视网膜血管搭桥手术机器人系统的研究

针对医生人工操作的生理学颤抖造成视网膜血管搭桥手术成功率低的问题,提出了用于辅助医生进行手术操作的机器人系统.在借鉴眼科显微手术机器人系统研究经验的基础上,基于视网膜血管搭桥手术的过程和特点,提出了合理的机器人系统整体设计方案,介绍了机器人的关键机构设计.对临床应用进行了初步探讨,确定了视网膜血管搭桥手术机器人系统的人机协同操作手术流程,提出了手术环境布置方案.最后,在开发研制原理样机的基础上列出了机器人性能指标,对视网膜表面平行运动进行了轨迹规划和仿真,在乒乓球模型上进行了可行性分析实验,并提出了安全保障措施.实验表明,系统设计满足要求,可以初步完成手术动作.     

机器人辅助腹腔介入治疗的空间运动约束及控制策略

描述了机器人辅助腹腔介入治疗中的手术规划模型和虚拟夹具（VF）方法,研究了引导型和障碍型两 类虚拟夹具的空间运动约束生成方法以及基于导纳控制的综合控制策略．通过建立引力势场和参考方向实现了对控 制对象的引导,通过建立斥力势场实现了空间避障（如腹腔内血管及肋骨）,从而为手术器械的运动及定位提供了 有效的辅助作用．VF 的刚度系数可以调节空间运动约束的苛刻程度．单个VF 和腹腔3 维空间中多个VF 的仿真实 验验证了空间运动约束和控制算法的有效性．本文的方法适用于类似的遥操作和人机协作系统．     

具有主动约束的医疗机器人系统的主从控制

在分析了穿刺手术机器人系统功能需求的基础上,搭建了主从遥操作系统的半实物仿真平台。在主从控制的基础上,提出一个利用虚拟夹具VF(Virtual Fixture)算法结合Proxy的方法的主动约束控制策略。实验结果表明,系统能够在给定运动约束的情况下完成相应的主从控制。     

一种基于双层插值的路径规划及跟踪算法

针对基于栅格地图的经典路径规划算法的不足,提出了一种双层插值的路径规划算法——T* 算法． 算法首先应用快速行军插值法生成目标波形图,波形图假设波以目标点为中心经四个邻节点向外扩散且沿波传播方 向栅格效用值单调递增;然后在生成的目标波形图上采用线性插值法,从机器人当前位置沿着波逆向搜索一条到达 目标点的平滑路径;得到规划的路径后,针对非完整约束的移动机器人,采用改进的虚拟车辆方法跟踪生成的路径． 实验验证了算法的有效性．     

微操作机器人系统拟实环境的实现

本文实现了一个具有显微图像效果的2D增强现实的微操作拟实环境．文中给出 了微操作工具的生成算法和它的运动学建模算法,并在虚拟显微镜的实现过程中对操作工具 和操作对象的显微图像进行了优化处理,实现了对微操作机器人系统的拟实,并获得了很好 的拟实效果．该拟实环境可有效地用于实际微操作的预演、再现,微操作路径规划及人员培 训．     

用于显微手术操作的机器人系统的体系结构分析

分析了两种主要的显微手术特性．然后，针对显微手术操作对机器人的需求，对用于显微手术操作的机器人系统的结构组成、工作方式和控制系统设计作了分析．通过分析一些研究实例，总结出设计显微手术机器人的规律性结果．     

通过显微图像特征抽取获得微操作目标纵向信息

工作于生物显微镜下的微操作机器人系统,是完成对生物细胞显微操作的专用操作系 统．由于各种原因,常规的反馈定位控制难以实现．系统中惟一可以利用的信息是由CCD摄 像机获得的显微平面图像,目标的纵向信息难以获得．本文提出了一种基于系列显微图像频 率特性比较的分析方法,完成对微操作系统中各目标体的纵向位置信息的获取,为本系统的 标定工作和位置控制的实现奠定了基础．     

基于小波的自动图像变形

图像变形算法中最费时的是在源图像和目标图像中确定变形特征基元；而到目前为止，大部分图像变形算法都是通过人工或半人工的方式来实现的．如果两幅源图像间的特征基元的确定能自动实现，则不但可以减轻用户的负担，而且可以极大地节省变形算法所需的时间，同时提高了算法的效率．提出了一种基于小波变换的自动图像变形方法．该方法完全依赖于给定的两幅源图像，自动生成期间的变形图像，不需要预先在两幅源图像中指定特征基元．实验结果证明，用本文的算法不仅能自动完成变形操作，而且也取得了满意的结果．     

