Calibration Challenges for Measuring Multi-Legged Ground Contact Forces*

Ground contact modeling for multi-legged locomotion is challenging, because of the coupling effect of legs and foot slippage. We have previously presented a non-holonomic multi-legged locomotion model that used a mixed Coulomb-viscous-friction ansatz. This model matched experimental motion tracking data of multiple robots. To validate its predictions for the contact forces, we integrated a robot with six high precision 6DOF force-torque sensors. We present the force-torque sensing framework used in our robot and the present challenging calibration problems that arise. We hope that once calibrated, we will be able to directly and simultaneously measure the contact wrenches of all six legs.