Robust command filtered control for course tracking of ships under actuator dynamics with input magnitude and rate saturation

2021 ◽  
pp. 147509022110522
Author(s):  
Qijia Yao
Keyword(s):  
Control Strategy ◽  
Disturbance Observer ◽  
Closed Loop ◽  
Tracking System ◽  
Tracking Error ◽  
Small Region ◽  
Great Difficulty ◽  
Environmental Disturbances ◽  
Actuator Dynamics ◽  
Angle Tracking

This article investigates the course tracking of ships subject to parametric uncertainties and environmental disturbances. Particularly, the actuator dynamics with input magnitude and rate saturation is also considered. When including the actuator dynamics, the ship course tracking system becomes a mismatching system, which brings a great difficulty to the control design. A novel robust command filtered control strategy is presented by incorporating a disturbance observer and an auxiliary anti-saturation system into the command filtered backstepping control architecture. The disturbance observer is designed to compensate for the mismatched lumped disturbance. The auxiliary anti-saturation system is introduced to tackle the effects of input magnitude and rate saturation. It is strictly proved that all the closed-loop error signals under the proposed controller are uniformly ultimately bounded and the course angle tracking error can converge to the adjustable small region around the origin. Moreover, the proposed controller is computationally simple and has the strong robustness against uncertainties and disturbances. The effectiveness and advantages of the proposed control strategy are verified through simulations and comparisons.

Adaptive sliding tracking control for nonlinear uncertain robotic systems with unknown actuator nonlinearities

Robotica ◽  
2021 ◽  
pp. 1-20
Author(s):  
Shubo Liu ◽  
Guoquan Liu ◽  
Shengbiao Wu
Keyword(s):  
Control Problem ◽  
Prior Knowledge ◽  
Control Strategy ◽  
Tracking Control ◽  
Disturbance Observer ◽  
Tracking Error ◽  
Small Neighborhood ◽  
Robotic Systems ◽  
Actuator Nonlinearities ◽  
Simulation Results

Abstract This study is concerned with the tracking control problem for nonlinear uncertain robotic systems in the presence of unknown actuator nonlinearities. A novel adaptive sliding controller is designed based on a robust disturbance observer without any prior knowledge of actuator nonlinearities and system dynamics. The proposed control strategy can guarantee that the tracking error eventually converges to an arbitrarily small neighborhood of zero. Simulation results are included to demonstrate the effectiveness and superiority of the proposed strategy.

Strictly-lower-convex-function-constructing disturbance observer based adaptive back stepping control for hypersonic flight vehicles

2017 ◽  
Vol 232 (13) ◽  
pp. 2552-2564
Author(s):  
Jingxing Zuo ◽  
Yunjie Wu ◽  
Lianghua Sun
Keyword(s):  
Convex Function ◽  
Flight Control ◽  
Disturbance Observer ◽  
Sliding Mode ◽  
Tracking Error ◽  
Small Region ◽  
Control Laws ◽  
Hypersonic Flight ◽  
Flight Vehicles ◽  
Adaptive Laws

This study concerns with the attitude and velocity tracking control problem for the longitudinal model of hypersonic flight vehicles, which is nonlinear in aerodynamics with model uncertainties and external disturbances. By employing back stepping sliding mode method and the strictly-lower-convex-function-constructing nonlinear disturbance observer (SNDOB), a novel composite controller is proposed to guarantee the system tracking error to converge to a small region containing the origin. Besides, several proper adaptive laws are also introduced to make the controller avoid of the differential explosion problem and be chatter-free. Compared with other robust flight control approaches, key novelties of the developed method are that one new SNDOB is proposed and drawn into the virtual control laws at each step to compensate the disturbances and that adaptive laws are utilized to simplify the tedious and complicated differential operations. Finally, it is demonstrated by the simulation results that the new method exhibits not only an excellent robustness but also a better disturbance rejection performance than the convention approach.

scholarly journals Composite Immersion and Invariance Based Adaptive Attitude Control of Asteroid-Orbiting Spacecraft in Elliptic Orbit