基于自适应眼底光学成像原理的目标跟踪仿真研究

针对运动物体可能具有较为复杂的运动轨迹,从而导致传统跟踪算法失败的问题,提出了一种基于人眼视网膜眼底凹区成像原理的跟踪仿真算法.首先利用线性、正弦等函数模拟仿真具有复杂运动轨迹的运动目标,利用多分辨率方法,采用金字塔结构生成人眼视网膜中央凹区仿真图像,在此基础上进行跟踪算法模拟.通过试验仿真,可以有效地实现目标跟踪,并...     

机器人装配操作的规划与控制

机器人装配操作是机器人研究与应用的一个重要领域．与机器人焊接、喷涂等作业 不同,机器人的装配操作是一种约束运动类操作,因此在规划和控制时必须考虑接触约束和 各种不确定性因素的影响．本文对机器人装配操作的规划和控制策略进行了详细的综述,并 对一些典型的装配操作任务进行了分析．文末提出了需要进一步深入研究的一些问题．     

A virtual fixture using a FE-based transformation model embedded into a constrained optimization for the dimensional inspection of nonrigid parts

Virtually mounting nonrigid parts onto their fixture is proposed by researchers to remove the need for the use of complex physical inspection fixtures during the measurement process. Current approaches necessitate the pre-processing of the free-state nonrigid part’s point cloud into a suitable finite element (FE) mesh and are limited by the use of the boundary conditions setting methods available in FE software. In addition to these limits, these approaches do not take into account the forces used to restrain the part during the inspection, as commonly mandated for aerospace panels. To address these shortcomings, this paper presents a virtual fixture method that predicts the fixed shape of the part without the aforementioned drawbacks of current approaches. This is achieved by embedding information retrieved from a FE analysis of the nominal CAD model into a boundary displacement constrained optimization. To evaluate the proposed method, two case studies on physical parts are performed using the proposed virtual fixture method to evaluate the profile and assembly force specifications of each part.     

渐进式约束扩展的机械臂运动规划算法

为了保证冗余机械臂带约束运动规划时的路径连续性,针对目前的直接插值和连续插值方法潜在的约束失效和路径失效问题,提出渐进式约束扩展的快速搜索随机树算法（PCE-RRT）。该算法在进行搜索树扩展时引入了一种渐进式约束扩展方法,该方法使用带有最近点信息的逆运动学计算策略,可以在保证任务约束的情况下迭代缩短最近点和扩展点的距离,让每一次扩展都能够保证搜索树的约束性和连续性。PCE-RRT可以使最终生成的搜索树很好地贴合于约束流形子空间,且树上任意两个相连节点都能满足连续条件。通过仿真实验对算法进行验证,实验结果表明该算法能够为机械臂带约束运动规划问题提供同时满足约束性和连续性条件的路径解。     

High-level motion planning for CPG-driven modular robots

Modular robots may become candidates for search and rescue operations or even for future space missions, as they can change their structure to adapt to terrain conditions and to better fulfill a given task. A core problem in such missions is the ability to visit distant places in rough terrain. Traditionally, the motion of modular robots is modeled using locomotion generators that can provide various gaits, e.g. crawling or walking. However, pure locomotion generation cannot ensure that desired places in a complex environment with obstacles will in fact be reached. These cases require several locomotion generators providing motion primitives that are switched using a planning process that takes the obstacles into account. In this paper, we present a novel motion planning method for modular robots equipped with elementary motion primitives. The utilization of primitives significantly reduces the complexity of the motion planning which enables plans to be created for robots of arbitrary shapes. The primitives used here do not need to cope with environmental changes, which can therefore be realized using simple locomotion generators that are scalable, i.e., the primitives can provide motion for robots with many modules. As the motion primitives are realized using locomotion generators, no reconfiguration is required and the proposed approach can thus be used even for modular robots without self-reconfiguration capabilities. The performance of the proposed algorithm has been experimentally verified in various environments, in physical simulations and also in hardware experiments.     

