Capture Of Non-cooperative Target Research Articles

Bioinspired flexible gripper for vacuum non-cooperative target capture

With the development of space exploration activities, the proliferation of non-cooperative targets in space, such as defunct satellites and space debris, has made the development of efficient and reliable non-cooperative target capture technologies in space a priority for space exploration. In this paper, a flexible gripper inspired by the dermo-muscular sac found in flatworms is presented to address the challenges of non-cooperative target capture in the vacuum environment of space. The gripper design leverages magnetorheological fluid and a magnetic field to enable adjustable stiffness, facilitating the effective grasping of delicate target objects while ensuring a stable connection post-capture. Extensive tests demonstrate the strong potential of the gripper for space applications, showcasing its ability to adjust pre-grip contact force and increase gripping force by adjusting indentation depth. The simplicity of the design contributes to ease of manufacturing, making it a promising tool for future space missions.

Artificial potential incorporated adaptive fixed-time sliding mode control for target capture

With the increasing development of space missions, techniques for space non-cooperative target capture are evolving into new stage with higher control requirements under various working scenarios. Imitation Human Hand Capture is an effective rigid envelope capture method and could grasp non-cooperative targets without any cooperative feature points. In order to guarantee the safety and increase the success rate of IHHC, an adaptive fixed-time sliding mode frame based on IHHC is proposed, in which the Imitation Human Hand Capture governs the stable grasp and the sliding mode frame governs the control performance. In the proposed control frame, a fixed-time sliding mode control method is employed and the settling time can be adaptively tuned with the artificial potential function formulated according to the base-target distance and the envelope state of the arms. The proposed control frame is verified through Lyapunov function and simulation tests. The results demonstrate the effectiveness of the proposed control frame.

A grasp planning algorithm under uneven contact point distribution scenario for space non-cooperative target capture

The contact point configuration should be carefully chosen to ensure a stable capture, especially for the non-cooperative target capture mission using multi-armed spacecraft. In this work scenario, the contact points on the base and on the arms are distributed on the opposite side of the target. Otherwise, large forces will be needed. To cope with this problem, an uneven-oriented distribution union criterion is proposed. The union criterion contains a virtual symmetrical criterion and a geometry criterion. The virtual symmetrical contact point criterion is derived from the proof of the force closure principle using computational geometry to ensure a stable grasp, and the geometry criterion is calculated by the volume of the minimum polyhedron formed by the contact points to get a wide-range distribution. To further accelerate the optimization rate and enhance the global search ability, a line array modeling method and a continuous-discrete global search algorithm are proposed. The line array modeling method reduces the workload of calculating the descent direction and the gradient available, while the continuous-discrete global search algorithm reducing the optimization dimension. Then a highly efficient grasping is achieved and the corresponding contact point is calculated. Finally, an exhaustive verification is conducted to numerically analyze the disturbance resistance ability, and simulation results demonstrate the effectiveness of the proposed algorithms.

Neural-network-based backstepping control for the post-capture tethered space combination using HDO

In this paper, a novel neural-network-based backstepping control method is designed for the post-capture tethered space combination system subjected to multi-source disturbances and actuator saturation. To cope with the multi-source disturbances, the so-called HDO is put forward which is capable of addressing both modeled and unmodeled disturbances. These disturbances are not necessarily matched disturbances and hence the backstepping design procedure is utilized. In virtue of the radial basis function neural networks (RBFNNs), the unknown nonlinearities is estimated. Additionally, the anti-windup technique is employed to handle the actuator saturation phenomenon which is unavoidable in the post-capture tethered space combination system. Sufficient conditions are derived to guarantee that the post-capture tethered space combination system is stabilized while carrying out the non-cooperative target capture mission. Finally, a number of numerical simulations are conducted on the post-capture tethered space combination to validate the proposed methodology.

Design of a non-cooperative target capture mechanism for capturing satellite launch adapter ring

Space debris is growing dramatically, which poses a serious threat to space exploration activities. Especially the large non-cooperative target, such as malfunctioning satellites. This paper proposes a capture mechanism for the launch adapter ring that is usually available on satellites as the capture object, which used for in-orbit capture of malfunctioning satellites. Firstly, introduce the design conditions, the overall design plan, carry out the mechanical mechanism design, sensor system configuration, electrical system design, and explain the capture process. Secondly, analyze the capture tolerance. Thirdly, by establishing the kinematics model of the captured finger, use D-H parameter method for kinematic analysis, and analyze the dynamic in the capturing process. In addition, the control strategy is proposed, and the clamping force model, friction identification model, and servo control strategy are established. Then, the prototype is manufactured, and the clamping force, stiffness, capture loads, and capture tolerance are tested. Finally, the air-floating platform is used to verify the capture test of the launch adapter ring in a microgravity environment. The experimental results show that the developed capture mechanism meets the design conditions and has the ability to capture launch adapter ring of satellites in orbit.

