Academic literature on the topic 'Manipulators (Mechanism) – Optical equipment'

Manipulators are widely used in industrial fields as automation equipment and robotic structures. Besides moving objects, manipulators often work with variable payloads, and the residual vibration significantly affects the position accuracy of manipulators. This paper mainly investigates the dynamic characteristics of flexible manipulators with time varying mass payloads and active control of the residual vibration is carried out. Finite element method is utilized to construct the dynamical model, and responses of the system are calculated by Bathe’s method. The influence of the time varying mass is analyzed in details, including an increasing mass case and a decreasing mass case. Then active control of the residual vibration is given based on a PID controller. To improve the control effect, genetic algorithm (GA) is applied to tune the parameters of the PID controller. Simulations demonstrate that the time varying mass affects the residual vibration of the system remarkably. For a decreasing mass system, a nonstructural negative damping is induced and the residual vibration may be strengthened, while for an increasing mass system, a nonstructural positive damping is caused and the residual vibration may be attenuated. The comparison of the control methods demonstrates that the GA-PID controller results in a significant improvement in the vibration reduction.

In order to increase reliability and accuracy of robot manipulators or other construction equipment used for lifting operations an optimum dynamic mode for moving its boom system has been calculated in the paper. Results of the research have made it possible to construct a mathematical model for manipulator movement and obtain kinematic characteristics of the optimum dynamic mode. While determining the optimum dynamic motion mode, a criterion action has been used as an optimization criterion which represents a time integral with an integrand function expressing a dynamic component of manipulator drive power. Functions for changing kinematic characteristics of an manipulator boom have been calculated when it moves from one predetermined position to another one and which correspond to optimum dynamic mode of motion. Search for an optimum motion mode has been performed by minimizing the optimization criterion using the Euler–Poisson equations. In this case a generalized angle of rotation has been used which permits to relate movement of the boom and oscillations of its support part. As a linking component differential equations of system motion have been also applied, in which relationships between an oscillation angle, rigidity of a manipulator support, and its mass-geometric characteristics have been recorded. Results of the work can be useful for refinement and improvement of existing engineering methods for calculating the drive mechanisms of manipulators both at design/construction stages and in real operation modes, and the results can also be used while making design or improvement of similar executive mechanisms for construction equipment and robots.

SUMMARYSpray-painting equipments are important for the automatic spraying of long conical objects such as rocket fairing. This paper proposes a spray-painting equipment that consists of a feed worktable, a gantry frame and two serial–parallel mechanisms and investigates the optimal design of PRR–PRR parallel manipulator in serial–parallel mechanisms. Based on the kinematic model of the parallel manipulator, the conditioning performance, workspace and accuracy performance indices are defined. The dynamic model is derived using virtual work principle and dynamic evaluation index is defined. The conditioning performance, workspace, accuracy performance and dynamic performance are involved in multi-objective optimization design to determine the optimal geometrical parameters of the parallel manipulator. Furthermore, the geometrical parameters of the gantry frame are optimized. An example is given to show how to determine these parameters by taking a long object with conical surface as painted object.

The article presents the design and application of multi-software platform for solving kinematic synthesis of robot manipulator systems. It also presents a modern theoretical and application approach for modelling coupled mechanical systems, which include mobile robots. Due to high requirements for accuracy, efficiency, reliability and life cycle of technical equipment, several parameters ensuring optimal operating parameters need to be taken into account while dealing with the design. This is the reason for linking computational models to optimization algorithms that allows us to find the appropriate design parameters of analysed mechanical system, mechanisms, including mobile robots mostly by iterative way. The commercial working interface of the program ADAMS and open architecture of MATLAB programming language enable to share common data while dealing with model simulations in parallel. Both of them were used while designing and implementing the algorithm for the evaluation and optimization of parameters of technical equipment from the point of view of selected properties. While working on the task of the spatial mechanism of the six-member robot manipulator system, the algorithm solving the optimal parameters was created by applying the selected optimization techniques of the program MATLAB. Presented algorithm involves the creation of a map operating positions, which is further linked to the solution of the motion of interest points in the robotic system following a prescribed trajectory. This requires the geometry optimization of the selected members of the spatial robotic system in order to achieve such parameters so that the trajectory of the interest point of the output member would precisely match with the prescribed trajectory. It is important to note that these types of tasks create wider space for solving the assignments dealing with the development and application of technical equipment like mobile robots and their outputs that are linked to the needs of the practice.

In view of the backward present rescue technique for small-caliber deep well, a kind of multifunctional rescue robot is designed, which is composed of a manipulator, a rescue mechanism, an anchorage mechanism, and a set of oxygen supply equipment. Owing to the different postures of the fallen person, the clasp arm of rescue mechanism needs to adjust itself to obtain an ideal rescue orientation in the narrow deep well. Furthermore, the clasp arm bears much more weight when it clasp and fix the fallen person. So, the optimal design about the clasp arm is studied. Meanwhile, based on SolidWorks software, the stress analyses for the designed clasp arm with loads have been finished. Results show that the performance of the optimal designed clasp arm is perfect, which make sure that the rescue robot is capable of carrying out complicated rescue.

