Quasi-optimal robust stabilization of control systems

In this paper, we investigate the problem of semi-global minimal time robust stabilization of analytic control systems with controls entering linearly, by means of a hybrid state feedback law. It is shown that, in the absence of minimal time singular trajectories, the solutions of the closed-loop system converge to the origin in quasi minimal time (for a given bound on the controller) with a robustness property with respect to small measurement noise, external disturbances and actuator noise

Fault estimation and fault-tolerant control for discrete-time dynamic systems

In this paper, a novel discrete-time estimator is proposed, which is employed for simultaneous estimation of system states, and actuator/sensor faults in a discrete-time dynamic system. The existence of the discrete-time simultaneous estimator is proven mathematically. The systematic design procedure for the derivative and proportional observer gains is addressed, enabling the estimation error dynamics to be internally proper and stable, and robust against the effects from the process disturbances, measurement noise, and faults. Based on the estimated fault signals and system states, a discrete-time fault-tolerant design approach is addressed, by which the system may recover the system performance when actuator/sensor faults occur. Finally, the proposed integrated discrete-time fault estimation and fault-tolerant control technique is applied to the vehicle lateral dynamics, which demonstrates the effectiveness of the developed techniques

Robust hybrid global asymptotic stabilization of rigid body dynamics using dual quaternions

A hybrid feedback control scheme is proposed for stabilization of rigid body dynamics (pose and velocities) using unit dual quaternions, in which the dual quaternions and veloc- ities are used for feedback. It is well-known that rigid body attitude control is subject to topological constraints which often result in discontinuous control to avoid the unwinding phenomenon. In contrast, the hybrid scheme allows the controlled system to be robust in the presence of uncertainties, which would otherwise cause chattering about the point of discontinuous control while also ensuring acceptable closed-loop response characteristics. The stability of the closed-loop system is guaranteed through a Lyapunov analysis and the use of invariance principles for hybrid systems. Simulation results for a rigid body model are presented to illustrate the performance of the proposed hybrid dual quaternion feedback control scheme

A survey on fractional order control techniques for unmanned aerial and ground vehicles

In recent years, numerous applications of science and engineering for modeling and control of unmanned aerial vehicles (UAVs) and unmanned ground vehicles (UGVs) systems based on fractional calculus have been realized. The extra fractional order derivative terms allow to optimizing the performance of the systems. The review presented in this paper focuses on the control problems of the UAVs and UGVs that have been addressed by the fractional order techniques over the last decade

Industrial Fieldbus Improvements in Power Distribution and Conducted Noise Immunity With No Extra Costs

Industrial distributed control continues the move toward networks at all levels. At lower levels, control networks provide flexibility, reliability, and low cost, although perhaps the simplest but most important advantage is the reduced volume of wiring. Powered fieldbuses offer particular notable benefits in system wiring simplification. Nevertheless, very few papers are dealing with the potentials and limitations in power distribution through the bus cable. Only a few of the existent fieldbus standards consider this possibility but often simply as an option without enough technical specifications. In fact, nobody talks about it, but power distribution through the bus and conducted noise disturbances are strongly related. This paper points out and analyzes these limitations and proposes a new low-cost fieldbus physical layer that enlarges power distribution capability of the bus and improves system robustness. We show an industrial application on water desalination plants and the very good results obtained owing to the fieldbus. Finally, we present electromagnetic compatibility test results that verify improvements against electrical fast transients on the sensor/actuator connection side as disturbances usually encountered in harsh-environment industrial applications

Disturbance Observer-based Robust Control and Its Applications: 35th Anniversary Overview

Disturbance Observer has been one of the most widely used robust control tools since it was proposed in 1983. This paper introduces the origins of Disturbance Observer and presents a survey of the major results on Disturbance Observer-based robust control in the last thirty-five years. Furthermore, it explains the analysis and synthesis techniques of Disturbance Observer-based robust control for linear and nonlinear systems by using a unified framework. In the last section, this paper presents concluding remarks on Disturbance Observer-based robust control and its engineering applications.Comment: 12 pages, 4 figure

Robust motion control SMC point of view

In this paper the robust motion control systems in the sliding mode framework are discussed. Due to the fact that a motion control system with n d.o.f may be mathematically formulated in a unique way as a system composed of n second order systems, design of such a system may be formulated in a unique way as a requirement that the generalized coordinates must satisfy certain algebraic constraint. Such a formulation leads naturally to sliding mode framework to be applied. In this approach constraint manifolds are selected to coincide with desired constraints on the generalized coordinates. It has been shown that the CMC can be interpreted as a realization of the acceleration controller thus possessing all robust properties of the acceleration controller framework. The possibility to treat both unconstrained motion (the motion without contact with environment) and constrained motion in the same way is shown