Design and Analysis of a Foot Contact Sensor for Posture Control of a Biped Robot

Development of a planar biped robot is currently underway at Yeditepe University. The robot consists of lower extremities with a torso that are designed at anthropomorphic dimensions. This study describes the design and testing of a foot contact sensor for the biped robot. Dynamic stability of a biped robot is commonly measured by the zero moment point (ZMP) method. Experimentally, ZMP is measured by multi-component force/torque sensors. Due to their low cost and ease of use, force sensitive resistors (FSR) are used to build a foot contact sensor for the biped robot. Four FSRs are mounted at the corners of the robot’s foot to measure the ground reaction force and its moment. Hence, by utilizing the data from the foot contact sensors, a real-time ZMP computation scheme can be implemented. The performance of the designed foot contact sensor is presented by numerical simulations of a planar biped robot’s postural stability control. Results indicate that reaction force computation by the FSR based force sensors is a viable method to monitor postural stability of biped robots. Force sensors and their electronics are currently being built to be used for the actual tests.