Wire-driven mechanism and highly efficient propulsion in water.

• Other Authors: Li, Zheng
• Format: Others
• Language: English; Chinese
• Published: 2013
• Subjects: Propellers
• Online Access: http://library.cuhk.edu.hk/record=b5549830; http://repository.lib.cuhk.edu.hk/en/item/cuhk-328652

自然生物的杰出表现往往令人们叹为观止。正因为如此，在机器人研究中对自然界动植物的模仿从未间断。本文受动物肌肉骨骼系统（尤其是蛇的脊柱以及章鱼手臂的肌肉分布）的启发，设计了一种新型的仿生拉线机构。该机构由柔性骨架以及成对拉线组成。柔性骨架提供支撑，拉线模拟肌肉将驱动器的运动和力传递给骨架，并控制骨架运动。从骨架结构分，拉线机构可分为蛇形拉线机构以及连续型拉线机构；从骨架分段来看，拉线机构可分为单段式拉线机构以及多段式拉线机构，其中每段由一或两对拉线控制。拉线机构的主要性能特征包括：大柔性，高度欠驱动，杠杆效应，以及远程传力。机构的柔性使得它可以产生很大的弯曲变形；欠驱动设计极大地减少了驱动器的数目，简化了系统结构；在杠杆效应下，骨架末端速度、加速度与拉线的速度、加速度相比得到数十倍放大；通过拉线将驱动器的运动和力远程传递给执行机构，使得拉线机构结构简单紧凑。基于以上特征，拉线机构不仅适合工作于狭窄空间，同时也适合于摆动推进，尤其是水下推进。 === 论文系统地介绍了拉线机构的设计，运动学，工作空间，静力学以及动力学模型。在常曲率假设下分别建立了蛇形拉线机构以及连续型拉线机构的运动学模型，在此基础上建立了一个通用运动学模型，以及工作空间模型。与传统避障相反，本文提出了一种利用现有障碍或主动布置约束来拓展工作空间的新方法。通过牛顿-欧拉法以及拉格朗日方程建立了蛇形拉线机构的静力学模型以及动力学模型。在非线性欧拉-伯努利梁理论下结合汉密尔顿原理建立了连续型拉线机构的静力学模型以及动力学模型。 === 论文中利用拉线机构设计了一系列新型水下推进器。与传统机器鱼推进器设计方法（单关节，多关节以及基于智能材料的连续型设计）相比，基于拉线机构的水下推进器的优点在于：所需驱动器少，能更好地模拟鱼的游动，易于控制，推进效率高，以及容易衍生新型推进器。设计制作了四条拉线驱动机器鱼，以此为平台验证了拉线推进器的性能以及优点。实验结果表明，基于蛇形拉线机构的推进器可以提供较大推力；基于连续型拉线机构设计的推进器受摩擦影响较小；基于单段式拉线机构的推进器可以模仿鱼类摆动式推进，具有很好的转弯性能；基于多段式拉线机构的推进器可以同时模仿摆动式推进和波动式推进，具有更好的稳定性以及游速。此外，基于拉线机构制造了一种新型矢量推进器。该推进器可以提供任意方向的推力，从而提高机器鱼的机动性能。实验中，在两个额定功率为1瓦的电机驱动下，机器鱼的最大游速为0.67 体长/秒；最小转弯半径为0.24倍体长；转弯速度为51.4 度/秒；最高推进效率为92.85%。最后，采用拉线推进器制作了一个室内空中移动机器人，取名为Flying Octopus。它由一个氦气球提供浮力悬停在空中，通过四个独立控制的拉线扑翼驱动可在三维空间自由运动。 === Attracted by the outstanding performance of natural creatures, researchers have been mimicking animals and plants to develop their robots. Inspired by animals’ musculoskeletal system, especially the skeletal structure of snakes and octopus arm muscle arrangement, in this thesis, a novel wire-driven mechanism (WDM) is designed. It is composed of a flexible backbone and a number of controlling wire groups. The flexible backbone provides support, while the wire groups transmit motion and force from the actuators, mimicking the muscles. According to its backbone structure, the WDM is categorized as serpentine WDM and continuum WDM. Depending on the backbone segmentation, WDM is divided into single segment WDM and multi-segment WDM. Each segment is controlled by one or two wire groups. Features of WDM include: flexible, highly under-actuated, leverage effect, and long range force and motion transmission. The flexibility enables the WDM making large deformation, while the under-actuation greatly reduces th number of actuators, simplifying the system. With the leverage effect, WDM distal end velocity and acceleration is greatly amplified from that of wire. Also, in the WDM, the actuators and the backbone are serperated. Actuator’s motion is transmitted by the wires. This makes the WDM very compact. With these features, the WDM is not only well suited to confined space, but also flapping propulsion, especially in water. === In the thesis, the design, kinematics, workspace, static and dynamic models of the WDM are explored systematically. Under the constant curvature assumption, the kinematic model of serpentine WDM and continuum WDM are established. A generalized model is also developed. Workspace model is built from the forward kinematic model. Rather than avoiding obstacles, a novel idea of employing obstacles or actively deploying constraints to expand workspace is also discussed for WDM-based flexible manipulators. The static model and dynamic model of serpentine WDM is developed using the Newton-Euler method and the Lagrange Equation, while that of continuum WDM is built under the non-linear Euler-Bernoulli Beam theory and the extended Hamilton’s principle. === In the