• Title, Summary, Keyword: nonlinear control

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Survey of Nonlinear Control Methods to Permanent Magnet Stepping Motors (스테퍼 모터를 위한 비선형 제어기법의 개관)

  • Kim, Wonhee;Shin, Donghoon;Lee, Youngwoo;Chung, Chung Choo
    • Journal of Institute of Control, Robotics and Systems
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    • v.20 no.3
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    • pp.323-332
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    • 2014
  • Stepper motor is widely used in positioning applications due to its durability and high torque to inertia ratio as well as low cost and ability to be easily controlled with open-loop. Due to increased resolution of position control and improved stability of motion control, microstepping has drawn attention in industry since it was introduced in 1970s. With the increase in computational power and decrease in cost of embedded processors in recent years, drives and control systems for stepper motors have become more sophisticate than ever. Thus, closed-loop control methods have been developed to improve the performance of the stepper motors. In this paper, we review not only basic principles of conventional control methods used for stepper motors but also that of microstepping control. In addition, we surveyed recent development in nonlinear control methods applied to stepper motors. The nonlinear control methods are presented in the view of Lyapunov stability. Nonlinear torque disturbance observer, sliding mode control, and nonlinear phase compensation are also presented.

Nonlinear Adaptive Control for Linear Motor through the Estimation of Friction Forces and Force Ripples (마찰력 및 리플력 추정을 통한 리니어 모터의 비선형 적응제어)

  • Kim, Hong-Bin;Lee, Byong-Huee;Han, Sang-Oh;Huh, Kun-Soo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.31 no.1
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    • pp.18-25
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    • 2007
  • Linear motor is easily affected by load disturbance, force ripple, friction, and parameter variations because there is no mechanical transmission to reduce the effects of model uncertainties and external disturbance. These nonlinear effects have been reduced for high-speed/high-accuracy position control either through the better motor design or via the better control algorithm that can compensate the nonlinear effects. In this paper, a nonlinear adaptive control algorithm is designed and applied for the position control of permanent magnet linear synchronous motor. In order to estimate and compensate the nonlinear effects such as friction and force ripple, the estimation and the nonlinear adaptive control laws are derived based on the virtual control input and a suitable Lyapunov function. The proposed controller is evaluated through the computer simulations. The control algorithm is also implemented to a DSP board and interfaced to the PMLSM for verifying the realtime control performance.

Neural Model Predictive Control for Nonlinear Chemical Processes

  • Song, Jeong-Jun;Park, Sunwon
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • pp.899-902
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    • 1993
  • A neural model predictive control strategy combining a neural network for plant identification and a nonlinear programming algorithm for solving nonlinear control problems is proposed. A constrained nonlinear optimization approach using successive quadratic programming combined with neural identification network is used to generate the optimum control law for complex continuous chemical reactor systems that have inherent nonlinear dynamics. The neural model predictive controller (MNPC) shows good performances and robustness. To whom all correspondence should be addressed.

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A Nonlinear Programming Approach to Biaffine Matrix Inequality Problems in Multiobjective and Structured Controls

  • Lee, Joon-Hwa;Lee, Kwan-Ho;Kwon, Wook-Hyun
    • International Journal of Control, Automation, and Systems
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    • v.1 no.3
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    • pp.271-281
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    • 2003
  • In this paper, a new nonlinear programming approach is suggested to solve biaffine matrix inequality (BMI) problems in multiobjective and structured controls. It is shown that these BMI problems are reduced to nonlinear minimization problems. An algorithm that is easily implemented with existing convex optimization codes is presented for the nonlinear minimization problem. The efficiency of the proposed algorithm is illustrated by numerical examples.

Robust stabilization of nonlinear uncertain systems without matching conditions (정합조건을 만족하지 않는 불확정 비선형 시스템의 강인 안정화)

  • 주진만;최윤호;박진배
    • 제어로봇시스템학회:학술대회논문집
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    • pp.159-162
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    • 1997
  • This paper describes robust stabilization of nonlinear single-input uncertain systems without matching conditions. We consider nonlinear systems with a vector of unknown constant parameters perturbed about a known value. The approach utilizes the generalized controller canonical form to lump the unmatched uncertainties recursively into the matched ones. This can be achieved via nonlinear coordinate transformations which depend not only on the states of the nonlinear system but also on the control input. Then the dynamic robust control law is derived and the stability result is also presented.

