一种质点力反馈模型的理论与实现研究

文中建立了一个质点力反馈模型的一般理论,并具体设计了实现各种力反馈的算法,最后在自行设计的力反馈系统上实现了该模型和算法。     

用于虚拟拆装的力反馈方法

研究虚拟拆装系统中,为增强用户的沉浸感,会引入力反馈设备,但目前力反馈设备价格昂贵,同时力反馈算法也不成熟导致了力反馈的引入无法商用和推广。使用力反馈操纵杆作为力反馈设备,对虚拟拆装中常见的结构约束关系进行分析,并对约束关系变化产生的力反馈进行建模和实验实现。结果表明在精度要求不高的拆装场合,力反馈方法能够给操作人员带来直观、真实的力觉操纵感受,同时由于力反馈操纵杆价格低廉,适于推广使用。     

大时延力反馈双边控制系统

阐述了力反馈双边控制遥操作的基本思想,讨论了其稳定性和透明性,介绍了一种既能保证稳定性、又能提高透明性的力反馈双边控制方法．最后给出了力反馈遥操作实验系统的实现,在6s时延条件下成功完成了曲面跟踪任务．     

虚拟现实力反馈设备的设计与实现

主要介绍了虚拟现实力反馈设备的设计与实现。文章先从力反馈设备的总体结构出发,根据设备的两种运作状态提出了设计的要求。然后讨论了运动空间、机械结构的确定等几个设计方面的关键问题的解决办法,其中重点介绍了传感器的设计。根据文中方法实现的小型力反馈设备在实际应用中取得了良好的效果。     

虚拟手术中表面网格模型的力反馈算法与仿真

提出一个带力反馈的虚拟腹部外科手术系统,并重点研究及实现了基于表面网格模型的力反馈算法。为了提高系统的稳定性,使用基于线段与表面三角网格的碰撞检测方法;基于四阶Runge-Kutta方法的表面网格mass-spring模型进行变形仿真;基于力的广度优先传播来解决变形仿真的局部性。通过仿真实验验证了该原型系统可以实现与可变形的三维模型的实时力觉交互。最后,把该方法应用到虚拟腹部外科手术系统中,并实现带力反馈的手术仿真操作。     

基于力反馈技术的毛笔笔道仿真

本文将力反馈技术引入虚拟绘制过程,提出一种基于力反馈技术的笔道仿真方法.首先通过分析力对毛笔变形的影响机理,采用弹簧-振子模型构建了一种新的毛笔力反馈仿真模型;然后通过计算毛笔模型变形时每个采样点处的笔触形状,得到笔触变化的时间序列,获得完整的笔道,实现力对笔道的动态控制.文中利用Phantom Desktop力反馈设备,成功地实现了具有力觉反馈的笔道仿真.仿真结果表明,该方法再现了传统笔道绘制中通过力触觉控制绘制的过程,有效地增强了虚拟绘制过程的真实感.     

遥操作系统中力反馈研究与实现

力反馈的研究与实现是遥操作系统研究的重要内容之一。该文设计了一种带力反馈的主从式遥操作系统。在系统中提出以虚拟手指空间位姿代替实际力作用线方向上位移的计算和基于实际材料的虚拟力外推的方法。该方法以虚拟手指的位姿来计算虚拟力,以实验所得实际材料的数据作为索引进行虚拟力的外推。实验结果表明,和以往的考虑力和变形关系的力反馈研究相比,此力反馈系统不仅简单易行,同时保证了较高的精度和刷新率。     

一种胆道虚拟手术仿真系统*

设计了一种用于外科医生仿真训练的具有实时力反馈的胆道虚拟手术仿真系统。主要讨论了本系统的结构设计、三维重建、碰撞检测、软组织的弹性变形和力反馈等方面的技术实现。通过对胆囊取石手术进行仿真模拟,分析该系统的应用情况和性能指标。实验结果表明,该系统能有效地进行胆道手术仿真训练,提供的力反馈功能具有较好的稳定性和实时性。     