2021 ◽  
Author(s):  
Keum W Lee ◽  
Sahjendra N Singh
Keyword(s):  
Attitude Control ◽  
Closed Loop ◽  
Tracking Error ◽  
Loop System ◽  
Closed Loop System ◽  
Immersion And Invariance ◽  
State Dependent ◽  
Dependent Vector ◽  
Yaw Angle ◽  
Angle Tracking

Abstract This paper proposes a new composite noncertainty-equivalence adaptive (CNCEA) control system for the attitude (roll, pitch, and yaw angle) control of a spacecraft in an orbit around a uniformly rotating asteroid based on the immersion and invariance (I&I) theory. For the design, it is assumed that the asteroid's gravitational parameters and the spacecraft's inertia matrix are not known. In contrast to certainty-equivalence adaptive (CEA) or noncertainty-equivalence adaptive (NCEA) systems, the CNCEA attitude control system's composite identifier uses the attitude angle tracking error, a nonlinear state-dependent vector function, and model prediction error for parameter estimation. The Lyapunov analysis shows that in the closed-loop system, the Euler angles asymptotically track the reference attitude trajectories. Interestingly, there exist two parameter error-dependent attractive manifolds, to which the closed-loop system's trajectories converge. Moreover, the composite identifier using two types of error signals provides stronger stability properties in the closed-loop system. Simulation results are presented for the attitude control of a spacecraft orbiting in the vicinity of the asteroid 433 Eros. These results show precise nadir pointing attitude regulation, despite uncertainties in the system.

Disturbance observer based dynamic surface flight control for an uncertain aircraft

2017 ◽  
Vol 232 (4) ◽  
pp. 729-744 ◽  
Author(s):  
Jianjun Ma ◽  
Peng Li ◽  
Zhiqiang Zheng
Keyword(s):  
Flight Control ◽  
Disturbance Observer ◽  
Sliding Mode ◽  
Tracking Error ◽  
Small Neighborhood ◽  
Dynamic Surface ◽  
Nonlinear Disturbance Observer ◽  
Actuator Dynamics ◽  
Highly Nonlinear ◽  
Nonlinear Disturbance

To handle the flight control problem of an uncertain aircraft with highly nonlinear characteristics, internal uncertainties and external disturbances, an adaptive dynamic surface controller based on nonlinear disturbance observer is designed in this paper. A novel nonhomogeneous nonlinear disturbance observer is designed to approximate the uncertainties and disturbances, which can exactly estimate the disturbances in finite time. Dynamic surface control is utilized to avoid the explosion of complexity in traditional backstepping design. Through Lyapunov synthesis, the closed-loop control system is demonstrated to be semi-globally uniformly ultimately bounded and the tracking error converges to a small neighborhood of origin. Besides, actuator dynamics are taken into account, and the controller for actuator dynamics with consideration of limitation is developed based on sliding-mode control theory. The effectiveness of the proposed control is shown by simulation experiments.

Guidance laws based on model predictive control and target manoeuvre estimator

2016 ◽  
Vol 38 (12) ◽  
pp. 1509-1519 ◽  
Author(s):  
Shaoming He ◽  
Defu Lin
Keyword(s):  
Stability Analysis ◽  
Model Predictive Control ◽  
Predictive Control ◽  
Angular Rate ◽  
Tracking Error ◽  
Small Region ◽  
Line Of Sight ◽  
Guidance Law ◽  
Angle Tracking ◽  
Guidance Laws

A new composite guidance law for intercepting manoeuvring targets with desired terminal line-of-sight (LOS) angle constraint is proposed in this paper. The presented guidance law is derived through generalized model predictive control (GMPC) augmented by a target manoeuvre estimator. More specifically, the target manoeuvre estimator is used to estimate and compensate for the unknown target manoeuvre online while the GMPC is used to obtain optimal LOS angle tracking performance. Stability analysis shows that the LOS angle tracking error and the LOS angular rate can converge to a sufficiently small region around zero asymptotically. The effectiveness of the proposed guidance law is validated by applying it to a surface-to-air missile for intercepting a head-on manoeuvring target under different scenarios.

