The paper “New Variable Passive-compliant Element Design for Quadruped Adaptation to Stiffness-varying Terrain”, written by Edin Kočo, Alan Mutka and Prof. Zdenko Kovačić, is now available online in the International Journal of Advanced Robotic Systems. The paper presents the design of a novel variable passive-compliant (VPC) element utilized as a lower-leg implant of a fully electrically driven quadruped robot. It is designed as a slider-piston mechanism which ensures that the force produced during foot-ground contact is directly perpendicular to the contact surface of an actuated revolute spring.
In this way, by altering the stiffness of quadruped legs in a closed-loop manner, the VPC element enables the quadruped robot to adapt to varying terrain characteristics, ensuring a constant hopping frequency over a wide range of terrain-stiffness variations.