Space Debris Capture Research Articles

Simulation and tension control of a tether-actuated closing mechanism for net-based capture of space debris

The growth of space debris in Earth's orbit is recognized as a serious threat to future space missions. To contain the growth of space debris in the long term, active removal of large defunct spacecraft is needed. A promising solution to this problem is the use of tether-nets. In the envisaged mission, a net is released from a chaser spacecraft toward a target debris; the net entangles the debris and the tether provides a flexible link between chaser and debris to tug the debris to a disposal orbit. The present work is focused on the simulation and control of a tether-actuated closing mechanism. In this concept, proposed only recently, the tether is looped through the center of the net and around the perimeter, and spooling the tether in draws the net perimeter closed. In this paper, a dynamic model of a tether-actuated closing mechanism for net-based capture of space debris is developed. The model of the winch, which is key to the control of the closing mechanism, is established based on literature on the design of reeling mechanisms for tether-nets. Two control laws for the winch velocity during deployment and closure of the net, respectively, are formulated and tested in simulation. Simulations of the capture of a Zenit-2 rocket upper stage are performed using a proportional-derivative tension control law with gain scheduling based on tether length. Results support feasibility of the tether-actuated closing mechanism.

Study on acceptable offsets of ejected nets from debris center for successful capture of debris

This study focused on the robustness of tether net in capturing space debris and investigated the effect of ejection alignment on capture success, with an assumption that there was an alignment between net ejection direction and direction to debris. The robustness of capture was significantly affected by the distance to the debris and the deployed size of the tether net at the timing of collision with the debris.

Fuzzy-Based Adaptive Super-Twisting Sliding-Mode Control for a Maneuverable Tethered Space Net Robot

The use of maneuverable tethered space net robot (TSNR) is a promising solution for active space debris capture and removal due to its large envelop and easy capture method. However, the flexibility and elasticity of the underactuated net present a new challenge to the control scheme. In this article, a fuzzy-based sliding-mode control is proposed and applied to the TSNR. The main contribution is that an adaptive super-twisting sliding-mode control (ASTSMC) is investigated with a novel adaption law based on a fuzzy estimator, eliminating the need for a derivative of uncertainty. The key advantage of the proposed scheme is that the passive adaption law of traditional ASTSMC is improved to an active law, and complex oscillations can be directly estimated and suppressed. The dynamics equations of the TSNR are first derived, and the control problem of the system is specified. For the unmeasurable and boundary-unknown uncertainties, the adaptive fuzzy logic scheme is employed to approximate the complex uncertainties. Stability analysis and approximation convergence of the proposed control scheme are then verified via Lyapunov stability analysis. Finally, numerical simulations on the TSNR are provided to confirm the effectiveness and robustness of the proposed scheme.

Controllable dry adhesion based on two-photon polymerization and replication molding for space debris removal

Abstract Space debris is a growing problem for the long-term usage of the low earth orbit. Currently no debris capture and removal method is successfully deployed in space. Anisotropic dry adhesive microstructures have a great potential to be an effectual approach for space debris capture. So far, no anisotropic dry adhesive structures have been produced with two-photon polymerization, which can then be replicated using a casting process. We 3D printed master molds with the use of two-photon polymerization and molded anisotropic dry adhesive structures with space rated polydimethylsiloxane. This paper describes the fabrication process and adhesion measurements on glass and acrylic glass surfaces. Our 3D dry adhesive microstructures showed an anisotropic adhesion factor of 7.52:1 and a maximum adhesion strength on glass and acrylic glass to be 1105.29 ± 40.93 and 1002.72 ± 8.24 mN/cm2. In conclusion, two-photon polymerization and the established molding process can be used to develop new types of mass producible anisotropic dry adhesives for the use in space and other applications where a high anisotropy of the holding force is needed. This promising approach can lead to faster design studies for dry adhesive structures.