Finite-time disturbance observer–based funnel voltage control strategy for vehicle-to-grid inverter in islanded mode

2021 ◽  
pp. 095965182110173
Author(s):  
Yuchen Dai ◽  
Liyan Zhang ◽  
Guofu Liu ◽  
Dezhi Xu ◽  
Chengshun Yang
Keyword(s):  
Control Strategy ◽  
Finite Time ◽  
Disturbance Observer ◽  
Sliding Mode ◽  
Tracking Error ◽  
Voltage Control ◽  
Lyapunov Theory ◽  
Voltage Control Strategy ◽  
Power Sources ◽  
Vehicle To Grid

Based on vehicle-to-grid technology, electric vehicles can be used as power sources in the case of power failure. With the aim to reduce voltage overshoot and improve the anti-disturbance ability of the vehicle-to-grid inverter, a high-performance voltage control strategy based on funnel control and finite-time disturbance observer is developed. First, the dynamic model of the inverter in dq-frame is established, and the lumped disturbance including the unmodeled part is considered. Next, a novel funnel variable is proposed to ensure that the voltage tracking error can be stabilized within the prescribed funnel boundary, and thus enhance the transient performance. Then, a novel finite-time disturbance observer is designed to estimate the lumped disturbance in the system such as load fluctuations, and improve the anti-disturbance ability of the controller. Moreover, the second-order sliding mode differentiator is introduced to estimate the derivative of the virtual control law and eliminate the explosion of complexity problem in the derivation process. Finally, the finite-time stability of the proposed voltage control strategy is analyzed via the Lyapunov theory. The effectiveness of the proposed control strategy is verified by two cases.

Studying noise immunity of radio information transmission systems with noise-like phase-shift keyed signals and synchronization delay errors

2019 ◽  
pp. 105-113
Author(s):  
G. N. Maltsev ◽  
A. V. Evteev
Keyword(s):  
Phase Shift ◽  
Information Transmission ◽  
Noise Immunity ◽  
Tracking System ◽  
Tracking Error ◽  
Information Symbol ◽  
Transmission Systems ◽  
Synchronization System ◽  
Correlation Receiver ◽  
Selection Of

Introduction: Radio information transmission systems with noise-like phase-shift keyed signals based on pseudo-random sequences have potential noise immunity provided by accurately tracking the delay of the received signal in the correlation receiver. When working with moving objects, the delay of the received signal varies continuously, and the reception quality for noise-like phase-shifted signals highly depends on the synchronization system operation and on the accuracy of estimating the received signal delay by the tracking system. To ensure the required signal reception quality, it is necessary to provide an informed choice of tracking system parameters, taking into account their effects, which are the random and systematic components of the delay tracking error, on the selected noise immunity indicator.Purpose: Analyzing how the errors in tracking the delay of a received phase-shift keyed signal based on a pseudorandom sequence by the synchronization system of a radio information transmission system can affect the probability of erroneous reception of an information symbol.Results: The calculation method was used to obtain families of dependencies of the probability of erroneous reception of an information symbol on the signal-noise ratio (SNR), and the values of the random and systematic components of the delay tracking error which are normalized to the capture band of the correlation receiver. It has been shown that at a fixed SNR, the values of the random and systematic components of the delay tracking error are critical for the erroneous reception probability. In all the cases discussed, all the dependencies are characterized by a slow change of the erroneous reception probability while the synchronization errors within the area of small SNR have fixed values. As the SNR value grows, the erroneous reception probability rapidly drops. To ensure the specified signal reception quality and the reliability of the selection of information symbols and messages in a radio information transmission system with noise-like phase-manipulated signals, its synchronization system requires a joint selection of the tracking system parameters, taking into account the limitations imposed by the operating conditions and technical implementation features.Practical relevance: The obtained results can be used in noise immunity analysis of radio information transmission systems with noise-like phase-shift keyed signals in a wide range of communication conditions, and in providing technical solutions for synchronization systems ensuring the required quality of signal reception.

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