Launches and Captures of the Space “Frisbees”: Dynamics Modelling and Simulation

Abstract

The current paper presents a concept of the non-conventional method of handling/transfer of the space objects/payloads, using single and multiple cooperative robotic manipulators with extremely flexible arms. Practical cases may involve launch only (as in the case of the ejection of the spacecraft), capture only (as in the case of the capture of the dysfunctional spacecraft or debris) or launch and capture, combined together (as in the case of a payload transfer from one platform to another). This method is seen as having numerous advantages over the traditional methods, employing propulsive systems on the payloads. These include: simplicity,reliability, re-usability, ability to handle passive payloads, and small power requirements. In this study, various operational scenarios of the launches and captures of the payloads are considered and designed in detail. In particular, we demonstrate the feasibility of the launch of the outgoing rotating payloads (called "frisbees") using a highly elastic robotic arm, capable of transferring its potential energy of the pre-deformed shape into the kinetic energy of the payload. Using the co-rotational FEM, we firstly simulate pre-launch phases, coiling the elastic elements in different shapes, for example, "U", "S" or even more complex shapes, and then propose and simulate the scenarios of ejecting the payloads utilising the kinetic energy of the elastic members (playing role of catapults). We also demonstrate the feasibility of the ejection of the payloads with required dynamic parameters, using cooperative robotic manipulator arms, performing coordinated throwing manoeuvres. This is done in compliance with the kinematics of the system and dynamics laws. The cases of the ejection of the payload is simulated using fully non-linear formulation, employing so-called co-rotational FEM,which enables to deal with large deformations, large rotations and large translations of the simulated elastic robotic arms. Numerical simulation allows to observe, to analyse and to suppress the transient strains and stresses in the flexible arms. In the cases of the payload capture, the co-rotational FEM method is used to simulate the process of de-spin, slowing and stopping the spinning object. This is also supplemented with the analysis of the strains and stresses on the members of the robotic arm manipulators. Various study cases are illustrated with the animations of the representative cases in Virtual Reality.