Design and Experimental Study of Space Continuous Robots Applied to Space Non-Cooperative Target Capture.

Space capture actuators face problems such as insufficient flexibility and electrical components that are vulnerable to extreme space environments. To address these problems, a centralized-driven flexible continuous robot based on a multiple scissor mechanism units is proposed in this study. The continuous robot body is composed of two scissor mechanism units coupled in series, and the base container’s three motors to drive the robot. The two scissor mechanism units ensure a wide range of flexible operations and the light weight of the robot. The centralized drive with three motors not only reduces the number of driving sources, but also ensures temperature control and protection of electrical components in the space environment. The kinematics and dynamics of the robot are analyzed, and the workspace and deformation performance of the robot are verified through experiments. Compared with other continuous robots, the proposed continuous robot retains the characteristics of continuous robots in a wide range of flexible operations. At the same time, the configuration is light and a small number of driving sources are used, which is suitable for extreme temperatures, vacuum, radiation, and strict resource-constrained environments in space.

Impedance control of multi-arm space robot for the capture of non-cooperative targets

Robotic systems are expected to play an increasingly important role in future space activities. The robotic on-orbital service, whose key is the capturing technology, becomes a research hot spot in recent years. This paper studies the dynamics modeling and impedance control of a multi-arm free-flying space robotic system capturing a non-cooperative target. Firstly, a control-oriented dynamics model is essential in control algorithm design and code realization. Unlike a numerical algorithm, an analytical approach is suggested. Using a general and a quasi-coordinate Lagrangian formulation, the kinematics and dynamics equations are derived. Then, an impedance control algorithm is developed which allows coordinated control of the multiple manipulators to capture a target. Through enforcing a reference impedance, end-effectors behave like a mass-damper-spring system fixed in inertial space in reaction to any contact force between the capture hands and the target. Meanwhile, the position and the attitude of the base are maintained stably by using gas jet thrusters to work against the manipulators' reaction. Finally, a simulation by using a space robot with two manipulators and a free-floating non-cooperative target is illustrated to verify the effectiveness of the proposed method.

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.

Passive impact/vibration control and isolation performance optimization for space noncooperative target capture

On-orbit capture is an important technique for the space debris removal, refueling, or malfunction satellite repairing. While due to the uncertainty of the motion parameters of the space noncooperative target, the impact between the capture device and the noncooperative target during the capturing process is inevitable, which may bring strong vibration perturbation to the base satellite, and potentially alter the position and the attitude of the servicing spacecraft, or even cause failure of on-orbit tasks. This article presents a new and alternative method for passive suppression of spacecraft impact and perturbation during noncooperative spacecraft capture. The passive device based on bioinspired X-shape is installed between the satellite and the capture device. In the capture process, nonlinear damping of the passive isolation structure can significantly reduce impact/vibration perturbation. For performance analysis, dynamic equations of the isolation system are established. Based on which, the relationship between structure parameters and isolation performance is systematically analyzed. Experiments are conducted for verification of the effectiveness of the proposed method. Moreover, an optimal process using the non-dominated sorting genetic algorithm II optimization method is developed to minimize impact/vibration perturbation effect, and optimal solutions can provide useful reference for the passive isolation system design.

Elephant’s Trunk Robot: An Extremely Versatile Under-Actuated Continuum Robot Driven by a Single Motor

