Investigation of force sensors for use in bipedal humanoid dynamic gait generation

A humanoid robot is being developed for implementing and evaluating dynamic gait algorithms. Force sensors are placed on the bottom of the feet of the robot to provide feedback for the control system. The use of resistive force sensors is being investigated as an inexpensive and lightweight alternative to multi-axis force/torque sensors. However, resistive force sensors have a more limited accuracy and response time. Sensors from three companies have been tested: Sensitronic, Interlink, and Inaba Rubber. The sensors were tested with a TA.XTPlus texture analyzer, which is capable of applying specific forces at different rates. The sensors were tested for repeatability of response, drift, and response time to both application and removal of the force. An inverting op-amp is used to convert the force measurement of the sensor to an output voltage, which is read by an oscilloscope. The force measurements from texture analyzer and the voltage output from the oscilloscope are recorded digitally. The data obtained from the measurements is analyzed and the potential uses and limits of the sensors as feedback mechanisms in a bipedal humanoid robot are discussed.