A degree-of-freedom analysis-driven configuration design approach for the capacitive compliant parallel six-axis force/torque sensors

Purpose The configuration of capacitive six-axis force/torque (F/T) sensors is critical to fulfilling diverse performance requirements. However, a systematic methodology for guiding sensor configuration design remains lacking. This study aims to propose a configuration design approach centered on degree-of-freedom (DOF) analysis, providing theoretical guidance for sensor configuration design. Design/methodology/approach By analyzing the signal conversion model of capacitive six-axis F/T sensors, the authors identified sensitivity isotropy as a critical performance metric. Through analyzing the mapping matrix, this study found that a 6-DOF elastic structure is essential for achieving sensitivity isotropy. Based on the DOF analysis method for compliant mechanisms, the authors analyzed the DOF characteristics of flexure building blocks and proposed a configuration design approach for compliant parallel sensors. Finally, this study designed and fabricated a sensor that satisfied sensitivity isotropy, verifying the feasibility of the methodology through its performance. Findings The sensor designed and fabricated in this study achieves an experimental precision of 0.5832%FS, outperforming both the precision and sensitivity of the commercial high-performance ATI Gamma sensor. This demonstrates the effectiveness of the proposed configuration design approach for capacitive six-axis F/T sensors. Originality/value The authors propose a configuration design approach that provides systematic theoretical guidance for capacitive six-axis F/T sensors. By following this approach, designers can quickly construct configurations meeting performance requirements, significantly improving design efficiency.