一种仿人机械臂的运动学逆解的几何求解方法

运用几何方法求解一种具有7个旋转自由度的仿人机械臂的运动学逆解,并运用特定的寻优指标,搜索与指定末端位姿对应的关节角空间最优解.这种解法没有理论误差并且解算速度足够快,有利于在线实时控制机械臂的运动.     

全局和声搜索方法及其在仿人灵巧臂逆运动学求解中的应用

仿人灵巧臂逆运动学(IK)问题可转化为等效的最小化问题,并采用数值优化方法求解.和声搜索(HS)是模拟乐师在音乐演奏中调整音调现象的一种启发式搜索方法,目前还尚未在机器人机械臂逆运动学问题中得到应用.本文提出一种基于粒子群体智能的全局和声搜索方法(GHSA),该方法在和声搜索算法中引入微粒群操作(PSO),采用粒子群策略替代常规和声搜索算法中的搜索法则创作新和声,通过粒子自身认知和群体知识更新和声变量位置信息平衡算法对解空间全局探索与局部开发间能力;同时算法还引入变异操作增强算法跳出局部最优解能力,基准函数测试表明该方法改善了全局搜索能力及求解可靠性.在此基础上以七自由度(7-DOF)冗余仿人灵巧臂为例,考虑以灵巧臂末端位姿误差和“舒适度”指标构建适应度函数并采用GHSA算法求解其逆运动学(IK)问题,数值仿真结果表明了该方法是解决仿人灵巧臂逆运动学问题的一种有效方法.     

基于分级规划策略的拟人机械臂仿人运动规划算法研究

为使拟人机械臂具有高精度的仿人运动,提出一种通过触发条件和分级规划策略 的仿人运动新方法。将人臂运动过程离散为不同运动阶段,在每一个运动阶段都有与之对应的 规划层,在不同的规划层中,拟人机械臂的运动特点不同。利用各自的特点建立不同规划层下 的运动模型及臂姿预测指标,对拟人机械臂臂姿进行预测。最后,以NAO 机器人为实验平台, 比较所提方法与最小势能法(MTPE)的静态臂姿与动态臂姿预测,并与运动捕捉系统(OptiTrack) 采集的真实人臂运动数据进行比较。实验表明,该方法具有较小的静态臂姿和动态臂姿预测误 差,能使拟人机械臂产生高度逼真的仿人运动。     

绳驱超冗余空间柔性机械臂遥操作系统设计与实验研究

针对绳驱超冗余空间柔性机械臂的运动特点和在大范围工作空间快速运动、避障及狭小空间作业和触碰情况下精细操作等在轨遥操作任务需求,设计并研制了适应多种工况的基于手控器和虚拟现实（VR）手柄组合的遥操作人机交互系统。对狭小空间作业和避障等工况进行分析,提出了基于自由度动态组合和末端―臂形同步规划的遥操作方法。最后,完成了穿越卫星太阳帆板狭缝的典型实验,实验验证了遥操作系统的工程实用性,以及柔性机械臂遥操作运动规划方法的可行性。因此,配合使用多种人机交互方式组合的遥操作系统和相应的运动规划方法,可使操作者以更加直观自然的方式参与到遥操作系统中,有效提高操作员完成复杂遥操作任务的安全性和操作性能。     

柔性臂仿仿人智能变结构控制

柔臂的位置控制中，最大的难点是柔性振动的抑制，常规控制方法往往不能同时得到良好的关节跟踪轨迹和对柔性振动的补偿，本文提出了仿人智能变结构控制方法，此方法综合了仿人智能控制与变结构控制的优点，仿真结果表明，这种控制方法能有效的抑制柔性振动，同时具有良好的关节跟踪能力。     

变时延巡检小车遥操作仿人智能预估控制

针对目前解决遥操作系统网络变时延问题的控制方案存在稳定性与操作性间的矛盾、过于依赖被控对象模型精度和抗干扰性差等不足,提出了一种HSIC-Smith控制算法.首先,根据巡检小车典型的动态响应误差曲线,确定能恰当描述系统动态特性的特征模型;其次,在Smith预估原理的基础上,应用仿人智能控制算法对巡检小车不同的运动状态,采用开、闭环相结合的控制模式来减小Smith预估误差带来的影响,从而改善网络时延变化对巡检小车遥操作系统动态性能;最后,将该方案与常规的PID-Smith预估算法进行对比实验.实验结果表明:在存在网络变时延的条件下,谊方案能对巡检小车系统迅速、准确地遥操作控制,且对网络时延变化具有较强的适应性.     

