Control methodology for an inflatable robotic arm

Soft robotic arms, made up of flexible components, have emerged recently. These systems can improve safety in collaborative operations, however, they also suffer from decreased precision and low payload. The control problem is then challenging due to link flexibility. The examined system is the so-called POP-UP robot, which is an anthropomorphic robotic arm with two inflatable links and three rigid joints designed and prototyped at DIMEAS. The system is composed by inflatable links and it is characterized by non-linearity. This structure is designed for aerospace applications and its main advantage regards the reduction of costs and storage, during the launch phase, with respect to a rigid equivalent manipulator and it is hard to derive a precise dynamic model suitable for control application. As a consequence it is very difficult to find a robust control law aiming to reduce the oscillations that arise after grasping a payload. This thesis aims to describe some methods to model an inflatable link and implement a vibration dumping control. A pseudo-rigid body model is defined and identified according to a set of experimental data. The same data are used to tune a FE model of the system. The frequency response of the flexible link to input from the motoreducer is evaluated, considering different payloads. This model is eventually used to develop a vibration control to the robot motion control. The obtained results are shown and discussed.