Showing papers on "Open-loop controller published in 2004"
1 Jan 2004
TL;DR: The problem of (asymptotic) stabilization of mechanical systems with underactuation degree one is considered and a state-feedback design is derived applying the interconnection and damping assignment passivity-based control methodology that endows the closed-loop system with a Hamiltonian structure with desired potential and kinetic energy functions.
Abstract: We consider the problem of (asymptotic) stabilization of mechanical systems with underactuation degree one. A state-feedback design is derived applying the interconnection and damping assignment passivity-based control methodology. Its application relies on the possibility of solving a set of partial differential equations that identify the energy functions that can be assigned to the closed-loop. The following results are established: 1) identification - in terms of some algebraic inequalities - of a subclass of these systems for which the partial differential equations are trivially solved; 2) characterization of all systems which are feedback-equivalent to this subclass; and 3) introduction of a suitable parametrization of the assignable energy functions that provides the designer with a handle to address transient performance and robustness issues. An additional feature of our developments is that the open-loop system need not be described by a port-controlled Hamiltonian (or Lagrangian) model, a situation that arises often in applications due to model reductions or preliminary feedbacks that destroy the structure. The new result is applied to obtain an (almost) globally stabilizing controller for the inertia wheel pendulum, a controller for the chariot with pendulum system that can swing-up the pendulum from any position in the upper half plane and stop the chariot at any desired location, and an (almost) globally stabilizing scheme for the vertical takeoff and landing aircraft with strong input coupling. In all cases we obtain very simple and intuitive solutions that do not rely on, rather unnatural and technique-driven, linearization or decoupling procedures but instead endows the closed-loop system with a Hamiltonian structure with desired potential and kinetic energy functions.
336 citations
TL;DR: In this paper, an all-digital approach based on the repetitive control technique was proposed for the control of a single-phase shunt active power filter with a full-bridge boost topology.
Abstract: Shunt active power filters have been proved as useful elements to correct distorted currents caused by nonlinear loads in power distribution systems. This work presents an all-digital approach, based on the repetitive control technique, for their control. In particular, a special digital repetitive plug-in controller for odd-harmonic discrete-time periodic references and disturbances is used. This approach does not introduce high gain at those frequencies for which it is not needed, and thus it improves robustness. Additionally, the necessary data memory capacity is lower than in traditional repetitive controllers. The design is performed for the particular case of single-phase shunt active filter with a full-bridge boost topology. Several experimental results are also presented to show the good behavior of the closed-loop system.
251 citations
6 Jul 2004
TL;DR: A dynamic feedback controller is developed to transform the closed loop part of the system into linear, controllable and decoupled subsystem and an estimator of resulting aerodynamic moments via Lyapunov function is developed.
Abstract: A nonlinear dynamic model for a quadrotor unmanned aerial vehicle is presented with a new vision of state parameter control which is based on Euler angles and open loop positions state observer. This method emphasizes on the control of roll, pitch and yaw angle rather than the translational motions of the UAV. For this reason the system has been presented into two cascade partial parts, the first one relates the rotational motion whose the control law is applied in a closed loop form and the other one reflects the translational motion. A dynamic feedback controller is developed to transform the closed loop part of the system into linear, controllable and decoupled subsystem. The wind parameters estimation of the quadrotor is used to avoid more sensors. Hence an estimator of resulting aerodynamic moments via Lyapunov function is developed. Performance and robustness of the proposed controller are tested in simulation.
242 citations
TL;DR: In this paper, a model-based controller for the regulation of a proton exchange membrane (PEM) fuel cell was proposed, which accounts for spatial dependencies of voltage, current, material flows, and temperatures in the fuel channel.
210 citations
TL;DR: Simulation and experimental results verify that the proposed adaptive fuzzy sliding-mode control design method can achieve favorable control performance with regard to parameter variations and external disturbances.
