Kinematic Modeling and Control of a Pneumatic 3D-printed Spatial Soft Manipulator using Configuration and Actuator Models

Over the past decades, various types of pneumatically driven soft manipulators have been designed, modeled and controlled to achieve different goals. The soft manipulator presented in this paper mainly consists of bellows segments based on pneumatic networks that enable spherical movements while being constrained in length along their central axes. This elongation constraint permits larger curvature angles and facilitates the use of alternative sensors, such as spatial bending sensors instead of rope-based sensors. Consequently, the individual actuator kinematics of each bellows segment are not measurable and need to be reconstructed. Therefore, a reconstruction method independent of the actuator’s elongation using a linearly scaled zenithal projection and a barycentric coordinate system is presented in this paper. Hence, the kinematic configuration and actuator models of the components of the soft manipulator can be fully defined. The models are validated experimentally. The use of a kinematic PI controller enables to fulfill a pick-and-place task showing the capability to manipulate objects in all six spatial degrees of freedom with the aid of a pneumatic network-based turntable.