An elephant-trunk manipulator with twisting flexional rods

Different from traditional multiple backbones continuum manipulators, a novel elephant-trunk manipulator, called ET Arm, is design and developed. The ET Arm is composed of one or two segments (called muscle segment). The muscle segment includes three reduced motors, three flexional rods connected to screw, multiple disks, springs and wired bellows. When any flexional rod and the screw at the end of the rod twist driven by motors, the length between the base disk and partition disk along the rod will change, which makes the muscle segment bend due to the constraint of circle-distributed rods and multiple spacer disks. The wired bellow makes the ET Arm stable. The main architecture design, important parameter relationships and the workspace of ET Arm are given or discussed. The simulation of single segment is presented. The experimental results of physical system with two segments show that the ET Arm is valid and it can bend freely in its workspace.