Analysis of configuration singularities of platform-type robotic manipulators.

by Lo, Ka-wah.Thesis (M.Phil.)--Chinese University of Hong Kong, 1995.Includes bibliographical references (leaves 76-81 (2nd gp.)).Acknowledgments --- p.iAbstract --- p.iiNotations --- p.iiiList of Figures --- p.vList of Tables --- p.viiChapter 1. --- IntroductionChapter 1.1 --- Motivation --- p.1Chapter 1.2 --- Literature Review --- p.4Chapter 1.3 --- Objective --- p.10Chapter 2. --- Comparison of Different ApproachesChapter 2.1 --- Sample Manipulator --- p.11Chapter 2.1.1 --- Force Decomposition Method --- p.12Chapter 2.1.2 --- Forward Rate Kinematics Base Method --- p.15Chapter 2.1.3 --- Grassmann Geometry Method --- p.18Chapter 2.2 --- Comparison Criteria --- p.20Chapter 2.2.1 --- Computational Complexity --- p.20Chapter 2.2.2 --- Scope of Application --- p.22Chapter 2.3 --- Summary --- p.23Chapter 3. --- Enumeration of Configuration SingularityChapter 3.1 --- Novel 6 DOF --- p.25Chapter 3.1.1 --- Result Analysis --- p.31Chapter 3.2 --- A 3 DOF with Symmetric Base --- p.33Chapter 3.2.1 --- Result Analysis --- p.35Chapter 3.3 --- A 3 DOF with Non-Symmetric Base --- p.36Chapter 3.3.1 --- Result Analysis --- p.37Chapter 3.4 --- A New Model of 6-SPS Defined by Kong et al --- p.40Chapter 3.5 --- A New Class of 6-SPS Platform-Type Parallel Manipulator --- p.45Chapter 3.5.1 --- The Hexagonal Base --- p.46Chapter 3.5.2 --- The Pentagonal Base --- p.50Chapter 3.5.3 --- The Tetragonal Base --- p.52Chapter 3.5.4 --- The Triangular Base --- p.55Chapter 3.6 --- Summary --- p.59Chapter 4. --- Numerical AnalysisChapter 4.1 --- Parameter Analysis --- p.60Chapter 4.1.1 --- One Unknown Variable --- p.61Chapter 4.1.2 --- Two Unknown Variables --- p.63Chapter 4.2 --- Critical Value of Ratio R/q --- p.69Chapter 4.3 --- Summary --- p.72Chapter 5. --- Conclusions and Future WorkChapter 5.1 --- Conclusions --- p.73Chapter 5.2 --- Future Work --- p.75References --- p.76Appendix --- p.8

Kinematics and Robot Design II (KaRD2019) and III (KaRD2020)

This volume collects papers published in two Special Issues “Kinematics and Robot Design II, KaRD2019” (https://www.mdpi.com/journal/robotics/special_issues/KRD2019) and “Kinematics and Robot Design III, KaRD2020” (https://www.mdpi.com/journal/robotics/special_issues/KaRD2020), which are the second and third issues of the KaRD Special Issue series hosted by the open access journal robotics.The KaRD series is an open environment where researchers present their works and discuss all topics focused on the many aspects that involve kinematics in the design of robotic/automatic systems. It aims at being an established reference for researchers in the field as other serial international conferences/publications are. Even though the KaRD series publishes one Special Issue per year, all the received papers are peer-reviewed as soon as they are submitted and, if accepted, they are immediately published in MDPI Robotics. Kinematics is so intimately related to the design of robotic/automatic systems that the admitted topics of the KaRD series practically cover all the subjects normally present in well-established international conferences on “mechanisms and robotics”.KaRD2019 together with KaRD2020 received 22 papers and, after the peer-review process, accepted only 17 papers. The accepted papers cover problems related to theoretical/computational kinematics, to biomedical engineering and to other design/applicative aspects

Motion design, control and implementation in robot manipulators

The dynamic performance of robots, specifically the tracking accuracy and motion duration, is influenced by both the nominal motion profile and the feedback control method employed. Three schemes are developed and experimentally tested to tackle the improvement of dynamic performance, in the absence of accurate dynamic models. Model Referenced Adaptive Controller Schemes (MRACS) can be designed to facilitate the characterisation of otherwise complex system dynamics. In one scheme an MRACS is used to force the robot to behave as if it were linear and decoupled, enabling simple model based dynamic tuning methods to be applied to the motion laws. Its promise as a technique is demonstrated, but the controller performance is found to be degraded by practical limitations. It is applied to both joint and Cartesian based motion laws. A computer controlled robot contains all the elements necessary for an autonomous self experimentation system. This feature is exploited in the derivation and implementation of two further schemes which are termed self learning. In these, the robot's trajectory is stored as a set of discrete data. Algorithms are developed for tuning this data subsequent to each run. Their use requires minimal knowledge of the dynamics, no additional transducers and little computation. The first of the self learning schemes is used to cyclically reduce the tracking errors. Once complete, the updating process can be curtailed. Errors on completion are close to the transducer resolution. The second of these schemes involves an incremental reduction in the duration of a given motion. Various parameters for detecting saturation are proposed and tested. A normalised ratio of peak to average velocity is found promising. Combining these two schemes, tuning for speed to near saturation then tuning for accuracy, provides a method for obtaining a near minimum time trajectory, with maximum possible tracking accuracy, at low cost

