A Positive and Negative Pressure Soft Linear Brake for Wearable Applications

Abstract

Linear brakes are devices used to restrict relative linear motions between two points. The use of soft robotic technology has enabled the fabrication of lightweight linear brakes making use of frictional forces generated by a vacuum on jamming layers. This kind of device has significant potential for wearable devices as they are lightweight yet produce significant linear tensions which can be used to transfer loads or to selectively prevent certain motions of the body. However, vacuum-based devices have limitations in terms of maximum pressure and due to the decreasing frictional forces as the jamming layers decrease in contact area as they separate during the motion. This article introduces a positive and negative pressure linear brake where both positive and negative pressure is applied to jamming layers located inside of a pouch motor which is pressurized using positive pressures. This results in a soft linear brake capable of large braking forces and of adjusting its behavior through the variation of both positive and negative pressures. The proposed brake could sustain a linear tensile force approaching 500 N even at lower pressures and was implemented as a lower back support device intended for factory and healthcare workers.