Abstract: An adaptive fuzzy sliding-mode control design method is proposed for induction servomotor system control. The proposed adaptive fuzzy sliding-mode control system is comprised of a fuzzy controller and a compensation controller. The fuzzy controller is the main tracking controller, which is used to approximate an ideal computational controller. The compensation controller is designed to compensate for the difference between the ideal computational controller and the fuzzy controller. A tuning methodology is derived to tune the premise and consequence parts of the fuzzy rules. The online tuning algorithm is derived in the Lyapunov sense; thus, the stability of the control system can be guaranteed. Moreover, to relax the requirement for the uncertain bound in the compensation controller, an estimation mechanism is investigated to observe the uncertain bound, so that the chattering phenomena of the control efforts can be relaxed. To illustrate the effectiveness of the proposed design method, a comparison between a conventional fuzzy control and the proposed adaptive fuzzy sliding-mode control is made. Simulation and experimental results verify that the proposed adaptive fuzzy sliding-mode control design method can achieve favorable control performance with regard to parameter variations and external disturbances.
144 citations
TL;DR: In this paper, a gain-scheduled approach for boiler-turbine controller design is presented to achieve tracking performance in the power output and drum pressure while regulating water level deviation.
143 citations
TL;DR: The feasibility study of upgrading primary feeders from radial and open loop to a normally closed-loop arrangement has been explored in this article, and the required supporting measures for these kinds of upgrading have been listed, and the most suitable and feasible arrangement was recommended to Taipower.
Abstract: The feasibility study of upgrading primary feeders from radial and open loop to a normally closed-loop arrangement have been explored in this paper. First, three possible feeder arrangements for forming a normally closed loop are discussed, and then the factors that may predominantly affect the system-type upgrading are discussed theoretically. Next, four existing distribution feeders with original radial arrangements, fed by three power transformers that are located at two different distribution substations of Taiwan Power Company (Taipower) are employed as sample systems. To form three types of closed-loop arrangement, all of the four radial feeders were tied together at their ends, two feeders at a time. The power flows, voltage profiles and short-circuit capacities of the feeders under both the tie breaker normally open and closed cases have been evaluated, and the impacts of the upgrading of system type on the distribution system and customers assessed. Finally, the required supporting measures for these kinds of upgrading have been listed, and the most suitable and feasible arrangement was recommended to Taipower.
136 citations
28 Sep 2004
TL;DR: Experimental results show that the controller is able to perform autonomously the tasks of taking-off, hovering and landing.
Abstract: In this paper we present a controller design and implementation on a mini-rotorcraft having four rotors A Lagrangian model of the helicopter was used for the controller synthesis The proposed controller is based on Lyapunov analysis Experimental results show that the controller is able to perform autonomously the tasks of taking-off, hovering and landing
133 citations
TL;DR: By introducing a novel reduced-order observer, an output-feedback-based control is constructively designed, which renders the closed-loop system asymptotically stable in the large when the nonlinearities and stochastic disturbance equal zero at the equilibrium point of the open- loop system.
111 citations
TL;DR: In this article, a novel high-performance current controller based on iterative learning was proposed and implemented for variable speed drive applications, which shows improved current tracking without the need for an accurate model.
Abstract: Switched reluctance motors (SRMs) are being considered for variable speed drive applications due to their simple construction and fault-tolerant power-electronic converter configuration. However, inherent torque ripple and the consequent vibration and acoustic noise act against their cause. Most researchers have proposed a cascaded torque control structure for its well-known advantages. In a cascaded control structure, accurate torque control requires accurate current tracking by the inner current controller. As SRM operates in magnetic saturation, the system is highly nonlinear from the control point of view. Developing an accurate current tracking controller for such a nonlinear system is a big challenge. Additionally, the controller should be robust to model inaccuracy, as SRM modeling is very tedious and prone to error. In this paper, we have reviewed various current controllers reported in the literature and discussed their merits and demerits. Subsequently, we have proposed and implemented a novel high-performance current controller based on iterative learning, which shows improved current tracking without the need for an accurate model. Experimental results provided for a 1-hp, 8/6-pole SRM, demonstrate the effectiveness of our proposed scheme.