Bio-inspired anti-impact manipulator for capturing non-cooperative spacecraft: theory and experiment

On-orbit capture of non-cooperative targets, i.e., malfunctioning satellites and space debris, is nowadays an urgent task. It is also a challenging task since the states of the non-cooperative targets are essentially unknown and have to be estimated by real-time visual detection. In the final approach stage, inevitable time-delay and measurement errors of the visual detection may cause a sudden impact between the servicing spacecraft and target, which can make the spacecraft unstable or even tumbling. Therefore, the compliant capture of a non-cooperative target is the key issue for the modern on-orbit servicing missions. The ‘robotic arm plus gripper’ type manipulator is normally used to capture space targets. However, sudden impact induced from the target cannot be efficiently suppressed in this conventional manipulator. To solve this limitation, inspired by animal limb structures, a novel bio-inspired anti-impact manipulator (BAM), consisting of a capture element, a bio-inspired structure and a buffer element, is proposed for the first time. The dynamical responses and isolation performance of the presently proposed BAM system are studied both theoretically and experimentally. In theoretical analysis, the mathematical model of the BAM system, described by a set of non-smooth ordinary differential equations, is established by the Lagrangian mechanics. The effects of system parameters are thoroughly investigated to verify the performance of the anti-impact system in various working conditions. In addition, the corresponding ground experiment is carried out to compare with the theoretical analysis. An interesting stick-slip phenomenon induced by the free-play nonlinear friction is observed in both theoretical and experimental studies. Finally, it is shown that the experimental result agrees well with the theoretical one, which verifies efficiency of the present BAM system.

Design and Analysis of Preload Control for Space Debris Impact Adhesion Capture Method

The growing space debris poses a serious threat to the safety of the space environment, and the necessity and urgency of active space debris removal have reached a consensus around the world. As one of the key technologies for debris removal, space debris capture has received extensive attention from researchers. In this paper, a space debris impact adhesion capture method is proposed, which involves a device integrated with gecko-inspired adhesion material at the front end and connected to the service spacecraft via a tether. The device can be launched from the service spacecraft, collides with the debris target and adheres to the debris surface to capture. The method provides the advantages of standoff distance allowed, high compatibility with different shaped targets and almost no risk of generating new debris. In order to provide a suitable preload for the adhesives, the device is put forward with a variable damping magnetorheological fluid buffer which could adjust the damping force in real time during the impact process to achieve reliable adhesion capture. The damping force fuzzy control method using impact force and remaining buffer stroke as input is designed. The simulations are carried out and the results show the effectiveness of the preload control method, thus proving a promotion for space debris impact adhesion capture method.

Numerical Study on Anchor Head Shapes for Lodging Anchors on Debris Structures for Capturing Space Debris

Numerical Study on Anchor Head Shapes for Lodging Anchors on Debris Structures for Capturing Space Debris

The Study of an Image Processing Method for Capturing Space Debris

The Study of an Image Processing Method for Capturing Space Debris

Post-capture attitude control with prescribed performance

The capture or docking of a spacecraft with a target spacecraft is an important component of future space debris capture and orbit servicing missions. One proposed concept includes using a robotic arm mounted on the chaser spacecraft to connect and manipulate the target's motion. This paper focuses on the post-capture attitude control of the target which will bring the target to rest and then control it in a prescribed way. The attitude control can be achieved by designing a robust control in the known chaser reference frame and treating the dynamics due to the uncertain inertia as an unknown disturbance. However, this can lead to poor performance since this uncertain torque can be large. In this paper, it is shown that the in-situ construction of the chaser-target dynamics can lead to improved performance. Based on the combined re-constructed model, a new disturbance observer based control with robust dynamic control allocation is developed. This approach is robust to the uncertainties in the re-constructed model and enables the prescription of convergence and stability properties. The proposed approach is demonstrated through numerical simulation of an actively controlled 12U CubeSat that has captured an inactive 12U CubeSat spacecraft.

RemoveDEBRIS: An in-orbit demonstration of technologies for the removal of space debris

ABSTRACTThe RemoveDEBRIS mission has been the first mission to successfully demonstrate, in-orbit, a series of technologies that can be used for the active removal of space debris. The mission started late in 2014 and was sponsored by a grant from the EC that saw a consortium led by the Surrey Space Centre to develop the mission, from concept to in-orbit demonstrations, that terminated in March 2019. Technologies for the capture of large space debris, like a net and a harpoon, have been successfully tested together with hardware and software to retrieve data on non-cooperative target debris kinematics from observations carried out with on board cameras. The final demonstration consisted of the deployment of a drag-sail to increase the drag of the satellite to accelerate its demise.

