【作者】 胡凌燕；

【导师】 刘国平； 刘小平；

【作者基本信息】 南昌大学 ， 机械电子工程， 2011， 博士

【摘要】 遥操作系统利用通信网络将主从设备连接起来,当操作者操纵主端设备进行某一个动作时,相应的控制信号通过通信通道传输到远距离端,指挥从端设备完成相应的操作。遥操作系统可以将人手延伸到人很难到达或是对人有害的环境中去执行任务,因此遥操作技术在工业、服务、医疗、国防、救援和空间技术等多个领域有着广泛的应用前景。在遥操作实际应用过程中,还有许多问题需要解决。如遥操作系统中通信时延是固有的,它会导致系统的不稳定。衡量遥操作系统性能的技术指标主要是系统稳定性、跟踪性和透明性,但在提高这些性能指标的研究过程中存在着相互矛盾和冲突。时延和力反馈是影响这些性能指标的主要因素。本文针对有任意固定时延和力反馈的主从机械臂遥操作系统进行研究,主要研究在不降低遥操作系统透明性前提下,如何改善主从机械臂跟踪性能并提高系统的稳定性。波变量通信能解决主从机械臂之间的数据通信时延导致的系统不稳定。本文根据建立了单自由度波变量遥操作系统的Simulink仿真模型。通过仿真实验对不同波阻抗条件下的波变量遥操作系统进行了比较,得出了波阻抗与系统性能的关系,并指出在实际波变量遥操作应用中,应该根据实际期望的系统阻尼特性来适当地选择波阻抗。为了更详尽地分析遥操作系统中主从机械臂的运动状态,本文分析了多自由度机械臂的数学模型,并将常用的单自由度波变量通信扩展成多自由度波向量通信,从而得到多自由度波向量遥操作系统的数学模型。在此基础上,本文建立了二自由度波向量遥操作系统的Simulink仿真模型。通过仿真实验,文章分析了力反馈增益和人手施加在主机械臂上的力对系统稳定性的影响。当力反馈增益增大时,系统的透明性提高,但稳定性将变差。当人手用力握住主机械臂操作时,能在一定程度上提高系统的稳定性,但由于人手容易疲劳,而且当人费力操作时,很难完成一些灵巧的动作。因此,有必要为波变量遥操作系统设计相应的力反馈算法来提高系统的稳定性。波变量通信能够保证任意时延下,遥操作系统的稳定性。但波变量转换也会引起从机械臂的速度命令信号偏离主机械臂的速度,从而造成从机械臂的实际速度偏离主机械臂的速度,而且随着时延的增大,相应的速度偏离也将增大。本文分析了该速度偏离产生的原因,并在从端设计了跟踪补偿控制器来补偿从机械臂速度对主机械臂速度的偏离,从而实现了从机械臂速度很好地跟踪主机械臂速度。该控制器所需要的数据全部来源于从端,避免了主从端额外的数据传递。同时,本文应用无源理论对该跟踪补偿控制器进行无源性分析。通过分析得出,只要合适地选择波过滤器,带跟踪补偿控制器的遥操作系统的稳定性就可以得到保证。仿真实验和大量的实际实验结果表明,本文设计的速度跟踪补偿控制器实际可行,并且在不降低遥操作系统透明性的前提下,明显地改善了从机械臂对主机械臂的运动轨迹跟踪。波变量的引入虽然解决了通信时延对系统稳定性的影响,但滞后的力反馈仍然会造成系统不稳定。本文分析了滞后的力反馈使主机械臂产生意外运动,造成系统不稳定的原因,并针对这种不稳定性,在主端设计了一种实际可行的力反馈控制算法来提高系统的稳定性。该力反馈算法根据传递到主机械臂端的反馈力和主机械臂的速度对传递到主端的反馈力进行校正,在实际应用中该算法容易实现。本文还应用无源理论证明了带力反馈控制算法的波变量遥操作系统是稳定的。仿真实验和实际的实验结果均证明了本文设计的力反馈控制算法可以提高系统的稳定性,而且相对于不带力反馈控制算法的波变量遥操作系统,操作者不需要很费力地操作主机械臂,来克服不正确的反馈力造成的主机械臂的额外运动,使波变量遥操作变得轻松自如。更多还原

【Abstract】 A teleoperation system includes a master manipulator and a slave manipulator which are connected by network. When human operator holds the master device and moves, the control signals will be transmitted to the slave side through the communication channel and the slave device will follow the corresponding movement. With teleoperator, human operator interacts with the remote environment where human operator is difficult to access or is dangerous for human being. Teleoperator can extend human hands to the remote places. Therefore teleoperator has a very broad application prospect in the fields of industry, medical care, services, national defense, rescues in dangerous environment, space technology and daily life.There are still a lot of problems to be solved in the application of teleoperator. Time delay is inherited, and it leads to system instability. Stability, trajectory tracking, transparency of force feedback are important indices to teleoperator performances. There often exist contradictions in getting these performances. It is a difficult problem to improve trajectory tracking together with stability and transpaency for a teleoperator with time delay and force feedback. Many researchers focus their attentions on these problems. We focused on how to improve trajectory tracking and stability of the teleoperation system with constant time delay and force feedback without scarifying transparency.The transmission of wave variables can solve the instability problem from signals communication between master and slave manipulators. We established simulation models for wave-variable teleoperators with single degree of freedom and two degrees of freedom. We did the simulation experiments to discuss the relationship between wave impedance and system performance. We should select wave impedance according the expected system damping in actual application. We also did simulation experiments to discuss the influences of the force feedback gain and the force from human operator on system performance. According simulation experiment, the system stability deteriorates with increasing of the force feedback gain, and the system stability will be improved when the human operator uses more force to hold the master manipulator. The human operator is easy to fatigue and is difficult to complete dexterous movements when he uses great force to operate. Therefore it is necessary to design a force feedback algorithm to improve system stability.The wave variables transmission can ensure passivity of the communication subsystem with arbitrary time delay. On the other hand it introduces velocity distortion between master manipulator and slave one, which results in not good trajectory tracking performance. The thesis analyzes the reason why the distortion arises and designs a tracking compensator at slave side to get rid of the distortion. With the compensator the slave manipulator can perfectly tracking the trajectory the master one. The data needed by the compensator is from slave side, so no extra signal transmit ion is needed. Passivity of the teleoperator with tracking compensator can be maintained by tuning the appropriate low-pass filter. The simulation experiments and the actual experiments have shown the perfect velocity or trajectory tracking is achieved with the tracking compensator, and the force presented to the human operator at the master side is also close to the environment force. In the other word, trajectory tracking is improved without scarifying system transparency.The transmission of wave variables rather than power variables in time-delay teleoperation system ensures system passivity--rendering the entire system stable, however the delayed force feedback will still lead to the unanticipated motion of master, which makes the system difficult to control and unstable. The thesis proposed a force feedback algorithm at master side to depress the unanticipated and disturbing motion. The algorithm corrects the force feedback to the master side according the force feedback to the master side and the velocity of the master manipulator. It is easy to accomplish. It also would not affect the passivity of the whole teleoperation system. The simulation and actual experiments showed that the teleoperator with proposed force feedback algorithm is more stable and easier to control for human operator than the traditional one.更多还原