Error Of Control System Research Articles

1P1-C15 本質安全なサーボ制御を実現するための双線形最適サーボ制御手法

Servo control is one of foundamental control techniques for control problems of many mechanical structures. Various kinds of control methods such as PID, LQ and H-infinity controls have been applied to active servo control designs. However, it is very important to guarantee against safety in the control problems of man-machine systems. Especially, driving recklessly due to software or hardware errors in active control systems must be avoided in some devices. Therefore, intrinsically safe control system is required for the devices. This paper discusses the use of an intrinsically safe servo control system consisting of passive elements instead of active actuators. For such a control system, semi-active control to vary passive parameters such as viscous damping is important. Therefore, a novel servo control method based on the bilinear optimal control theory is proposed for the system in this paper. The effectiveness of the method is verified by simulations.

本質安全なサーボ制御を実現するための双線形最適サーボ制御手法

Servo control is one of foundamental control techniques for control problems of many mechanical structures. Various kinds of control methods such as PID, LQ and H-infinity controls have been applied to active servo control designs. However, it is very important to guarantee against safety in the control problems of man-machine systems. Especially, driving recklessly due to software or hardware errors in active control systems must be avoided in some devices, e.g., nursing care or medical devices. Therefore, an intrinsically safe control system is required for the devices. This note discusses the use of an intrinsically safe servo control system consisting of passive elements instead of active actuators. For such a control system, semi-active control to vary passive parameters such as viscous damping is important. Therefore, a novel servo control method based on the bilinear optimal control theory is proposed for the system in this note. The effectiveness of the method is verified by simulations.

REINFORCEMENT FUZZY-RULE EMULATED NETWORKS AND ITS APPLICATION ON NONLINEAR DISCRETE-TIME SYSTEMS

The adaptive control algorithm based on Multi-Input Fuzzy Rules Emulated Networks (MIFRENs) with the reinforcement learning algorithm is introduced for a class of nonlinear discrete-time systems. Because of the unknown future values of systems, the long term cost function is estimated by the first MIFREN through the human knowledge with the defined IF-THEN rules and the proposed learning algorithm. The main controller is constructed by another MIFREN and the parameters in side this network have been tuned to minimize the estimated cost function and the control system error. All designed parameters are given with the Lyapunov method and the proposed theorem. The numerical simulation results are demonstrated the system performance with the selected nonlinear discrete-time systems

Passivity‐based control on dynamic visual feedback systems with movable camera configuration

AbstractThis paper deals with control of dynamic visual feedback systems with a movable camera configuration. This configuration consists of a robot manipulator and a camera that is attached to the end‐effector of another robot manipulator. This system, which can be interpreted as the dynamic visual feedback system with an eye‐in‐hand configuration and a fixed camera one as a special case, can enlarge the field of view. First, the dynamic visual feedback system with an eye‐to‐hand configuration is given with the fundamental representation of a relative rigid body motion. Second, we construct the dynamic visual feedback system with a movable camera configuration by combining the camera control error system. Next, we derive the passivity of the dynamic visual feedback system. Based on the passivity, stability and L2‐gain performance analysis are discussed. Finally the validity of the proposed control law can be confirmed by comparing the experimental results. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(6): 1–11, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10091

Time-delay Positive Feedback Control for Nonlinear Time-delay Systems with Neural Network Compensation

摘要: A new adaptive time-delay positive feedback controller (ATPFC) is presented for a class of nonlinear time-delay systems. The proposed control scheme consists of a neural networks-based identification and a time-delay positive feedback controller. Two high-order neural networks (HONN) incorporated with a special dynamic identification model are employed to identify the nonlinear system. Based on the identified model, local linearization compensation is used to deal with the unknown nonlinearity of the system. A time-delay-free inverse model of the linearized system and a desired reference model are utilized to constitute the feedback controller, which can lead the system output to track the trajectory of a reference model. Rigorous stability analysis for both the identification and the tracking error of the closed-loop control system is provided by means of Lyapunov stability criterion. Simulation results are included to demonstrate the effectiveness of the proposed scheme. 关键词: Time-delay system / neural networks / system identification / adaptive control / linearization compensation