It is difficult to introduce highly versatile automation using robots to handling deformable objects such as thread, cloth, wire, long beams, and thin plates in plant production processes, compared to the handling of rigid objects. Office equipment handles deformable objects such as paper and plastic. Problems unique to these objects is caused by speeding up such equipment and demand for upgrading its accuracy. In agriculture and medical care, automatic, intelligent handling of deformable objects such as fruit and animals has long been desired and practical systems sought. Deformable objects whose handling should be versatiley and accurately automated are classified into two groups based on handling: (A) Flexible, mostly thin, fine objects capable of elastic deformation (B) Soft objects easily crushed, such as soft fruits or animals The problem in handling the first group is controlling object deformation of an infinite degree of freedom with a finite number of manipulated variables. In contrast, a significant problem in handling the second group is often how to handle them without exerting excessive stress and how to handle them safely and reliably. The handling of these two groups differ greatly in mechanics and control theory, and this special issue focuses on the first group — flexible objects — mechanical collection and transport studies, control, and software. Recent studies on their handling are classified into four groups for convenience based on handled objects and types of handling task: (a) Control of deformation, internal force, and vibration or path planning of flexible objects (mainly thin plates and beams) using single or multiple manipulators. (b) Task understanding in insertion of elastic into rigid parts and vice versa, and the study of human skills to help robots accomplish these task. (c) Approaches on improved accuracy, intelligent control, and vibration damping in handling and transfer of sheets and strings with low flexural rigidity, represented by paper or wire. (d) Strategies for grasping and unfolding sheets such as cloth whose flexural rigidity is almost nil. For (a), studies are active on deformation control by two robot hands attempting to grasp cloth. 1-3) In the automobile industry, so-called flexible fixtureless assembly systems are advancing in which two robots process or assemble parts in mid-air without a fixed table to reduce lead time and cost. These systems are mostly developed assuming handled parts are rigid. Nguyen et al. work assuming parts such as sheet metal whose deformation must be taken into consideration.1) Nakagaki et al. propose form estimation that considers even plastic deformation in wire handling by robots, in connection with the development of robots for electric wire installation.4) Many studies cover flexible wire as elastic beams,3-9) but comparatively few focus on bending deformation of thin plates. This special edition includes a paper by Kosuge et al. on thin-plate deformation control. Vibration control of grasped objects becomes important as speed increases. Matsuno kindly contributed his paper on optimum path planning in elastic plate handling. In controlling the deformation of elastic bodies, the mechanics of objects handled is often unknown. This special issue features a paper by Kojima et al. on an approach to this problem by adaptive feed-forward control. For (b), we consider three cases: (1) A cylindrical rigid body inserted into a hole on an elastic plate. (2) An elastic bar inserted into a hole on a rigid body. (3) A tubular elastic body put on a cylindrical rigid body. This special issue carries papers on these problems by Brata et al., Matsuno et al., and Hirai. For (2), a paper by Nakagaki et al.10) covers electric wire installation. For (3), the paper by Shima et al.11) covers insertion of a rigid axis into an elastic hose. Robot skill acquisition is an important issue in robotics in general, and the above papers should prove highly interesting and information because they treat studies by comparing robot and human skills in accomplishing work and acquiring concrete skills knowledge. For (c), attempts are made to theoretically analyze sheet handling mechanisms and control developed based on trial and error, and to structure design theory based on such analysis. These attempts are related to the increased accuracy and speed and enhanced intelligence of sheet-handling office automation equipment such as printers, facsimile machines, copiers, and automated teller machines. Yoshida et al. conducted a series of studies on the effects of guides forming paper feed paths and of inertia force of paper by approximating sheets with a chain of discrete masses and springs.12-14) This special edition also features a study on sheet sticking and jamming. Okuna et al. handles a system of similar nature, mechanical studying the form of paper guides.15) Introducing mechanisms to control the positioning of sheets is effective in raising sheet transfer accuracy. Feedback control that regulates feed roller skew angle as a manipulated variable is proposed.16) Increased reliability in separating single sheets from stacked effectively reduces the malfunction rate in sheet-handling equipment. Ways of optimizing the form of sheet-separation rollers17) and estimating frictional force between separation gates and sheets 18) are also proposed. This special issue contains a proposal by Nakazawa et al. of a mechanism that uses reactive sheet buckling force, made in connection with development of a newspaper page turner for the disabled as technology for separating single sheets. Dry frictional force is most widely used for transporting sheets, but is not stable and may even act as an obstacle to improving accuracy. Niino et al. propose a sheet transfer mechanism that uses electrostatic force.19) For improving the accuracy of flexible wire transmission, this special issue carries a study on transporting flexible thin wire through tension control at multiple points, from a study by Morimitsu et al. on optical fiber installation. The thickness of wire used in equipment is becoming increasingly slim and flexible, along with the equipment it is used in. Tension control in the production process is an important factor in the manufacture of such thin wire. Production efficiency constantly calls for increased transfer speed. It has thus become important to estimate air resistance and inertia and to measure and control the tension of running wire. Studies20,21) by Batra, Fraser, et al. which deal the motion of string in the spinning process provide good examples for learning analytical techniques for air drag and inertia. In string vibration where inertia dominates, attempts are made to control vibration by boundary shaking22,23) and feed-forward/back control.24) For (d), highly versatile robots for handling cloth are being developed, and the software technology for automatic cloth selection and unfolding by robot hands is a popular topic.25-27) Ono et al. comment on the nature of problems in developing intelligent systems for handling cloth and similar objects whose bending rigidity is low and which readily fold and overlap—a paper that will prove a good reference in basic approaches in this field. Mechanical analyses are indispensable to studies on (a) through (c). In contrast, information technology such as characteristic variable measurement, image processing, and discrimination, rather than mechanical analyses, play an important roles in studies on (d). This special issue features a study by Hamashima, Uraya et al. on cloth unfolding as an example of such studies. Studies up to now largely assumed that properties of grasped objects did not change environmental influences such as temperature and humidity. Such influence is often, however, a major factor in handling fiber thread and cloth. This special issue has a paper contributed by Taylor, who studies handling method to prevent influence by such environmental factors. The objective of this special issue will have been achieved if it aids those studying the handling of flexible objects by providing approaches and methodologies of researchers whose target objects differ and if it aids those planning to take up study in this field by providing a general view of this field. References: 1) Nguyen, W. and Mills, J., ""Multi-Robot Control For Plexible Fixtureless Assembly of Flexible Sheet Metal Auto Body Parts,"" Proceedings of the 1996 IEEE International Conference on Robotics and Automation, 2340-2345, (1996). 2) Sun, D. and Shi, X. and Liu, Y., ""Modeling and Cooperation of Two-Arm Robotic System Manipulating a Deformable Object,"" Proceedings of the 1996 IEEE International Conference on Robotics and Automation, 2346-2351, (1996). 3) Kosuge, K., Sakaki, M., Kanitani, K., Yoshida, H. and Fukuda, T., ""Manipulation of a Flexible Object by Dual Manipulators,"" IEEE International Conference on Robotics and Automation, 318-323, (1995). 4) Nakagaki, H., Kitagaki, K., Ogasawara, T. and Tukune H., ""Handling of a Flexible Wire -Detecting a Deformed Shape of the Wire by Vision and a Force Sensor,"" Annual Conference on Robotics and Mechatronics (ROBOMEC'96), 207-210, (1996). 5) Wakamatsu, H., Hirai, S. and Iwata, K., ""Static Analysis of Deformable Object Grasping Based on Bounded Force Closure,"" Trans. of JSML, 84-618 (C), 508-515, (1998). 6) Katoh, R. and Fujmoto, T., ""Study on Deformation of Elastic Object By Manipulator -Path Planning of End -Effector-,"" J. of the Robotics Society of Japan, 13-1, 157-160, (1995). 7) Yukawa, T., Uohiyama, M. and Inooka, M., ""Stability of Control System in Handling a Flexible Object by Rigid Arm Robots,"" JSME Annual Conference on Robotics and Mechatronics (ROBOMEC'95), 169-172, (1995). 8) Yukawa, T., Uohiyama, M. and Cbinata, G., ""Handling of a Vibrating Flexible Structure by a Robot,"" Trans. JSME, 61-583, 938-943, (1995). 9) Sun, D. and Liu, Y., ""Modeling and Impedance Control of a Two-Manipulator System Handling a Flexible Beam,"" Trans. of the ASME, 119, 736-742, (1997). 10) Nakagaki, H., Kitagaki, K. and Tukune, H., ""Contact Motion in Inserting a Flexible Wire into a Hole,"" Annual Conference on Robotics and Mechatronics (ROBOMEC'95), 175-178, (1995). 11) Shimaji, S., Brata, A. and Hattori, H., ""Robot Skill in Assembling a Cylinder into an Elastic Hose,"" Annual Conference on Robotics and Mechatronics (ROBOMEC'95), 752-755, (1995). 12) Yoshida, K. and Kawauchi, M., ""The Analysis of Deformation and Behavior of Flexible Materials (1st Reprt, Study of Spring-Mass Beam Model of the Sheet,"" Trans. of JSME, 58-552, 1474-1480, (1992). 13) Yoshida, K., ""Analysis of Deformation and Behavior of Flexible Materials (2nd Report, Static Analysis for Deformation of the Sheet in the Space Formed by Guide Plates),"" Trans. JSME, 60-570, 501-507, (1994). 14) Yoshida, K., ""Dynamic Analysis of Sheet Defofmation Using Spring-Mass-Beam Model,"" Trans. JSME, 63-615, 3926-3932 (1997). 15) Okuna, K., Nishigaito, T. and Shina, Y., ""Analysis of Paper Deformation Considering Guide Friction (Improvement of Paper Path for Paper-Feeding Mechanism),"" Trans. JSME, 60-575, 2279-2284, (1994). 16) Fujimura, H. and Ono, K., ""Analysis of Paper Motion Driven by Skew-Roll Paper Feeding System,"" Trans. JSME, 62-596, 1354-1360, (1996). 17) Shima, Y., Hattori, S., Kobayashi, Y. and Ukai, M., ""Optimum of Gate-Roller Shape in Paper Isolating Methods,"" Conference of Information, Intelligence and Precision Equipment (IIP'96), 61-62, (1996). 18) Suzuki, Y, Hattori, S., Shima, Y. and Ukai, M., ""Contact Analysis of Paper in Gate-Roller Handling Method"", Conference on Information, Intelligence and Precision Equipment (IIP'95), 19-20, (1995). 19) Niino, T., Egawa, S. and Higuchi, T., ""An Electrostatic Paper Feeder,"" J. of the Japan Society for Precision Engineering, 60-12,1761-1765, (1994). 20) Batra, S., Ghosh, T. and Zeidman, M., ""An Integrated Approach to Dynamic Analysis of the Ring Spinning Process , PartII: With Air Drag,"" Textile Research Journal, 59, 416-424, (1989). 21) Fraser, W., Ghosh, T. and Batra, S., ""On Unwinding Yarn from a Cylindrical Package,"" Proceedings of Royal Society of London, A, 436, 479-438, (1992). 22) Jacob, S., ""Control of Vibrating String Using Impedance Matching,"" Proceedings of the American Control Conference (San Francisco),468-472, (1993). 23) Lee, S. and Mote, C., ""Vibration Control of an Axially Moving String by Boundary Control,"" Trans. of the ASME, J. of Dynamic Systems, Measurement, and Control, 118, 66-74, (1996). 24) Ying, S. and Tan, C., ""Active Vibration Control of the Axially Moving String Using Space Feedforward and Feedback Controllers,"" Trans. ASME, J. of Vibration and Acoustics, 118, 306-312, (1996). 25) Ono, E., Ichijo, H. and Aisaka, N., ""Flexible Robotic Hand for Handling Fabric Pieces in Garment Manufacture,"" International Journal of Clothing Science and Technology, 4-5,18-23, (1992). 26) Paraschidis, K., Fahantidis, N, Petridis, V., Doulgeri, Z., Petrou, L. and Hasapis, G, ""A Robotic System for Handling Textile and Non Rigid Flat Materials,"" Computers in Industry, 26, 303-313, (1995). 27) Fahantidis, N., Paraschidis, K, Petridis, V., Doulgeri, Z., Petrou, L. and Hasapis, G., ""Robot Handling of Flat Textile Materials,"" IEEE Robotics & Automation Magazine, 4-1, 34-41, (1997).

