Application of the Lyapunov Exponent Based on Current Vibration Control Parameter (CVC) in Control of an Industrial Robot.

Controlling dynamics of industrial robots is one of the most important and complicated tasks in robotics. In some works[3,7], there are algorithms of the manipulators steering with flexible joints or arms. However, introducing them to calculation of trajectory results in complicated equations and a longer time of counting. On the other hand, works [4,5,6]show that improvement of the tool path is possible thanks to the previousidentification of the robot errors and their compensation. This text covers application of Largest Lyapunov Exponent (LLE) as a criterion for control performance assessment (CPA) in a real control system. The main task is to find a simple and effective method to search for the best configuration of a controller in a control system. In this context, CPA criterion based on calculation of LLE by means of a new method [9–11] is presented in the article

유연 시스템의 모델 프리 최적 추정 및 센서 배치 프레임워크 개발

학위논문 (석사)-- 서울대학교 대학원 : 공과대학 기계항공공학부, 2019. 2. 이동준.본 논문에서는 데이터기반 주성분분석 기법 및 최대 사후 확률 추정기법을 활용하여 제한된 개수의 관성센서만을 사용하는 고자유도 유연 시스템의 모델프리 최적 추정 및 센서 배치 최적화 프레임워크를 개발하였다. 우선, 사전에 유연 시스템을 대표적인 시나리오에 대하여 충분히 가진하여 얻은 데이터로부터 주성분분석을 적용시켜 우세 모드와 열세 모드로 분할하였다. 이렇게 구한 각 모드의 특이값을 기반으로 필요한 최소한의 관성센서 개수를 정할 수 있었으며 시스템 끝단의 위치와 같은 출력의 사전 분포를 구할 수 있었다. 출력의 사전 분포와 관성센서의 위치에 따른 최대 사후 확률 추정을 할 수 있었으며, 추정 성능을 최대화하기 위한 센서 배치 최적화기법 또한 제시하였다. 그리하여 최적화된 센서 배치로 유연 시스템의 실시간 출력 최적 추정이 가능하였다. 최종적으로 본 논문에서 제시한 추정 및 센서 배치 최적화 프레임워크를 실험을 통하여 검증하였다.In this thesis, we propose a novel model-free optimal estimation and sensor placement framework for a high-DOF (degree-of-freedom) EKC (elastic kinematic chain) with only a limited number of IMU (inertial measurement unit) sensors based on POD (proper orthogonal decomposition) and MAP (maximum a posteriori) estimation. First, we (o-line) excite the system richly enough, collect the data and perform the POD to extract dominant and non-dominant modes. We then decide the minimum number of IMUs according to the dominant modes, and construct the prior distribution of the output (i.e., top-end position of EKC) based on the singular value of each POD mode. We also formulate the MAP estimation given the prior distribution and dierent placements of the IMUs and choose the optimal IMU placement to maximize the posterior probability. This optimal placement is then used for real-time output estimation of the EKC. Experiments are also performed to verify the theory.Acknowledgements ii List of Figures v List of Tables vi Abbreviations vii 1 Introduction 1 2 System Modeling and Problem Statement 6 2.1 System Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.2 Problem Statement . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3 Optimal Estimation and Sensor Placement 9 3.1 Output Estimation . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3.1.1 Linearization . . . . . . . . . . . . . . . . . . . . . . . . . 9 3.1.2 Mode Reduction . . . . . . . . . . . . . . . . . . . . . . . 11 3.1.3 Maximum a Posteriori Estimation . . . . . . . . . . . . . 17 3.2 Sensor Placement Optimization . . . . . . . . . . . . . . . . . . . 21 4 Experiments 23 4.1 Testbed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 4.1.1 Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 4.1.2 Output Estimation Result . . . . . . . . . . . . . . . . . . 26 4.2 Mock-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 4.2.1 Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 4.2.2 Output Estimation Result . . . . . . . . . . . . . . . . . . 37 5 Conclusion and Future Work 41 5.1 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 5.2 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42Maste

