Design and simulation analysis of humanoid lower limb with a parallel compliant actuator

This article presents a design method for humanoid lower limbs with a parallel compliant actuator. The integration of series-parallel main actuators and parallel efficient energy storage mechanisms significantly improves energy efficiency of the humanoid lower limb. The lower limb design is semi-anthropomorphic, with similar mass and mass distribution. Then a three-degree-of-freedom kinematic model of the humanoid lower limbs is established in the Cartesian coordinate system. Besides, The Lagrange equation is utilized to establish the inverse dynamics model, resulting in the derivation of the relationship between joint torque and joint angle. Subsequently, the parameters of elastic elements in the energy storage mechanism are optimized. The energy storage performance of the humanoid lower limbs is simulated in ADAMS. The simulation results validate that the parallel compliant actuation design can improve the energy efficiency of the lower limb, compared with rigid actuation systems.