Stiffness Design of a Resonance-Based Planar Snake Robot With Parallel Elastic Actuators

This letter proposes an N-link snake robot with parallel elastic actuators (PEA) and a stiffness property that reduces the energy consumption during fast movement. Each PEA couples the actuator output to a spring element, enhancing the periodic gait as demonstrated in previous studies of walking robots. The PEA can mimic each joint of a typical snake robot, which is also controlled by sinusoidal periodic signals. If the actuator output is synchronized with the resonance frequency of the spring, the PEA can greatly reduce the actuator torque and power. Therefore, this letter proposes PEAs to reduce the energy consumption of N-link snake robots. After analyzing the robot dynamics, we explain how the torque of each joint is minimized. The energy consumption is evaluated by measuring the motor current in experimental tests. During fast movement of the robot, the PEA reduced the current consumption by 72%.