Fine Operation Control Method Based On Multi-Sensor For Space Manipulator

With the continuous development of the aerospace industry, space manipulator as a kind of high flexibility and high autonomy space agency is playing a more and more important role. However, the space environment is complex, small, difficult to obtain information, and has large communication delay and many uncertain factors, the execution of the fine operation task of the space manipulator is more dependent on its own ability. Combining with the on-site environmental information, doing self decomposition and planning for complex tasks and introducing multi sensor to autonomously avoid dynamic and unknown obstacles in the action execution phase have the important significance for the space manipulator safely performing the task of fine operation under the complex multi constraint environment. Therefore,aiming at enhancing the space manipulator autonomous planning ability and operation safety, and doing research on fine operation control method of space manipulator based on multi sensor, meet the needs of national space exploration unmanned and have important theoretical significance and engineering value to the development of national space technology.The space manipulator will also play a more and more important role, and the key technology related to the space manipulator will become an important technical reserves for the development of the national aerospace industry.The research of this paper is supported by the National Key Basic Research Program of China "Basic theory research on operational reliability system control of space mechanism"(2013CB73305). This paper regards the redundant modular mechanical arm as study subject, and aims at the goal of enhance the fine operation ability of the space manipulator, and does some in-depth study focusing on the key technologies of task planning before the execution of the fine operation task and control of obstacle avoidance based on multi sensors in the implementation process. The main work of this paper is as follows:1) Task planning of the space manipulator for complex and fine tasks.Aiming at the tedious steps and various constraints of the spatial fine manipulation task, consider the on orbit capability of space manipulator, a double task planning framework composing of the mission profile analysis and the middle of the task intermediate point planning. Aiming at the complex fine operation task, the task profile analysis planning domain is established,then the autonomous task profile analysis is realized based on the hierarchical task network, and the basic original task sequence is Obtained. Considering the effect of multi constraint on the mission, the method of task intermediate point planning is proposed based on the heuristic algorithm, which makes the original task further simplify to the multi segment feasible paths and improves the autonomy of the execution of fine manipulation tasks in the complex multi constrained environment of the space manipulator.2) Multi sensor layout optimization of space manipulator. In order to deal with the influence that the inaccurate and dynamic change of environment information brings to the task execution, the multi sensor layout optimization method for space manipulator is studied by introducing multi sensors.According to the characteristics of space manipulator, the optimization criterion of sensor placement is analyzed and the optimization objective function is established. This paper proposes a collision detection algorithm considering the detection capability of the sensor, based on which the layout optimization objective function is solved by using the Monte Carlo Method,and optimal layout scheme of sensors is obtained.3) The obstacle avoidance control of space manipulator based on sensor information feedback. Based on the optimal layout of multi sensors, the real time obstacle avoidance problem of the space manipulator using multi sensors in the dynamic unknown environment is further studied. And a manipulator collision detection algorithm based on point cloud model is proposed, which can effectively distinguish the obstacles and the manipulator itself, and the performance of the algorithm is analyzed by experiments. Aiming at the continuous trajectory tracking task, a real-time obstacle avoidance control method is proposed by using the zero space of redundant manipulator. For the point-to-point task, an obstacle avoidance control method of compensating the temporary deviation of the end trajectory is proposed, which improves the obstacle avoidance flexibility of the key parts.4) Precision compensation control strategy for space manipulator with sensor feedback noise. Aiming at the problem that the control effect of space manipulator is stochastic due to the feedback noise, the goal of improving the success rate of the space manipulator is proposed, and the noise suppression control model is established. Based on the analysis of the influence of the feedback noise on the control effect of the manipulator, a real-time evaluation method is proposed based on the Bayesian approach. By introducing the cost performance function, a control variable adjusting strategy of considering of the cost of adjustment is proposed, which can reduce the volatility of the task execution results of the space manipulator by using the modification of the real-time control variables.