微创手术机器人力反馈主手重力补偿研究

针对医生操作微创手术机器人力反馈主手进行主从微创手术时力反馈主手各杆件重力阻碍操作性能的问题,基于虚位移原理对力反馈主手各关节的重力矩进行推导,并采用Adams仿真软件对其进行验证．该方法适用于开链和闭链结构的机器人臂,与传统的牛顿－欧拉法和拉格朗日法相比,它不需考虑速度、加速度,且简单有效．然后采用电机驱动的方式对力反馈主手的各连杆重力进行补偿,实现了重力的完全补偿．实验结果表明,基于虚位移原理的主动重力补偿能够达到较好的补偿效果,将未补偿前的重力矩作用减小了60%以上,提高了力反馈主手的操作性能．     

一种三维力反馈训练仿真控制系统设计

针对空间站舱外任务需要研究人员通过遥操作控制平台对空间站机械臂遥操作来完成,而空间站机械臂研制成本高,无法实现现场调试,直接投入使用风险性高,系统安全性与可靠性无法保障的缺陷与不足,设计了一种面向空间站机械臂的遥操作力反馈训练的仿真控制系统.重点阐述了该系统的工作原理以及系统硬件和软件设计思路.该系统的力反馈手柄具有3个自由度,充分模拟操作空间;力反馈手柄末端位置信息和力反馈信息,由微控制器STM32系列单片机与PC实现数据传输.实验结果验证了该系统面向空间站虚拟机械臂的力反馈控制仿真功能、系统硬件和软件的可靠性,为空间站机械臂的虚拟仿真提供了一种可行方案.     

遥操作机器人的新型力反馈算法*

在采用液压挖掘机改造的遥操作机器人双向伺服控制系统中,针对大臂和前臂两个自由度构建力反馈控制算法。以准确地获取从端机器人与环境的作用力,使反馈力能够更好地反映从端工作状况为目的,采用构建干扰力补偿项的方法消除干扰力对反馈力的影响;以机器人转角为输入,以空载时检测到的液压缸作用力为输出,通过径向基函数构建干扰力补偿项,此补偿项可对多种因机器人的机械本体动力学特性产生的干扰力之合力进行补偿。实验证明,在以液压机构为从手的双向力反馈系统中,通过构建干扰力补偿项的方法提高力反馈效果的方法是可行的,采用的带有干扰力     

基于力反馈的手部康复训练装置研究进展

携带力反馈功能的装置进行训练已经成为手功能康复训练的重要手段.详细介绍了典型的用于手部康复训练的力反馈装置,通过对其优缺点进行比较,发现手部康复训练力反馈装置存在安全性要求高、重量较大、功能比较欠缺和实时性差的问题,并提出了相应的解决思路.最后展望了手部康复训练力反馈装置的发展趋势.     

Evaluating the Effect of Force Feedback in Cell Injection

Conventional methods of manipulating individual biological cells have been prevalent in the field of molecular biology. These methods do not have the ability to provide force feedback to an operator. Poor control of cell injection force is one of the primary reasons for low success rates in cell injection and transgenesis in particular. Therefore, there exists a need to incorporate force feedback into a cell injection system. We have developed a force feedback interface, which has the capability of measuring forces in the range of and provide a haptic display of the cell injection forces in real time. Using this force feedback interface, we performed several human factors studies to evaluate the effect of force feedback on cell injection outcomes. We tested our system with 40 human subjects and our experimental results indicate that the subjects were able to feel the cell injection force and confirmed our research hypothesis that the use of combined vision and force feedback leads to a higher success rate in cell injection task compared to using vision feedback alone.     

基于非线性力反馈模型的软组织变形仿真

虚拟手术仿真研究中反馈力一般采用线性模型,但软组织的反馈力往往呈现出非线性的特点.通过对软组织生物力学特性的分析,将非线性性质应用到软组织力反馈模型的研究.在保持原线性反馈力方向不变的前提下,加入非线性扰动,建立了反馈力的非线性模型,从而使反馈力更加真实.首先构建了人体肝脏物理模型,然后给出了非线性力反馈模型方程,并对人体肝脏物理模型变形和反馈力进行了仿真.为了减小计算量采用了整体刚度矩阵缩减算法.仿真结果表明该模型有较好的非线性和可调节性.     

