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Development of nonlinear disturbance observer based control and nonlinear PID： A personal note

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Control Theory and Technology 2018年第4期16卷 284-300页

作者： wen-hua chen Department of Aeronautical and Automotive Engineering Loughborough University Loughborough Leicestershire LE11 3TU U.K.

This paper gives an overview of early development of nonlinear disturbance observer design technique and the disturbance observer based control （DOBC） design. Some critical points raised in the development of the methods have been reviewed and discussed which are still relevant for many researchers or practitioners who are interested in this method. The review is followed by the development of a new type of nonlinear PID controller for a robotic manipulator and its experimental tests. It is shown that, under a number of assumptions, the DOBC consisting of a predictive control method and a nonlinear disturbance observer could reduce to a nonlinear PID with special features. Experimental results show that, compared with the predictive control method, the developed controller significantly improves performance robustness against uncertainty and friction. This paper may trigger further research and interests in the development of DOBC and related methods, and building up more understanding between this group of control methods with comparable ones （particularly control methods with integral action）.

关键词： Disturbance observer nonlinear control PID controller disturbance observer based contro

Recursive Filter with Partial Knowledge on Inputs and Outputs

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International Journal of Automation and computing 2015年第1期12卷 35-42页

作者： Jinya Su Baibing Li wen-hua chen Department of Aeronautical and Automotive Engineering Loughborough University School of Business and Economics Loughborough University

This paper investigates the problem of state estimation for discrete-time stochastic linear systems, where additional knowledge on the unknown inputs is available at an aggregate level and the knowledge on the missing measurements can be described by a known stochastic distribution. Firstly, the available knowledge on the unknown inputs and the state equation is used to form the prior distribution of the state vector at each time step. Secondly, to obtain an analytically tractable likelihood function, the effect of missing measurements is broken down into a systematic part and a random part, and the latter is modeled as part of the observation noise. Then, a recursive filter is obtained based on Bayesian inference. Finally, a numerical example is provided to evaluate the performance of the proposed methods.

关键词： Bayesian inference Kalman filter missing measurements state estimation unknown inputs

Robust Assignment of Airport Gates with Operational Safety Constraints

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International Journal of Automation and computing 2016年第1期13卷 31-41页

作者： Shuo Liu wen-hua chen Jiyin Liu Department of Aeronautical and Automotive Engineering Loughborough University School of Business and Economics Loughborough University

This paper reviews existing approaches to the airport gate assignment problem （AGAP） and presents an optimization model for the problem considering operational safety constraints. The main objective is to minimize the dispersion of gate idle time periods （to get robust optimization） while ensuring appropriate matching between the size of each aircraft and its assigned gate type and avoiding the potential hazard caused by gate apron operational conflict. Genetic algorithm is adopted to solve the problem, An illustrative example is given to show the effectiveness and efficiency of the algorithm. The algorithm performance is further demonstrated using data of a terminal from Beijing Capital International Airport （PEK）.

关键词： Gate assignment problem operational safety constraints robust optimization conflict avoidance genetic algorithm.

Nonlinear composite bilateral control framework for n-DOF teleoperation systems with disturbances

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Science China(Information Sciences) 2018年第7期61卷 182-199页

作者： Zhenhua ZHAO Jun YANG Cunjia LIU wen-hua chen School of Automation Southeast University Key Laboratory of Measurement and Control of CSEMinistry of Education Department of Aeronautical and Automotive Engineering Loughborough University

This paper proposes a new nonlinear composite bilateral control framework for n-degree-offreedom(n-DOF) teleoperation systems with external disturbances. Different with the existing methods which usually regard the dynamics of the master and slave robots as linear impedance models, the proposed control framework fully considers the nonlinear dynamics of the n-DOF teleoperation systems. Central to the proposed framework is the utilization of nonlinear disturbance observers for estimating the disturbances in master and slave robot systems. The nonlinear composite bilateral controller is constructed by incorporating the disturbance estimations into the nonlinear feedback linearization controller. The proposed control method guarantees satisfactory position tracking performance and desired remote force haptic simultaneously for the n-DOF teleoperation systems with external disturbances. The effectiveness of the proposed control framework is validated by its applications on 2-DOF teleoperation systems.

关键词： teleoperation system nonlinear bilateral control remote force haptic disturbance rejection nonlinear disturbance observer

Model Predictive Control of Nonlinear Systems: Stability Region and Feasible Initial Control

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International Journal of Automation and computing 2007年第2期4卷 195-202页

作者： Xiao-Bing Hu wen-hua chen Department of Informatics University of Sussex Falmer Brighton BN1 9QH UK Department of Aeronautical and Automotive Engineering Loughborough University LE11 3TU UK

This paper proposes a new method for model predictive control （MPC） of nonlinear systems to calculate stability region and feasible initial control profile/sequence, which are important to the implementations of MPC. Different from many existing methods, this paper distinguishes stability region from conservative terminal region. With global linearization, linear differential inclusion （LDI） and linear matrix inequality （LMI） techniques, a nonlinear system is transformed into a convex set of linear systems, and then the vertices of the set are used off-line to design the controller, to estimate stability region, and also to determine a feasible initial control profile/sequence. The advantages of the proposed method are demonstrated by simulation study.

关键词： Model predictive control (MPC) stability region terminal region linear differential inclusion (LDI) linear matrix inequality (LMI).

