There has been developed the insole-type GRF measurement system using the flexible piezoresistive force sensor and rigid force sensor, such as force sensitivity resistor (FSR) and optoelectronic based force sensor.
The surface of flexible force sensor can be distorted, causing the unpredictable output of sensor and the output can drift during long period loading. On the other hand, the rigid force sensor can measure more accurate GRF than the flexible force sensor. To compare the performance of force sensors, we conducted the static loading test and dynamic loading test. For static loading test, the quasi loading and unloading experiments were considered and the walking test was conducted for dynamic test.