Soft robotics represents a rising trend in recent years, due to the ability to work in unstructured environments or in strict contact with humans. Introducing soft parts, robots can adapt to various contexts overcoming limits relative to the rigid structure of traditional ones. Main issues of soft robotics systems concern the relatively low force exertion and control complexity. Moreover, several fields of application, as space industry, need to develop novel lightweight and deployable robotic systems, that can be stored into a relatively small volume and deployed when required. In this paper, POPUP robot is introduced: a soft manipulator having inflatable links and rigid joints. Its hybrid structure aims to match the advantages of rigid robots and the useful properties of having a lightweight and deployable parts, ensuring simple control, low energy consumption and low compressed gas requirement. The first robot prototype and the system architecture are described highlighting design criteria and effect of internal pressure on the performances. A pseudo-rigid body model is used to describe the behavior of inflatable links looking forward to control design. Finally, the model is extended to the whole robot: multi-body simulations are performed to highlight the importance of suitable sensor equipment for control development, proposing a visual servoing solution.

The rising interest in soft robotics, combined to the increasing applications in the space industry, leads to the development of novel lightweight and deployable robotic systems, that could be easily contained in a relatively small package to be deployed when required. The main challenges for soft robotic systems are the low force exertion and the control complexity. In this manuscript, a soft manipulator concept, having inflatable links, is introduced to face these issues. A prototype of the inflatable link is manufactured and statically characterized using a pseudo-rigid body model on varying inflation pressure. Moreover, the full robot model and algorithms for the load and pose estimation are presented. Finally, a control strategy, using inverse kinematics and an elastostatic approach, is developed. Experimental results provide input data for the control algorithm, and its validity domain is discussed on the basis of a simulation model. This preliminary analysis puts the basis of future advancements in building the robot prototype and developing dynamic models and robust control.

The interest in soft systems for space missions represents a growing trend in recent years. The development of inflatable robots, combined with the improvement of deployment mechanisms, allows to build novel lightweight and deployable robotic manipulators. In several space applications, the use of soft robots could minimize bulk and mass, reducing space mission costs. The main challenges in soft robotics are the control of the system and the exertion of high forces. In this manuscript, the concept of an inflatable manipulator with two inflatable links and three degrees of freedom is proposed. After a review about the possible materials to be used for the inflatable parts, the robot mechanical structure, the deploying strategy and the pneumatic line are presented. Then, an elastostatic approach is proposed to model the robot with the aim of developing its control. The last section shows preliminary experimental tests performed on the link prototype with the purpose to evaluate a static characterization in relation to the supplied pressure. Results suggest the validity of the adopted approach to model the system and clarify the pressure influence about the system performances. The study puts the basis for the development of the first prototype of the robotic system.

This paper describes the latest application of the inflatable robotic manipulator called POPUP. It consists of two inflatable links, made of fibers with high elastic module, electric motors and a gripper. This architecture allows volume and weight reduction, still maintaining the same payload compared to traditional solutions if the internal pressure is set properly. This robot, specifically designed for space application, here goes into action for debris mitigation by means of a vision system. First, some of the aspects related to the physical modelling are discussed to point out the working ranges of such a system, mainly defined by wrinkling effects. Then, a debris capture procedure is simulated to investigate the possibility to catch the target despite the soft nature of the robot. The multibody model takes into account robot dynamics and contact forces with the target. A control strategy based on closed loop inverse kinematics and visual servoing is proposed. The strategy relies on joint velocity command, computed starting from signals of two camera systems, one observing from the robot base, another moving with the end-effector. This ensures the correct tracking of the target and allows to overcome potential errors deriving from a flexible kinematic chain. Results show the POPUP successfully reaching the target and dictate the next steps for a real-world application.