含弧形自由度仿人灵巧手掌的机构设计

提出了一种人手掌的简化模型,根据该模型,设计了仿人灵巧手掌的机构,使得只作为仿人灵巧手手指及其控制部件机架的手掌形成弧形自由度参加手部动作,提高了仿人灵巧手通用性、灵活性和抓持物体的适应性。经优化设计和仿真,机构完全符合灵巧手进行运动时手掌的运动要求。     

主被动混合式微创手术机械臂机构设计及灵巧度优化

研制出一款可开展微创手术的双机械臂机器人系统,该系统配合手术微器械可以实现精确的腹腔内手术操作．通过分析微创手术的手术环境及手术操作特点,提出了采用机器人开展微创手术对机器人自身机构设计的基本要求,并在此基础上重点对机械臂机构进行设计和优化．该机械臂可以按照微创手术的实际需求,实现机器人的术前摆位、术中器械操作及器械的快速拆装更换,并且可以从机构上保证术中器械在患者腹壁切口处位置不变,避免术中因手术器械运动而对腹壁切口造成非手术性损伤．此外,借助于机器人雅可比矩阵的奇异值,构造了基于条件数和可操作度的综合灵巧度评价指标函数,并采用序列二次规划算法对机械臂杆件参数进行优化．优化结果表明,机械臂具有良好的各向同性及可操作度,很好地满足了微创手术对机械臂机构灵活性的要求．     

柔性臂仿人智能变结构控制

柔性臂的位置控制中，最大的难点是柔性振动的抑制，常规控制方法往往不能同时得到良好的关节跟踪轨迹和对柔性振动的补偿。本文提出了仿人智能变结构控制方法，此方法综合了仿人智能控制与变结构控制的优点，仿真结果表明，这种控制方法能有效的抑制柔性振动，同时具有良好的关节跟踪能力。     

Kinematics and control of a fully parallel force-reflecting hand controller for manipulator teleoperation

Force feedback can enhance the efficiency of a teleoperation system by providing the operator with a sense of feel of the forces and torques arising from the interaction of the slave manipulator with the remote environment. This article addresses the kinematic analysis and control of a Parallel FOrce-Reflecting Hand Controller (PFORHC) whose design and implementation are based on a fully parallel mechanism. Kinematic analysis on the PFORHC is performed and results in a closed-form solution for the inverse kinematics. The forward kinematics is solved by Newton-Raphson's method. A fixed-gain PD control scheme is developed for force feedback control. Experiments are conducted to study the performance of the force-reflecting capability of the PFORHC. Experimental results show that the force control scheme utilizing a handgrip force sensor provides smaller steady-state errors as compared to the case utilizing no handgrip force sensor.     

Teaching humanoid robotics by means of human teleoperation through RGB-D sensors

This paper presents a graduate course project on humanoid robotics offered by the University of Padova. The target is to safely lift an object by teleoperating a small humanoid. Students have to map human limbs into robot joints, guarantee the robot stability during the motion, and teleoperate the robot to perform the correct movement.We introduce the following innovative aspects with respect to classical robotic classes: i) the use of humanoid robots as teaching tools; ii) the simplification of the stable locomotion problem by exploiting the potential of teleoperation; iii) the adoption of a Project-Based Learning constructivist approach as teaching methodology.The learning objectives of both course and project are introduced and compared with the students’ background. Design and constraints students have to deal with are reported, together with the amount of time they and their instructors dedicated to solve tasks. A set of evaluation results are provided in order to validate the authors’ purpose, including the students’ personal feedback. A discussion about possible future improvements is reported, hoping to encourage further spread of educational robotics in schools at all levels.     

基于仿人机械手的五指力封闭抓取算法

手是人类在长期进化过程中形成的最完美的工具,能够灵活、精细的进行抓取物体等操作。机械手设计初衷是取代人手完成工作,是机器人系统的重要组成部分,因此抓取物体等操作一直是仿人机械手的研究重点。传统的抓取方法是利用机械手三指形成力封闭完成任务。但由于机械手本身结构复杂等原因,易出现控制信号偏差或某自由度未达到要求水平,使得抓取过程中目标物体脱落等问题。为了使机械手达到稳定抓取的效果,本文提出了一种效仿人手抓取的五指力封闭抓取算法,其本质是利用冗余机制解决传统三指抓取过程中可能出现的抓取不平稳或脱落的问题。首先,基于三指力平衡算法的思想上提出了满足五指力封闭抓取算法的条件。然后,对五指力封闭抓取算法进行了充分性和必要性的证明。最后,通过仿真环境下的实验抓取不同目标物体,验证了五指力封闭算法的可行性及必要性。     

Development of human-machine interface for teleoperation of a mobile manipulator

Human-robot control interfaces have received increased attention during the past decades for conveniently introducing robot into human daily life. In this paper, a novel Human-machine Interface (HMI) is developed, which contains two components. One is based on the surface electromyography (sEMG) signal, which is from the human upper limb, and the other is based on the Microsoft Kinect sensor. The proposed interface allows the user to control in real time a mobile humanoid robot arm in 3-D space, through upper limb motion estimation by sEMG recordings and Microsoft Kinect sensor. The effectiveness of the method is verified by experiments, including random arm motions in the 3-D space with variable hand speed profiles.     

