The analysis of new 3 DOF parallel delta type leg for a quadruped robot to maximize actuation torque reduction

The legged type robot generally requires high torques for stable walking and running. However, the robot's electric motor driven actuators usually have a low payload to weight ratio. To overcome this problem and use actuators' power more efficiently, we apply a parallel mechanism to a robot's leg design. A parallel mechanism can distribute a payload over actuators and reduce the actuation torque, and thus enhance the robot's walking stability. The process of optimal design of 3 DOF parallel delta type leg is 1) definition of workspace and payload based on tasks, such as walking and climbing a stair, 2) derivation of inverse kinematics and equation of motion, 3) optimization of a robot leg's mechanism, and finally 4) feasibility of the 3 DOF Parallel Delta type Leg (3PDL) for a quadruped robot compared with the 3 DOF Serial type Leg (3SL). In this paper, it is shown that the optimal 3PDL has a strong tendency of greatly reducing the maximum actuation torque and enhancing the manipulability in the certain workspace.