Prototype development and gait planning of biologically inspired multi-legged crablike robot

• An event sequence analysis method is proposed for studying gait of legged animals.
• Environmental self-adaptive gait has low energy loss and high motion efficiency.
• The robot adapts to the terrains automatically relying on self-adaptive trajectory.
• We develop multi-legged crablike prototype with its dSPACE experimental platform.
• Reducing motion speed will increase gravity fluctuation and toe-force.

In order to investigate the walking gait of the legged robot with multiple redundant walking legs, the motion features of the biologic crab are studied. To study the motion property of multi-legged animals in depth, an event sequence analysis method is proposed, and employed to design the motion pattern of multi-legged robot. A low-consumption environmental self-adaptive bionic gait with its phase factor of 0.25 and duty factor of 0.454 is analyzed based on the analysis of pace order, gait parameters and single leg’s terminal trajectory on uneven terrain. According to the structures and motion patterns of biologic crab, a multi-legged crablike prototype with its experimental platform is developed. The contrast tests of environmental self-adaptive bionic gait and double tetrapod gait are experimented at the same velocity, and slope climbing tests are performed as well. The experimental results show that, although the double tetrapod gait enables four legs to support the robot’s body at any time, there exists halt or backward phenomena periodically. However, the robot using the new gait has lower gravity fluctuation in displacement and velocity without halt or backward problem, and the decreasing of motion speed leads to the increasing of the gravity fluctuation and the toe-force.