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An Adaptive Controller Cooperating with Fuzzy Controller for Unstable Nonlinear Time-invariant Systems (불안정 비선형 시불변 시스템을 위한 퍼지제어기가 결합된 적응제어기)

  • Dae-Young, Kim;In-Hwan, Kim;Jong-Hwa, Kim;Byung-Kyul, Lee
    • Journal of the Korean Society of Marine Engineering
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    • v.28 no.6
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    • pp.946-961
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    • 2004
  • A new adaptive controller which combines a model reference adaptive controller (MRAC) and a fuzzy controller is developed for unstable nonlinear time-invariant systems. The fuzzy controller is used to analyze and to compensate the nonlinear time-invariant characteristics of the plant. The MRAC is applied to control the linear time-invariant subsystem of the unknown plant, where the nonlinear time-invariant plant is supposed to comprise a nonlinear time-invariant subsystem and a linear time-invariant subsystem. The stability analysis for the overall system is discussed in view of global asymptotic stability. In conclusion. the unknown nonlinear time-invariant plant can be controlled by the new adaptive control theory such that the output error of the given plant converges to zero asymptotically.

Embedded Hardware Implementation of an FPGA Based Nonlinear PID Controller for the ROBOKER Arm (ROBOKER 팔의 제어를 위한 FPGA 기반 비선형 제어기의 임베디드 하드웨어 구현)

  • Kim, Jeong-Seob;Jeon, Hyo-Won;Jung, Seul
    • Journal of Institute of Control, Robotics and Systems
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    • v.13 no.12
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    • pp.1153-1159
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    • 2007
  • This paper presents the hardware implementation of nonlinear PID controllers for the ROBOKER humanoid robot arms. To design the nonlinear PID controller on an FPGA chip, nonlinear functions as well as the conventional PID control algorithm have to be implemented by the hardware description language. Therefore, nonlinear functions such as trigonometric or exponential functions are designed on an FPGA chip. Simulation studies of the position control of humanoid arms are conducted and results are compared. Superior performances by the nonlinear PID controllers are confirmed when disturbances are present. Experiments of humanoid robot arm control tasks are conducted to confirm the performance of our hardware design and the simulation results.

A New Robust Variable Structure Controller With Nonlinear Integral-Type Sliding Surface for Uncertain More Affine Nonlinear Systems with Mismatched Uncertainties and Disturbance (부정합조건 불확실성과 외란을 갖는 비선형 시스템을 위한 비선형 적분형 슬라이딩 면을 갖는 새로운 강인한 가변구조제어기)

  • Lee, Jung-Hoon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.7
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    • pp.1295-1301
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    • 2010
  • In this note, a systematic general design of a new robust nonlinear variable structure controller based on state dependent nonlinear form is presented for the control of uncertain affine nonlinear systems with mismatched uncertainties and mismatched disturbance. After an affine uncertain nonlinear system is represented in the form of state dependent nonlinear system, a systematic design of a new robust nonlinear variable structure controller is presented. To be linear in the closed loop resultant dynamics, the nonlinear integral-type sliding surface is applied. A corresponding control input is proposed to satisfy the closed loop exponential stability and the existence condition of the sliding mode on the nonlinear integral-type sliding surface, which will be investigated in Theorem 1. Through a design example and simulation studies, the usefulness of the proposed controller is verified.

Nonlinear Control of General System based on a Model with Coefficients of State-Depended Representation

  • Nakamura, Masatoshi;Zhang, Tao
    • 제어로봇시스템학회:학술대회논문집
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    • pp.76.1-76
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    • 2002
  • This paper addresses a method for nonlinear controller construction for a general nonlinear system with the separation of controller construction and manipulated values generation. The nonlinear system model is firstly expressed with the coefficients of state-depended representation. The nonlinear control is designed without any approximation based on the model with state-depended representation. At the stage of controller implementation for the nonlinear system, the manipulated values are calculated accurately by use of an algorithm of the numerical analysis. The numerical error for calculating the manipulated value can be reduced to zero by selecting the sampling interval being a small val...

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A semi-active stochastic optimal control strategy for nonlinear structural systems with MR dampers

  • Ying, Z.G.;Ni, Y.Q.;Ko, J.M.
    • Smart Structures and Systems
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    • v.5 no.1
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    • pp.69-79
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    • 2009
  • A non-clipped semi-active stochastic optimal control strategy for nonlinear structural systems with MR dampers is developed based on the stochastic averaging method and stochastic dynamical programming principle. A nonlinear stochastic control structure is first modeled as a semi-actively controlled, stochastically excited and dissipated Hamiltonian system. The control force of an MR damper is separated into passive and semi-active parts. The passive control force components, coupled in structural mode space, are incorporated in the drift coefficients by directly using the stochastic averaging method. Then the stochastic dynamical programming principle is applied to establish a dynamical programming equation, from which the semi-active optimal control law is determined and implementable by MR dampers without clipping in terms of the Bingham model. Under the condition on the control performance function given in section 3, the expressions of nonlinear and linear non-clipped semi-active optimal control force components are obtained as well as the non-clipped semi-active LQG control force, and thus the value function and semi-active nonlinear optimal control force are actually existent according to the developed strategy. An example of the controlled stochastic hysteretic column is given to illustrate the application and effectiveness of the developed semi-active optimal control strategy.