ADAPT: Advanced Differential and Agile Parallel Transmission Mechanism for High-Performance Humanoid Robots

Abstract

Agile humanoid locomotion requires high joint torque and velocity, but conventional serial actuation, whether using high-reduction or Quasi-Direct Drive (QDD) actuators, faces limitations in size, weight, and efficiency. This paper proposes the Advanced Differential and Agile Parallel Transmission (ADAPT), a novel leg architecture that efficiently utilizes commercial actuators. Specifically, ADAPT integrates a Hip Pitch-Knee Differential Mechanism with a Knee-Ankle Parallel Transmission. This mechanism mechanically couples multiple actuators to generate output exceeding a single actuator’s capability, while concentrating the leg’s mass near the hip to minimize inertia. We validated the proposed design on a self-developed single-leg platform using a nonlinear kino-dynamic trajectory optimization framework. Experimental results from dynamic tasks including soccer kicking and vertical jumping demonstrate that the robot generates joint torques significantly exceeding the capability of a single actuator. This validates that the proposed architecture effectively overcomes the limitations of serial actuation, enabling high-performance dynamic behaviors efficiently.