In order to increase the productivity and reliability of a hydraulic-powered loader crane, according to the normative-technical documentation regulating the safe operation of multi-link cranes, it is allowed to combine movements with the simultaneous movement of several links of the boom system. As a result, the paper considers a technique for conducting experimental studies in the plane of changing the boom system of a loader crane with a load. Experimental studies were carried out under the condition of simultaneous angular movement of the jib and a decrease in the linear movement of the telescopic section. To carry out experimental studies, an experimental installation of a hydraulic-driven loader crane was designed and manufactured. Measuring and recording equipment has been selected and adjusted. In the framework of experimental studies of the dynamics of movement of the boom system of a loader crane with a load, a control system for drive mechanisms has been developed, which makes it possible to realize the optimal modes of movement of the links of the boom system. As a result, experimental studies were carried out under the condition of the simultaneous movement of the jib and the telescopic section with a load at the end of the boom system. A package of data on real and optimal modes of movement of the links of the boom system of the loader crane was received. The processed data are presented in graphical form and a comparative analysis with real and optimal modes of movement is carried out. The developed method of experimental research has made it possible to determine the effect of the simultaneous movement of the boom and jib on the oscillations of the load, and the effect of the oscillations of the load on the dynamic loads arising in the boom system and the drive mechanisms of the loader crane.

