Locomotion speed capability analysis of six-legged robots: Optimization and application

Abstract

Locomotion speed is a key performance index of legged robots. However, methods to analyze and improve the locomotion speed capability are seldom developed, especially for six-legged robots. This paper develops a method to analyze and improve the omnidirectional walking speed and the turning speed of six-legged robots. The models of the inverse kinematics and the influence coefficients are built. Making use of the only-position-related property of the influence coefficients, a general optimization model of the locomotion trajectory is established. A two-step optimization method is introduced to solve the optimization problem. Based on the optimization, a comprehensive speed capability analysis is conducted on both omnidirectional walking and turning of the six-parallel-legged robot. The results clearly show the relationships among the speed capability, the walking direction and the duty cycle. The two-step optimization method improves the speed capability by 12.4%–13.2% for turning and 18.5%–20.5% for omnidirectional walking. Finally, the costs of the speed improvement are analyzed, including the stability, the energy consumption and the calculation time.