High-speed pressure sensor grid for humanoid robot foot

This paper describes a 32 × 32 matrix scan type high-speed pressure sensor for the feet of humanoid robots that has 1 kHz sampling rate. This sensor has matrix scan circuit. The matrix scan method has a problem of interference by bypass current. To resolve this problem, we suggest a novel method using a very thin conductive rubber. We adopted a very thin (0.6 mm) force sensing conductive rubber sheet for high speed sensing. Each sensing area is 4.2 × 7.0 mm and can measure vertical force of approximately 0.25-20 N. Walking cycle of humanoid robot as well as human being is about 0.4-0.8 s and dual leg phase is about 0.1-0.15 s. The target of the sensor is biped walk stabilization so that high-speed input is important. Matrix scan type circuit is connected to sensor, and the system runs 1 kHz with 14 bit resolution at 4.2 × 7.0 mm grid for 32 × 32 points, and the sensor size is the same as humanoid robot foot 135 × 228 mm, The system is running high-speed because of the very thin conductive rubber and simultaneous measurement. The sensor system, a novel scan method, and evaluation results are described.