Design and characterization of contraction motion actuator converted from swelling pneumatic balloon actuator for large deformation and force

This paper presents outputs enhancement of contracting pneumatic balloon actuator. A pantograph mechanism converts swelling motion of balloon into contracting motion. Newly designed circular membrane for a balloon allows large deformation of a balloon compared with a conventional balloon having a rectangle membrane. Here, a balloon having a circular membrane swells to be biased to one side. The other side of membrane swells little. Then, double balloon design having two balloons back to back each other is proposed to achieve large deformation. Proposed pneumatic contracting motion actuator has achieved several times as large output as our conventional actuator. Developed actuator contracts by 10 mm and generates 4 N at 60 kPa in the case of 30 mm×10 mm×0.7 mm device (radius 2.8 mm balloon). The outputs of the contraction actuator was enhanced almost three times in force and five times in stroke.