In the past decades, a number of parallel manipulators have been extensively studied. However, most efforts are dedicated to six degrees of freedom (DOF) or three-DOF manipulators. There is a need for equipment providing more than three DOF's arranged in parallel and based on simpler arrangements than six-DOF arrangements in application. This paper presents a novel four-DOF parallel platform manipulator with base mounted prismatic actuators. The manipulator is driven by four linear actuators. The movable platform of the manipulator can translate along two directions and rotate around two axes respectively. The kinematics model is formulated, which describes the inverse and forward kinematics transformation. It is very easy to develop a five-axis NC machine-tool which is of large-workspace based on the four-DOF parallel mechanism presented in this paper.

Currently, the traffic safety on the railways remains a topical problem of removing unwanted trees and shrubs in the right of way of railways. To improve the efficiency removal of unwanted shoots and branches and stumps, reducing the share of manual labor and facilitation of staff by the authors in 2015 were investigated little links resources saving compact means of mechanization, allowing their use in hard to reach places. These means of mechanization considered in combination with modern the vehicles, which can provide them with the necessary energy, both on the railroad track, and away from it. The design scheme drawn up manipulators for mathematical description of the motion of their units in the plan and profile of the railway, shows a diagram of the dynamic interaction between the rotary operating element with tree and shrub vegetation and stumps, and on the basis of these formulas and reasoned input parameter values it was built a number of plots. The article presents the main findings and recommendations of the study of kinematics and dynamics little links of the mechanism of forest machines. It was concluded that a number of promising kinematic schemes associated with the rotation of the body part telescopic of manipulators machines, substantiated possible working range of the of manipulators according to the scheme of their location on the machine base, a certain range of angles of rotation around the axis of the working equipment of its fastening, the issues of the impact of deviations small diameter unwanted shoots from the vertical cutting force.

The main requirements for hydraulic equipment of forest transport machines of manipulator type are revealed. It is established that the main drawback of the used hydraulic drives of manipulators is their increased power and high energy consumption. The main ways of increasing the technical level of hydraulic manipulators of forest transport vehicles are considered. The constructive optimization and improvement of the hydraulic drive mechanism for lifting the boom and turning the column of the manipulator is justified. New designs with the use of hydro-mechanical dampers and energy-saving devices are proposed. As energy-saving devices, it is proposed to use a hydraulic accumulator. The main advantages of the design, which are to increase the reliability and expand the technological capabilities of hydraulic manipulators forest transport machines. The principles of influence on the hydraulic system that reduce the pressure in the piston group and reduce energy consumption are substantiated. The proposed energy-saving hydraulic drive reduces the maximum pressure during braking to 3 MPa. The recovery energy when the column is rotated is 25 % of the energy consumed. The diameter of the dampener's lockable cavities should be 48 mm with the internal diameter of the dampener 65 mm. Minimal changes in the design are achieved to increase the technical level of the hydraulic drive of manipulators of forest transport machines and its competitiveness among existing analogues.

Future robots are expected to cooperate with humans in daily activities. Efficient cooperation requires new techniques for transferring human skills to robots. This thesis presents an approach on how a robot can extract and replicate a motion by observing how a human instructor conducts it. In this way, the robot can be taught without any explicit instructions and the human instructor does not need any expertise in robot programming. A system has been implemented which consists of two main parts. The first part is data acquisition and motion extraction. Vision is the most important sensor with which a human can interact with the surrounding world. Therefore two cameras are used to capture the image sequences of a moving rigid object. In order to compress the incoming images from the cameras and extract 3D motion information of the rigid object, feature detection and tracking are applied to the images. Corners are chosen as the main features because they are more stable under perspective projection and during motion. A reliable corner detector is implemented and a new corner tracking algorithm is proposed based on smooth motion constraints. With both spatial and temporal constraints, 3D trajectories of a set of points on the object can be obtained and the 3D motion parameters of the object can be reliably calculated by the algorithm proposed in this thesis. Once the 3D motion parameters are available through the vision system, the robot should be programmed to replicate this motion. Since we are interested in smooth motion and the similarity between two motions, the task of the second part of our system is therefore to extract motion characteristics and to transfer these to the robot. It can be proven that the characteristics of a parametric cubic B-spline curve are completely determined by its control points, which can be obtained by the least-squares fitting method, given some data points on the curve. Therefore a parametric cubic B–spline curve is fitted to the motion data and its control points are calculated. Given the robot configuration the obtained control points can be scaled, translated, and rotated so that a motion trajectory can be generated for the robot to replicate the given motion in its own workspace with the required smoothness and similarity, although the absolute motion trajectories of the robot and the instructor can be different. All the above modules have been integrated and results of an experiment with the whole system show that the approach proposed in this thesis can extract motion characteristics and transfer these to a robot. A robot arm has successfully replicated a human arm movement with similar shape characteristics by our approach. In conclusion, such a system collects human skills and intelligence through vision and transfers them to the robot. Therefore, a robot with such a system can interact with its environment and learn by observation.

