【作者】 李会军；

【导师】 宋爱国；

【作者基本信息】 东南大学 ， 测试计量技术及仪器， 2005， 博士

【摘要】 工作在交互方式下的空间遥操作机器人是实现空间危险和未知环境下作业的有力手段。但是,空间站内的遥操作机器人与地面控制站中的操作者之间信号双向传输存在较大的时延,严重影响了系统的稳定性和可操作性。基于虚拟预测环境的控制技术是解决时延对系统影响的有效手段,然而这种方法的有效性依赖于环境模型的精度,虚拟环境的建模误差对空间遥操作机器人系统的不良影响将随时延的增大而加剧。为了解决空间遥操作机器人系统中的时延问题,本文结合国家航天863项目“空间遥操作机器人虚拟预测环境的建模与控制”的需要,对空间遥操作机器人的虚拟预测环境建模技术、虚拟环境模型在线修正技术、通讯时延以及图形图像融合等关键技术进行了理论研究和实验研究。首先深入分析了空间遥操作机器人工作环境的图形建模和动力学建模特点,以及环境的几何模型和动力学模型的相互依存和影响关系、虚拟环境几何参数与动力学参数的协同关系,认为虚拟环境的动力学模型与几何模型必须协调一致,才能更好地满足基于虚拟预测环境的空间机器人遥操作;提出了利用视觉、位置和力觉等多传感器信息建立工作环境的虚拟几何模型:首先由环境的先验知识和在线检测的视觉信息初始化环境的几何模型,然后缓慢运动从手,虚拟环境根据接收到的远地力和位置信息对几何模型进行校验,保证虚拟预测环境初始几何模型的准确性;将从机械手与环境作用过程分为碰撞、稳定接触和离开三个阶段,对空间遥操作机器人系统的动力学模型进行分区描述;提出一种新的计算虚拟预测力的方法,把图形更新和虚拟力计算分在两个不同的回路进行,使虚拟力计算不受图形更新速度的影响,提高了虚拟预测力反馈的频率。为了提高虚拟环境模型的精确性,提出一种新的畸变校正和虚实注册方法,将虚拟环境模型叠加在远地视频图像上,在同一窗口同时观察命令在远地真实工作环境和虚拟环境中的执行情况,比较二者的差别以便对虚拟环境几何模型进行在线修正;根据力和位置等反馈信息,利用滑动平均最小二乘法辨识环境的动力学参数,用于修正虚拟预测环境的动力学参数,实现了环境动力学模型的在线修正,提高虚拟预测力反馈的准确性。本文在理论分析的同时,根据空间环境微重力的特点,建立了基于虚拟预测环境的单自由度主从式空间遥操作机器人实验系统,该系统具有视觉和力觉反馈功能。在此实验平台上针对质量-弹簧-阻尼环境,利用计算机网络进行了基于虚拟预测环境的遥操作实验,实现了局域网内主从手的远程控制,对理论分析结果和所提出的虚拟预测环境建模算法进行了相关的实验验证,结果表明本文所提出的方法有效地减小了时延对空间遥操作机器人系统的不良影响,在时延为0～30秒(双向时延)内具有良好的力和位置跟踪,虚拟环境模型的参数能够在线修正,虚拟预测力反馈误差小于5%F.S.。本文的研究不仅促进了虚拟预测环境技术的理论研究,而且在一定的时延范围内较好地解决空间遥操作机器人系统中通讯时延影响的难题。本文的研究工作和研究结果为研制高效率、高操作精度的空间遥操作机器人系统奠定了基础,对空间机器人遥操作具有一定的指导意义,为高性能的空间遥操作机器人的实际应用提供了技术实现途径。可以预计:基于虚拟预测环境技术的遥操作机器人系统的应用,将极大地改善空间遥操作机器人的作业能力,人们可以将自己的智慧同机器人的适应能力相结合,完成空间站内外的作业任务,如空间站内的科学实验、日常维护以及空间站外轨道卫星的修理等。更多还原

【Abstract】 Space tele-robot with human-robot interaction is a powerful tool for performing tasks in unknown or hazard environment. Due to the large communication time delay between the tele-robots in space and the operator at the local site, the stability and maneuverability of the system are decreased. Control technology based on predictive environment model is an effective method to solve this problem. However, it depends heavely on the accuracy of the virtual environment model, and the negative effects increase rapidly as the time delay becomes larger.In this dissertation, a novel method is proposed to precisely model the environment of the tele-robot. The properties of the graphic and dynamic model of the space teleoperation and the relation between them are analysised. The virtual environment model is built at the local site based on the visual and force information from the remote side. The interaction between the slave arm and the environment is divided into three pecedures: transition to and from contact conditions and stable contact. Different models are used to describe the procedures respectively. In order to improve the frequency of the virtual force feedback, the force calculation and graphic update are done in two separate loops. Graphic model is overlayed on the video images by a novel register method to observe the results of the commands both in the virtual and real environment and to correct the model when the discrepancy is beyond a certain threshold. Sliding average least square method is proposed to identify the dynamical parameters of the real environment with position and force feedback and the results are used to update the corresponding parameters of the model.Besides the theoretic analysis, considering of the small gravity in space, a tele-robot system is developed, which is in fact a one-DOF master-slave teleloperation system with visual and force feedback. The proposed method of modeling and modifying on-line is verified in this system by experiments. Results showed that the technology proposed in this dissertation reduced the effect of time delay in teleoperation and that with time delay of 0~30 seconds the errors of virtual force reflection are less than 5%F.S. after model modification.The research in this dissertation not only advances the theory in virtual environment technology, but also solves the problems of constant time delay in a certain range. It is promising that teleoperation system based on virtual predictive environment will improve the performance of space robot to fulfill tasks such as science experiment, daily maintenance in space station and repair of the on-orbit satellite.更多还原