High-speed matrix pressure sensor for humanoid robot by using thin force sensing resistance rubber sheet

This paper describes a 32 × 32 matrix scan type distributed force sensor for humanoid robot foot which is developed for 1 kHz sampling rate. It is an analog version of the key matrix scan like sensor, and there are many efforts to achieve distributed tactile sensing by using this scheme. A thin (0.6 mm) force sensing resistance rubber sheet for this purpose is developed in order to achieve high speed sensing. Each sensing area is 4.2 × 7.0 mm and can measure approximately 0.25-20 N. The walking cycle of the humanoid robot as well as the human being is about 0.4-0.8 s and the dual leg phase is about 0.1-0.15 s. The sensor is utilized for biped walk stabilization so that high-speed input is important. A Schottky diode is adopted for each sensing element to prevent the interference effect of other sensing areas. An air-flow based calibration system solves analog differences of the circuit and elements. The sensor system, evaluation results, and experiments using humanoid type robot are described.