Class Of Control Laws Research Articles

Robust Nonlinear Model Predictive Control for Regulation of Microalgae Culture in a Continuous Photobioreactor

This paper proposes the design of a robust predictive control strategy which guarantees robustness towards parameters mismatch for a simplified macroscopic continuous photobioreactor model, obtained from mass balance based modelling. Firstly, this work is focused on classical robust nonlinear model predictive control law under model parameters uncertainties implying solving min-max optimization problem for setpoint trajectory tracking. Secondly, a new approach is proposed, consisting in reducing the basic min-max problem into a regularized optimization problem based on the use of linearization techniques, to ensure a good trade-off between tracking accuracy and computation time. Finally, the developed control law is compared to classical and robust predictive controllers. Its effciency is illustrated through numerical results and robustness against parameter uncertainties is discussed for the worst case model mismatch.

Hierarchical Control Strategy based on Robust MPC and Integral Sliding mode - Application to a Continuous Photobioreactor

This paper proposes the design of a hierarchical control strategy formed by a two-level controller: a Linearized Robust MPC (LRMPC) and an Integral Sliding Mode (ISM) control laws. The proposed strategy guarantees robustness towards parameters mismatch for a macroscopic continuous photobioreactor model, obtained from mass balance based modelling. Firstly, as a starting point, this work focuses on classical robust nonlinear model predictive control law under model parameters uncertainties implying solving a basic min-max optimization problem for setpoint trajectory tracking. We reduce this problem into a regularized optimization problem based on the use of linearization techniques, to ensure a good trade-off between tracking accuracy and computation time. Secondly, in order to eliminate the static error due to the fact that the nonlinear model is approximated through linearization in the LRMPC law, an ISM controller is synthesized relying on the knowledge of the nonlinear model of the system. Finally, the efficiency of the developed hierarchical approach is illustrated through numerical results and robustness against parameter uncertainties is discussed for the worst case model mismatch.

Fractional order tension control for stable and fast tethered satellite retrieval

The retrieval of a tethered satellite system is intrinsically unstable. This paper develops a new control strategy to retrieve the tethered satellite system stably and quickly using the fractional order control theory. The governing equation of the tethered satellite system and classic linear feedback tension control law were first reviewed and examined as a benchmark. Then, a new fractional order tension control law has been to avoid the tethered satellite winds around the main satellite near the end of retrieval by existing integer order tension control laws. The newly proposed control law has been discretized and implemented by the Laplace transform and Tustin operator. Unlike the existing integer order control laws, which are based on the feedback of current state and memoryless, the fractional order control law has the memory of previous states and thus controls the tether retrieval more smoothly while maintaining the retrieving speed. The effectiveness and advantage of the new fractional order tension control law is demonstrated numerically by comparing with its integer order counterpart. The results show that the new control law not only retrieves the subsatellite without winding around the main satellite, but also provides a better control performance with smaller in-plane libration angles.

Space-Indexed Control for Aircraft Vertical Guidance with Time Constraint

With the growth of civil aviation traffic capacity, safety and environmental considerations urge today for the development of guidance systems with improved accuracy for spatial and temporal trajectory tracking. This should induce increased practical capacity by allowing timely operations at minimum separation standards while at takeoff and landing and trajectory dispersion should be reduced, resulting in better controlled noise impacts on airport surrounding communities. Current civil aviation guidance systems operate with real-time corrective actions to maintain the aircraft trajectory as close as possible to a space-indexed planned trajectory while the flight management system copes indirectly with overfly time constraints. In this paper, the design of new longitudinal guidance laws is considered so that accurate vertical tracking is achieved while overfly time constraints are satisfied. Here, distance to land is adopted as the independent variable for the aircraft flight dynamics since it is today available onboard aircraft with acceptable accuracy. A representation of aircraft longitudinal guidance dynamics is developed according to this spatial variable, and a space-indexed nonlinear inverse control law is established to make the aircraft follow accurately a vertical profile and a desired airspeed. The desired airspeed is defined by an outer space-indexed control loop to make the aircraft overfly different waypoints according to a planned timetable. Numerical simulation experiments with different wind conditions for a transportation aircraft performing a descent approach for landing under this new guidance law are described. The resulting guidance performances are compared with those obtained from a classical time-based guidance control law.

Advances in Modeling and Control of Tethered Unmanned Helicopters to Enhance Hovering Performance

The hovering capabilities of unmanned helicopters can be seriously affected by wind. One possible solution for improving hovering performance under such circumstances is the use of a tethered setup that takes advantage of the tension exerted on the cable that links the helicopter to the ground. This paper presents a more elaborate strategy for helicopter control in this augmented setup, that extends previous work on the subject by the authors. Particularly, a combination of classical PID control laws, together with model inversion blocks, constitutes the basis of the new controller. Additionally, feed-forward action for counteracting rotational couplings is also taken into account. The resulting nonlinear control structure considers also a viscoelastic model of the tether which accurately reproduce the behavior of real ropes. Several simulations under artificially generated wind influences are presented to endorse the validity of the new proposed controller.

