On the Development of a Multi-Modal, Selectively Lockable, Compact, Affordable Knee Joint Assembly for Bipedal Robots

Contemporary advances in humanoid bipeds include complicated mechanisms supporting fully actuated robotics. While these solutions offer unprecedented versatility that relies on sophisticated locomotion systems, the efficient traversing capabilities of natural, passive-inspired gait may be overlooked. In this paper, we focus on the development of a disengage-able, selectively lockable, affordable knee joint assembly suitable for either active or underactuated biped operation. The multi-modal nature of the design facilitates actuated bidirectional rotation as well as disengaged operation, while the knee lock ensures legs remain rigid during stance phase. Experimental validation of the performance of the knee assembly demonstrated both controllable knee joint actuation and fully passive rotation, various modes of operation, and torque evaluations. Further investigations include validation testing of operational and locking performance on a physical bipedal robot. System parameter optimizations can reduce energy consumption. The design proved feasible and is open-sourced to facilitate replication and co-development with others.