thesis, a number of novel WDM based underwater propulsors are developed. Compared with existing fish-like propulsor designs, including single joint design, multi-joint design, and smart material based continuum design, the proposed WDM-based propulsors have advantages in several aspects, such as employing less actuators, better resembling the fish swimming body curve, ease of control, and more importantly, being highly efficient. Also, brand new propulsors can be easily developed using the WDM. To demonstrate the features as well as the advantages of WDM propulsors, four robot fish prototypes are developed. Experiments show that the serpentine WDM-based propulsor could provide large flapping force while the continuum WDM-based propulsor is less affected by joint friction. On the other hand, single segment WDM propulsor can make oscillatory swim while multi- segment WDM propulsor can make both oscillatory and undulatory swims. The undulatory swimming outperforms the oscillatory swimming in stability and speed, but is inferior in turning around. In addition, a novel robot fish with vector propulsion capability is also developed. It can provide thrust in arbitrary directions, hence, improving the maneuverability of the robot fish. In the experiments, with the power limit of two watts, the maximum forward speed of the WDM robot fishes can reach 0.67 BL (Body Length)/s. The minimum turning radius is 0.24 BL, and the turning speed is 51.4°/s. The maximum Froude efficiency of the WDM robot fishes is 92.85%. Finally, the WDM-based propulsor is used to build an indoor Lighter-than-Air- Vehicle (LTAV), named Flying Octopus. It is suspended in the air by a helium balloon and actuated by four independently controlled wire-driven flapping wings. With the wing propulsion, it can move in 3D space effectively. === Detailed summary in vernacular field only. === Detailed summary in vernacular field only. === Detailed summary in vernacular field only. === Li, Zheng. === Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. === Includes bibliographical references (leaves 205-214). === Abstracts also in Chinese. === Abstracth --- p.i === 摘要 --- p.iii === Acknowledgement --- p.v === List of Figures --- p.xi === List of Tables --- p.xvii === Chapter Chapter 1 --- Introduction --- p.1 === Chapter 1.1 --- Background --- p.1 === Chapter 1.2 --- Related Research --- p.2 === Chapter 1.2.1 --- Flexible Manipulator --- p.2 === Chapter 1.2.2 --- Robot Fish --- p.10 === Chapter 1.3 --- Motivation of the Dissertation --- p.13 === Chapter 1.4 --- Organization of the Dissertation --- p.14 === Chapter Chapter 2 --- Biomimetic Wire-Driven Mechanism --- p.16 === Chapter 2.1 --- Inspiration from Nature --- p.16 === Chapter 2.1.1 --- Snake Skeleton --- p.18 === Chapter 2.1.2 --- Octopus Arm --- p.19 === Chapter 2.2 --- Wire-Driven Mechanism Design --- p.20 === Chapter 2.2.1 --- Flexible Backbone --- p.20 === Chapter 2.2.2 --- Backbone Segmentation --- p.26 === Chapter 2.2.3 --- Wire Configuration --- p.28 === Chapter 2.3 --- Wire-Driven Mechanism Categorization --- p.31 === Chapter 2.4 --- Summary --- p.32 === Chapter Chapter 3 --- Kinematics and Workspace of the Wire-Driven Mechanism --- p.33 === Chapter 3.1 --- Kinematic Model of Single Segment WDM --- p.33 === Chapter 3.1.1 --- Kinematic Model of the Serpentine WDM --- p.34 === Chapter 3.1.2 --- Kinematic Model of the Continuum WDM --- p.39 === Chapter 3.1.3 --- A Generalized Kinematic Model --- p.43 === Chapter 3.2 --- Kinematic Model of Multi-Segment WDM --- p.47 === Chapter 3.2.1 --- Forward Kinematics --- p.47 === Chapter 3.2.2 --- Inverse Kinematics --- p.51 === Chapter 3.3 --- Workspace --- p.52 === Chapter 3.3.1 --- Workspace of Single Segment WDM --- p.52 === Chapter 3.3.2 --- Workspace of Multi-Segment WDM --- p.53 === Chapter 3.4 --- Employing Obstacles to Expand WDM Workspace --- p.55 === Chapter 3.4.1 --- Constrained Kinematics Model of WDM --- p.55 === Chapter 3.4.2 --- WDM Workspace with Constraints --- p.61 === Chapter 3.5 --- Model Validation via Experiment --- p.64 === Chapter 3.5.1 --- Single Segment WDM Kinematic Model Validation --- p.64 === Chapter 3.5.2 --- Multi-Segment WDM Kinematic Model Validation --- p.66 === Chapter 3.5.3 --- Constrained Kinematic Model Validation --- p.70 === Chapter 3.6 --- Summary --- p.73 === Chapter Chapter 4 --- Statics and Dynamics of the Wire-Driven Mechanism --- p.75 === Chapter 4.1 --- Static Model of the Wire-Driven Mechanism --- p.75 === Chapter 4.1.1 --- Static Model of SPSP WDM --- p.75 === Chapter 4.1.2 --- Static Model of SPCP WDM --- p.81 === Chapter 4.2 --- Dynamic Model of the Wire-Driven Mechanism --- p.88 === Chapter 4.2.1 --- Dynamic Model of SPSP WDM --- p.88 === Chapter 4.2.2 --- Dynamic Model of SPCP WDM --- p.92 === Chapter 4.3 --- Summary --- p.94 === Chapter Chapter 5 --- Application I - Wire-Driven Robot Fish --- p.95 === Chapter 5.1 --- Fish Swimming Introduction --- p.95 === Chapter 5.1.1 --- Fish Swimming Categories --- p.95 === Chapter 5.1.2 --- Body Curve Function --- p.96 === Chapter 5.1.3 --- Fish Swimming Hydrodynamics --- p.101 === Chapter 5.1.4 --- Fish Swimming Data --- p.103 === Chapter 5.2 --- Oscillatory Wire-Driven Robot Fish --- p.104 === Chapter 5.2.1 --- Serpentine Oscillatory Wire-Driven Robot Fish Design --- p.105 === Chapter 5.2.2 --- Continuum Oscillatory Wire-Driven Robot Fish Design --- p.110 === Chapter 5.2.3 --- Oscillatory Robot Fish Propulsion Model --- p.114 === Chapter 5.2.4 --- Robot Fish Swimming Control --- p.116 === Chapter 5.2.5 --- Swimming Experiments --- p.118 === Chapter 5.3 --- Undulatory Wire-Driven Robot Fish --- p.125 === Chapter 5.3.1 --- Undulatory Wire-Driven Robot Fish Design --- p.125 === Chapter 5.3.2 --- Undulatory Wire-Driven Robot Fish Propulsion Model --- p.130 === Chapter 5.3.3 --- Swimming Experiments --- p.131 === Chapter 5.4 --- Vector Propelled Wire-Driven Robot Fish --- p.136 === Chapter 5.4.1 --- Vector Propelled Wire-Driven Robot Fish Design --- p.136 === Chapter 5.4.2 --- Tail Motion Analysis --- p.140 === Chapter 5.4.3 --- Swimming Experiments --- p.142 === Chapter 5.5 --- Wire-Driven Robot Fish Performance and Discussion --- p.144 === Chapter 5.5.1 --- Performance --- p.144 === Chapter 5.5.2 --- Discussion --- p.147 === Chapter 5.6 --- Summary --- p.149 === Chapter Chapter 6 --- Aplication II - Wire-Driven LTAV - Flying Octopus --- p.151 === Chapter 6.1 --- Introduction --- p.151 === Chapter 6.2 --- Flying Octopus Design --- p.152 === Chapter 6.2.1 --- Flying Octopus Body Design --- p.152 === Chapter 6.2.2 --- Wire-Driven Flapping Wing Design --- p.153 === Chapter 6.3 --- Flying Octopus Motion Control --- p.156 === Chapter 6.3.1 --- Propulsion Model --- p.156 === Chapter 6.3.2 --- Motion Control Strategy --- p.157 === Chapter 6.3.3 --- Motion Simulation --- p.159 === Chapter 6.4 --- Prototype and Indoor Experiments --- p.161 === Chapter 6.4.1 --- Flying Octopus Prototype --- p.161 === Chapter 6.4.2 --- Indoor Experiments --- p.163 === Chapter 6.4.3 --- Discussion --- p.165 === Chapter 6.5 --- Summary --- p.166 === Chapter Chapter 7 --- Conclusions and Future Work --- p.167 === Chapter Appendix A - --- Publication Record --- p.170 === Chapter Appendix B - --- Derivation --- p.172 === Chapter Appendix C --- Matlab Programs --- p.176 === References --- p.205