Adaptive Fuzzy Sliding Controller with Dynamic Compensation for Multi-Axis Machining

The precision of multi-axis machining is deeply influenced by the tracking error of multi-axis control system. Since the multi-axis machine tools have nonlinear and time-varying behaviors, it is difficult to establish an accurate dynamic model for multi-axis control system design. In this paper, a novel adaptive fuzzy sliding model controller with dynamic compensation is proposed to reduce tracking error and to improve precision of multi-axis machining. The major ad-vantage of this approach is to achieve a high following speed without overshooting while maintaining a continuous CNC machine tool process. The adaptive fuzzy tuning rules are derived from a Lyapunov function to guarantee stability of the control system. The experimental results on GJ-110 show that the proposed control scheme effectively minimizes tracking errors of the CNC system with control performance surpassing that of a traditional PID controller.

Improving contouring accuracy by tuning gains for a bi-axial CNC machine

Contour errors in continuous-path computer numerical control (CNC) systems usually result from unmatched axial dynamics and undesirable nonlinearities. The errors due to unmatched dynamics can be largely reduced by using a simple controller so as to keep the order of axial dynamics low and by tuning appropriately the proportional gains to match the dynamics. Experimental results show that the resulting matched axial dynamics can, on one hand, effectively eliminate the linear contour errors, and, on the other hand, largely reduce the circular contour errors due to unmatched axial dynamics. On the basis of the matched axial dynamics, circular contours will be made circular with accuracies greatly improved. However, because of limitation in the bandwidths of the axial dynamics, there will be radial contour errors. The radial contour error can be further reduced by a simple approach of feedforward compensation. Experiments conducted show the effectiveness of feedforward compensation in improving circular contouring accuracies.

Time-delay Positive Feedback Control for Nonlinear Time-delay Systems with Neural Network Compensation

A new adaptive time-delay positive feedback controller (ATPFC) is presented for a class of nonlinear time-delay systems. The proposed control scheme consists of a neural networks-based identification and a time-delay positive feedback controller. Two high-order neural networks (HONN) incorporated with a special dynamic identification model are employed to identify the nonlinear system. Based on the identified model, local linearization compensation is used to deal with the unknown nonlinearity of the system. A time-delay-free inverse model of the linearized system and a desired reference model are utilized to constitute the feedback controller, which can lead the system output to track the trajectory of a reference model. Rigorous stability analysis for both the identification and the tracking error of the closed-loop control system is provided by means of Lyapunov stability criterion. Simulation results are included to demonstrate the effectiveness of the proposed scheme.

Disturbance Rejection and Set-point Following of Periodic Signals Using Predictive Control with Constraints

This paper proposes a continuous-time model predictive control design for disturbance rejection and set-point following of periodic signals. By assuming input disturbance in the form of sinusoid, the periodic frequency is embedded into the design model. Hence, from internal model principle, the steady-state error of the model predictive control system is ensured to be zero for both disturbance rejection and set-point following. Furthermore, with the design framework of model predictive control, hard constraints on the derivative and amplitude of the control signals are imposed as part of the performance specification. Simulation studies have been used to show the efficacy of the design with or without hard constraints.

Passivity-based Control of Dynamic Visual Feedback Systems with Movable Camera Configuration

This paper deals with control of dynamic visual feedback systems with a movable camera configuration. This configuration consists of a robot manipulator and a camera that is attached to the end-effector of another robot manipulator. This system which can be interpreted the dynamic visual feedback system with an eye-in-hand configuration and a fixed camera one as a special case, can enlarge the field of view. Firstly the dynamic visual feedback system with an eye-to-hand configuration is given with the fundamental representation of a relative rigid body motion. Secondly we construct the dynamic visual feedback system with a movable camera configuration by combining the camera control error system. Next, we derive the passivity of the dynamic visual feedback system. Based on the passivity, stability and L2-gain performance analysis are discussed. Finally the validity of the proposed control law can be confirmed by comparing the experimental results.

