Author(s):  
Qijia Yao

Space manipulator is considered as one of the most promising technologies for future space activities owing to its important role in various on-orbit serving missions. In this study, a robust finite-time tracking control method is proposed for the rapid and accurate trajectory tracking control of an attitude-controlled free-flying space manipulator in the presence of parametric uncertainties and external disturbances. First, a baseline finite-time tracking controller is designed to track the desired position of the space manipulator based on the homogeneous method. Then, a finite-time disturbance observer is designed to accurately estimate the lumped uncertainties. Finally, a robust finite-time tracking controller is developed by integrating the baseline finite-time tracking controller with the finite-time disturbance observer. Rigorous theoretical analysis for the global finite-time stability of the whole closed-loop system is provided. The proposed robust finite-time tracking controller has a relatively simple structure and can guarantee the position and velocity tracking errors converge to zero in finite time even subject to lumped uncertainties. To the best of the authors’ knowledge, there are really limited existing controllers can achieve such excellent performance under the same conditions. Numerical simulations illustrate the effectiveness and superiority of the proposed control method.


2012 ◽  
Vol 468-471 ◽  
pp. 1123-1127
Author(s):  
Jin Ning Zhi ◽  
Jian Wei Yang ◽  
Jun Zhe Dong

In order to improve the dynamic performance of five-axis heavy vehicle, a variable universe fuzzy control method is proposed to optimize suspension parameters. Five-axis multi-body dynamic model including electro-hydraulic proportional valve was firstly established in software ADAMS/Car. The variable universe fuzzy controller based on fuzzy neural network was also designed in MATLAB/Simulink, and then the co-simulation was conducted. The dynamic characteristics of five-axis heavy vehicle are studied to verify the effect of suspension parameters optimized by variable universe fuzzy control method in the A, B and C-level random pavement and different speed conditions. Simulation results show that compared with passive suspension, the real-time optimization of variable fuzzy control based on FNN can improve the ride comfort and the dynamic load of tire. Under different driving conditions, ride comfort can be increased by about 25%-30%, and the dynamic load of tire generally decreases by 25%-35%. Therefore this method has a certain practicability and effectiveness.


2014 ◽  
Vol 6 ◽  
pp. 179293 ◽  
Author(s):  
Yifan Wang ◽  
Xin Gao ◽  
Hanxu Sun ◽  
Qingxuan Jia ◽  
Wencan Zhao ◽  
...  

A control method based on real-time operational reliability evaluation for space manipulator is presented for improving the success rate of a manipulator during the execution of a task. In this paper, a method for quantitative analysis of operational reliability is given when manipulator is executing a specified task; then a control model which could control the quantitative operational reliability is built. First, the control process is described by using a state space equation. Second, process parameters are estimated in real time using Bayesian method. Third, the expression of the system's real-time operational reliability is deduced based on the state space equation and process parameters which are estimated using Bayesian method. Finally, a control variable regulation strategy which considers the cost of control is given based on the Theory of Statistical Process Control. It is shown via simulations that this method effectively improves the operational reliability of space manipulator control system.


2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Xin Gao ◽  
Yifan Wang ◽  
Hanxu Sun ◽  
Qingxuan Jia ◽  
Xiaojian Yang ◽  
...  

The operational reliability of the space manipulator is closely related to the control method. However the existing control methods seldom consider the operational reliability from the system level. A method to construct the operational reliability system control model based on particle filter for the space manipulator is presented in this paper. Firstly, the definition of operational reliability and the degree of operational reliability are given and the state space equations of the control system are established as well. Secondly, based on the particle filter algorithm, a method to estimate the distribution of the end position error and calculate the degree of operational reliability with any form of noise distribution in real time is established. Furthermore, a performance model based on quality loss theory is built and a performance function is obtained to evaluate the quality of the control process. The adjustment value of the end position of the space manipulator can be calculated by using the performance function. Finally, a large number of simulation results show that the control method proposed in this paper can improve the task success rate effectively compared to the simulation results using traditional control methods and control methods based on Bayesian estimation.


