Trajectory Planning For Spinning Target Capture And Control Of Complex System

Since the past few decades, more and more satellites have been sent up into space. However, some of them are getting out of order, so that the space environment deteriorates. As a result, it has been all along the hot topic in many countries around the world to repair or remove the failure satellites on-orbit. Based on spinning non-cooperative target satellites’ capture and on-orbit repairing tasks, the thesis focuses on autonomous trajectory planning for capturing target satellites and dynamic control of the complex after target satellite captured.Setting GEO satellites in orbit as an example, the researcher has established dynamic model of spacecrafts which are out of operation. At the same time, the spinning motion characteristics were analyzed theoretically. Further, estimated motion value of the SinoII satellite on-orbit was obtained based on the ground observation data which was regarded as initial value of subsequent algorithms. On the basis of Lagrange method and the law of conservation of linear momentum, the dynamic equations of free-floating space robot system have been built.It was proved that Sino-II satellite has larger nutation Angle and nutation angular velocity except the spinning angular velocity. Based on that, the capture algorithm which aimed to capture the docking ring was proposed. Due to the different quality distributions under different aircraft spin axis, the two capture tasks where spinning axis and is vertical(or close to the vertical) or parallel(or close to parallel) to docking ring surface were considered respectively. For the vertical one, the movement rule of docking ring given point is simple with small motion range. Combined with the spin motion compensation method, the decomposition speed control was adopted to solve the task. For the parallel one, the range and velocity of the given point in space docking ring movement are large. Therefore, the "Dynamic Closest Point" for docking ring target acquisition method was put forward. Specifically, the position and velocity of "Dynamic Closest Point" to the mechanical arm were estimated in the real-time firstly. Eventually, the effective capture of target point was realized with using decomposition speed control.After target had been captured, the system of inertia parameters changed. Inertia parameters identification method which was based on equivalent single body and equivalent two- body was proposed to achieve high precision stability control. The whole system has become the equivalent single body under the circumstance where all of the mechanical arm joints were locked in a certain configuration system. The equivalent mass, inertia, and the location of the center mass were recognized by a simple orbital maneuvering. The whole system has become the equivalent two-body, when one was unlocked. Two equivalent inertia parameters of the rigid body can be identified based on the momentum conservation theorem and mass properties of system which have been recognized. What is more, the inertia parameters of the target spacecraft were obtained. Stable control of the complex system was realized based on the identification inertia parameters with overcoming the effects of environmental interference of force and torque and achieving control of the optimal time.