Upper-lower limb coordination and active posture compensation for transverse ledge brachiation robots

Abstract

A ledge transverse brachiation robot (TBR) is a type of bio-inspired robot that realizes transverse movement along ledges on walls by swinging its lower limbs, while the upper limbs alternate between grasping and release actions. Partial ledge contact inevitably leads to deviations in posture, which can hinder brachiation landings and impede the accumulation of energy required to complete more than two continuous cycles. This study proposes a TBR configuration that uses reactive wheels as an active posture compensation system to allow novel styles of coordinated locomotion. The smooth and efficient transfer of energy between brachiation cycles is achieved by synchronizing the movements of the upper and lower limbs. Forward movement is achieved through the expansion and contraction of the upper limbs, while the overall rhythm is coordinated by introducing intermittent pauses in the continuous oscillation of the lower limbs. Active posture control compensation is achieved using a horizontal reaction wheel by utilizing angular momentum conservation, which corrects deviations in grip posture during the single-hand holding phases to ensure the efficient conservation of energy for subsequent brachiation cycles. In simulations, cost of transport (COT) values revealed approximately a 40% increase in efficiency following the execution of only five consecutive brachiation cycles, thereby demonstrating the efficacy of the proposed schemes.