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This paper presents a new steering control structure for cars equipped with 4-wheel steering. This control structure is based on a simplified linear model of the lateral dynamics of such cars and aims to decouple the control of sideslip from the control of yaw rate. The control design is based on a linear multivariable plant which incorporates the model of the lateral dynamics mentioned above and...
Two robust control design methodologies are analyzed and compared in this article: the H-infinity control system design and the CRONE control system design. The aim of this article is to give practical considerations that will help a designer to choose between these two methodologies. The example of an electrohydraulic actuator is given in order to evaluate the implementation of each methodology and...
This paper addresses the stabilization problem of an uncertain intrinsically nonlinear SISO plant containing non-smooth nonlinearities (dead-zone, backlash, hysteresis) in the actuator device. A unified framework for its solution is here proposed, assuming that the parameters of the nonlinearities are uncertain as well. To this purpose, the hysteresis model used in [8] has been modified into an “extended”...
In this paper the problem of fatigue mitigation in a slender flexible antenna has been addressed. The structure is subject to wind loads, which cause continuous stress cycles, giving rise to structural fatigue and breakage and reducing the service life. A robust active controller is introduced with the aim to reduce the amplitude of the stress cycles, despite model uncertainties; in particular an...
High performance control of fluid actuator system depends on several important choices, like the model on which the synthesis is based and the control criteria. In the case of the optimal LQG control design, the choice of the weighting matrices determines the closed-loop performances and robustness. In the present paper a methodology of LQG synthesis inspired from the literature is applied on an electro-pneumatic...
This article deals with the association of a linear robust controller and an input-output linearization feedback for the control of a perturbed and non-linear system. This technique is applied to the control of a hydraulic system whose actuator is non-linear and whose load is time-variant. The piston velocity of the actuator needs to be controlled and a pressure-difference inner-loop is used to improve...
This paper is concerned with the problem of fault diagnosis for a class of bilinear stochastic systems with unknown disturbances. At first, the filter with restricted structure is designed so that the unknown disturbances are decoupled from the residual and the effects of process and measurement noises to the residual are minimized. The filter design with general structure is also discussed. The chi-squared...
For many practical reasons, e.g. computational limitations, multirate controllers are frequently used in modern control. The main point of this paper tackles with a new LMI-based method for H∞ multirate controller design. The key point of this method is based on the now well-known result that a multirate problem can be turned via a lifting procedure into an equivalent LTI single rate problem with...
This paper proposes a new approach in order to use the tunnel current as a position sensor at nanoscale. It is shown that electron tunneling commonly used in Scanning Tunneling Microscopes (STM) can be used to control the motion of a Nano Electromechanical System (NEMS) with an accuracy of 1.10−12m/√Hz, at ambient temperature, and using only one electrostatic actuator. The designed control strategy...
The control of systems that involve friction presents interesting challenges. Recent research has focused on detailed modeling of friction phenomena in order to use robust on-line friction compensation procedures, attempting to cancel out the friction force effect in the feedback control. The friction modeling problem remains a very difficult challenge. The friction effect acting in a dynamic system...
A wheel slip controller for ABS brakes is formulated using an explicit constrained LQR design. The controller gain matrices are designed and scheduled on the vehicle speed based on local linearizations. A Lyapunov function for the nonlinear control system is dervied using the Riccati equation solution in order to prove stability and robustness with respect to uncertainty in the road/tyre friction...
This paper investigates the reliable tracking problem against helicopter actuator impairment under different trimming points with parameters uncertainty. First, the model of actuator faults is presented. Then a reliable robust tracking controller design methodology is developed. The algorithm is based on the iterative linear matrix inequalities (ILMIs), which has less conservativeness than the standard...
This paper propose a stabilizing switched controller for an electropneumatic clutch actuator system with input restrictions. These restrictions arise from the fact that the allocation of air to and from the actuator chamber is governed by on/off valves. The derived dual-mode controller is a combination of two previous developed switched controllers for the same system, and asymptotic stability in...
The High Redundancy Actuator (HRA project investigates the use of large numbers of small actuation elements to achieve fault tolerance. The large number of components involved poses a unique challenge from a control perspective. This paper presents the two main options to control the HRA: using robust control (passive fault tolerance), and reconfigurable control (active fault tolerance). The robust...
Fault Tolerant Controls are highly reliable control systems aimed at increasing system reliability and reducing safety hazards. FTCs are designed to accommodate faults at their early stage of development to prevent those minor faults from developing into failures that might jeopardize system stability and availability. FTC design is a topic of active and ongoing research activities with applications...
We report the multiphoton fabrication of hybrid microstructures of photoresist and chemically responsive protein hydrogel for microactuation, such as a lever and a rotary stepper. By two-step direct laser writing (DLW) technology, we combine chemically responsive protein hydrogel with mechanical robust photoresist into pH-responsive hybrid actuators that contain only biocompatible materials. The fabrication...
This paper presents a minimalist, four-finger hand comprised of two pairs of tendon-driven, underactuated fingers decoupled by an independent, central, rotating axis. This mechanical configuration allows for finger-gaiting while also retaining the passive adaptability and other capabilities of the underactuated finger pairs. As a result, the hand, requiring only four actuators, is capable of a unique...
The paper deals with the problem of robust predictive fault-tolerant control for non-linear discrete-time systems described by the Takagi-Sugeno models as well as application to the so-called Twin-Rotor system. Approach proposed in this paper is in fact series of three, i.e. it starts from fault estimation, which is subsequently compensated with a robust controller. While robust controller is designed...
In this paper a novel approach to the design of active controllers aimed at reducing vibrations in helicopter applications is proposed. In particular the role of variability in the vibratory response of the helicopter (such as due to, e.g., varying flight condition and actuator nonlinearities) is taken into account in the synthesis of a robust parameter-varying controller, based on a discrete-time...
In this paper, the robust force control of a solenoid actuator is studied. Such control problem is of interest in the study of gear shifting control in electric vehicles (EVs) equipped with an automated manual transmission (AMT). Experimental system identification together with the finite element method (FEM) is the approach considered in this paper to model the dynamic behavior of the solenoid actuator...
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