109 citations
TL;DR: The modularity of the adaptive controller is experimentally demonstrated on a K2A Cybermotion mobile robot that has been modified to allow for the implementation of torque-level control inputs and is evaluated vis-a/spl grave/-vis a least-squares update law.
Abstract: A new adaptive controller is developed for wheeled mobile robots with parametric uncertainty in the dynamic model. The main theoretical contribution is the modular manner in which the control law and parameter update law are designed. This feature allows for design flexibility in the selection of the update law, and can be exploited to improve the transient response of the adaptive controller. The proposed controller also has the important feature of being applicable to both the tracking and regulation problems. The modularity of the adaptive controller is experimentally demonstrated on a K2A Cybermotion mobile robot that has been modified to allow for the implementation of torque-level control inputs. In particular, the adaptive controller with a gradient update law is evaluated vis-a/spl grave/-vis a least-squares update law.
Patent•
21 Jun 2004TL;DR: A vehicle mode controller, a driving mode collecting means, and a plurality of subsystem controllers including an engine management system, transmission controller, steering controller, brake controller, and suspension controller are used in this paper.
Abstract: A vehicle mode controller, a driving mode collecting means, and a plurality of subsystem controllers including an engine management system, a transmission controller, a steering controller, a brakes controller and a suspension controller, provide an improved system and method of operating a vehicle control system in a host vehicle in a manner suitable for a respective driving surface in a plurality of different off-road surfaces and terrains such as might be encountered when driving off-road. An improved method is provided for controlling a vehicle control system by avoiding unplanned combinations of subsystem configuration modes and minimizing the transition time when changing between subsystem configuration modes.
TL;DR: In this paper, a hydraulic actuated clutch control system for commercial cars is analyzed and the design of closed-loop controller is presented, based on a simplified system model and a physical full-order model is also described and used to assess through computer simulations the dependence of the closedloop system performances on some plant and controller key parameters.
6 Jul 2004
TL;DR: This work presents three online controllers for maintaining dynamic stability of a humanoid robot using force/torque sensor, including a damping controller that increases system damping and a landing orientation controller to manage fast and stable ground contact.
Abstract: This work presents three online controllers for maintaining dynamic stability of a humanoid robot using force/torque sensor. Those are damping controller, landing orientation controller and landing position controller. The legs of a humanoid robot are relatively long and serially connected with compliant force/torque sensor at the ankle. This architecture has the inherent characteristics of a lightly damped system. Most research on balance control overlook the deterministic vibration caused by structural compliance. In addition, the vibration was not positively considered to improve the characteristics of the system. Therefore, a simple inverted pendulum model with compliant joint is proposed. For this model, the damping controller that increases system damping is proposed as a balance controller. Furthermore, the performance of maintaining balance against external forces is experimentally shown. A landing orientation controller at the ankle joints is presented to manage fast and stable ground contact. A landing position controller is implemented in order to modify the prescribed trajectory of the swing foot and to reduce the landing impact during unexpected landing. The effectiveness of the proposed controllers is confirmed by walking experiments that has been applied on the KAIST humanoid robot platform KHR-1.
Patent•
20 Jul 2004
TL;DR: A synchronous rectifier PWM (SR-PWM) controller controls a MOSFET in response to the value of a secondary current and the status of a synchronous signal for both discontinuous and continuous operation mode as discussed by the authors.
Abstract: A synchronous rectifier PWM (SR-PWM) controller controls a MOSFET in response to the value of a secondary current and the status of a synchronous signal for both discontinuous and continuous operation mode. The secondary current is generated in a secondary circuit and is detected by two threshold-detection terminals of the SR-PWM controller. The SR-PWM controller produces the synchronous signal by detecting a switching signal of the transformer via a detection terminal of the SR-PWM controller. Furthermore, a delay-time is inserted after the MOSFET is turned off and before the next switching cycle starts to ensure a proper operation of the MOSFET. In one embodiment, an equivalent series resistance (ESR) of an output capacitor can be used as a sensor to detect the secondary current. Therefore, no additional current sensor is required and the efficiency can be improved.
