoupled six-axis force/moment sensor is considered, with the aim of reducing the coupling errors of the sensors designed based on Maltese cross-beams geometry to negligible values. The reasons behind the creation of the coupling phenomenon in the Maltese cross-geometry are first analyzed using finite element and the design changes are made based on observations. After that, the numerical shape-optimization process is implemented by selecting eight design variables and a new objective function including all important coupling errors. The results show that the largest coupling error of the proposed optimal design decreases to less than 0.019% in rated load while the safe operation is secured and good isotropy of sensitivity is observed (condition number of normalized compliance matrix is 1.41), which are expected to provide design guideline for self-decoupled multi-axis force/moment sensors with measurement accuracy better than 0.1%.