Experimental evaluation of steering actuator configuration on the behaviour of a soft growing robot

Abstract

Soft growing robots are a novel concept that uses fluid flow to increase in length at the tip. Using effective steering mechanisms, soft-growing robots can grow along the desired path. Series pneumatic artificial muscles (sPAMs) are used as steering actuators in contemporary soft-growing robots. This paper presents the experimental evaluation of the effect of the sPAM configuration on the bending of a soft-growing robot. The paper also includes the design and fabrication of the robot body and the sPAMs, the experimental setup, and the analysis of the observed results. The soft-growing robot body and sPAMs are made of low-density polyethylene (LDPE). The effect of four sPAM configurations (n sPAMs in m groups) on the bending angle and the blocked force is experimentally evaluated. Experimental results show that the bending angle is proportional to the number of sPAMs in a group (Bending angle reduces from 33° to 12° as the number of sPAMs in the group is reduced from 6 to 2). The blocked force applied by the robot tip remains constant over all the tested sPAM configurations. Hence, by varying sPAM configurations, a designer will be able to change the bending angle of a soft-growing robot without affecting tip forces.