Failure tolerant teleoperation of a kinematically redundant manipulator: an experimental study

Teleoperated robots in harsh environments have a significant likelihood of failures. It has been shown in previous work that a common type of failure such as that of a joint "locking up," when unidentified by the robot controller, can cause considerable performance degradation in the local behavior of the manipulator even for simple point-to-point motion tasks. The effects of a failure become more critical for a system with a human in the loop, where unpredictable behavior of the robotic arm can completely disorient the operator. In this experimental study involving teleoperation of a graphically simulated kinematically redundant manipulator, two control schemes, the pseudoinverse and a proposed failure-tolerant inverse, were randomly presented under both nonfailure and failure scenarios to a group of operators. Based on performance measures derived from the recorded trajectory data and operator ratings of task difficulty, it is seen that the failure-tolerant inverse kinematic control scheme improved the performance of the human/robot system.     

Human control model in teleoperation rendezvous

This paper proposes a human control model in teleoperation rendezvous on the basis of human information processing （perception, judgment, inference, decision and response）. A predictive display model is introduced to provide the human operator with predictive information of relative motion. By use of this information, the longitudinal and lateral control models for the operator are presented based on phase plane control method and fuzzy control method, and human handling qualities are analyzed. The integration of these two models represents the human control model. Such a model can be used to simulate the control process of the human operator, which teleoperates the rendezvous with the aid of predictive display. Experiments with human in the loop are carried out based on the semi-Physical simulation system to verify this human control model. The results show that this human control model can emulate human operators＇ performance effectively, and provides an excellent way for the analysis, evaluation and design of the teleoperation rendezvous system.     

Sensory reflex control for humanoid walking

Since a biped humanoid inherently suffers from instability and always risks tipping itself over, ensuring high stability and reliability of walk is one of the most important goals. This paper proposes a walk control consisting of a feedforward dynamic pattern and a feedback sensory reflex. The dynamic pattern is a rhythmic and periodic motion, which satisfies the constraints of dynamic stability and ground conditions, and is generated assuming that the models of the humanoid and the environment are known. The sensory reflex is a simple, but rapid motion programmed in respect to sensory information. The sensory reflex we propose in this paper consists of the zero moment point reflex, the landing-phase reflex, and the body-posture reflex. With the dynamic pattern and the sensory reflex, it is possible for the humanoid to walk rhythmically and to adapt itself to the environmental uncertainties. The effectiveness of our proposed method was confirmed by dynamic simulation and walk experiments on an actual 26-degree-of-freedom humanoid.     

Predictive control approaches for bilateral teleoperation

Performance and stability are both affected due to time delay in bilateral teleoperation. Recent researches have reported the effectiveness of applying predictive control approaches to cope with the time delay effect which improve both stability and transparency. In this regard, this article aims to provide a systematic review of the predictive control approaches in bilateral teleoperation. The survey also tries to compare and assess the main features and properties of the predictive control schemes as much as possible. The survey elaborates initially the most common schemes and then qualitative and quantitative comparisons along with discussions are made with respect to stability, transparency, and robustness.     

Modeling and control of cooperative teleoperation systems

This paper presents a multilateral control architecture for teleoperation in multimaster/multislave environments. The proposed framework incorporates flow of position and force information between all master and slave robots, rather than merely between corresponding units. Within this architecture, cooperative performance measures are defined to enhance coordination among the operators and the robots for achieving the task objectives. A /spl mu/-synthesis-based methodology for cooperative teleoperation control is also introduced. This approach guarantees robust stability of cooperative teleoperation in the presence of dynamic interaction between slave robots, as well as unknown passive operators and environment dynamics. It also improves task coordination by optimizing relevant performance objectives. Experiments carried out with a two-master/two-slave single-axis system demonstrate the effectiveness of the proposed approach.     

Bilateral parallel force/position teleoperation control

The extension of parallel force/position control to teleoperation systems is considered in this article. In the proposed four‐channel bilateral controller, higher priority is granted to position control at the master side and to force control at the slave side. The primary goal of this control architecture is the enhancement of force and position tracking performance in the presence of uncertainties in the system and environment. The stability and performance of the proposed controller is investigated by analyzing the three decoupled single‐degree‐of‐freedom systems obtained from decoupling and projecting the closed‐loop system dynamics onto the slave task‐space orthogonal directions. Experimental results demonstrate significant improvement in transparency. © 2002 Wiley Periodicals, Inc.