Application of Improved Fuzzy Controller in Networked Control System

Abstract Aiming at the problem of network-induced delay and data dropout in networked control system, an improved fuzzy controller is proposed in this paper. Considering the great influence of a controller on the performance of control system, an improved controller with a second order fuzzy controller and network-induced delay compensator being added to the basic fuzzy controller is proposed to realize self-regulation on-line. For this type of controller, neither plant model nor measurement of network delay is required. So it is capable of automatically adjusting quantified factor, proportional factor, and integral factor according to the control system error and its derivative. The design makes full use of the advantages of quickness in operation and reduction of steady state error because of its integral function. The controller has a good control effect on time-delay and can keep a better performance by self-regulation on-line in the network with data dropout and interference. It is good in quickness, adaptability, and robustness, which is favorable for controlling the long time-delay system.

5129 ギヤチェッカーの検査における誤差要因の影響評価および校正法 : VGCによる評価(S63-5 振動(1),S63 伝動装置の基礎と応用)

Tooth flank form deviation of micrometers influences vibration and noise characteristics of gears. Its precise measurement is, therefore, crucial in quality control, but the calibration system of gear checker with the appropriate traceability and uncertainty evaluation is not established yet in the sense of ISO standard. Virtual Gear Checker (VGC) is a computer program considering mechanics and possible error factors of real gear checkers, such as form error of component, movement error, sensing error and control system error. In this research, influence of error factors on measurement of gear checker is estimated using VGC, effective error factors are clarified and calibration method of gear checker is proposed.

An average operator-based PD-type iterative learning control for variable initial state error

This note studies the effect of variable initial state error in iterative learning control (ILC) systems and proposes a new ILC algorithm based on an average operator. Then, it is shown that, when the proposed algorithm is applied to linear time-invariant (LTI) systems, the effect of the initial state error can be exactly estimated under a specific condition, while the existing algorithms guarantee only the boundness of the error or the convergence from stochastic point of view. To show the validity of the proposed algorithm, a numerical example is given.

Measurement accuracy in control of segmented-mirror telescopes.

Design concepts for future large optical telescopes have highly segmented primary mirrors, with the out-of-plane degrees of freedom actively controlled. We estimate the contribution to errors in controlling the primary mirror that results from sensor noise and, in particular, compare mechanical measurements of relative segment motion with optical wave-front information. Data from the Keck telescopes are used to obtain realistic estimates of the achievable noise due to mechanical sensors. On the basis of these estimates, mechanical sensors will be more accurate than wave-front information for any of the telescope design concepts currently under consideration, and therefore supplemental wave-front sensors are not required for real-time figure control. Furthermore, control system errors due to sensor noise will not significantly degrade either seeing-limited or diffraction-limited observations.

A study of composite resonance in AC/DC converters

Control-system errors and imbalances in the AC system may generate and magnify abnormal harmonics in the AC-bus voltages and the DC current. In this paper, a technique based on harmonic impedance matrices has been used to simulate the steady-state response of AC/DC converters. The technique allows the computation of converter impedances or admittances viewed from the DC or AC bus. At any operating point, a linear circuit may represent the converter and harmonic magnification factors are calculated. High harmonic magnification indicates the possibility of composite resonance. The impact of a small negative-sequence imbalance in the AC system voltages is shown for a six-pulse current-controlled converter.