Flight dynamics, parametric modelling and real-time control of a 1-DOF Tailplane

This article presents aerodynamic modelling and real-time control of a 1-degree-of-freedom free to pitch Tailplane. The system is designed to serve as an experimental test facility for investigating flight dynamics principles, model validation and different feedback control paradigms. A high-fidelity plant model is an important first step in many flight-related applications such as control system design, analyses and pilot training. To achieve these objectives, a detailed study is conducted employing analytical as well as system identification (SI) techniques. Analytical approach although less accurate complements SI process. This synergy is exploited along with statistical and time domain tests to arrive at a high-fidelity model. It is demonstrated that such an integrated approach is suitable for modelling a class of unmanned air vehicles. The SI model is then employed for controller synthesis. Finally, real-time pitch control under stick command is demonstrated utilizing classical proportional integrator control law.

A system for controlling the boiler heat load

The system controlling the load of a coal-fired boiler operating in the configuration with a common steam line that is used at cogeneration stations is considered. An analysis method is proposed, and the mathematical description of the controlled plant is obtained. Results obtained from a study of classic and adaptive control laws are presented.

Micro-Helicopter for Long-Distance Missions: Description and Attitude Stabilization

This paper presents the development of a micro coaxial helicopter (MCR UAV) whose main characteristic is that it should be carried by an air shuttle transporter and then released in a desired place far away from the launching site, to develop surveillance missions in hover flight. A real-time embedded system is built in order to validate the proposed aerodynamic prototype, and a classic control law based on a classical backstepping procedure for the dynamic system is implemented to test this vehicle in autonomous flight. Finally, simulation and practical results are presented for hover flight.

Modeling of the relative humidity via functional networks and control of the temperature via classic controls for a bird incubator

The control of the relative humidity and the temperature is important for the birds to be born. It is not easy to control the relative humidity, but it is possible to obtain the measure of the relative humidity as a consequence of the control of the temperature in a bird incubator. In this article, (1) the mathematical model for the control of tem- perature in the bird incubator is presented, (2) a functional network to approximate the relative humidity behavior in the bird incubator is proposed, (3) a control for the tem- perature in the bird incubator is proposed, the error of the proportional control applied to the mathematical model of the temperature of the bird incubator is assured to be uni- formly stable, (4) the comparison results of four classic control laws for the control of the temperature considering the proposed mathematical model of the temperature and the functional network to approximate the relative humidity behavior in the bird incubator are presented.

Vertical rotor for the implementation of control laws

This work presents a new laboratory educational device with which both undergraduates and postgraduates may visualize and test classic control laws and fuzzy logic controllers. A platform can move up and down impelled by a propeller attached to an electric motor. The user chooses the control law and its parameters under which the system is driven. The system is supervised by an uncommon sensoring method: a small camera detects the position of the platform and estimates its speed making use of a simple artificial vision algorithm.

Dealing with mathematical modeling in applied control

The first part of the paper presents some conjectures deduced from o long practice of systems mathematical modeling. So, it is underlined the over-emphasis developed in the sixty years history of classical control on the mathematical model. Two lessons derived from the conservativeness-versatility dualism of the mathematical models versus the mathematical theories in providing the classical control law are advanced. A third reflection concerns the spectacular decreasing of the mathematical model importance in the intelligent control. The second part of the paper shows our arguments in favor of proposed conjectures and intends especially to highlight the new intelligent control paradigm.

Distance-Based and Orientation-Based Visual Servoing From Three Points

This paper is concerned with the use of a spherical-projection model for visual servoing from three points. We propose a new set of six features to control a 6-degree-of-freedom (DOF) robotic system with good decoupling properties. The first part of the set consists of three invariants to camera rotations. These invariants are built using the Cartesian distances between the spherical projections of the three points. The second part of the set corresponds to the angle-axis representation of a rotation matrix measured from the image of two points. Regarding the theoretical comparison with the classical perspective coordinates of points, the new set does not present more singularities. In addition, using the new set inside its nonsingular domain, a classical control law is proven to be optimal for pure rotational motions. The theoretical results and the robustness to points range errors of the new control scheme are validated through simulations and experiments on a 6-DOF robot arm.

Robust scheduled control of longitudinal flight with handling quality satisfaction

AbstractClassic flight control systems are still widely used in the industry because of acquired experience and good understanding of their structure. Nevertheless, with more stringent constraints, it becomes difficult to easily fulfil all the criteria with these classic control laws. On the other hand, modern methods can handle many constraints but fail to produce low order controllers. The following methodology proposed in this paper addresses both classic and modern flight control issues, to offer a solution that leverages the strengths of both approaches. First, an H∞ synthesis is performed in order to get controllers which satisfy handling qualities and are robust with respect to mass and centre of gravity variations. These controllers are then reduced and structured by using robust modal control techniques. In conclusion, a self-scheduling technique is described that will schedule these controllers over the entire flight envelope.