Experimental Tests of Autonomous Ground Vehicles with Preview

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International Journal of Automation and computing 2010年第3期7卷 342-348页

作者： Cunjia Liu wen-hua chen John Andrews Department of Aeronautical and Automotive Engineering Loughborough University Loughborough LE11 3TU UK Nottingham Transportation Engineering Centre Faculty of Engineering University of Nottingham Nottingham NG7 2RD UK

This paper describes the design and experimental tests of a path planning and reference tracking algorithm for autonomous ground vehicles. The ground vehicles under consideration are equipped with forward looking sensors that provide a preview capability over a certain horizon. A two-level control framework is proposed for real-time implementation of the model predictive control （MPC） algorithm, where the high-level performs on-line optimization to generate the best possible local reference respect to various constraints and the low-level commands the vehicle to follow realistic trajectories generated by the high-level controller. The proposed control scheme is implemented on an indoor testbed through networks with satisfactory performance.

关键词： Model predictive control autonomous vehicle online optimization nonholonomic constraint eigenvalue.

Chattering-free sliding mode control with unidirectional auxiliary surfaces for miniature helicopters

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International Journal of Intelligent Computing and Cybernetics 2012年第3期5卷 421-438页

作者： Jian Fu wen-hua chen Qing-xian Wu Department of Automation Nanjing University of Aeronautics and AstronauticsNanjingChina Department of Aeronautical and Automotive Engineering Loughborough UniversityLoughboroughUK

Purpose-This article proposes a chattering-free sliding mode control scheme with unidirectional auxiliary surfaces(UAS-SMC)for small miniature autonomous helicopters(Trex 250).Design/methodology/approach-The proposed UAS-SMC scheme consists of a nested sequence of rotor dynamics,angular rate,Euler angle,velocity and position ***-It is demonstrated that the UAS-SMC strategy can eliminate the chattering phenomenon exhibiting in the convenient SMC method and achieve a better approaching ***/value-The proposed control strategy is implemented on the helicopter and flight tests clearly demonstrate that a much better performance could be achieved,compared with convenient SMC schemes.

关键词： Unmanned aircraft Approaching speed Flight control Sliding mode control Helicopters Chattering

Design of Accelerated Life Test Plans——Overview and Prospect

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Chinese Journal of Mechanical Engineering 2018年第1期31卷 19-33页

作者： wen-hua chen Liang Gao Jun Pan Ping Qian Qing-Chuan He Key Laboratory of Reliability Technology for Mechanical and Electrical Product of Zhejiang Province Zhejiang Sci-Tech University College of Mechanical and Electrical Engineering Sichuan Agricultural University

Accelerated life test(ALT) is currently the main method of assessing product reliability rapidly, and the design of efficient test plans is a critical step to ensure that ALTs can assess the product reliability accurately, quickly, and economically. With the promotion of the national strategy of civil-military integration, ALT will be widely used in the research and development(R&D) of various types of products, and the ALT plan design theory will face further challenges. To aid engineers in selecting appropriate theories and to stimulate researchers to develop the theories required in engineering, with focus on the demands for theory research that arise from the implementation of ALT, this paper reviews and summarizes the development of ALT plan design theory. The development of the theory and method for planning optimal ALT for location-scale distribution, which is the most applied and mature theory of designing the optimal ALT plan, are described in detail. Taking this as the center of radiation, some problems that ALT now faces, such as the verification of the statistical model, limitation of sample size, solutions of resource limits, optimization of the test arrangement, and management of product complexity, are discussed, and the general ideas and methods of solving these problems are analyzed. Suggestions for selecting appropriate ALT plan design theories are proposed, and the urgent solved theory problems and opinions of their solutions are proposed. Based on the principle of convenience for engineers to select appropriate methods according to the problems found in practice, this paper reviews the development of optimal ALT plan design theory by taking the engineering problems arising from the ALT implementation as the main thread, provides guidelines on selecting appropriate theories for engineers, and proposes opinions about the urgent solved theory problems for researchers.

关键词： Accelerated life test Test plan Optimal design Reliability assessment

Novel Accelerating Life Test Method and Its Application by Combining Constan Stress and Progressive Stress

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Chinese Journal of Mechanical Engineering 2018年第5期31卷 17-24页

作者： wen-hua chen Fan Yang Ping Qian Jun Pan Qing-Chuan He Zhejiang Province's Key Laboratory of Reliability Technology for Mechanical and Electronic Product Zhejiang Sci-Tech University School of Engineering Huzhou University

Constant stress accelerated life tests(ALTs) can be applied to obtain a high estimation accuracy of reliability measure?ments, but these are time?consuming tests. Progressive stress ALTs can yield failures more quickly but cannot guaran tee the estimation accuracy of reliability measurements. In this paper, a progressive?constant combination stress ALT is proposed to combine the merits of both tests. The optimal plan, in which the design variables are the initial pro?gressive stress level, the progressive stress ramp rate, the sample allocation proportion of the progressive stress and the constant stress level, is determined using the principle of minimizing the asymptotic variance of the maximum likelihood estimator of the natural log reliable life for the connectors. A comparison between the optimal PCCSALT plan and the CSALT plan with the same sample size and estimation accuracy shows that the test time is reduced by 13.59% by applying the PCCSALT.

关键词： Constant stress Progressive stress Accelerated life test Optimal test plan Reliability test