【作者】 郭闯强；

【导师】 刘宏；

【作者基本信息】 哈尔滨工业大学 ， 机械工程， 2012， 博士

【摘要】 随着对空间探索的深入，空间机器人系统逐渐成为开发太空资源的有效工具，尤其是空间大型机械臂在国际空间站的建设和维护中发挥了不可替代的作用。空间大型机械臂具有输出力矩大、工作空间大、控制精度高、设计寿命长、可靠性要求高等特点，因此，与其相关的各种设计和控制技术都具有很大的挑战性。随着我国载人空间站建设步伐的推进，空间大型机械臂技术受到了国家相关部门的高度重视，已经成为国内航天领域的一大研究热点。本文在“空间大型机械臂地面原理样机的研制”项目支持下，着重对该系统的关键部件——关节控制系统进行了深入研究，旨在研制出一种具有高可靠性、高精度、强容错能力等特点的关节控制系统，并在此基础上围绕机械臂关节高精度位置控制技术、振动抑制策略，以及机械臂笛卡尔空间的轨迹规划方法等问题展开深入研究。针对空间大型机械臂寿命长和可靠性要求高，但在轨维护困难等特点，提出了一种基于FPGA-FPGA的可重构关节控制系统。该系统在FPGA内嵌的微处理器支持下，利用软硬件结合的方法实现了CAN通讯管理、传感器信息采集与处理、电机驱动、运动控制、轨迹规划等复杂功能，兼具冷备份和热备份两种控制结构的优点，且能够在主份和备份子控制系统之间发生多个不重合故障的情况下，通过重组优质资源来维持关节功能的完备性。在同样计算假设条件下，相对于传统冷备份控制结构，电机伺服单元的可靠性从92.25%提高到了95.9%。在此基础上，针对空间环境特点，设计了电源管理系统和温度控制系统，并采取相应的抗辐射措施，从设计角度尽可能地提高了关节控制系统的可靠性。为了实现双绕组永磁同步电机的高效、容错控制，本文以单绕组工作情况为基础，利用VHDL语言在FPGA控制器上通过硬件逻辑实现了电机电流的抗饱和矢量闭环控制。控制周期小于50μs，有利于提高系统的响应速度和抗干扰能力，进而提出了一种新的双绕组永磁同步电机容错矢量控制方法，既实现两套绕组电流均衡控制，又能够在单个控制器发生故障的情况下维持电机的不间断运行，从而使电机伺服系统的容错能力得到进一步的提高。同时，本文设计了贯穿关节控制器、机械臂中央控制器、宇航员三个层次的故障检测与容错策略，实现了故障的实时检测和容错处理，从运行控制的角度保证了机械臂工作的安全性。为了提高柔性关节输出端的位置控制精度，本文设计了一种级联型非线性抗饱和全闭环控制器，由带速度前馈的非线性位置环、二自由度抗饱和速度环以及抗饱和电流环构成，具有全局渐进稳定性。实验结果表明，该控制器能够在关节发生较大柔性变形的情况下保证关节输出端的位置控制精度。此外，本文利用机械臂名义计算力矩信息，从力矩传感器反馈信息中分离出由振动引起的力矩分量，然后将该分量用于关节振动的负反馈控制。实验结果表明，此项措施能够快速抑制关节的柔性振动，且基本不影响轨迹跟踪精度。由于空间机械臂与其载体之间存在动力学耦合，利用逆广义雅可比矩阵的方法虽然可以实现自由漂浮空间机械臂末端位姿的规划，但无法约束机械臂运动对载体姿态产生的扰动影响。为解决这一问题，实现机械臂末端在笛卡尔空间多位置点约束条件下运动路径的优化设计，本文首先利用改进三次样条函数对机械臂末端运动轨迹进行参数化，将机械臂运动对载体姿态的扰动量表达为关于样条函数插值点以及相邻约束位姿之间运动时间的目标函数，继而采用遗传算法实现目标函数全局优化处理。仿真结果表明，该方法能够在多个目标位姿约束条件下，有效减小空间机械臂运动对载体姿态产生的扰动影响。更多还原