Backstepping Control for Multi-Machine Web Winding System

This work treat the modeling and simulation of non-linear dynamic behavior of a web winding process during traction. We designate by a winding process any system applying the cycles of unwinding, transport, treatment, and winding to various flat products. This system knows several constraints, such as the thermal effects caused by the frictions, and the mechanical effects provoked by metal elongation, that generates dysfunctions due to the influence of the process conditions. Several controllers are considered, including Proportional-integral (PI) and Backstepping control. This paper presents the study of Backstepping controls strategy of the winding system. Our winding system is simulated in MATLAB SIMULINK environment, the results obtained illustrate the efficiency of the proposed control with no overshoot, and the rising time is improved with good disturbances rejections comparing with the classical control law.

Survey on Some Automotive Semi-Active Suspension Control Methods: a Comparative Study on a Single-Corner Model

AbstractIn this paper, we propose an overview and a benchmark of the most classic semi-active suspension control laws. Based on a recent result where the optimal semi-active performance trade-off was derived (see Poussot-Vassal et al. (2010)), here, a complete benchmark to evaluate the main semi-active suspension control design methods is proposed. The present paper gives a quick picture of the present state of the art in the semi-active suspension control field in terms of comfort and road-holding trade-off.

Design and Flight Test Results of Robust Attitude Controller for the ETS-VIII Spacecraft

AbstractThis paper reports the flight test results of robust attitude controller for Engineering Test Satellite VIII (ETS-VIII) spacecraft. The main mission of ETS-VIII is to support next-generation mobile digital communications, and for this purpose it is equipped with two large deployable antenna reflectors and a pair of large solar paddles that rotate around the pitch axis. For the spacecraft, the authors have proposed and demonstrated several control methods based on the advanced control theories for the linear parameter varying multi-input multi-output system. The aim is to develop a baseline for future controller design technology for this class of satellite instead of existing classical PID control laws. This paper describes the on-orbit experiment results and compares these controllers performance.

Autopilot Supported by Nonlinear Model Following Reconfigurable Flight Control System

The reconfigurable flight control system was developed, applying a nonlinear aircraft model following control algorithm to support the autopilot. The model of a six degrees of freedom airplane with nonlinear aerodynamics and second-order dynamics of control system actuators was supplemented by aircraft autopilot based on classical control laws. The autopilot commands the aircraft in normal operations. In failure cases, the control system reconfiguration is performed using comparison of control external loads on damaged aircraft with loads in undamaged aircraft operation. Fuzzy logic method produces the control signals preventing the consequences of failures. The objective of reconfiguration is to continue the performed flight, including maneuvers, and, if this is not possible, to obtain the steady flight. The aircraft simulation model was tested for consistency with the expected flight performance. The selected autopilot functions were validated and reconfiguration applied in selected cases of failures. T...

Global set-point tracking control for a class of nonlinear systems with iISS inverse dynamics

In this paper, we consider the problem of global set-point tracking control for a class of nonlinear systems with dynamic uncertainty. Unlike the existing works, the investigated system is with the integral input-to-state stable (iISS) inverse dynamics and more general uncertain nonlinearities. By using a recursive design method, a partial-state feedback controller is designed. The tuning function technique is applied in this procedure to avoid the overparametrization. It is shown that the developed control procedure could guarantee that the tracking error is driven to the origin and the other signals are bounded. In addition, it can also reduce to a linear or even a classical PI control law under some sufficient conditions. Simulation results are illustrated to show the effectiveness of the proposed algorithm. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society

Experimentally supported 2D systems based iterative learning control law design for error convergence and performance

This paper considers iterative learning control law design for both trial-to-trial error convergence and along the trial performance. It is shown how a class of control laws can be designed using the theory of linear repetitive processes for this problem where the computations are in terms of linear matrix inequalities (LMIs). It is also shown how this setting extends to allow the design of robust control laws in the presence of uncertainty in the dynamics produced along the trials. Results from the experimental application of these laws on a gantry robot performing a pick and place operation are also given.

Fuzzy-Sliding Mode Speed Control for Two Wheels Electric Vehicle Drive

Electric vehicles (EV) are developing fast during this decade due to drastic issues on the protection of environment and the shortage of energy sources, so new technologies allow the development of electric vehicles (EV) by means of electric motors associated with static converters. The proposed propulsion system consists of two induction motors (IM) that ensure the drive of the two back driving wheels. The electronic differential system ensures the robust control of the vehicle behavior on the road. It also allows controlling, independently, every driving wheel to turn at different speeds in any curve. This paper presents the study of an hybrid Fuzzy-sliding mode control (SMC) strategy for the electric vehicle driving wheels, stability improvement, in which the fuzzy logic system replace the discontinuous control action of the classical SMC law. Our electric vehicle fuzzy-sliding mode control's simulated in Matlab SIMULINK environment, the results obtained present the efficiency of the proposed control with no overshoot, the rising time is perfected with good disturbances rejections comparing with the classical control law.