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.