Minimal-order Observer Research Articles

A new approach to static output feedback stabilization of linear dynamic systems

The topic of this study is output feedback control of linear control system with output. Use of condensed forms of the linear system under static output feedback (SOF) control is made to derive sufficient conditions for stabilization. A minimal-order control-free observer is presented.

Multidimensional feedforward compensator for industrial systems through pole assignment regulator and observer

A feedforward-compensator-design technique is presented for industrial control systems. The proposed feedforward compensator can improve dynamic characteristics of multidimensional systems by modifying the input signals. The multidimensional feedforward-compensator design is based on the pole assignment regulator, the minimal-order observer, and the conversion from a closed-loop system to an open-loop system. The effectiveness of the proposed feedforward compensator is demonstrated by a simulation study of temperature control of a thermal power plant and by experiments of the contour control of an articulated robot arm.

A DIALOG-ORIENTED AND GRADIENT-BASED STABILITY MARGIN IN UNCERTAIN SYSTEMS

ABSTRACT Gradients and matricial gradients for optimally increasing the stability margin and the admissible uncertainty of a dynamic system are the targets of this presented article. To design a dynamic system, the gradients are used in a dialog between a system scientist and gradient-based computer support. The stability margin is derived for output state controllers, including regular state controllers. The resonant frequency and the damping factors are investigated as a direct function of the maximum admissible uncertainty. The resulting gradients are extended to observer-assisted controllers, to minimum-order observers, and to dynamic-output state controllers.

B01 宇宙機の能動的内部擾乱除去フィルタ(OS10-1 宇宙機と宇宙構造物の制御)

Inner disturbance compensation is required for high accurate attitude control of spacecrafts. In this paper, an active inner disturbance accommodation filter based on the minimal-order observer is studied, which is useful to estimate and eliminate the inner disturbance. And MDM/MDP method is applied to the feedback control, where MDM/MDP method is one of the robust control strategies to prevent spillover instability. These methods are verified through experiments with a satellite free test bed and numerical simulations.

New sensorless vector control methods based on a new minimum-order flux state observer in the ?D-module? for permanent magnet synchronous motors

This paper proposes new sensorless vector control methods that can be applied to both salient-pole and non-salient-pole permanent magnet synchronous motors (PMSM). The proposed method estimates the phase of rotor flux by the “D-module observer,” which is newly developed for sensorless vector controls of PMSM. The “D-module observer” has the following attractive features. (1) It is a new state observer requiring no additional approximation to the motor mathematical model. (2) It is a minimum-order state observer. (3) Observer gain guaranteeing proper estimation in a wide operating range except for singular zero-speed can be a simple constant, and can be easily designed. (4) It utilizes motor parameters in the simplest manner. (5) Its structure is very simple and is realized at the minimum computing cost. (6) It can be applied to both salient-pole and non-salient-pole PMSM. (7) It can be realized in both rotor and stator reference frames. Detailed designs and analyses for the “D-module observer” and “D-module observer”-based sensorless vector control systems in both rotor and stator reference frames are given. Their validity and usefulness are examined and confirmed through extensive experiments. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(2): 46–62, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20046

On Disturbance Decoupled Observers for Linear Descriptor Systems

Conditions for the existence of disturbance decoupled minimal-order observers for a class of descriptor systems are presented. Basically, these conditions are associated to the solution of a generalized Sylvester equation under a constraint that describes the disturbance decoupling of the estimated state. Thus, under some structural conditions of the considered descriptor system, a sequence of coordinate transformation allows to define a reduced-order normal system. Both eigenstructure assignment and regional pole placement techniques can be applied to solve the constrained reduced-order Sylvester equation. For regional pole placement, a LMI technique is proposed and a illustrative numerical example i reported.

On the solution of a Sylvester equation appearing in descriptor systems control theory

The solution of a generalized Sylvester equation associated to a linear descriptor system and subject to some rank and regional pole-placement constraints, is studied in this paper. Under the hypothesis of strong-detectability of the descriptor system, a sequence of coordinate transformations is proposed such that the considered problem can be solved through a Sylvester equation associated to a detectable reduced-order normal system. Thus, solutions to this equation can be found either by eigenstructure assignment or by regional pole-placement in LMI-type regions of the complex plane. The proposed results are motivated from its use for designing minimal-order observers and for computing output feedback control laws by a particular technique. Some numerical results are reported and possible extensions for the proposed approach are commented.

