A Differential-Mechanism-Based Leg Configuration Balances the Load and Dynamic Contribution for All Actuators of the Quadruped Robot

Kinematic performance of a quadruped robot is determined by the mechanical structure. This article presents a novel leg structure for legged robots that integrates a differential mechanism into the conventional design. This approach enables all actuators to be positioned within the robot's torso at fixed locations, significantly reducing the leg's inertia. Furthermore, the new structure introduces a parallel transmission system that balances motion and torque distribution among the joint actuators, effectively reducing torque peaks and enhancing the drive capability during dynamic motions. A family of configurations of differential leg structures is constructed, and their mapping to the classic serial leg structure is dissected in kinematic and mathematic. Simulations of various single-leg models are conducted to validate the performance of the new configuration under typical gait conditions. Subsequently, a leg prototype is designed, manufactured, and tested in experiments involving tasks, such as trajectory tracking, weighted squats, and squat jumps. The development of a prototype quadruped robot featuring this novel leg structure is also presented.