空間站探索是世界熱點研究問題，空間站巨大因此往往在外太空在軌建造和組裝，因此需要由宇航員和機器人開展大量的艙外工作（ Extra-Vehicular Activities，EVAs）。目前，宇航員的艙外工作存在以下三個方面的問題：（1）宇航員在移動攀爬和任務操作相互衝突的問題， 宇航員在艙外工作時不能一邊沿著扶手攀爬，一邊搬運載荷；（2）當前的空間機器人工作空間有限，在空間站表面有許多地方無法達到開展艙體檢查等在軌服務；（3）當前的空間機器人在狹窄空間裡操作效率不高，不能很好地避開障礙物和做精細化靈巧操作。
本論文針對以上問題提出了2 個機器人系統，四腿行走機器人（ Four-legged Robot Walker, FLRW ） 和圓弧軌道機器人（Circular Rail Robot System , CRRS）。四腿行走機器人擅長多退的扶手攀爬和操作，攀爬和操作可同時開展。四腿行走機器人還有一個可旋轉頭部（可旋轉的視覺系統）來增強攀爬過程中的視覺範圍。圓弧軌道機器人通過移動機器人在圓弧軌道的運動能完全覆蓋空間站的所有工作空間，該系統是在太空應用的第一個弧形軌道系統，同時也有最小的轉彎半徑。
本論文對提出的2 個機器人系統的移動性進行了深入的研究，四腿機器人側重在雙臂攀爬的策略、攀爬步態，並開展了全艙攀爬的在軌任務模擬驗證。圓弧軌道機器人開展了艙體軌道系統、多艙體軌道切換器、移動基座平臺、移動平臺驅動和轉彎半徑的深入設計與分析，並且完成了移動軌道平臺的原型樣機試製驗證。
本論文對提出的2 個機器人系統的操作臂開展了非球形腕部掛接、冗餘操作臂奇異點辨識研究，提出了一種雅克比初等變換（MJET）演算法進行操作臂奇異分析，該演算法可以將冗餘機械臂的6x7 奇異矩陣轉化到3x4 的子矩陣，大大提高了運算效率。論文還開展了在多移動物體環境下的避障研究，提出了一種即時的多移動物體障礙回避（MMOA）演算法，該演算法採用超曲面函數描述障礙物的包絡，採用偽距離即時計算與移動障礙物距離，取得了控制精度和即時性的平衡。
本論文對提出的2 個機器人系統的操作臂開展了動力學建模和在軌裝配研究，採用拉格朗日建模方法對操作臂建模，並與商務軟體ADAMS 對比驗證建模準確度。同時，並運用阻抗控制演算法針對ORU 的在軌抓取、安裝和轉移等在軌任務的實現驗證。
最後論文進行了總結和後續工作展望。
Space station exploration is a global hot research topic. The space stations are usually large in scale so that they have to be fabricated and assembled in space, which involves a large number of Extra-Vehicular Activities (EVAs) by astronauts and robots. There are three main problems of EVA mission. (1) Astronauts experience a conflict between climbing and manipulation during EVA missions, as they cannot carry payloads while handrail climbing. (2) Current space robots have workspace limitations and cannot reach the whole exterior of a space station, making it challenging to carry out inspection and servicing. (3) It is also difficult for robots to avoid obstacles and perform fine manipulation tasks in a compact workspace.
Two robotics systems, the Four-Legged Robot Walker (FLRW) and the Circular-Rail Robot System (CRRS), are proposed to address the above problems. The FLRW is good at handrail climbing as it has multiple, identical legs. It also has a rotatable vision system to enhance its field of view during climbing. The CRRS provides full coverage of the space station workspace, as it is a mobile robot that drives on a circular rail system around the space station. This system is the first design of robotic system with circular-rail in space and also has the smallest turning radius.
The mobility of both robots is addressed. The FLRW analysis focuses on the climbing strategy and climbing gait analysis. The circular rail system, rail switch, mobile platform, driving force and turning radius of CRRS are carefully designed and analyzed. A prototype of the CRRS mobile platform is implemented for verification.
The proposed manipulator is designed with redundant joint and non-spherical-wrists. A Modified Jacobian Elementary Transformation (MJET) approach is proposed to determine all of the singularity conditions. This approach has a singularity isolation feature to reduce the computational workload. A Multiple Moving Obstacle Avoidance (MMOA) approach is proposed for manipulator path planning in a compact workspace. A super-quadric surface function is used to describe the shape of an obstacle, and the pseudo-distance from the manipulator to the obstacle is measured and controlled in real time. This approach achieves a good balance between computational complexity and accuracy.
The proposed manipulator is modeled using the Lagrangian dynamics formulation and the dynamics of the proposed manipulator is verified with the commercial software ADAMS (Automatic Dynamic Analysis of Mechanical Systems). The mathematics model has similar output in ADAMS under a constant torque input and a sine torque input. The Orbital Replacement Unit (ORU) assembly task is implemented using impedance control. Both simulation and hardware tests are completed for verification, and the experimental results show that the controller is good for on-orbit servicing tasks.
The contributions of the thesis are summarized and future work is proposed.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Chen, Yongquan.
Thesis (Ph.D.) Chinese University of Hong Kong, 2014.
Includes bibliographical references (leaves 131-148).
Abstracts also in Chinese.

