Towards Differential Magnetic Force Sensing for Ultrasound Teleoperation

Low-profile, low-cost force/torque sensing is important in many applications. It can enable haptic feedback, performance evaluation, training, data collection, and teleoperation of ultrasound procedures. In this paper we introduce a new concept of differential magnetic field based multi-axis force sensing. A magnet is separated from two adjacent Hall effect sensors by a flexible suspension. The differential signal from the two sensors allows precise deflection measurement, and combining several of these on a compliant structure enables multi-axis force sensing. The concept is motivated, described, simulated, and tested. In initial experiments, the best-case deflection resolution is found to be 856 nm, with full-scale range of 1.5 mm and a root-mean-square force/torque error of 10.37% compared to an off-the-shelf sensor. This paper demonstrates the feasibility and potential of this force sensing mechanism.