Search results for "Control theory"
showing 10 items of 1333 documents
Robust output feedback control of non-collocated low-damped oscillating load
2021
For systems with order of dynamics higher than two and oscillating loads with low damping, a non-collocation of the sensing and control can deteriorate robustness of the feedback and, in worst case, even bring it to instability. Furthermore, for a contactless sensing of the oscillating mechanical load, like in the system under investigation, the control structure is often restricted to the single proportional feedback only. This paper proposes a novel robust feedback control scheme for a low-damped fourth-order system using solely the measured load displacement. For reference tracking, the loop shaping design relies on a band reject filter, while the plant uncertainties are used as robustne…
Cascade Controller Including Backstepping for Hydraulic-Mechanical Systems
2012
Abstract Development of a cascade controller structure including adaptive backstepping for a nonlinear hydraulic-mechanical system is considered in this paper where a dynamic friction (LuGre) model is included to obtain the necessary accuracy. The paper compares the performance of two variants of an adaptive backstepping tracking controller with earlier results. The new control architecture is analysed and enhanced tracking performance is demonstrated when including the extended friction model. The complexity of the backstepping procedure is significantly reduced due to the cascade structure. Hence, the proposed control structure is better suited to real-time implementation.
Experimental nonlinear electrical reaction-diffusion lattice
1998
International audience; A nonlinear electrical reaction-diffusion lattice modelling the Nagumo equation is presented. It is shown that this system supports front propagation with a given velocity. This propagation is observed experimentally using a video acquisition system, and the measured velocity of the front is in perfect agreement with the theoretical prediction.
Canard-cycle transition at a fast–fast passage through a jump point
2014
Abstract We consider transitory canard cycles that consist of a generic breaking mechanism, i.e. a Hopf or a jump breaking mechanism, in combination with a fast–fast passage through a jump point. Such cycle separates two types of canard cycles with a different shape. We obtain upper bounds on the number of periodic orbits that can appear near the canard cycle, and this under very general conditions.
How to control stock markets
1994
This paper provides a different approach to the analysis of imperfect stock markets. The model we are concerned with is described by the interaction of three institutional classes of agents (the specialist trader, the professional trader and the non-professional trader), sharing different information. The dynamical discrete-time system obtained can be changed into a second-order linear difference equation forced by the fundamental value of the specialist trader. Using typical tools of control theory, we study the behaviour of the professional trader’s fundamental value influenced by the specialist’s one. © 1994 Taylor & Francis Group, LLC.
State Estimation of a Mobile Manipulator via Non-uniformly Sampled Position Measurements
2011
Abstract We derive an exact deterministic nonlinear estimator to compute the continuous state of a nonlinear time-varying system based on discrete, non uniformly time spaced, state measurements. The system consists of a robot arm mounted on a mobile non holonomic vehicle. The paper also discusses the effect on the estimation error of a bounded input additive noise.
Architecture to Serve Disabled and Elderly
2013
We propose an architecture (discussed in the context of a dressing and cleaning application for impaired and elderly persons) that combines a cognitive framework that generates motor commands with the MOSAIC architecture which selects the right motor command according to the proper context. The ambition is to have robots able to understand humans intentions (dressing or cleaning intentions), to learn new tasks only by observing humans, and to represent the world around it by using conceptual spaces. The cognitive framework implements the learning by demonstration paradigm and solves the related problem to map the observed movement into the robot motor system. Such framework is assumed to wo…
Safety Assurance of a High Voltage Controller for an Industrial Robotic System
2020
Abstract Due to the risk of discharge sparks and ignition, there are strict rules concerning the safety of high voltage electrostatic systems used in industrial painting robots. In order to assure that the system fulfils its safety requirements, formal verification is an important tool to supplement traditional testing and quality assurance procedures. The work in this paper presents formal verification of the most important safety functions of a high voltage controller. The controller has been modelled as a finite state machine, which was formally verified using two different model checking software tools; Simulink Design Verifier and RoboTool. Five safety critical properties were specifie…
Extended Horizon Adaptive Model Algorithmic Control
1997
Abstract A new, original, robust adaptive control strategy termed Extended Horizon Adaptive Model Algorithmic Control is presented. In EHAMAC, a new, combined, ’single-loop’/’cascade’ adaptive least-squares parameter estimator is coupled with a new, simple but powerful Extended Horizon Model Algorithmic Control so that open-loop stable non-minimum phase systems can be effectively controlled in the time-varying environment. In the new, cascade structure of the ALS estimator, the covariance windup and blowup are totally eliminated. Moreover, the sacramental square-root update of the covariance matrix is no longer needed On the other hand, employing EHMAC facilitates robustness design so that …
Adaptive estimation of Laguerre models with time-varying delay
2000
Abstract An Orthonormal Basis Functions (OBF) approach is effectively used in adaptive parameter estimation of linear(ized) open-loop stable, possibly nonminimum phase plants with time-varying delay. In particular, discrete Laguerre models are considered in detail. A special attention is paid to the numerical conditioning issue in case of ’poor’ excitation of a plant under control, where OBF models are of particular value. Closed-loop predictive control simulations confirm the usefulness of adaptive OBF modelling, especially for systems with time-varying delays.