在世界各地，自然或人為災難隨時可能發生。災難回應作為災難處理的重要環節顯得尤為重要，隨著科學技術的進步和提高，人們希望通過使用各種科學手段來提高災難的回應效率。機器人技術作為21世紀高科技結合的產物被廣泛應用於這一領域。一般情況下，設計者會採用功能集成的思想對機器人進行設計，他們的主要設計思想是根據自己對環境的理解和認知得到機器人的設計需求，然後針對設計需求，通過功能集成和疊加的方式來完成對機器人的設計，採用這種方式機器人一旦設計完畢，其功能也隨之確立並不可更改，這種設計思想是基於環境狀況的，即一旦災難現場的環境不符合預先的設定，機器人的執行能力將大幅下降，同時功能疊加的設計方式會產生功能與功能之間相互約束，影響其專業性。
本文介紹了一種基於分散式設計思想的全新設計理念，並且根據這一理念設計了一套基於任務需求的救援機器人系統。機器人系統不會根據設計者對災難現場的預先理解和認知而被一體化設計，相反根據"如何到達"和"如何操作"把機器人系統拆分成移動單元和操作單元兩個環節，針對每個環節分別設計了符合現場需求的通用移動模組和任務執行模組，救援人員可以根據災難現場的即時任務需求而迅速搭建出有針對性的機器人系統任務解決方案，和傳統的機器人系統相比，具適應性廣、靈活性高、針對性強等特點。
在本論文中，對三種通用的移動平臺和兩種通用的模組化關節以及一個快速連接器分別進行了結構設計、理論分析及樣機設計，並採用基本的通用模組，根據即時的任務需求構建出有針對性的多個機器人系統。實驗表明該機器人系統可以提供對災難環境有針對性的系統解決方案，具有一定容錯性、經濟性及災難環境的適應性。文章的創新點如下，首次針對于救援機器人提出分散式的設計思想，並以該思想為基礎設計了基於通用模組的救援機器人系統，針對不同任務對移動性能的不同要求設計了三種移動平臺，為滿足不同的救援操作要求設計了兩種模組化關節以及快速連接器。同時，文中為實際的地震救援任務提出了一套救援機器人系統解決方案。
Natural and man-made disasters nowadays still present a large amount of risk. Disaster response is an important phase of disaster management, and the enhancement of its effectiveness and accountability has attracted an increasing amount of attention. Robots can help rescuers in doing this task because of its wide range of applications. In general, the rescue robot concept assumes one or more targeted tasks while design, and one or a set of robot(s) is/are designed by integrating different functions to accomplish those tasks. Once the design of a robot is finished, its function cannot be changed. However, this kind of design is environment-dependent, as once a disaster environment changes, the execution performance of the robot will reduce. Furthermore the function-integrated design concept may cause internal constraints between functions, and fail to provide a targeted solution for different disaster environments.
This dissertation introduces a novel design concept, based on which a requirement-oriented rescue robot system is developed. This design concept adopts a distributed strategy, according to which tasks are no longer seen as a whole but divided into two parts: traversability and operation. Several functional modules are designed to meet the different requirements of the two parts separately, and the entire robot system can be assembled using different functional modules according to the real-time requirements of the disaster environment. Compared with the traditional rescue robot system, this system can provide a more targeted solution for different disaster situations, and is more adaptable and flexible.
This dissertation details the basic functional modules, including three kinds of mobile bases for traversability and two sets of modular joints for operation, and analyzes a quick connector that makes the connection easier and more convenient. Several possible combinations of the rescue robot system are displayed to show how to construct a rescue robot system according to different requirements. This kind of rescue robot system can provide targeted solutions to different disaster tasks. Robustness is also enhanced, as the replacement of the functional modules is flexible and easy to overhaul. Furthermore, the functional modules can be decomposed and reused to make the robot system more economical. This dissertation makes several contributions. It presents a systematic solution for rescue robot, develops three mobile bases for high traversability and two kinds of modular joints and a quick connector for rescue operation. Furthermore, it also develops a rescue robot system for missions in earthquake.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Yang, Yong.
Thesis (Ph.D.) Chinese University of Hong Kong, 2014.
Includes bibliographical references (leaves 226-236).
Abstracts also in Chinese.

Next generation optical access networks have to cope with the contradiction between the intense computation and ultra-low latency requirements of the immersive applications and limited resources of smart mobile devices. In this chapter, after presenting a brief overview of the related work on multi-access edge computing (MEC), the authors explore the potential of full and partial decentralization of computation by leveraging mobile end-user equipment in an MEC-enabled FiWi-enhanced LTE-A HetNet, by designing a two-tier hierarchical MEC-enabled FiWi-enhanced HetNet-based architecture for computation offloading, which leverages both local (i.e., on-device) and nonlocal (i.e., MEC/cloud-assisted) computing resources to achieve low response time and energy consumption for mobile users. They also propose a simple yet efficient task offloading mechanism to achieve an improved quality of experience (QoE) for mobile users.

Although there are capacitive surface micromachined force sensors with adequate resolution for cell manipulation and microneedle injections, it comes with the sacrifice of dynamic range and linearity. In contrast, optical based force sensors can provide the desired resolution and maintain relatively large sensing ranges compared to similar capacitive sensors. Plus, optical interferometry provides a sensing method that uncouples the conflicting design parameters, such as sensitivity and linearity. The current drawback to optical interferometry is the large off-chip equipment that is currently used in the operation of optical sensors. However, innovative techniques are being applied to surface micromachined microphones that allow off-chip components to be integrated onto the sensing chip. These same techniques can easily translate to the force sensor presented in this research, due to the similarities in the sensing methods. The thrust of this work is to explore a mechanism approach for enhancing the performance of a surface micromachined optical force sensor. A new design is presented which introduces a special mechanism, known as the Robert’s mechanism, as an alternate means in which the device is structurally supported. The new design’s implementation is achievable using an equivalent compliant mechanism. Initially, an analytical set of pseudo-rigid-body-model equations were developed to model the compliant design. A more accurate model was then constructed using FEA methods. The geometric parameters of the compliant Robert’s mechanism were then optimized to obtain a sensor with improved linearity and sensitivity. Overall, the force sensor provides higher sensitivity, larger dynamic range and higher linearity compared to a similar optical force sensor that uses a simple structural supporting scheme. In summary, this paper demonstrates the effectiveness of using a mechanism approach for enhancing the performance of MEMS sensors. The expected impact is to improve biomedical experiments and help further advance research that can improve quality of life.