Smoothing voter: a novel voting algorithm for handling multiple errors in fault-tolerant control systems

Voting algorithms are used to arbitrate between variant results in a wide range of highly dependable real-time control applications. These applications include N-Modular Redundant hardware systems and diversely designed software systems based on N-Version Programming. The most sophisticated and complex voting algorithms can even tolerate malicious (or Byzantine) variant errors. Voting algorithms can be implemented in either hardware or software depending on the characteristics of the application and the type of voter selected. The behaviour of voting algorithms in multiple error scenarios is considered in this article. Complete disagreement is defined as those cases where no two variant results are the same. A novel algorithm for real-time control applications, the smoothing voter, is introduced and its behaviour compared with three previously published voters. Software implemented error-injection tests, reported here, show that the smoothing voter achieves a compromise between the result selection capabilities of the median voter and the safety features of the majority voter. The smoothing voter is an appropriate voter for applications in which maximising the number of correct outputs and minimising the number of benign errors of the system is the main concern, and a slight degradation in safety can be tolerated.

Evaluation the performance of voting algorithms used in fault tolerant control systems

Redundant application algorithm “variants” are used to minimise errors in fault-tolerant real-time control systems. Voting algorithms arbitrate between variant results to generate a single output. Both variants and voting algorithms can be implemented in either hardware or software. The behaviour of voting algorithms in multiple error scenarios within a Tiple Modular Redundancy (TMR) system is considered in this paper. Complete disagreement is defined as those cases where no two variant results are the same. A special experimental harness to test a range of voters is introduced and the testing method is explained. Several performance measures to evaluate the behaviour of voters are evaluated. The meaning and the degree of usefulness of these performance criteria from the viewpoint of application engineer is explained. Finally various presentation methods from which the strength and weakness points of each voter can be studied are suggested.

Robust, Digital, Nonlinear Control of Magnetic-Levitation Systems

This paper presents a robust, adaptive, nonlinear controller for a class of magnetic-levitation systems, which includes active-magnetic bearings. The controller is analytically and experimentally shown to be superior to a classical linear control system in stability, control effort, step-response performance, robustness to parameter variations, and force-disturbance rejection performance. Using an adaptive backstepping approach, a Lyapunov function is generated along with an adaptive control law such that the nonlinear, closed-loop, continuous system is shown to guarantee stability of the equilibrium and convergence of the parameter estimates to constant values. The control system error coordinates are proven to be bounded in the presence of a bounded force disturbance input. The novelty of this controller is that it is digitally implemented using Euler integrators with anti-windup limits, it is single-input-single-output requiring only a measurement of the position of the levitating object, and it is designed to adaptively estimate not only the uncertain model parameters, but also the constant forces applied to the levitating object in order to ensure robustness to force disturbances. The experimental study was conducted on a single-axis magnetic-levitation device. The controller is shown to be applicable to active-magnetic bearings, under specific conditions, as well as any magnetic-levitation system that can be represented in output-feedback form.

Jet engine fan noise reduction system utilizing electro pneumatic transducers

A jet engine fan noise reduction system. The noise reduction system includes active noise control to suppress fan (15) tone noise of an airplane flyover noise signature. The active noise control includes microphones (1, 11) with acoustic transducers upstream and downstream of the engine fan (15) and fan exit guide vane (16) stage to sense control system errors. Control signals are derived from the fan angular speed or blade passing frequency and the error signal sensed by the acoustic transducers. The control output signals actuate (modulate) air control valves (45) on each side of the fan stage to direct conditioned (pressure and temperature regulated) high pressure primary air flow, thereby producing acoustic cancelling of fan tone noise.

Complete Disagreement in Redundant Real-Time Control Applications

Redundant application algorithm “variants” are used to minimise errors in fault-tolerant real-time control systems. Voting algorithms arbitrate between variant results to select a single, hopefully correct, output. Both variants and voting algorithms can be implemented in either hardware or software. The behaviour of voting algorithms in multiple error scenarios is considered in this paper. Complete disagreement is defined as those cases where no two variant results are the same. A novel algorithm for real-time control applications, the smoothing voter, is introduced and its behaviour compared with previously published algorithms. Software implemented error-injection tests, reported here, show that the smoothing voter achieves a compromise between the result selection capabilities of the median voter and the safety features of the majority voter.