Crabbot: A Pole-Climbing Robot Driven by Piezoelectric Stack

Problems of large sizes and low displacement resolutions widely exist in most of the pole-climbing robots based on electromagnetic or electrostatic motors, which greatly decrease the reachable workspace and influence their utility for inspection tasks. Here, we present a piezoelectric pole-climbing robot (Crabbot) to overcome these shortcomings, which has the advantages of small size, high load-to-weight ratio and high resolution. Moreover, Crabbot can climb poles with different cross-sections through the designed crab-like clamp. This robot was composed of two clamping units and an elongation unit, and the stepping displacements were amplified by the designed flextensional mechanism. A prototype with weight of 0.35 kg was manufactured, the external dimension was 50 x 54 x 86 mm. Experimental results showed that the robot achieved a maximum speed of 100.9 mu m/s under a voltage of 150 V and a frequency of 9 Hz; moreover, a load weight ratio of 1.42 and a displacement resolution of 85 nm were obtained. As a demonstration of its potential for industrial applications, Crabbot achieved stable step motion on climbing poles of different cross-sections under different climbing angles.