1,721,422 research outputs found
An Advanced Multi-Orbit Precise Targeting Tool to Rapidly Design Multi-Payload Dispenser Delivery Strategy
No full textModel Predictive Trajectory Generation and Control for Ballistic Lander Deployment on Small Bodies from Small-Sat Platforms: the Taste Mission Case Study
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Inverse Reinforcement Learning for Collision Avoidance and Trajectory Prediction in Distributed Reconfigurations
No full textThermal Image Generation Tool for Spacecraft Relative Navigation in Proximity Maneouvering Phases
Full text linkIntegrated vibration suppression attitude control for flexible spacecrafts with internal liquid sloshing
Full text linkVibration suppression during attitude control is a fundamental research topic whenever control of the rotational motion of a spacecraft with flexible appendages and internal liquid sloshing is of interest. The proposed method is based on an attitude control system with centralized sensors and actuators, without the usage of collocated devices for vibration management. In this way, it is possible to develop and implement a computationally efficient real-time control system that is suitable for any kind of spacecraft, even with advanced control capabilities. An integrated vibration suppression attitude control is designed and analyzed, exploiting also a numerical simulation verification procedure based on validated code. The developed attitude control system applies two fundamental control schemes: classical proportional-derivative (PD) control, with nonadaptive band-stop filters, and wave-based control. The proposed wave-based control implementation allows managing three-dimensional attitude dynamics in steady state pointing, without cross-coupling between the separate body axes. To overcome this limitation, the paper presents the integration of the wave-based control with the filtered PD control scheme, allowing us to have a complete three-dimensional real-time MIMO controller, with vibration suppression capabilities and robustness to system uncertainties. The paper also presents the development of an accurate dynamical model of a generic flexible spacecraft with internal liquid sloshing based on a multibody formulation
Dynamics and Control of Modular and Extended Space Structures in Cislunar Environment
No full textProposed future space programmes, which, among others, include a space station in lunar vicinity, pose some interesting research problems in the field of non-Keplerian dynamics. This paper investigates the orbit-attitude dynamics and the control of rotational motion of an extended space structure in cislunar environment. The paper presents a fully coupled model for orbit-attitude dynamics, which is based on a Circular Restricted Three-Body Problem formulation. The equations of motion take also into account the most relevant perturbing phenomena, such as the Solar Radiation Pressure (SRP), the fourth-body (Sun) gravity and the variation in the gravitational attraction due to the finite dimension of the large space structure. Preliminary results exploiting efficient control methods are presented. Single and dual-spin stabilisation are compared and the results are carefully analysed to highlight a control strategy that is less resource consuming. The space of orbit-attitude solutions is studied to highlight possible stable conditions that may be exploited to host the cislunar station with minimum control effort. The outcomes of the research presented in this paper are intended to highlight drivers for the lunar outpost design and station-keeping cost minimisation. Furthermore, a case study for a large space structure in selected non-Keplerian orbits around Earth-Moon collinear Lagrangian points is discussed to point out some relevant conclusions for the potential implementation of such a mission
Neural-based predictive control for safe autonomous spacecraft relative maneuvers
Full text linkThe justification for this work and the goal of the paper is to develop an algorithm that addresses the following features: To develop a neural-based reconstruction algorithm for system dynamics identification, which allows an autonomous spacecraft to refine the on-board dynamic model as it flies, coping with unmodeled perturbations and nonlinearities. It is achieved by supervised learning of an RNN. To develop a planning algorithm that can adapt to the perturbed environments using the neural reconstructed dynamics. This prevents the failure of traditional algorithms in the presence of unmodeled terms in the dynamic model enhancing the autonomy and flexibility of the spacecraft. The task is performed using the developed MBRL method. To develop a relative trajectories prediction algorithm to ensure collision-free simultaneous reconfigurations. This is required when coordinated maneuvers are needed, where the hypothesis of the formation evolution according to natural dynamics does not hold. The neighboring trajectories are predicted by IRL and LSTM to guarantee safe reconfigurations
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