Minimal-order observer and output-feedback stabilization control design of stochastic nonlinear systems

Minimal-order observer and output-feedback stabilization control design of stochastic nonlinear systems

04/01540 Characteristics of an improved heat-pump cycle for cold regions: Ma, G. and Chai, Q. Applied Energy, 2004, 77, (3), 235–247

Control of the air-handling units (AHU) is required to maintain satisfactory comfort conditions with low energy consumption. In the case of failure in sensor fusion systems of AHUs, full-order observers can be used as the supportive tool to provide an acceptable estimation of state variables. In this paper, a multivariable nonlinear model of the AHU is considered in the presence of uncertainties. The indoor temperature and relative humidity are controlled via manipulation of valve positions of air and cold water flow rates. In proposed hybrid control system, full and minimum-order observers are designed for the estimation of indoor temperature and relative humidity. Also, a regulator for disturbance rejection and a servo system for tracking objectives are presented. Minimum-order observers are designed when one or two states are available. The efficiency of full-order and two minimum-order observers in estimation, regulation and tracking objectives is compared for the nominal and uncertain models. Moreover, it is investigated that how the amount of model uncertainty affects the AHU performance and control inputs. It is generally predicted that when a minimum-order observer with two sensors is used, less control inputs are required. In addition, using full or minimum-order observers guarantees the robust performance of AHUs.

Minimal-order observer and output-feedback stabilization control design of stochastic nonlinear systems

A minimal-order observer and output-feedback stabilization control are given for single-input multi-output stochastic nonlinear systems with unobservable states, unmodelled dynamics and stochastic disturbances. Based on the observer designed, the estimates of all observable states of the system are given, and the convergence of the estimation errors are analyzed. In addition, by using the integrator backstepping approach, an output-feedback stabilization control is constructively designed, and sufficient conditions are obtained under which the closed-loop system is asymptotically stable in the large or bounded in probability, respectively.

スライディングモード制御則との双対性を利用した最小次元オブザーバ設計法

スライディングモード制御則との双対性を利用した最小次元オブザーバ設計法

角速度センサを用いた天井クレーンの振れ角検出(G10-5 計測・制御,G10 機械力学・計測制御部門)

A method is proposed to estimate the sway angel by minimal-order observer using data from an angular velocity sensor mounted on the load. (1) Some parameters which are difficult to identify exist in the crane system. The matrix L which controls an observer is constructed so as not to be influenced by these parameters. (2) The measured angular velocity includes a higher frequency vibration caused by the pitching motion of the load. The pole of the observer is set to minimize this influence. The observer designed in this way is valid for the estimation of the sway angle using angular velocity sensor output.

A visual servoing system with feature prediction using a motion observer

AbstractA visual servo is an eye‐in‐hand robot system that directly uses real‐time visual information for control. This paper proposes a novel visual servoing system with motion observer (MOB)‐based feature prediction. The position of the target object cannot be observed directly. The motion observer is designed as a minimum‐order observer and is useful for high‐performance servoing. The effectiveness of the proposed method is shown by simulations and experiments. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(1): 67–73, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10154

Steering and suspension system of a full car model using fuzzy reasoning and disturbance observers

This paper presents the development of a steering and suspension system of a full car model subject to road and wind disturbances by using fuzzy reasoning and disturbance observers. The time variations of the road and wind disturbances are estimated by using the minimum-order observer. The steering angles of front/rear wheels are determined by using the feed-forward control derived from the disturbance observer for the side force of wind and the feedback control derived from fuzzy reasoning. The suspension controls at front/rear and left/right suspension locations are respectively determined by using fuzzy reasoning. The fuzzy reasoning is based on single input rule modules to reduce fuzzy control rules. The simulation result indicates that the proposed steering and suspension system is very effective in the performance of vehicle maneuverability and ride comfort.