1 Jan 2004
TL;DR: The dynamic feedback controller is based on a suitable combination of passivity based control, flatness and a /spl Sigma/ - /spl Delta/ modulator implementation of the average designed controller and does not require the use of an electromechanical velocity sensor for measuring the angular velocity.
Abstract: This paper considers the development of a smooth "starter" for a DC motor based on a switch controlled DC-to-DC power converter of the "buck" type. The dynamic feedback controller is based on a suitable combination of passivity based control, flatness and a /spl Sigma/ - /spl Delta/ modulator implementation of the average designed controller. The scheme proposes an indirect regulation of the motor shaft speed by means of input current regulation on the "buck" converter circuit. As a consequence, the proposed feedback controller does not require the use of an electromechanical velocity sensor for measuring the angular velocity. The effectiveness of the proposed controller was verified by computer simulations using the P-Spice circuit simulation program.
TL;DR: In this article, the authors present a prototype smart panel with 16 decentralized vibration control units for the reduction of sound radiation/transmission, which consists of a collocated accelerometer sensor and piezoceramic patch actuator with a single channel velocity feedback controller.
TL;DR: In this paper, three different adaptive controllers for a permanent magnet linear synchronous motor (PMLSM) position-control system are proposed, including a backstepping adaptive controller, a self-tuning adaptive controller and a model reference adaptive controller.
Abstract: Three different adaptive controllers for a permanent magnet linear synchronous motor (PMLSM) position-control system are proposed. The proposed controllers include: a backstepping adaptive controller, a self-tuning adaptive controller, and a model reference adaptive controller. The detailed systematic controller design procedures are discussed. A PC-based position control system is implemented. Several experimental results including transient responses, load disturbance responses, and tracking responses of square-wave, sinusoidal-wave, and triangular-wave commands are discussed and compared. The proposed system has a good robustness performance even though the inertia of the system is increased to 10 times. The experimental results validate the theoretical analysis.
TL;DR: In this article, a sliding mode controller is presented to control Lorenz chaos subject to sector nonlinear input, and the proposed control law is robust against both the uncertainty in system parameters and external disturbance.
Abstract: In this paper, a sliding mode controller is presented to control Lorenz chaos subject to sector nonlinear input. The proposed control law is robust against both the uncertainty in system parameters and external disturbance. Simulation results show that the system state can be regulated to a specified point in the state space. It is also seen that the system still possesses the advantage of fast response and good transient performance even though the control input is nonlinear.
21 Nov 2004
TL;DR: In this article, a fuzzy logic proportional plus conventional integral controller is proposed for damping local modes and inter-area modes of oscillation in a multimachine power system, which combines the advantages of a FLC and a conventional PI controller.
Abstract: This paper presents a new approach to the implementation of the effect of FACTS devices on damping local modes and interarea modes of oscillation based on a simple fuzzy logic proportional plus conventional integral controller in a multimachine power system. The proposed controller uses a combination of a FLC and a PI controller. In comparison with the existing fuzzy controllers, the proposed fuzzy controller combines the advantages of a FLC and a conventional PI controller. By applying this controller to the FACTS devices such as UPFC, TCSC and SVC the damping of local modes and interarea modes of oscillations in a multimachine power system will be handled properly. In addition, the paper considers the conventional PI controller and compares its performance with respect to the proposed fuzzy controller. Also the effects of the auxiliary signals in damping multimodal oscillation have been shown. Finally, several fault and load disturbance simulation results are presented to highlight the effectiveness of the proposed FACTS controller in a multimachine power system.
1 Jan 2004
TL;DR: The principle of feedback is introduced together with the popular proportional-integral-derivative controller in a general way and under different forms and its influence on dynamics of simple linear processes is emphasized.
