Dynamic model of an online programmable textile soft actuator

Soft actuators exhibiting versatile behaviors have potential applications in robotics. This paper proposes kinematics, kinetics, and dynamic models of an online-programmable soft actuator. The actuator is composed of four strings and an inflatable textile tube folded inside a housing structure. Each string is controlled by a single DC motor which has an optical encoder. Pulling a string produces bending in one direction, while pulling the four strings in a coordinated manner produces additional motions. With the proposed forward and inverse kinematic model, the actuator was able to follow a desired end-effector trajectory in the Cartesian space. Furthermore, due to the dynamic model, our simulation study shows that the soft actuator can handle external force changes at the end-effector, such as mass changes and friction forces.