A High Range-to-Resolution Multiaxis mu Force and Torque Sensing Platform

This article presents a novel multiaxis mu Force sensor with a range-to-resolution ratio of 55 000, which makes the sensing device highly useful for wide range of applications. The presented device relies on a sensing strategy where a 2-D encoded micropattern is encrypted to the mobile part of the compliant platform. This encoded pattern allows multiaxis visual sensing of displacements over a long range, whereas Fourier computations ensure subpixel interpolation leading to the high resolution. The device is fabricated on a silicon wafer by means of clean room technology to comply with both precision encoding requirements and reliable mechanical behavior. This article presents the design, modeling, and fabrication as well as the experimental validation of the multiaxis mu Force-Torque sensor. A modeling strategy is proposed for an effective estimation of force/torque with its capability to adapt nonlinear stiffness evolution during the external loading. Experimentation demonstrates a sensing resolution of 2 mu N over a validated range of 110 mN. The proposed sensor measures the force along the two planar axes, and also the torque along the axis orthogonal to the plane, thus, validating its axial decoupling capabilities.