DELAYED FEEDBACK CONTROL WITH A MINIMAL-ORDER OBSERVER FOR STABILIZATION OF CHAOTIC DISCRETE-TIME SYSTEMS

Delayed feedback control (DFC) is a powerful method for stabilizing unstable periodic orbits embedded in chaotic attractors, which uses a small control input fed by the difference between the current state and the delayed state. One drawback of the DFC is known as the odd number limitation; that is, DFC can never stabilize a target unstable fixed point of a chaotic discrete-time system, if the Jacobian of its linearized system around the unstable fixed point has an odd number of real eigenvalues greater than unity. To overcome it, in this paper we propose a dynamic DFC method using output measurements of the chaotic systems. The proposed dynamic DFC is realized by using an output feedback controller with a minimal-order observer that has the least order for estimating the state of the chaotic system from the control input and the output measurements. In addition to the design procedure of the controller, we derive a necessary and sufficient condition for the existence of such controllers.

T-DOF GENERALIZED PREDICTIVE CONTROL AND AN APPLICATION FOR A LARGE DEAD TIME PROCESS OF A THERMAL POWER PLANT

In this paper we describe a two-degree of freedom (T-DOF) configuration of a generalized predictive control (GPC) and an application for an NOx decomposition process of a combined cycle power plant. T-DOF GPC that is designed with feedforward signals, measurable disturbance signals and a reference signal is able to prevent an undesirable action that is caused by the feedforward control. We also describe that the present T-DOF GPC is a similar to the controller with the minimal order observer. We show experimental results accomplished on a commercial power plant.

Visual Servoing System with Feature Prediction using Motion Observer

Visual servo is the eye-in-hand robot system directly using real time visual information for control. In this paper, we propose a novel visual servoing system with Motion Observer (MOB) based Feature Prediction. The position of the target object cannot be directly observed. Motion Observer is designed using a minimum order observer and is useful for high performance servoing. We show the effectiveness of the proposed method is shown through simulations and experiments.

Disturbance Cancellation Control of a Circular Cylinder with Elastic Supports under Vortex-Induced Vibration.

This paper investigates disturbance cancellation control to suppress vortex-induced vibration of a circular cylinder in a cross flow. The controller consists of an optimal regulator and a feedforward control. The external force of the vortex shedding is assumed to be a harmonic force, and the magnitude of the disturbance is estimated by a minimal-order observer for the feedforward control. The cylinder is supported by two pairs of elastic beams, and electro-magnets are used as control devices. Experiments have shown that the present method is effective in reducing the vibration amplitude of circular cylinders. We investigate the effect of frequency error in the observer on disturbance cancellation control.

Digital Control of a Permanent Magnet Synchronous Motor Drive without Mechanical Sensors

The permanent magnet synchronous motor (PMSM) is preferable for servo applications and domestic appliances, where high operating efficiency, low power loss, and ease of maintenance are required; however, the cost of the PMSM drive system is relatively high if mechanical sensors are used to measure the rotor position. In this paper, a minimal-order position observer is applied to the PMSM drive. As the rotor position is estimated with the measurements of the phase currents and line voltages, the expensive mechanical transducers are eradicated. Consequently, the cost of the whole system is reduced and the reliability increased. A number of meaningful issues have been addressed to enforce the theoretical basis of this approach, including the derivation of the discrete plant model, discussion of the modeling error and its influence on state estimation, and stability analysis of the complete system under model uncertainties. Simulation and experimental results under different operating conditions are presented, demonstrating the potential to apply the proposed control and estimation techniques to practical applications.

Dynamic Improvement for Linear Constrained Control Continuous-Time Systems with a State Observer

The main idea of this paper is to apply a dynamic improvement technique to linear constrained control continuous-time systems with a state observer. Two known cases with the full-order observer and the minimal-order observer are used for reconstructing the inaccessible state. This leads to using a large set of initial states where the control saturation does not occur to the cost of a slow dynamic of the closed-loop. As soon as the state tends to the origin, the dynamics becomes better and better while the constraints on the control vector are respected.