Continuous-bodied “trunk and tentacle” robots have increased self-adaptability and obstacle avoidance capabilities, compared with traditional, discrete-jointed, robots with large rigid links. In particular, continuous-bodied robots have obvious advantages in grasping objects across a wide range of external dimensions. Not only can they grasp objects using end effectors like traditional robots, but their bodies can also be regarded as a gripping device, and large objects with respect to the robot’s scale can be captured by the entire structure of the robots themselves. Existing trunk-like robots have distributed multidrive actuation and are often manufactured using soft materials, which leads to a complex actuator system that also limits their potential applications in dangerous and extreme environments. This paper introduces a new type of elephant’s trunk robot with very few driving constraints. The robot consists of a series of novel underactuated linkage units. With a single-motor drive, the robot can achieve stable grasping of objects of different shapes and sizes. The proposed robot simplifies the requirements of the sensing and control systems during the operation process and has the advantage of accomplishing the capture task without determining the exact shape and position of the target object. It is especially suitable for operations such as non-cooperative target capture in extremely dangerous environments, including those in outer space. Based on theoretical analysis and model design, a trunk robot prototype was developed, and a comprehensive experimental study of the bending/extension and grasping operation functions was conducted to verify the validity of the proposed robot design.

Kinematics-based incremental visual servo for robotic capture of non-cooperative target

This paper presents the concept and experimental results of a kinematics-based incremental visual servo control approach for robotic manipulators with an eye-in-hand configuration to capture non-cooperative targets autonomously. The vision system is adopted to estimate the real time position and motion of the target by an integrated algorithm of photogrammetry and the adaptive extended Kalman filter. The unknown intercept point of trajectories of the target and the end-effector is dynamically predicted and updated based on the target estimates and is served as the desired position of the end-effector. An incremental control law is developed for the robotic manipulator to avoid multiple solutions of the robotic inverse kinematics. The end-effector is then controlled by the proposed control scheme to approach the dynamically estimated interception point directly. The proposed approach is validated experimentally by custom built robotic manipulator. To demonstrate the effectiveness of the proposed approach, uncertainties, such as, joint flexibility of the robotic manipulator, backlash of actuators, nonlinear target motion, camera mounting bias, etc., have not been considered in the control law. The experimental results show that the predicted minimum tracking time is reduced asymptotically as the end-effector approaches the target, which demonstrate the proposed control scheme is effective and reliable. The advantages of the proposed control approach are: it does not require a robotic dynamic model that most of the existing robotic control based on; it avoids the multiple solution problem in the inverse kinematics; it is insensitive to system uncertainties; and it is much easier for engineering implementation.

Mechanical design and analysis of a gripper for non-cooperative target capture in space

Space grippers are the key devices for accomplishing space non-cooperative target capture, which has a great significance for satellite services and space debris removal. This article proposes a novel mechanical gripper device for the capture of aluminum honeycomb panels of non-cooperative satellites. The gripper was modeled and assembled in the three-dimensional modeling platform UGNX. The model was imported into the simulation software ADAMS. ADAMS is capable of analyzing the kinematic feasibility of the gripper model. Collision and penetrating power analysis of the mechanical claws into an aluminum honeycomb plate were carried out in LS-DYNA. Through non-vertical piercing experiment, the maximum approaching angle tolerance is 10°. The established rigid connection can withstand a destructive force greater than 1000 N. A prototype of the mechanical gripper is built. A ground test was carried out with this prototype, in which a test-platform simulated the space microgravity environment. The results certified that the prototype could reach the target at a relative speed of 0.5 m/s and then quickly complete the grabbing motion and establish a rigid connection. The experiment shows that this mechanical gripper can accomplish the task of repeatedly capturing the surface of non-cooperative space satellites.

Performance Analysis and Gains Tuning Procedure for a Controlled Space Manipulator Used for Non-cooperative Target Capture Operations

In the near future robotic systems will be playing an increasingly important role in space applications such as repairing, refuelling, re-orbiting spacecraft and cleaning up the increasing amount of space debris. Space Manipulator Systems (SMSs) are robotic systems made of a bus (which has its own actuators such as thrusters and reaction wheels) equipped with one or more deployable arms. The present paper focuses on the issue of maintaining a stable first contact between the arms terminal parts (i.e. the end-effectors) and a non-cooperative target satellite, before the actual grasp is accomplished. The selected approach is a modified version of the Impedance Control algorithm, in which the end-effector is commanded in order to make it behave like a mass-spring-damper system regardless of the reaction motion of the base, so to absorb the impact energy. A very important aspect in the analysis of the control performance is the evaluation of the field of applicability of the controller itself. In the present work the influence of this issue on the effectiveness of the proposed control architecture will be analysed, together with the control gains tuning which allows for a robust achievement of the mission requirements. Several numerical results will be presented and discussed.

