ROCR: An Energy-Efficient Dynamic Wall-Climbing Robot

We present a novel bioinspired dynamic climbing robot, with a recursive name: ROCR is an oscillating climbing robot. ROCR, pronounced “Rocker,” is a pendular, two-link, serial-chain robot that utilizes alternating handholds and an actuated tail to propel itself upward in a climbing style based on observation of human climbers and brachiating gibbons. ROCR's bioinspired pendular climbing strategy is simple and efficient. In fact, to our knowledge, ROCR is also the first climbing robot that is designed for efficiency. ROCR is a lightweight, flexible, and self-contained robot. This robot is intended for autonomous surveillance and inspection on sheer vertical surfaces. Potential locomotion gait strategies were investigated in simulation using Working Model 2D, and were evaluated on a basis of climbing rate, energy efficiency, and whether stable open-loop climbing was achieved. We identified that the most effective climbing resulted from sinusoidal tail motions. The addition of a body stabilizer reduced the robot's out-of-plane motion at higher frequencies and promoted more reliable gripper attachment. Experimental measurements of the robot showed climbing efficiencies of over 20% and a specific resistance of 5.0, while consuming 27 J/m at a maximum climbing speed of 15.7 cm/s (0.34 body lengths/s) - setting a first benchmark for efficiency of climbing robots. Future work will include further design optimization, integration of more complex gripping mechanisms, and investigating more complex control strategies.