Preliminary implementation of a system layout for the control of an inflatable robotic arm prototype

Robot gonfiabile per applicazioni spaziali Inside the human nature the desire of exploring always existed. From the ancient Greek tales of Ulysses, to the Phoenicia civilization who allegedly circumnavigate the African continent, to the discovery of the American continent and the sea explorations of the most remote island and part of Planet Earth, the humanity as soon as the technology was available start to look up into the sky. The space exploration began in the 60s, with USSR and USA competing for the space exploration. The collaboration between the nations interested in the space exploration then increased. In fact, in 1998, the International Space Station, orbiting around planet Earth, has been launched, as the biggest scientific international project of all time. [?] The robots became crucial for space application, replacing humans in dangerous situation. Humans can’t operate in lack of oxygen, and is safer to manipulate, repair and construct on the space with robots. Therefore, aerospace robotic application increased through the years, and not only for the exploration of the planets and satellites in the solar system. [1] The Canadarm2 is an example of this. It can move all along the ISS, performing all the operations needed in that field, thanks to a 17.6 m length when fully extended However, developing a robot for space application is a difficult challenge, starting from the design and arriving to the control. The environment in the space is totally different than the one on planet Earth. One of the problem is the rigid structure of the manipulator, which is heavy and therefore forces the manipulator itself to have an high payload. Soft robotics can face this challenge. In fact, robots made of soft materials are lighter and some applications are already present on planet Earth. With their low mass, they open the chance to launch them in the space thanks to a spacecraft and the possibility to transport them with less cost, since they are lighter. The inflatable links of soft robots are of course easier to launch in the space, since their mass is lower than the one of a traditional robot. With the possibility of inflating the robot on the field of application, the space occupied at the moment of the launch is a fraction of the case with a rigid structure. [3]. Having these advantages leads to some disadvantages. In particular, in performance, given the fact that inflatable links are present their stiffness and damping factor have to be taken into account. Positioning theend effector and controlling it in the 3 directions of the cartesian space is not properly accurate because of the oscillations of the inflatable link during the motions. [4]. Controlling the robot is therefore not easy Usually, the control algorithms for rigid body robot manipulators are based on precise mathematical models. [5]. The aim of the project is to implement and test a control for the robotic arm on the field. The robot will be controlled thanks to a PS4 controller. Before the beginning of this project, the communication system and the robot structure were already present. However, the control was present only in a draft way, in the sense that the control mode were defined, but not acceptable on the field. The aim of the project is to start from these drafts and to implement a wokrking control in the joint space, in the operational space and to try to implement a new function, the target reaching control.