Online inserting virtual characters into dynamic video scenes

The seamless integration of virtual characters into dynamic scenes captured by video is a challenging problem. In order to achieve consistent composite results, both the virtual and real characters must share the same geometrical constraints and their interactions must follow some common sense. One essential question is how to detect the motion of real objects—such as real characters moving in the video—and how to steer virtual characters accordingly to avoid unrealistic collisions. We propose an online solution. First, by analysis of the input video, the motion states of the real pedestrians are recovered into a common world 3D coordinate system. Meanwhile, a simplified accuracy measurement is defined to represent the confidence of the motion estimate. Then, under the constraints imposed by the real dynamic objects, the motion of virtual characters are accommodated by a uniform steering model. The final step is to merge virtual objects back to the real video scene by taking into account visibility and occlusion constraints between real foreground objects and virtual ones. Several examples demonstrate the efficiency of the proposed algorithm. Copyright © 2011 John Wiley & Sons, Ltd.     

基于区域的手指三维运动跟踪

提出了基于区域的多连接体(手指)的三维运动跟踪算法.该算法首先用多约束融合的方法以及手指的运动特性,得到初始帧手指的三维结构;然后根据刚性多连接体的运动模型以及相应的姿势约束模型,给出了这一特殊运动模型三维运动估计的优化算法,此算法能够鲁棒地估计手指的三维运动;最后利用区域跟踪的方法获取多连接体三维运动,并在真实的手指序列图象中实现了该算法.实验结果证实了该算法的有效性.     

Eliminating constraint drift in the numerical simulation of constrained dynamical systems

By means of the Udwadia–Kalaba approach we propose an explicit equation of constrained motion developed to simulate constrained dynamical systems without error accumulation due to constraint drift. The basic idea is to embed a small virtual force and a small virtual impulse to the equation of motion, in order to avoid the drift typically experienced in constrained multibody simulations. The embedded correction terms are selected to minimally alter the dynamics in an acceleration and kinetic energy norm sense. The formulation allows one to use a standard ODE solver, avoiding the need for iterative constraint stabilization. The equation is based on the pseudoinverse of a constraint matrix such that it can be used under redundant constraints and kinematic singularities. The proposed method takes into account the finite word-length of the computational environment, and also accommodates possibly inconsistent initial conditions.     

一个基于图基约束集映射的参数化设计模型

文中提出了一个基于图基约束集映射的参数化设计模型 .对图基的概念作了阐述 .提出了一个适合于图基参数化的数据模型和约束集的多元组表示与映射方法 .给出了基于图基实例的约束求解方法和定位算法 ,并对计算方法作了归纳 .在此基础上 ,给出了一个基于图基的一致联动方法 .实践证明 ,基于图基联动的设计方法摆脱了传统的基于点、线、圆、圆弧低层次线素繁琐的交互设计工作 ,提高了 CAD系统的自动化程度 ,使设计人员对产品的设计、维护以及后续分析等过程都具有十分重要的意义 .     

Optimal trajectory planning for industrial robots

An analysis of the results of an algorithm for optimal trajectory planning of robot manipulators is described in this paper. The objective function to be minimized is a weighted sum of the integral squared jerk and the execution time. Two possible primitives for building the trajectory are considered: cubic splines or fifth-order B-splines. The proposed technique allows to set constraints on the robot motion, expressed as upper bounds on the absolute values of velocity, acceleration and jerk. The described method is then applied to a 6-d.o.f. robot (a Cartesian gantry manipulator with a spherical wrist); the results obtained using the two different primitives are presented and discussed.     

虚拟手术中基于可变方向凸包的碰撞检测算法

为了实现机器人辅助虚拟手术中快速精确的碰撞检测,提出了基于可变方向凸包的层次包围盒碰撞检测算法。在虚拟场景中,手术器械末端运动复杂多变且软体组织持续形变,分析器械和软组织的作用形式,根据器械运动学参数,预测软组织的变形,将其与固定方向凸包检测方法相结合,通过改变方向向量集合,提高包围盒树的紧密性,进而减少相交测试的次数,加速碰撞检测。仿真实验证明了可变方向凸包的碰撞检测算法可以实现精确的碰撞检测;与固定方向凸包算法相比在快速碰撞检测方面具有优越性,当软组织包含的面片数目越多时,快速性优势越显著。