Underactuated miniature bending joint composed of serial pulleyless rolling joints

This paper proposes a miniature bending joint composed of serial rolling joints; it refers to the classification of small joints of other products and studies on surgical applications according to the structures and transmissions. To achieve this, a pulleyless rolling joint is introduced as a unit component and the basic design principle is established for the joint. A simple mechanism guarantees a smooth rolling contact using elastic fixtures. Underactuation, which prevents S-shaped curvature similar to buckling, is applied to drive the bending joint with a limited number of wire cables. Using a 1-DOF real-sized prototype, experiments were performed to measure the motion accuracy and payload capacity from various angles to evaluate the efficacy of an improved design that enhances the payload on the distal end. This novel joint is applicable to a wider variety of surgical tools and catheters relative to other candidates owing to its small constant curvature, reasonable payload capacity, and miniature size.     

欠驱动水平机械臂的遗传优化分层滑模控制

对具有非驱动关节的水平二自由度机械臂系统,提出了基于遗传算法的在全局参数空间内进行全参数寻优的改进分层滑模变结构控制方法．解决了水平欠驱动系统的变结构控制问题以及由于欠驱动系统控制缺少通用的参数计算方法而产生的控制精度低的问题．仿真结果表明了该控制方法的有效性,并且优化后的控制器具有较好的适应性和控制效果．     

弹性欠驱动四指灵巧手设计与试验

全驱动灵巧手需要较多独立驱动单元,控制系统复杂,导致体积和重量过大,费用昂贵,在实际应用中有极大局限性。欠驱动灵巧手具有驱动单元少、控制简单等特点。在保证具有一定运动灵巧性的前提下,欠驱动灵巧手能极大降低灵巧手本体及控制系统的复杂度和制造维护成本,体现出更高的实际应用价值。由此提出一种新颖的仿人单腱弹性欠驱动四指灵巧手的设计方案。同时,完成四指灵巧手本体结构设计,及分析获得关节弹簧刚度的选取方法。对影响关节驱动转矩的滑轮单元进行几何参数的优化分析,得到手指传动机构的较优设计方案。通过多指手样机对不同形状、大小物体的抓握试验,证明本欠驱动四指灵巧手具有抓取自适应能力和较强抓取能力。     

多模式刚柔结合欠驱动抓取机构的设计、分析与实验测试

结合刚性欠驱动抓取机构与柔顺机构,提出一种多模式刚柔结合欠驱动抓取机构,并对所提出的机构进行分析与实验研究。基于刚体替代法,设计了二指多模式欠驱动抓取机构的刚柔结合方案。运用正运动学分析与载荷平衡方程,对驱动单元进行静力学建模。结合伪刚体模型法、载荷平衡方程与操作对象平衡位置枚举搜索,建立两点抓取与包络抓取模式下抓取力与驱动力矩的关系式。将驱动单元静力学建模与抓取单元静力学建模相结合,可以得到完整的多模式抓取力模型。进一步地,考虑由于接触引起的柔性杆件变形,结合线性插值,对抓取力模型进行修正。基于修正后的抓取力模型,对机构尺寸参数进行优化设计,综合提升机构在两点抓取模式和包络抓取模式下的载荷输出性能。RecurDyn仿真结果显示,在两点抓取模式和包络抓取模式下,修正后完整的抓取力模型与仿真值的最大相对误差为7.62%,并且所提出的优化算法有效提升了机构的两点抓取力与综合包络抓取力。实验结果显示,优化后的抓取机构抓取力有较大的提升,修正后完整的抓取力模型与实验值的最大相对误差为1.87%,验证了抓取力建模、优化设计的有效性。     

基于神经网络前馈补偿的欠驱动机器人越障控制

针对欠驱动巡检机器人相对于传统机器人控制量少于控制对象的特点,依靠Lagrange定理建立机器人系统动力学模型和电缆弯曲数学模型.根据障碍物外形特点给出障碍物特征量的提取方法;根据障碍物较大,常规的运动控制输出量不宜变化过大的特点,以及机器人越障过程中要保持机体平衡,依据动力学模型提出了基于神经网络补偿的前馈-反馈控制器,以实现对系统姿态控制和越障控制.控制器具有自学习、自动补偿的能力,对非线性对象有较好的控制作用.仿真结果表明,该方法相对于常规PID控制、普通模糊控制具有超前调节、超调量小、抗扰动能力强的特点.通过实验,验证了基于神经网络补偿的前馈-反馈控制器的合理性.     