Advanced Strategies for Robot Manipulators

Amongst the robotic systems, robot manipulators have proven themselves to be of increasing importance and are widely adopted to substitute for human in repetitive and/or hazardous tasks. Modern manipulators are designed complicatedly and need to do more precise, crucial and critical tasks. So, the simple traditional control methods cannot be efficient, and advanced control strategies with considering special constraints are needed to establish. In spite of the fact that groundbreaking researches have been carried out in this realm until now, there are still many novel aspects which have to be explored

Parallel Manipulators

In recent years, parallel kinematics mechanisms have attracted a lot of attention from the academic and industrial communities due to potential applications not only as robot manipulators but also as machine tools. Generally, the criteria used to compare the performance of traditional serial robots and parallel robots are the workspace, the ratio between the payload and the robot mass, accuracy, and dynamic behaviour. In addition to the reduced coupling effect between joints, parallel robots bring the benefits of much higher payload-robot mass ratios, superior accuracy and greater stiffness; qualities which lead to better dynamic performance. The main drawback with parallel robots is the relatively small workspace. A great deal of research on parallel robots has been carried out worldwide, and a large number of parallel mechanism systems have been built for various applications, such as remote handling, machine tools, medical robots, simulators, micro-robots, and humanoid robots. This book opens a window to exceptional research and development work on parallel mechanisms contributed by authors from around the world. Through this window the reader can get a good view of current parallel robot research and applications

Dynamic state estimation for mobile robots

The scientific goal of this thesis is to tackle different approaches for effective state estimation and modelling of relevant problems in the context of mobile robots. The starting point of this dissertation is the concept of probabilistic robotics, an emerging paradigm that combines state-of-the-art methods with the classic probabilistic theory, developing stochastic frameworks for understanding the uncertain nature of the interaction between a robot and its environment. This allows introducing relevant concepts which are the foundation of the localisation system implemented on the main experimental platform used on this dissertation. An accurate estimation of the position of a robot with respect to a fixed frame is fundamental for building navigation systems that can work in dynamic unstructured environments. This development also allows introducing additional contributions related with global localisation, dynamic obstacle avoidance, path planning and position tracking problems. Kinematics on generalised manipulators are characterised for dealing with complex nonlinear systems. Nonlinear formulations are needed to properly model these systems, which are not always suitable for real-time realisation, lacking analytic formulations in most cases. In this context, this thesis tackles the serial-parallel dual kinematic problem with a novel approach, demonstrating state-of-the-art accuracy and real-time performance. With a spatial decomposition method, the forward kinematics problem on parallel robots and the inverse kinematics problem on serial manipulators is solved modelling the nonlinear behaviour of the pose space using Support Vector Machines. The results are validated on different topologies with the analytic solution for such manipulators, which demonstrates the applicability of the proposed method. Modelling and control of complex dynamical systems is another relevant field with applications on mobile robots. Nonlinear techniques are usually applied to tackle problems like feature or object tracking. However, some nonlinear integer techniques applied for tasks like position tracking in mobile robots with complex dynamics have limited success when modelling such systems. Fractional calculus has demonstrated to be suitable to model complex processes like viscoelasticity or super diffusion. These tools, that take advantage of the generalization of the derivative and integral operators to a fractional order, have been applied to model and control different topics related with robotics in recent years with remarkable success. With the proposal of a fractional-order PI controller, a suitable controller design method is presented to solve the position tracking problem. This is applied to control the distance of a self-driving car with respect to an objective, which can also be applied to other tracking applications like following a navigation path. Furthermore, this thesis introduces a novel fractional-order hyperchaotic system, stabilised with a full-pseudo-state-feedback controller and a located feedback method. This theoretical contribution of a chaotic system is introduced hoping to be useful in this context. Chaos theory has recently started to be applied to study manipulators, biped robots and autonomous navigation, achieving new and promising results, highlighting the uncertain and chaotic nature which also has been found on robots. All together, this thesis is devoted to different problems related with dynamic state estimation for mobile robots, proposing specific contributions related with modelling and control of complex nonlinear systems. These findings are presented in the context of a self-driving electric car, Verdino, jointly developed in collaboration with the Robotics Group of Universidad de La Laguna (GRULL)

Dynamic modelling of hexarot parallel mechanisms for design and development

In this research, the kinematics, dynamics, and general closed-form dynamic formulation of the centrifugal high-G hexarot-based manipulators have been developed through the different mathematical modeling techniques. The vibrations of the mechanism have also been investigated

Technology for large space systems: A special bibliography with indexes (supplement 04)

This bibliography lists 259 reports, articles, and other documents introduced into the NASA scientific and technical information system between July 1, 1980 and December 31, 1980. Its purpose is to provide information to the researcher, manager, and designer in technology development and mission design in the area of the Large Space Systems Technology Program. Subject matter is grouped according to systems, interactive analysis and design. Structural concepts, control systems, electronics, advanced materials, assembly concepts, propulsion, solar power satellite systems, and flight experiments