Electrical interference suppression technique for 26 × 26 high-density ground reaction sensor array

This paper presents an effective interference suppression technique for a 26 × 26 high-density ground reaction sensor array (HD-GRSA) to achieve a superior gait ground velocity sensing resolution. The HD-GRSA is developed for improving inertial measurement units (IMUs) based personal navigation system accuracy. The HD-GRSA can measure dynamic ground force and shear associated with a human bipedal locomotion. A two-channel electronic detection system is designed to interface with the HD-GRSA. Each channel includes a front-end capacitance-to-voltage (C/V) converter, an analog-to-digital converter (ADC), timing control circuit and bias network. The interference suppression is realized by designing matching sensing lines on the system PCB to achieve a symmetric configuration. As a result, any pair of selected matching sensing lines from the HD-GRSA, when interfaced with the front-end C/V converter, can effectively reject interferences as a common-mode signal. System characterization reveals that the prototype HD-GRSA achieves a low output signal uncertainty around 2.2 mV_RMS, corresponding to a gait ground velocity resolution of 17 μm_RMS/sec, which closely matches to the system design specification.