Abstract Umbilical is a critical equipment in subsea production system for extracting offshore hydrocarbon resources, providing electrical and hydraulic power, control signal transmission and chemical injection. A diversity of components such as electrical cables, optical cables, steel tubes and filler bodies compose the cross-section of an umbilical. Different components perform different physical properties, so different cross-sections will present different geometrical characteristic, carrying capacities, thermal distribution, the cost and the ease of manufacture. Therefore, the cross-sectional design of the umbilical is a typical multi-objective optimization problem. The methodology of pseudo mechanical mechanism is introduced in this paper. Pseudo forces are assumed based on geometrical characteristics, carrying capacities and thermal productivities of different electrical cables, optical cables, steel tube and filler bodies. Each component is analogized to a sphere with different diameters on a funnel surface. Moreover, potential energy and interaction force between different components are defined to avoid the overlap and congestion. Then, the pseudo mechanical model is established and mathematics description is presented corresponding to the cross-section of an umbilical. Iteration algorithm procedure is given to solve this problem. Finally, a case of an umbilical is studied and the optimal cross-section is obtained, which is compared with the result used in practical engineering. It is shown that the methodology of the pseudo mechanical mechanism is effective to obtain the optimal design of cross-section of an umbilical.

Cartilage damage is difficult to self-heal due to an avascular microenvironment and distinct mechanical properties. These features are a challenge in designing a cartilaginous tissue with repairing effect without producing any local infections. Thus, a biodegradable scaffold in which the drug can be incorporated is preferable. Drug delivery systems based on collagen sponges have progressively become remarkable biomaterials for different medical applications. The aim of this work was to design and characterize some collagen/chondroitin sulfate supports with doxycycline for cartilage tissue regeneration. The doxycycline should prevent the development of potential infections. Collagen, chondroitin sulfate and doxycycline gels were cross-linked with different concentrations of glutaraldehyde and then freeze-dried in order to obtain collagen matrices. The structural characteristics for the new synthesized biomaterials were firstly assessed by infrared spectroscopy (FT-IR), and scaffolds morphology was then evaluated by optical microscopy and water uptake. The enzymatic biodegradation was also performed. Also, the sponges surface properties were quantified through contact angle. The in vitro doxycycline kinetics release was performed with a dissolution equipment and the release mechanism was investigated. The obtained results recommend these new scaffolds based on doxycycline/collagen/chondroitin sulfate as a promising approach for the treatment of cartilage problems.

Abstract High cycle fatigue in blades is triggered by oscillating forces. Devices such as shrouds, that exploit dry friction, are commonly introduced in the blade assembly to reduce the blade vibrations. If severe wear occurs, the effectiveness of the dry friction damping decreases, vibrations increase, and the number of cycles to failure of the blade diminishes. Mating surfaces in shrouds undergo high loads combined with relative displacement of low amplitude. This is the typical condition known as fretting. Coatings are commonly applied on damping surfaces of turbine blades to mitigate wear. This study investigates the wear mechanism of contact interfaces coated by Tribaloy® T-800, a coating greatly used in aeroengines. The experimental campaign was performed with a point contact test rig. The investigation was carried out using as test parameters temperature, normal load and fretting amplitude. Nine sets of parameters were analyzed at different test durations. Friction coefficients were computed using the hysteresis loops measured during the fretting tests. The worn surfaces were measured by an optical equipment based on focus variation and the volume losses were accurately measured. The wear region was observed by scanning electron microscopy at the end of each test. At room temperature, the friction coefficient was found substantially independent of the normal load. The wear rates at room temperature were higher than at high temperature. Observation of the worn surfaces by scanning electron microscopy revealed several brittle cracks. The damage mechanism changes from brittle (at room temperature) to ductile (at high temperature). The volume loss as a function of the dissipated energy was found independent of the normal load, showing that dissipated energy is a better variable rather than the number of wear cycles to show results of wear tests.

It has long been thought that an optical sensor, such as a light waveguide implemented total analysis system (TAS), is one of the most functional components that will be needed to realize a “ubiquitous human healthcare system”. A transparent resin-based TAS chip incorporated with a light waveguide [1] is quite preferable in such a cost-effective and disposal use. In line with the technical demand, we have already proposed a specially fabricated structure for an epoxy resin-based monolithic light waveguide capable of illuminating a cell or particle running along a microfluidic channel [2], as well as of obtaining directivity of fluorescence with a radially arranged waveguide structure (as shown in Figure 1) and a sequential light scanning mechanism based on a forced vibrated optical fiber [3]. Utilizing this TAS system, we have successfully detected preliminary results of fluorescence directivity of a 5-μm-diameter polystyrene particle with scanning angle range of 180 degrees, at illuminating light scanning frequency of approximately 1.7 kHz [4]. However, the transmittance of the trial-manufactured light waveguides was slightly lower owing mainly to its smaller cross section size, and, as a result, signal-to-noise ratio of detected fluorescence signal waveform was not as good as we have expected. To improve the S/N ratio, it is necessary to increase illuminating power of a laser source, and, at the same time, to increase multiplication factor of a photo-electron multiplier sensor to beyond its performance limit. Unfortunately, with the capability of the current equipment, it is difficult to drastically improve the S/N ratio. In this paper, we attempted to apply AC detection method to measure extremely weak fluorescence with a high frequency modulated laser source of its wavelength of 488 nm, and with a high speed lock-in-amplifier having both higher reference frequency up to 3MHz and smaller time constant.

