A Novel Propeller Design for Micro-Swimming robot

The applications of a micro-swimming robot such as minimally invasive surgery, liquid pipeline robot etc. are widespread in recent years. The potential application fields are so inspiring, and it is becoming more and more achievable with the development of microbiology and Micro-Electro-Mechanical Systems (MEMS). The aim of this study is to improve the performance of micro-swimming robot through redesign the structure. To achieve the aim, this study reviewed all of the modelling methods of low Reynolds number flow including Resistive-force Theory (RFT), Slender Body Theory (SBT), and Immersed Boundary Method (IBM) etc. The swimming model with these methods has been analysed. Various aspects e.g. hydrodynamic interaction, design, development, optimisation and numerical methods from the previous researches have been studied. Based on the previous design of helix propeller for micro-swimmer, this study has proposed a novel propeller design for a micro-swimming robot which can improve the velocity with simplified propulsion structure. This design has adapted the coaxial symmetric double helix to improve the performance of propulsion and to increase stability. The central lines of two helical tails overlap completely to form a double helix structure, and its tail radial force is balanced with the same direction and can produce a stable axial motion. The verification of this design is conducted using two case studies. The first one is a pipe inspection robot which is in mm scale and swims in high viscosity flow that satisfies the low Reynolds number flow condition. Both simulation and experiment analysis are conducted for this case study. A cross-development method is adopted for the simulation analysis and prototype development. The experiment conditions are set up based on the simulation conditions. The conclusion from the analysis of simulation results gives suggestions to improve design and fabrication for the prototype. Some five revisions of simulation and four revisions of the prototype have been completed. The second case study is the human blood vessel robot. For the limitations of fabrication technology, only simulation is conducted, and the result is compared with previous researches. The results show that the proposed propeller design can improve velocity performance significantly. The main outcomes of this study are the design of a micro-swimming robot with higher velocity performance and the validation from both simulation and experiment

Linear actuators for locomotion of microrobots

University of Technology, Sydney. Faculty of Engineering.The successful development of the miniaturisation techniques for electronic components and devices has paved the way for the miniaturisation in other technological fields. In the past two decades, the research achievements in micromechatronics have spurred fast development of micro machines and micro robotic systems. Miniature or micro actuators are the critical components to make these machines more dexterous, compact and cost effective. The main purpose of this dissertation is to develop micro actuators suitable for the locomotion of an in-pipe or endoscopic microrobot. The content of the thesis covers the selection of the actuation principle, robotic system design, actuator design and prototype construction, performance analysis, and design, analysis, and implementation of the appropriate drive control system. Among different types of actuation principles, piezoelectric and electromagnetic actuators are the two major candidates for the micro robotic systems. In order to find a suitable actuation principle for the desired robotic application, a comparative study was conducted on the scaling effects, attainable energy density, and dynamic performances of both types of actuators. Through the study, it was concluded that the electromagnetic actuator is more suitable for the endoscopic microrobot. Linear actuators are the common design used for the locomotion of microrobots due to many advantages compared to their rotational counterparts. Through a thorough review and comparison of the electromagnetic linear actuator topologies, a moving-coil tubular linear actuator was chosen as the first design due to its simplest structure. Via the magnetic circuit analysis and numerical magnetic field solutions, the actuator was designed for optimum force capability, and the electromagnetic force and the machine parameters of the actuator were predicted. According to the results obtained from the magnetic field analysis, the dynamic model of the actuation system with a driving control scheme was established and used in the actuation performance analysis of the robotic system. Based on the experience achieved through the first design, a new moving-magnet tubular linear actuator was designed. The methodology developed in the design and analysis of the moving-coil linear actuator was adopted for the moving-magnet actuator design. However, the optimal design is more complicated due to the multi-pole and multi-phase structure of the moving-magnet actuator. The electromagnetic force of the actuator was analysed under the condition of different excitation methods. An enhanced parameter computation method is proposed for predicting the actuator parameters. Based on the results of magnetic field analysis, a comprehensive dynamic model of the actuator was developed. Through the coupled field-circuit analysis, this model can predict accurately the dynamic performance of the actuator. The characteristics analysis shows that the performance of the moving-magnet actuator is much better than that of the moving-coil actuator. Two prototypes of the moving-magnet tubular linear actuator with different dimensions were constructed to verify the performance and the scaling theory. Various precision machining techniques were employed during the fabrication. The performances and parameters of the two different prototypes were measured and the results agree substantially with the theory. The brushless DC drive method was chosen for the driving control of the proposed linear actuator because of the compact circuit topology and simple implementation, which are two essential factors for micro applications. A sensorless control scheme based on the back EMF was developed as physical position sensors are not permitted in such a micro system. The control scheme was then applied to the locomotion control of the proposed microrobot. The system simulation shows that the control performances of both the actuator and microrobot are satisfactory. A dSPACE prototyping system based driving control hardware was designed and implemented to experimentally verify the control design. The experimental results agree substantially with the theoretical work

Laser-micromachined SMA actuators for micro-robot applications.

