Expand the Net Force Direction Range for Aerial Hose-type Robots Using Passive Orientation Control of Nozzle Unit With Multiple Water Jets

Abstract

Fluid injection has promising potential as a novel actuation approach for robots to enable the rapid switching of large forces. The proposed nozzle unit can drastically expand the injection range using a passive rotation mechanism to automatically follow the intended injection direction. Concretely, the nozzle unit consists of the passive joint to rotate and two active rotating nozzles to realize the net force. If the unit emits the jets inwardly, the nozzle posture converges to the direction of net force without any additional control. By modeling the proposed nozzle unit, we theoretically validate the stability of the proposed unit near the equilibrium point. Moreover, we demonstrate that some geometrical parameters could modify the responsiveness of the posture. The developed nozzle unit experimentally verifies that the nozzle unit can direct the net force direction in the range of 180 degrees from the upward to the downward direction.