Manufacturing of a 3D Soft Sensor for Feedback Control of Pneumatic Muscles and Applications with Cylindrical Structures

Abstract

Presented is the manufacturing process and characterization of a 3-D Helical soft sensor composed of Eutectic Gallium Indium (eGaIn) as the conductive pattern and silicone rubber as the substrate. A novel eGaIn writing process was used to achieve the 3D structure. The process did not require any molds. Different diameter sensors and coil densities are shown to show repeatability and versatility of the process. A multilayer sensor is also shown. Some example applications for the sensors are shown. Sensors were tested up to deformations of 50% diametrically and 21% axially. Diametrically, resistance changes of up to 20 ohms are achieved. The results show negligible hysteresis diametrically and a change of 0.2 ohms axially, showing the sensor to be sensitive, reliable, and compact solution for applications where diameter change needs to be measured. In addition, presented is the modeling and control of a pneumatic artificial muscle actuator with an integrated 3-D sensor for position feedback. A theoretical model and experimental characterization of the muscle-sensor package are presented with high correlation and repeatability. A position feedback sliding mode controller is implemented with a position error of <0.9% of maximum muscle contraction. Finally, further applications of the sensor are discussed.