2006 ◽  
Vol 18 (5) ◽  
pp. 608-617 ◽  
Author(s):  
Hiroki Nakanishi ◽  
◽  
Kazuya Yoshida

One of the most important phases of orbital servicing by a space robot is capturing a target satellite. In this phase, there is the risk that contact will push the target and robot away from each other. Controlling the impedance of the manipulator effectively prevents this. For a free-flying space robot, however, conventional methods used for fixed base robots cannot be used because the motion of the base interferes with the manipulator motion. An impedance control method for a space manipulator arm is proposed, where the end tip of the manipulator is controlled as if a mass-damper-spring system fixed in inertial space. Possible applications in orbital servicing are also discussed.


2020 ◽  
Author(s):  
Chao Li ◽  
Zheng Chen ◽  
Can Yang ◽  
Bin Yao ◽  
Shiliang Pu

Abstract To achieve high-accuracy tracking of dual-linear-motor-driven (DLMD) gantry, high-level synchronization between redundant actuators is a nonnegligible factor and also a difficult issue to be solved prior. Especially, when both XY axes are simultaneously operating to accomplish complex tasks efficiently, additional coupling effects will be generated by the dynamic load presented on the crossbeam, which makes the synchronization issue more complicated compared to the case with static load. However, due to the absence of an accurate model to fully reveal the complete coupling characteristics, existing approaches to this issue still have inherent limitations. Therefore, this paper focuses on the systematic physical modeling and synchronization control of DLMD gantry with a dynamic load presented on the crossbeam. A complete coupling mathematical model is established firstly, by fully considering two linear motions (X-axis and Y-axis) and also including the additional rotational motion of the crossbeam. Built upon the effective model information, corresponding solutions by compensating the dynamic load effects and actively controlling the rotational dynamic to regulate the internal forces have been proposed, leading to a novel adaptive robust synchronization control method. Comparative experiments are carried out, and the results show the effectiveness and superiority of the proposed method in dealing with synchronization issue subjected to dynamic load effects.


2012 ◽  
Vol 546-547 ◽  
pp. 1014-1019 ◽  
Author(s):  
Zhi Gang Chen ◽  
Cui Ru Wu ◽  
Guang Yu Zhang

This paper discusses the control of free flying space manipulators in the impact process which happens in the capturing operation. To solve the intense coupling of the kinematics and dynamics between the space manipulator and the base, this paper builds the noncontact impedance control model of the 6-joint space manipulator system, which can control the space manipulator before impacting with the objects. Computer simulations are performed to verify that the noncontact impedance control method can make the end-effector of the space manipulator keep desired dynamic characteristics and the adjustment of virtual impedance parameters can control the impact force value efficiently.


2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Xin Gao ◽  
Yifan Wang ◽  
Hanxu Sun ◽  
Qingxuan Jia ◽  
Gang Chen ◽  
...  

In order to maintain and enhance the operational reliability of a robotic manipulator deployed in space, an operational reliability system control method is presented in this paper. First, a method to divide factors affecting the operational reliability is proposed, which divides the operational reliability factors into task-related factors and cost-related factors. Then the models describing the relationships between the two kinds of factors and control variables are established. Based on this, a multivariable and multiconstraint optimization model is constructed. Second, a hierarchical system control model which incorporates the operational reliability factors is constructed. The control process of the space manipulator is divided into three layers: task planning, path planning, and motion control. Operational reliability related performance parameters are measured and used as the system’s feedback. Taking the factors affecting the operational reliability into consideration, the system can autonomously decide which control layer of the system should be optimized and how to optimize it using a control level adjustment decision module. The operational reliability factors affect these three control levels in the form of control variable constraints. Simulation results demonstrate that the proposed method can achieve a greater probability of meeting the task accuracy requirements, while extending the expected lifetime of the space manipulator.


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