Hui Fong-fong.Thesis (M.Phil.)--Chinese University of Hong Kong, 2000.Includes bibliographical references (leaves 84-85).Abstracts in English and Chinese.Chapter 1 --- INTRODUCTION --- p.1Chapter 1.1 --- Objective --- p.1Chapter 1.2 --- Background --- p.1Chapter 1.3 --- Mechanism and History of SMA --- p.3Chapter 1.4 --- Organization of the thesis --- p.4Chapter 2 --- LITERATURY SURVEY --- p.6Chapter 2.1 --- Previous achievements in micro robot --- p.6Chapter 2.1.1 --- Micro-robot with mechanical devices --- p.6Chapter 2.1.2 --- Micro-robot with smart materials --- p.7Chapter 2.1.3 --- Micro-robot with micro actuators --- p.8Chapter 2.2 --- Previous work in improving the SMA wire response --- p.10Chapter 2.2.1 --- Fixed external cooling System --- p.10Chapter 2.2.2 --- Dynamic external cooling system --- p.12Chapter 2.2.3 --- Physical Conversion --- p.13Chapter 2.3 --- Summary of literature survey --- p.14Chapter 3 --- 3-DOF SMA MICRO ROBOT~AN APPLICATION FOR SMA ACTUATORS --- p.15Chapter 3.1 --- Robot conceptual design --- p.15Chapter 3.2 --- Structural analysis for the propulsion of robot --- p.17Chapter 3.3 --- Two-way shape memory effect --- p.18Chapter 3.4 --- Material Selection --- p.19Chapter 3.4.1 --- Nickel-Titanium Alloys --- p.19Chapter 3.4.2 --- Copper-based Alloys --- p.20Chapter 3.4.3 --- Comparison of Ni-Ti and Copper-based alloys --- p.20Chapter 3.5 --- Fabrication process of micro robot --- p.21Chapter 3.5.1 --- Setting the shape of Nitinol wires --- p.22Chapter 3.5.2 --- Modifying the spring length --- p.23Chapter 3.5.3 --- Training for two-way memory --- p.24Chapter 3.5.3.1 --- Over deformation in Martensitic condition --- p.25Chapter 3.5.3.2 --- Trained by repeating Cycling --- p.25Chapter 3.5.3.3 --- Trained by Pseudoelastic Cycling --- p.26Chapter 3.5.3.4 --- Training by Constrained Temperature Cycling of Deformed Martensite --- p.26Chapter 3.5.4 --- Fabrication of Body part --- p.26Chapter 3.6 --- Locomotion methods --- p.28Chapter 3.7 --- Bending control --- p.29Chapter 4 --- HEAT TRANSFER ENHANCEMENT BY INCREASING CONVECTIVE SURFACE AREA --- p.31Chapter 4.1 --- Heat transfer --- p.31Chapter 4.2 --- Simplified Heat Transfer Analysis --- p.32Chapter 4.2.1 --- Analysis of Theoretical Results --- p.36Chapter 4.3 --- Verifying the reliability --- p.38Chapter 4.4 --- Mathematical Model to Match Experimental Conditions --- p.39Chapter 4.4.1 --- Mathematical modification by considering the connector --- p.39Chapter 4.4.2 --- Matching by introducing the correction factor --- p.40Chapter 4.5 --- Experimental model and modification of parameters --- p.41Chapter 5 --- LASER-MICROMACHINING --- p.44Chapter 5.1 --- Laser micro-fabrication of micro grooves on SMA wires --- p.44Chapter 5.2 --- Background on Laser-micromachining --- p.45Chapter 5.3 --- Basic Mechanisms in Lasers --- p.46Chapter 5.4 --- System Description --- p.47Chapter 5.5 --- Laser characteristic and groove fabrication --- p.48Chapter 5.5.1 --- Focal Spot Size --- p.48Chapter 5.5.2 --- Beam-focusing conditions --- p.49Chapter 5.6 --- Grooves measurement --- p.54Chapter 5.6.1 --- WYKO measurement --- p.54Chapter 5.6.2 --- SEM estimation --- p.57Chapter 6 --- EXPERIMENTAL RESULTS --- p.58Chapter 6.1 --- Experimental Setup for Temperature Measurement --- p.58Chapter 6.2 --- Experimental and Theoretical Comparison --- p.59Chapter 6.2.1 --- Improved Performance of lasered SMA wires --- p.59Chapter 6.2.2 --- Comparison of Experimental and Theoretical Results --- p.60Chapter 6.3 --- Effect of Micro-grooves on SMA Force Output --- p.63Chapter 6.3.1 --- Force Measurement Setup --- p.64Chapter 7 --- OPTIMUM PARAMETERS FOR HEAT TRANSFER --- p.66Chapter 7.1 --- Assumptions --- p.66Chapter 7.2 --- Mathematical Formulation --- p.66Chapter 7.2.1 --- Width of groove --- p.67Chapter 7.2.2 --- Depth of groove --- p.70Chapter 7.2.3 --- Number of groove --- p.72Chapter 7.3 --- Experimental Validation --- p.75Chapter 7.3.1 --- Repetition time and the depth of groove --- p.75Chapter 7.3.2 --- Validating the depth effect --- p.77Chapter 8 --- CONCLUSION --- p.80Chapter 9 --- FUTURE WORK --- p.81Chapter A. --- APPENDIX --- p.82Chapter A. 1 --- Procedures for quick WYKO surface profile measurements --- p.82BIBLIOGRAPHY --- p.8

