Non-invasive low cost method for linear and angular accelerations measurement in biped locomotion mechanisms

A new non-invasive low cost method for accelerations measurement in biped locomotion mechanisms is presented. The aim is to measure all the joint accelerations of the locomotion system during the walking that is difficult because of the non-accessibility of several joint axes. Our measurement approach is non-direct using two triaxial accelerometers aligned on the main axis of each body, that ensures measurement of five accelerations per joint, two angular and three linear. By considering negligible the vertical rotation of a leg in the absolute frame during walking, the vertical rotational acceleration of the hip is measurable by two accelerometers aligned along the sagittal axis. For tibia and thigh, the accelerometers are aligned along vertical axes. The calculation of accelerations in articulation references is achieved by solving a system of Newton mechanics equations. The theoretical statements were validated experimentally on the robot for vertical flexion-extension movement.