Effective Capture of Nongraspable Objects for Space Robots Using Geometric Cage Pairs

Capture and removal of space debris are challenging in robotic on-orbit servicing activities. A large portion of space debris does not possess any graspable features, which makes the conventional grippers inapplicable. To handle such nongraspable objects, a space robotic capture system is presented. A dual-arm space robot simulator that has the advantages of miniaturization and scalability is designed for ground tests. Inspired by the robotic caging, we propose a novel capture method that uses a series of hollow-shaped end-effector pairs to cage the antipodal pairs of the nongraspable objects. To apply the caging-pair method steadily, space robots need exerting a squeezing action on objects, which can be characterized by the motion and force manipulation of two robotic arms in the assigned directions. Based on the velocity and force manipulability transmission ratios, a caging compatibility index is proposed to describe the capturing ability in this manner. Via the optimization of the desired caging compatibility index, an effective algorithm is proposed to plan the near-optimal joint configurations for the pregrasping cages. Finally, both simulation studies and experimental tests are conducted to evaluate the performance of the proposed capture method.

Adaptive space debris capture approach based on origami principle

Space debris capture is the base of the on-orbit servicing and space debris removal. Due to the lack of fixed grasping points and the uncertainty of motion parameters, the traditional spacecraft manipulator approach cannot be applied in the space debris capture. In this article, a novel adaptive capture approach based on origami principle is developed. Main advantages of the proposed method are as follows: (1) it can capture target without fixed points. Through multimodule unfolding, the capture mechanism can form a suitable configuration for the space debris, restrict its motion, and capture it. (2) As the caging configuration of the capture device can be changed through different module unfolding, it can satisfy different size of the space target. (3) It can save the launch space of the capture mechanism. The multimodule capture mechanism has small volume after folding, which can greatly save the storage space in launch stage. The structure of the capture mechanism based on origami principle is developed, and the grasping configuration design is proposed for different size of the space debris target. In addition, considering the disturbance in process of capture is nonlinear and is hard to obtain accurately, a novel extended state observer-based sliding control is developed for the capture process control. The simulation results demonstrate the efficiency of the control algorithm.

The Study of an Image Processing Method for Tracking and Capturing Space Debris

The Study of an Image Processing Method for Tracking and Capturing Space Debris

Multiple Point Contact Impedance Control for Capture of Space Debris on Microgravity Environment

Multiple Point Contact Impedance Control for Capture of Space Debris on Microgravity Environment

Study of joint force controlled robot arm for capture of space debris

Study of joint force controlled robot arm for capture of space debris

Investigation of spherical helix inflatable mechanism for capture of space debris

Investigation of spherical helix inflatable mechanism for capture of space debris

System for Space Debris Capture Using Joint Impedance Controlled Manipulator

System for Space Debris Capture Using Joint Impedance Controlled Manipulator

Dynamics analysis of a convex spring for space debris capture mechanism

Dynamics analysis of a convex spring for space debris capture mechanism

Evaluation of durability in harpoon for space debris capture

Evaluation of durability in harpoon for space debris capture

Optimal Design of Passive Control of Space Tethered-Net Capture System

The space tethered-net is an important tool for space debris capture. But its rebound movement limits its effective working distance. To solve this issue, a passive control method using “Energy dissipation band (EDB)” is proposed in this paper. A semi-spring damper model of the EDB is first built and verified by the tests, and then the strengths of the bands are optimized with Radial Basis Function assisted optimization method with Batch infill Sampling criterion (RBFBS). Simulation results show that this passive control method can significantly increase the effective work distance of the space tethered-net, and RBFBS algorithm is able to optimize the strengths of the EDBs effectively and efficiently. This paper provides a new idea for the optimal design of the space tethered-net, which can be applied to the future flexible capture tasks.