Search results for " Observer"

Le filtre de Kalman étendu à grand-gain adaptatif et ses applications

2010

The work concerns the “observability problem”—the reconstruction of a dynamic process’s full state from a partially measured state— for nonlinear dynamic systems. The Extended Kalman Filter (EKF) is a widely-used observer for such nonlinear systems. However it suffers from a lack of theoretical justifications and displays poor performance when the estimated state is far from the real state, e.g. due to large perturbations, a poor initial state estimate, etc. . . We propose a solution to these problems, the Adaptive High-Gain (EKF). Observability theory reveals the existence of special representations characterizing nonlinear systems having the observability property. Such representations ar…

Comments on “Finite-Time $H_{\infty }$ Fuzzy Control of Nonlinear Jump Systems With Time Delays Via Dynamic Observer-Based State Feedback”

2014

This paper investigates a defect appearing in “Finite-time H∞ fuzzy control of nonlinear jump systems with time delays via dynamic observer-based state feedback,” which the observer-based finite-time H∞ controller via dynamic observer-based state feedback could not ensuring stochastic finite-time boundedness, and satisfying a prescribed level of H∞ disturbance attenuation for the resulting closed-loop error fuzzy Markov jump systems. The corrected results are presented, and the improved optimal algorithms and new simulation results are also provided in this paper.

State feedback control against sensor faults for Lipschitz nonlinear systems via new sliding mode observer techniques

2011

This paper investigates the problem of simultaneous state and fault estimation and observer-based fault tolerant controller design for Lipschitz nonlinear systems with sensor failure. A new estimation technique is presented in this paper to deal with this design problem. In the proposed approaches, the original system is first augmented by a descriptor model transformation, then a new Proportional and Derivative sliding mode observer technique is developed to obtain accurate estimations of both system states and sensor faults. The designing observer is generalized from the PD observer in [3], but is not a trivial extension. Based on the state estimates, a observer-based control strategy is …

2014

State estimation problem is considered for a kind of wireless network control system with stochastic uncertainty and time delay. A sliding mode observer is designed for the system under the situation that no missing measurement occurs and system uncertainty happens in a stochastic way. The observer designed for the system can guarantee the system states will be driven onto the sliding surface under control law, and the sliding motion of system states on sliding surface will be stable. By constructing proper Lyapunov-Krasovskii functional, sufficient conditions are acquired via linear matrix inequality. Finally, simulation result is employed to show the effectiveness of the proposed method.

A sliding mode approach to H∞ non-fragile observer-based control design for uncertain Markovian neutral-type stochastic systems

2015

This paper is focused on designing an H ∞ sliding-mode control for a class of neutral-type stochastic systems with Markovian switching parameters and nonlinear uncertainties. An H ∞ non-fragile observer subjected to the transition rates of the switching mode is firstly constructed. By some specified matrices, the connections among the designed sliding surfaces corresponding to every mode are established. Then, the state-estimation-based sliding mode control law is designed to guarantee the reachability of the sliding surface in finite time interval. Furthermore, a stochastic stability criterion is established for all admissible uncertainties, which can guarantee the error system and sliding…

A Rotor Flux and Speed Observer for Sensorless Single-Phase Induction Motor Applications

2012

It is usual to find single-phase induction motor (SPIM) in several house, office, shopping, farm, and industry applications, which are become each time more sophisticated and requiring the development of efficient alternatives to improve the operational performance of this machine. Although the rotor flux and rotational speed are essential variables in order to optimize the operation of a SPIM, the use of conventional sensors to measure them is not a viable option. Thus, the adoption of sensorless strategies is the more reasonable proposal for these cases. This paper presents a rotor flux and rotational speed observer for sensorless applications involving SPIMs. Computer simulations and the…

On temporal deixis and cognitive models in early Indo-European

2013

Crosslinguistic evidence suggest that there are two different (often coexistent) basic cognitive models for time, on the basis of which the world’s languages express time in terms of conceptual metaphor from the source spatial domain to the target temporal domain: i) the Time-based (Time-Reference-Point) model, in which time is conceptualized in terms of sequentially arrayed objects moving in space, so that a temporal event is relative to another earlier or later temporal event; ii) the Ego-based (Ego-Reference-Point) model, which is considered to have a more complex structure in which times are conceptualized as objects relative to a canonical deictic observer (Ego) located at the hic et n…

Trajectory robust control of autonomous quadcopters based on model decoupling and disturbance estimation

2021

In this article, a systematic procedure is given for determining a robust motion control law for autonomous quadcopters, starting from an input–output linearizable model. In particular, the suggested technique can be considered as a robust feedback linearization (FL), where the nonlinear state-feedback terms, which contain the aerodynamic forces and moments and other unknown disturbances, are estimated online by means of extended state observers. Therefore, the control system is made robust against unmodelled dynamics and endogenous as well as exogenous disturbances. The desired closed-loop dynamics is obtained by means of pole assignment. To have a feasible control action, that is, the fo…

ROS/Gazebo-Based Simulation of Quadcopter Aircrafts

2018

The main purpose of this work is to present a tutorial description on how to design and develop an observer, which is capable of estimating the position and the orientation of a drone commanded by a controller, whose shape and structure are unknown. Starting from Newton's and Euler's laws, a mathematical model describing the dynamics of a quadcopter has first been obtained. By linearizing this model it is possible to implement a Luenberger observer and validate it with simulations in a Linux environment, thanks to the use of the Ardupilot controller and the Gazebo simulator. Finally, starting from the results obtained from the simulation, it is possible to evaluate the error made in the est…

Wind gust estimation for precise quasi-hovering control of quadrotor aircraft

2021

Abstract This paper focuses on the control of quadrotor vehicles without wind sensors that are required to accurately track low-speed trajectories in the presence of moderate yet unknown wind gusts. By modeling the wind disturbance as exogenous inputs, and assuming that compensation of its effects can be achieved through quasi-static vehicle motions, this paper proposes an innovative estimation and control scheme comprising a linear dynamic filter for the estimation of such unknown inputs and requiring only position and attitude information. The filter is built upon results from Unknown Input Observer theory and allows estimation of wind and vehicle state without measurement of the wind its…