Structural dynamics branch research and accomplishments for fiscal year 1987

This publication contains a collection of fiscal year 1987 research highlights from the Structural Dynamics Branch at NASA Lewis Research Center. Highlights from the branch's four major work areas, Aeroelasticity, Vibration Control, Dynamic Systems, and Computational Structural Methods, are included in the report as well as a complete listing of the FY87 branch publications

Incorporation of the influences of kinematics parameters and joints tilting for the calibration of serial robotic manipulators

Serial robotic manipulators are calibrated to improve and restore their accuracy and repeatability. Kinematics parameters calibration of a robot reduces difference between the model of a robot in the controller and its actual mechanism to improve accuracy. Kinematics parameter’s error identification in the standard kinematics calibration has been configuration independent which does not consider the influence of kinematics parameter on robot tool pose accuracy for a given configuration. This research analyses the configuration dependent influences of kinematics parameters error on pose accuracy of a robot. Based on the effect of kinematics parameters, errors in the kinematics parameters are identified. Another issue is that current kinematics calibration models do not incorporate the joints tilting as a result of joint clearance, backlash, and flexibility, which is critical to the accuracy of serial robotic manipulators, and therefore compromises a pose accuracy. To address this issue which has not been carefully considered in the literature, this research suggested an approach to model configuration dependent joint tilting and presents a novel approach to encapsulate them in the calibration of serial robotic manipulators. The joint tilting along with the kinematics errors are identified and compensated in the kinematics model of the robot. Both conventional and proposed calibration approach are tested experimentally, and the calibration results are investigated to demonstrate the effectiveness of this research. Finally, the improvement in the trajectory tracking accuracy of the robot has been validated with the help of proposed low-cost measurement set-up.Thesis (M.Phil.) (Research by Publication) -- University of Adelaide, School of Mechanical Engineering , 201

Study to design and develop remote manipulator systems

A description is given of part of a continuing effort both to develop models for and to augment the performance of humans controlling remote manipulators. The project plan calls for the performance of several standard tasks with a number of different manipulators, controls, and viewing conditions, using an automated performance measuring system; in addition, the project plan calls for the development of a force-reflecting joystick and supervisory display system

Technology for large space systems: A special bibliography with indexes (supplement 06)

This bibliography lists 220 reports, articles and other documents introduced into the NASA scientific and technical information system between July 1, 1981 and December 31, 1981. Its purpose is to provide helpful information to the researcher, manager, and designer in technology development and mission design in the area of the Large Space Systems Technology (LSST) 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

Structural dynamics branch research and accomplishments for FY 1988

Fiscal year 1988 research highlights from the Structural Dynamics Branch at NASA Lewis Research Center are described. Highlights from the branch's major work areas -- aeroelasticity, vibration control, dynamic systems, and computational structural methods -- are included as well as a complete listing of the FY 88 branch publications

Space-Capable Long and Thin Continuum Robotic Cable

Design of continuum robots, i.e. robots with continuous backbones, has been an active area of research in robotics for minimally invasive surgery, search and rescue, object manipulation, etc. Along the same lines, NASA developed Tendril , the first long and thin continuum robot of its kind, intended for in-space inspection applications. The thesis starts with describing and discussing the key disadvantages of the current state of the art mechanical design of Tendril\u27\u27 producing undesirable effects during operation. It then includes the design specifics of a novel concept for construction of a next generation long and thin, space-cable, multi-section, continuum cable-like robot, with a modified mechanical design for better performance. The new design possesses key features including controllable bending along its entire length, local compression and a compact actuation package. This new design is detailed in two versions. The first is a planar variant (suited for a 2D workspace), explaining the principle which allows the cable robot to achieve the above mentioned features. It is followed by a refined spatial version (suited for 3D workspace), where the functional characteristics are achieved within the desired aspect ratio of thin (less than 1 cm diameter) and relatively longer length (more than 100 cm) of the robotic cable. A new forward kinematic model is then developed extending the established models for constant-curvature continuum robots, to account for the new design feature of controllable compression (in the hardware) and is validated by performing experiments with the robot in (2D) planar and (3D) spatial scenarios. This new model is found to be effective as a baseline to predict the performance of such a long and thin continuum cable\u27\u27 robot