LaMMos - Latching Mechanism based on Motorized-screw for Reconfigurable Robots and Exoskeleton Suits

Reconfigurable robots refer to a category of robots that their components (individual joints and links) can be assembled in multiple configurations and geometries. Most of existing latching mechanisms are based on physical tools such as hooks, cages or magnets, which limit the payload capacity. Therefore, robots re- quire a latching mechanism which can help to reconfigure itself without sacrificing the payload capability. This paper presents a latching mechanism based on the flexible screw attaching principle. In which, actuators are used to move the robot links and joints while connecting them with a motorized-screw and dis- connecting them by unfastening the screw. The brackets used in our mechanism configuration helps to hold maximum force up to 5000N. The LaMMos - Latching Mechanism based on Motorized- screw has been applied to the DeWaLoP - Developing Water Loss Prevention in-pipe robot. It helps the robot to shrink its body to crawl into the pipe with minimum diameter, by recon- figuring the leg positions. And it helps to recover the legs positions to original status once the robot is inside the pipe. Also, LaMMos add stiffness to the robot legs by dynamically integrate them to the structure. Additionally, we present an application of the LaMMos mechanism to exoskeleton suits, for easing the mo- tors from the joints when carrying heavy weights for long periods of time. This mechanism offers many interesting opportunities for robotics research in terms of functionality, pay- load and size.Comment: 14 pages, 15 figure

Design and Development of Soft Earthworm Robot Driven by Fibrous Artificial Muscles

Earthworm robots have proven their viability in the fields of medicine, reconnaissance, search and rescue, and infrastructure inspection. These robots are traditionally typically hard-shelled and must be tethered to whatever drives their locomotion. For this reason, truly autonomous capabilities are not yet feasible. The goal of this thesis is to introduce a robot that not only sets the groundwork for autonomous locomotion, but also is safe for human-robot interaction. This was done by ensuring that the actuation principle utilized by the robot is safe around humans and can work in an untethered design. Artificial muscle actuation allowed for these prerequisites to be met. These artificial muscles are made of fishing line and are twisted, wrapped in conductive heating wire, and then coiled around a mandrel rod. When electrical current passes through the heating wire, the artificial muscles expand or contract, depending on how they were created. After the muscles were manufactured, experiments were done to test their functionality. Data was collected via a series of experiments to investigate the effect of various processing parameters on the performance, such as the diameter of the mandrel coiling rod, the applied dead weight, the applied current, cyclic tests, and pulse tests. After acquiring data from the artificial muscles, a prototype was designed that would incorporate the expansion and contraction artificial muscles. This prototype featured two variable friction end caps on either side that were driven via expansion muscles, and a central actuation chamber driven via an antagonistic spring and contraction artificial muscle. The prototype proved its locomotion capabilities while remaining safe for human-robot interaction. Data was collected on the prototype in two experiments – one to observe the effect of varying induced currents on axial deformation and velocity, and one to observe the effect of varying deadweights on the same metrics. The prototype was not untethered, but future research in the implementation of an on-board power source and microcontroller could prove highly feasible with this design