The use of force feedback and auditory cues for performance of an assembly task in an immersive virtual environment

Using an immersive virtual environment, this study investigated whether the inclusion of force feedback or auditory cues improved manipulation performance and subjective reports of usability for an assembly task. Twenty-four volunteers (12 males and 12 females) were required to assemble and then disassemble five interconnecting virtual parts with either auditory, force, or no feedback cues provided. Performance for the assembly task was measured using completion time and number of collisions between parts, while the users preferences across conditions were evaluated using subjective reports of usability. The results indicated that the addition of force feedback slowed completion time and led to more collisions between parts for males. In contrast, females exhibited no change in the mean completion time for the assembly task but did show an increase in collision counts. Despite these negative performance findings when adding force feedback, users did report perceived increases in realism, helpfulness and utility towards the assembly task when force feedback was provided. Unlike force feedback, the results showed that auditory feedback, indicating that parts had collided during the assembly task, had no negative performance effects on the objective measures while still increasing perceived realism and overall user satisfaction. When auditory cues and force feedback were presented together, performance times, number of collisions, and usability were not improved compared to conditions containing just auditory cues or force feedback alone. Based on these results, and given the task and display devices used in the present study, the less costly option of excluding auditory and force feedback cues would produce the best performance when measured by the number of collisions and completion time. However, if increased ratings of usability for an assembly task are desired while maintaining objective performance levels and reduced cost, then the inclusion of auditory feedback cues is best.     

Stable Switching PD Control Using Hunt-Crossley Model for a Press Platform

This study proposes a switching proportional-derivative (PD) controller for a press platform for inspecting the surfaces of a wind turbine blade. We use the Hunt-Crossley model to represent the probe shape or the nonlinearity of the inspection platform. This model consists of a nonlinear spring and a damper; therefore, it is more accurate than linear spring-damper models. We prove the global asymptotic stability of a PD force feedback controller and a PD position feedback (force) controller. However, both the controllers suffer from implementation-related problems. Specifically, the PD force feedback controller makes the impact force large, and the PD position feedback controller cannot easily measure small position changes when the platform contacts the surface. These problems of each controller are solved by switching the two controllers. The PD force feedback control and PD position feedback control are used when the platform is in the contact and noncontact states, respectively. We prove that the proposed switching PD force/position feedback controller is globally asymptotically stable. Further, simulations show satisfactory performance resulting from stable switching between the two control schemes.

     

Usability of optically simulated haptic feedback

In this contribution a method will be described to optically simulate haptic feedback without resorting to mechanical force feedback devices. This method exploits the domination of the visual over the haptic modality. The perception of haptic feedback, usually generated by force feedback devices, was simulated by tiny displacements on the cursor position relative to the intended force. The usability of optically simulated haptic feedback (OSHF) was tested experimentally by measuring effectiveness, efficiency and satisfaction of its users in a Fitts’ type target-acquisition task and comparing the results with the usability of mechanically simulated force feedback and normal feedback. Results show that OSHF outperforms mechanically simulated haptic feedback and normal feedback, especially in the case of small targets.     

Feedback stabilization and tracking of constrained robots

Mathematical models for constrained robot dynamics, incorporating the effects of constraint force required to maintain satisfaction of the constraints, are used to develop explicit conditions for stabilization and tracking using feedback. The control structure allows feedback of generalized robot displacements, velocities, and the constraint forces. Global conditions for tracking, based on a modified computed-torque controller and local conditions for feedback stabilization, using a linear controller, are presented. The framework is also used to investigate the closed-loop properties if there are force disturbances, dynamics in the force feedback loops, or uncertainty in the constraint functions     

导管操作系统中力觉传感器信息的获取与控制研究

针对导管操作系统中力觉传感器反馈力的获取与控制进行了研究,导管前端采用光纤力传感器测量导管的顶端力;导管侧壁采用基于PVDF材料开发的微力传感器来测量导管的侧壁力。该导管操作系统对力觉传感器的输出信息进行了监测,实现了一种带有受力信息监测的主—从模式的新型导管操作系统。实验结果表明:该系统能够较好地实现受力信息的反馈。