【Abstract】 In the wake of developments in space exploration, robotic system has graduallybecome a useful tool of opening up space resources, especially are the space largemanipulators playing an irreplaceable role in the construction and maintenance of theinternational space station. The space large manipulators are characterized by highoutput torque, wide working space, high control accuracy, long design life-span, andhigh reliability; thus the design and control techniques related to the space largemanipulator are extremely challenging. With the development of manned space stationin China, the space large manipulator technique has attracted much attentions of therelevant departments of the government, and been becoming a research hotspot in thedomestic space field. Supported by the project titled Development of Ground PrinciplePrototype for Space Large Manipulator, my doctoral work was devoted to developing ajoint control system (a key component of the space large manipulator system) with highreliability, high precision, and strong fault tolerance. On the basis of it, the workfocusing on the high-precision position control and vibration suppression strategy forthe robotic joint, and the trajectory planning method in the Cartesian space for themanipulator was conducted for a further investigation.On-orbit maintenance for the space large manipulator system is difficult to becarried out, whereas the mission of the space large manipulator system demands longlife-span and high reliability. A reconfigurable joint control system was thereforedeveloped on the basis of FPGA-FPGA to resolve the contradictions. Supported by theembedded microprocessor of FPGA, the design methodology combining hardware andsoftware was adopted to realize some specific functions, such as CAN communicationmanagement, sensor information collection and processing, motor drive, motion controland trajectory planning, etc. The merits of both cold-backup and hot-backup structureswere integrated into the newly proposed joint control system. Moreover, thecompleteness of joint function can be maintained via reorganization of fine resources incase of multiple misalignment faults between the master and slave control sub-systems.Compared to the traditional cold-backup structure of the controller, the reliability of themotor servo unit was raised from92.25%to95.90%. Furthermore, a powermanagement system and a temperature control system were designed with the corresponding anti-radiation measures, aiming to make the joint control system adapt tothe space environment. Thus the reliability of the joint control system can be improvedfrom the view of design as much as possible.To achieve the effective and fault-tolerant control of the servo system of dual-winding PMSM, the anti-windup vector closed-loop control of motor current with thecycle shorter than50μs was realized by means of hardware logic of FPGA using VHDLlanguage, when only single winding of the motor was at work. The response speed andanti-jamming ability of the motor servo system were therefore improved. A fault-tolerant vector control method for dual-winding PMSM was also presented, which wascapable of keeping current balance between the two windings of PMSM andmaintaining continuous operation of the motor even if one of the joint controllers failedto work. As a consequence, the fault-tolerant ability of motor servo system would befurther improved. Meanwhile, the real-time fault detection and the corresponding fault-tolerant solution were performed throughout the joint controller, the central controller ofrobotic arm, and the astronaut. That is, the security of manipulator can be guaranteedfrom the view of operation control.A cascade non-linear global close-loop anti-windup controller, composed of non-linear position control loop with speed feedforward,2-dof anti-windup speed controlloop and anti-windup current loop, was developed to improve the position controlaccuracy of the flexible joint’s output port. The controller exhibited global asymptoticstability. The experimental results indicated that the newly proposed controller was ableto guarantee the position control accuracy of the output port, even when a relativlylarger plastic deformation existed in the joint. In addition, the nominal calculated outputtorque of the joint was used to decompose the torque components, which were causedby the joint vibration, from the feedback information provided by the torque sensor. Thedecomposed torque components would be used for the negative feedback control ofjoint vibration. The experimental results showed that the approach was capable ofsuppressing the vibration of the joint rapidly, exerting little influence on the precision oftrajectory tracking.The terminal position and attitude of the free-floating space manipulator systemcan be planned using the inverse generalized Jacobian matrix method. However, theattitude disturbance of basement arising from the motion of manipulator cannot berestrained, as a result of the dynamic coupling between the space manipulator and its basement. To optimize the path of the space manipulator tip under the condition ofmulti-position restraint in the Cartesian space, the motion trajectory was parameterizedon the basis of revised cubic spline. The disturbance of basement arising from themotion of manipulator was thus expressed by the objective function about theinterpolating point of the spline and the migration time between two adjacent restrainedpositions. The global optimization of the objective function was realized using thegenetic algorithm. The simulation results indicated that the presented approach caneffectively reduce the influence of disturbance on the attitude of basement, which wascaused by the motion of manipulator, under the condition that the restraints wereexerted on multiple objective positions and attitudes of the manipulator tip.更多还原