Design and analysis of a flexible tendon-driven joint for in-pipe inspection robots

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (pages 53-54).Leaks in water distribution pipelines result in potentially significant losses of water resources and energy. The detection of such leaks is crucial for effective water resource management. In-pipe robots equipped with sensing devices are high potential solutions for accurate, efficient, and inexpensive leak detection. This work discusses the design, prototyping, and analysis of a tendon-driven flexible robotic joint that connects the sub-modules of an in-pipe snake-like robot. A simple, robust, well-sealed, and waterproof joint design is proposed. It enables the robot to handle complex pipeline geometry as it inspects the pipeline network during active hours. The joint designed has two degrees of freedom that enable the robotic platform to maneuver in 3 dimensions regardless of its roll orientation. Experiments were conducted to obtain the mechanical properties of the flexible joint and to confirm its functionality. The results of which are presented and discussed.by Hisham H. Al Hasan.S.B

Lunar deep drill apparatus

A self contained, mobile drilling and coring system was designed to operate on the Lunar surface and be controlled remotely from earth. The system uses SKITTER (Spatial Kinematic Inertial Translatory Tripod Extremity Robot) as its foundation and produces Lunar core samples two meters long and fifty millimeters in diameter. The drill bit used for this is composed of 30 per carat diamonds in a sintered tungsten carbide matrix. To drill up to 50 m depths, the bit assembly will be attached to a drill string made from 2 m rods which will be carried in racks on SKITTER. Rotary power for drilling will be supplied by a Curvo-Synchronous motor. SKITTER is to support this system through a hexagonal shaped structure which will contain the drill motor and the power supply. A micro-coring drill will be used to remove a preliminary sample 5 mm in diameter and 20 mm long from the side of the core. This whole system is to be controlled from earth. This is carried out by a continuously monitoring PLC onboard the drill rig. A touch screen control console allows the operator on earth to monitor the progress of the operation and intervene if necessary

Design optimisation of shape memory alloy linear actuator applications

Shape memory alloy (SMA) actuators have drawn much attention and interest in recent decades due to their unique properties; and, are expected to be increasingly integrated within commercial automotive applications. Key advantages of SMA actuators include: potentially simplified construction, whereby the SMA can act as both sensor and actuator simultaneously; compatibility with Joule heating and convective ambient cooling; and, potential mass advantages over competing actuation technologies. These attributes potentially allow for the development of simpler, more reliable and cost effective actuation systems with significant reduction in mechanical complexity and size. SMA is readily available in commercial quantities and exhibits high wear resistance and durability, which make it an ideal candidate for application in automotive grade applications. Despite these identified advantages, SMA actuators are subject to a series of technical challenges associated with:  - Relatively small strain (displacement or stroke)  - Achievable frequency (actuation speed)  - Controllability (and stability)  - Positional accuracy  - Energy efficiency These technical challenges contribute to a relatively low success rate of commercial SMA actuator applications; and, provide motivation for this program to generate relevant research outcomes that enhance the commercialisation of SMA actuators. An extensive literature review of over 500 journal and patent documents was conducted to provide a clear roadmap for the commercial imperatives for SMA design. The formulated research methodology identifies milestones required for achieving the research objectives, which were addressed as research themes. Based on this literature review, the following research themes were identified:  - Design methods to resolve SMA actuator limitations  - Development of simple and practical numerical models for SMA actuator response  - Data for SMA linear actuator design Specific research contributions within these themes are presented within the thesis, with the objective of enhancing the commercial application of shape memory alloy (SMA) linear actuators, and include:  - A comprehensive analysis of SMAs: history, commercial applications, strength and limitations, design challenges and         opportunities.  - A novel investigation of transient heat transfer scenarios for cylindrical systems associated with their crossover and critical radii.  - Development of novel latent heat models for analytical and numerical applications, and proposal of readily applied activation and deactivation charts compatible with the requirements of SMA actuator designers.  - A novel investigation of the morphological effects of SMA-pulley systems (i.e. pulley diameter, SMA and lagging diameter) on structural and functional fatigue