Abstract: This paper explores the design of leg morphology in a six-legged robot. Inspired by nature, where animals have different leg morphology, we examined how the difference in leg morphology influences behaviors of the robot. To this end, a systematic search was conducted by scanning over the parameter space consisting of default angles of leg joints of the six-legged robot, with two main objectives: to maximize the kinematic flexibility and walking performance of the robot. Results show that (1) to have a high kinematic flexibility with both the torso and swing legs, the femur segment should tilt downwards by 5? – 10? and the tibia segment should be vertically downwards or with a slight inward tilt; (2) to achieve relatively energy-efficient and steady walking, the tibia segment should be approximately vertically downwards, with the femur segment tilting upwards to lower the torso height. The results of this study suggest that behaviors of legged robots can be passively enhanced by careful mechanical design choices, thereby leading to more competent legged machines.

Key words: six-legged robot, leg morphology, kinematic flexibility, walking performance