Wide band gap semiconductor devices such as Silicon Carbide (SiC) or Gallium Nitride (GaN) capable of operation at high temperature over 300 degrees offer the potential of higher performance with reduced size, weight and eventually cost in power electronics equipment. For these high-temperature-resistant devices, the authors have proposed a new chip mounting structure that the stress relaxation function rests with the circuit metal on the substrate rather than the joint layer. In this study, to evaluate thermal fatigue of the new structure precisely, material properties of the high-temperature-resistant joint layer were measured by a new method and this method enabled analysis using measured properties. The joint layer which became very thin was formed by a low temperature sinter technology using silver (Ag) nano particles. The shear test to obtain the nonlinear properties of the joint layer was carried out by a proposed new method using bimetal fixtures which are composed of two materials whose Coefficient of Thermal Expansion (CTE) is different. Displacement of shear direction on the joint layer formed between the fixtures can be generated by heating the fixtures. Micro displacement was measured by Digital Image Correlation Method (DICM) using optical microscope and minute load on the joint layer was detected by strain gauge attached at fixture. Using the properties of the joint layer obtained as the test results, shear behavior on the chip joint was evaluated by Finite Element Analysis (FEA). Furthermore, harsh Thermal Cycle Test between −50 and 300 degree Celsius was carried out in the samples as the same structure as FEA model. From these results, the fatigue mechanism became clear and an improvement of the thermal cycle life was discussed.

Abstract As the key equipment to control the pressure stability of the coolant system, the pressurizer plays a role in maintaining the primary system pressure in the reactor. During the operation of the sea-based reactor, the internal free liquid level of the pressurizer will fluctuate greatly with different marine cycles, causing additional acceleration in the horizontal or vertical direction, which will cause the water level measured by the differential pressure measurement method to deviate from the actual water level. It will adversely affect the judgment and control of the signal. Moreover, the fluctuating liquid level will frequently trigger the water level alarm signal, resulting in the submersion of the sprinkler tuber and the exposure of the electric heating rod, which will reduce the safety and economy of the reactor. Therefore, this research is aimed at suppressing the fluctuation range of the water level and correcting the deviation of the water level measurement so as to improve the inherent safety of the reactor. In the present study, the experimental system consists of a motion excitation drive mechanism and an optical system. The experimental system has successfully established sloshing phenomenon of the pressurizer under different forms of motion by Laser induced fluorescence (LIF) technique and the experimental results obtained are compared with numerical results. The results of the research show that the pressurizer can make significant free surface fluctuation when excitation close to the natural frequency of the pressurizer. The suppression model developed by FLUTENT can effectively reduce the fluctuation range of free liquid level. In addition, the deviation of water level measurement enlarges with the swing angle increasing. The deviation can be reduced to the allowable error range by means of angle correction.

Recently, new cycles for power generation, such as wet cycles and cycles for CO2 capture, have gained increasing interest. These new cycles use some sort of dilution in the air/fuel mixture, e.g. steam or CO2. Gas turbine cycles using LCV gases can also be said to fit this description. Almost all modern gas turbines use a lean premixed combustion system, since it combines low NOx emissions with high combustion efficiency. The main objective of this paper is to study the influence of different diluents on the NOx and CO emissions at different inlet temperature, equivalence ratio, pressure and mass flow. The studied combustor was a premixed swirl stabilized combustor with optical access and emission sampling equipment. The combustor uses Danish natural gas as its main fuel. Computational fluid dynamics (CFD) has been employed to perform the investigations. It is common knowledge that turbulence models based on the Buissinesq assumption are not generally capable of handling a highly swirling flow in a correct way. Therefore, a differential Reynolds stress model (DRSM) has been employed for modeling of the turbulence. The turbulent combustion has been modeled with the level-set flamelet library approach (FLA). In this approach a laminar flamelet is linked to turbulent flow field via a non-reacting scalar G and its variance. The laminar flamelet is modeled with separate code. This code solves the combustion development with a detailed reaction mechanism for a laminar, non-stretched and premixed one-dimensional flame. This is of great importance when emissions are to be predicted. All fluid dynamics computations were performed with the commercial CFD code Star-CD, version 3.20, where the FLA combustion model was implemented through Fortran based user subroutines. The computed flow field was validated against experimental data during non-reaction flow conditions. The computations showed good agreement with the experimental data. The computed CO and NOx emissions showed the same trends as the experimental data for the reacting case with an undiluted flame, when the equivalence ratio was altered. The computed emissions were used to build up an emission map for different dilutions during different operation conditions.

Two-phase gas-liquid reactions often occur in chemical processes such as hydrogenation or oxidation. The flow of microbubbles in millichannels offers large specific contact surface for enhanced mass transfer and intensified chemical reactions. For low pressure loss, a combination of micro nozzles and millistructured channels is an alternative equipment design. Continuous dispersion flow through micro orifices with high flow velocity and pressure gradient deforms the phase boundary of bubbles triggering their break-up. In the nozzle’s outlet larger eddies are generated close to the wall disintegrating into smaller vortices with high flow oscillation. This has a major impact since eddies equaling bubble sizes initiate their break-up. In this work bubble break-up and its location in micro nozzles is studied in a flexible microchannel reactor concept. The dependence of the break-up location is investigated related to hydraulic diameter of the orifice, gas content, flow rate, and energy dissipation rate and its related volume. Regions of backflow increase energy loss; hence, the nozzle’s outlet angle was optimized reducing recirculation zones. Bubble dispersion and bubbly flow are studied in different orifices and channel elements with widths up to 7 mm. The outlet angle was varied between 6 and 45° to investigate different backflow regions. The effect of orifice dimensions on bubble sizes is evaluated for hydraulic diameters of 0.25 to 0.5 mm. The channel elements are fixed under a view glass enabling optical investigation of bubble size, first break-up points, and recirculation zones via high-speed camera. Analysis of bubble diameters and tracking of suspended particles was carried out by GIMP and ImageJ software. Generated bubble diameters are in the range of less than 0.1 mm up to 0.7 mm with narrow size distribution depending on the total flow rate through the channel. First break-up points; hence, the maximum energy input location are shifted closer to the outlet of the orifice with increasing velocities and smaller hydraulic diameters. However, the entire break-up region stays nearly constant for each orifice indicating stronger velocity oscillations acting on the bubble surface. A relation between smaller bubble diameter and larger energy dissipation was identified. Orifice outlet angles above 6° resulted in flow detachments and recirculation zones around the effluent jet. Ongoing investigation is carried out to further understand the mechanism and the influence of various parameters.