Characterization of electrical interferences for ground reaction sensor cluster

This paper presents the characterization of electrical interferences for a high-resolution error-correcting biomechanical ground reaction sensor cluster (GRSC), developed for improving inertial measurement unit (IMU) position sensing accuracy. The GRSC is composed of 13 × 13 sensing nodes, which can measure dynamic ground forces, shear strains, and sole deformation associated with a ground locomotion gait. The integrated sensing electronics consist of a front-end multiplexer that can sequentially connect individual sensing nodes in a GRSC to a capacitance-to-voltage converter followed by an ADC, digital control unit, and driving circuitry to interrogate the GRSC. The characterization data shows that the single-ended (z-axis pressure) mode exhibits a large output interference due to the un-matched interconnect traces design, thus limiting sensing resolution to 8 bits. The differential mode (x/y-axes shear strain) shows a reduced interference effect, achieving a 10-bit resolution.