STAS: an Antagonistic Soft Pneumatic Actuator Assembly for High Torque Output

The benefits of soft robotic actuation have been recognized and soft actuators are increasingly used. Soft robots are generally lightweight, inexpensive, and highly compliant. They are often used for interaction with small objects which only require relatively low force output. Nevertheless, large-scale applications can still benefit from the advantages of soft actuators if force output is sufficiently large. Some soft actuation has been employed in large-scale applications, but the area remains greatly underexplored. This article presents the Soft Torque-generating Actuation System (STAS) a lean soft actuation architecture capable of producing relatively large torque output while maintaining compliant interaction with the environment. Design and fabrication of the system are described, and a theoretical model is introduced for predicting torque output. The model is validated against measured torque output, and the system is further characterized in terms of power output. The model is shown to adequately predict torque output at low actuator angles. The system is shown to require only 30.0 kPa to achieve a large torque output of 10 N-m. The system also reaches a peak power output of 1.29 Watts. Finally, a versatile application of STAS is shown through a wearable joint-assistive device. The STAS is a promising architecture for a new type of high force actuation using soft actuators.