Coordinated motion control of a dual-arm space robot with joint-limit avoidance and uncertain inertial parameters

In this article, a new adaptive coordinated motion control approach is introduced for a dual-arm free-floating space robot. This adaptive algorithm is used for the post-capture of a large noncooperative target with joint-limit avoidance and uncertain dynamic parameters. To overcome the problem of dynamics coupling between the space base, its manipulators, and the target, we develop a dual-arm space robotic system. One arm is used to complete the capture task and the other is used to counteract the disturbance to the space base. In this case, a new coordinated motion control law is derived based on reaction null space control. An improved joint-limit avoidance algorithm is implemented for large noncooperative target capture; otherwise, a significant base disturbance may result if the joint-limit constraints are not explicitly considered. Based on momentum conservation, the linear regression form of the estimation problem is obtained, and we further identify the unknown inertial parameters of the target. Finally, the simulation results demonstrate the effectiveness of the proposed algorithm.

Incremental visual servo control of robotic manipulator for autonomous capture of non-cooperative target

This paper develops a new autonomous incremental visual servo control law for the robotic manipulator to capture a non-cooperative target, where the control input is the incremental joint angle to avoid the multiple solutions in the existing inverse kinematics. The position and motion of the non-cooperative target are estimated by an eye-to-hand vision system in real time by integrated photogrammetry and extended Kalman filter. The estimated position and motion of the target are fed into the newly developed position-based visual servo control law to drive the manipulator incrementally towards the dynamically predicted interception point between trajectories of the end effector and the target. To validate the proposed approach, a hardware-in-the-loop simulation has been conducted where the position and motion of the target is estimated by a real eye-to-hand camera and fed into the simulation of the robotic manipulator. The simulation results show the proposed incremental visual servo control law is stable and able to avoid the multiple solutions in the total inverse kinematics.

Autonomous robotic capture of non-cooperative target by adaptive extended Kalman filter based visual servo

This paper presents a real-time, vision-based algorithm for the pose and motion estimation of non-cooperative targets and its application in visual servo robotic manipulator to perform autonomous capture. A hybrid approach of adaptive extended Kalman filter and photogrammetry is developed for the real-time pose and motion estimation of non-cooperative targets. Based on the pose and motion estimates, the desired pose and trajectory of end-effector is defined and the corresponding desired joint angles of the robotic manipulator are derived by inverse kinematics. A close-loop visual servo control scheme is then developed for the robotic manipulator to track, approach and capture the target. Validating experiments are designed and performed on a custom-built six degrees of freedom robotic manipulator with an eye-in-hand configuration. The experimental results demonstrate the feasibility, effectiveness and robustness of the proposed adaptive extended Kalman filter enabled pose and motion estimation and visual servo strategy.

A space robot manipulator system: designed for capture

The paper describes a space robot hand arm system designed for non-cooperative object capture. According to analysis on the characteristics of non-cooperative target capture on-orbit, a three fingers end-effector was designed. The detailed design of a modular space manipulator joint was described. To meet the nice performance of hand arm system in space applications, a communication and computing embedded systems was designed. We established an experimental platform in library for single joint test, with that proved the joint had enough precision, speed, and torque performance. At the same time, we constructed an experimental system for manipulator on air-bearing table, with that proved the manipulator had nice location precision. Experimental results showed that the hand arm system was able to meet the needs of the on-orbit application.

Autonomous robotic capture of non-cooperative target using visual servoing and motion predictive control

This paper presents a framework for autonomous capture operation of a non-cooperative mobile target in a 3-dimensional workspace using a robotic manipulator with visual servoing. The visual servoing with an eye-in-hand configuration is based on motion predictive control using Kalman filter for the on-line state and parameter estimation of the target. A transitional decision making process is developed to guide the robotic manipulator between the different phases of the capture operation by employing a custom metric that translates visual misalignments between the end-effector and the target into a guidance measurement. These phases include the target acquisition and approach stage and the alignment and capture phase. Experiments have been carried out on a custom designed and built robotic manipulator with 6 degrees of freedom. The objective is to evaluate the performance of the proposed motion predictive control scheme for the autonomous capturing task and to demonstrate the robustness of the proposed control scheme in the presence of noise and unexpected disturbances in vision system, sensory-motor coordination and constraints for the execution in real environments. Experimental results of the visual servoing control scheme integrated with the motion predictive Kalman filter indicate the feasibility and applicability of the proposed control scheme. It shows that when the target motion is properly predicted, the tracking and capture performance has been improved significantly.