形状自适应欠驱动三关节机器人手指设计

根据欠驱动原理研制的三指10个自由度的机器人手爪具有驱动元件数量少、抓取物体范围广泛等优点．在欠驱动手爪的4个主要机构中,欠驱动手指对抓取物体具有被动柔顺和形状自适应的特性．首先对三关节欠驱动手指机构进行静力学分析,提出合理的设计目标和约束条件;然后根据设计目标,采用遗传算法得到手指机构的各个关节连杆尺寸和抓取物体时的特殊构形,使得在抓取给定物体时各关节指面的接触力达到均匀分布,得到高效的力传递和更加紧凑的机构尺寸．     

基于模型预测控制的UUV路径跟踪控制研究

水下无人航行器(UUV)的路径跟踪控制是实现UUV多种军、民用途的重要技术基础。针对UUV路径跟踪控制中的欠驱动、非完整约束、模型的非线性,基于非线性连续模型预测控制算法设计了UUV垂直面路径跟踪控制器。建立了垂直面运动模型并基于状态空间模型给出了垂直面预测模型,通过给定性能指标,运用泰勒级数展开与李导数求解出了连续时间状态下的最优控制律,实现了欠驱动UUV路径跟踪控制。通过仿真实验,验证了垂直面路径跟踪控制器设计的有效性。     

Distributed hierarchical control for multiple vertical takeoff and landing UAVs with a distance‐based network topology

A distributed formation control algorithm is proposed for multiple vertical takeoff and landing (VTOL) unmanned aerial vehicles (UAVs) in this paper. The neighboring information is obtained by active measurements rather than by nonactive communications as done in the current literatures. By properly expanding the distance‐based network topology structure between each pair of UAVs, a distributed algorithm is proposed such that the switching topology remains connected along the time. Since a VTOL UAV system is typically underactuated, a hierarchical idea is introduced to derive the control design procedure. More specifically, the studied formation control problem of multiple VTOL UAVs is first transformed into the consensus problem of their corresponding error systems. Then, a command force and an applied torque are synthesized for each VTOL UAV such that the error systems reach a consensus. It is demonstrated in terms of Lyapunov theory that the proposed distributed hierarchical control algorithm guarantees the formation realization of multiple VTOL UAVs while maintaining the network connectivity. Finally, simulations are performed to validate the theoretical results.     

HIT prosthetic hand based on tendon-driven mechanism

An underactuated finger structure actuated by tendon-driven system is presented.Kinematics and static analysis of the finger is done,and the results indicate that the prosthetic finger structure is effective and feasible.Based on the design of finger,a prosthetic hand is designed.The hand is composed of 5 independent fingers and it looks more like humanoid.Its size is about 85% of an adult＇s hand and weights about 350 g.Except the thumb finger,each finger is actuated by one DC motor,gear head and a tendon,and has three curling/extension joints.The thumb finger which is different from other existing prostheses is a novel design scheme.The thumb finger has four joints including three curling/extension joints and a joint which is used to realize the motion of the thumb related to the palm,and these joints are also driven by one DC motor,harmonic drive and a tendon.The underactuation and adaptive curling/extension motion of the finger are realized by joint torsion springs.A high-powered chip of digital signal processing （DSP） is the main part of the electrical system which is used for the motors control,data collection,communication with external controlling source,and so on.To improve the reliability of the hand,structures and sensors are designed and made as simply as possible.The hand has strong manipulation capabilities that have been verified by finger motion and grasping tests and it can satisfy the daily operational needs and psychological needs of deformities.     

绳驱动五指灵巧手的设计

通过研究人手的生理结构特点,模仿人手结构,应用欠驱动原理和适应性原理对五指灵巧手进行了初步设计。该灵巧手共有16个自由度,采用了绳驱动机构,具有结构简单、重量轻等优点。通过灵巧手模型的抓取实验,验证了其运动方式和抓取性能。