A Fully Integrated, Reconfigurable Multiaxis Force Sensor via Inductive Displacement Sensing

Multiaxis force sensors (MFSs) are crucial for robotic manipulation and interaction in unstructured environments. Existing strain sensing-based MFSs usually have fixed functions and sensitivities, and are typically expensive and fragile, requiring complex fabrication and assembly. It is challenging to develop MFSs to meet the requirements of application scenarios. This article presents a fully integrated, reconfigurable MFS (RMFS), which utilizes an array of printed-circuit-board (PCB) coils to detect the multiaxis displacement/rotation of a metal target at high resolution without mechanical or electrical connections. The RMFS design requires simple fabrication at a very low cost and can be assembled in a few minutes. The basic characteristics, design criteria, and calibration method of the RMFS were investigated. The RMFS prototype achieved an ultrahigh resolution of 1 mN for triaxial force sensing (0.005%), with a maximum error of 1.9% for 20 N loading, a maximum crosstalk error of 5.7%, and extremely small drifts, over 10 h. Experiments show that the RMFS can respond rapidly and accurately to single and multiaxis force loadings. A reconfigured RMFS for <inline-formula> <tex-math notation="LaTeX">${z}$ </tex-math></inline-formula>-axis force and <inline-formula> <tex-math notation="LaTeX">${x}/{y}$ </tex-math></inline-formula>-axis torque sensing was realized by simply changing the metal target configuration. The RMFS shows promising features to be implemented in diverse applications from robotics, human–machine interaction, and biomedical systems.