Abstract: The principle of feedback is introduced together with the popular proportional-integral-derivative controller in a general way and under different forms. Its influence on dynamics of simple linear processes is emphasized.
Patent•
7 Oct 2004
TL;DR: In this article, a power converter includes a switch and a controller, which switches electrical power in the power converter and generates a switching signal to control the switch in response to a voltage control loop and a second feedback signal associated with a current control loop.
Abstract: A power converter includes a switch and a controller. The switch switches electrical power in the power converter. The controller generates a switching signal to control the switch in response to a first feedback signal associated with a voltage control loop and a second feedback signal associated with a current control loop. The controller can also allow the switching frequency to hop from frequency to frequency according to a digital pattern.
TL;DR: In this article, a robust statCOM voltage controller design for power system damping is presented, which is carried out applying robustness criteria for stability and performance, and the robust design has been demonstrated to provide extremely good damping characteristics over a range of operating conditions.
TL;DR: In this paper, an adaptive fuzzy logic controller (AFLC) is proposed for precision contour machining which adjusts both input and output membership functions simultaneously, according to a continuous measurement of the performance of the controller itself and estimated disturbance values.
8 Dec 2004
TL;DR: Different approaches to improve efficiency in vector controlled induction motor drives at steady state condition are compared and fuzzy search controller presented a good trade off between convergence time and oscillations of stator current ripple is compared.
Abstract: This paper deals with energy optimization of induction motor drives. In many applications, efficiency optimization of induction motors represents an important factor of control especially for autonomous electrical traction. In this paper different approaches to improve efficiency in vector controlled induction motor drives at steady state condition are compared. Three methods are possible to control the excitation: Methods based on induction motor losses, methods based on the use of look-up table and methods based on search controllers of minimum. We expose in this paper some methods, which use the search controller techniques. These techniques consist in changing flux level in small steps to keep the output power of the motor constant and find the minimum of input power. These controllers are efficient at steady state condition and do not require knowledge of motor and converter parameters. However, the search controller using the stator current instead of power give similar results to their using power. This technique is less complex and doesn't need measurement of PWM quantities. The proposed search controller is based on fuzzy algorithm. The advantages of this controller are compared with others known as Rosenbrock method and Golden section. Fuzzy search controller presents a good trade off between convergence time and oscillations of stator current ripple.
1 Jan 2004
TL;DR: The proposed controller can handle the new flexibility introduced by new powertrain configurations, this is shown by using the same controller on two different vehicle configurations.
Abstract: In this paper a vehicle motion controller is presented. The idea is to use generalized forces acting on the center of gravity of the vehicle and then use a control allocation-like method to distribute the generalized forces to wheel forces. The controller is designed based on feedback linearization of a simple vehicle model. The performance of the controller is evaluated by simulations on a more complex vehicle model. The proposed controller can handle the new flexibility introduced by new powertrain configurations, this is shown by using the same controller on two different vehicle configurations.
TL;DR: In this paper, a fuzzy logic unit (FLU) is used to generate the required weightage for the transient controller and voltage controller to prevent electric power system losing synchronism after a large sudden fault and to achieve good post-fault voltage level.
Patent•
14 Jan 2004TL;DR: In this paper, a media access controller with a power-save mode is presented, which minimizes power loss by disabling clocks applied to all blocks, including CPU, during the power save mode.
Abstract: There is provided a media access controller with a power-save mode. Particularly, the media access controller of the present invention minimizes power loss by disabling clocks applied to all blocks, including CPU, of the media access controller during the power-save mode. The media access controller of the present invention includes: a power-save master for securing stable transmission/reception of data through bus by respective processors contained in the controller; a wake-up timer for noticing that the power-save mode is expired; a power control unit for determining whether to supply a power to a phase-locked loop, and a timing when clocks for the media access controller are applied and disabled; and a locktime register for storing a locktime when an output of the phase-locked loop is settled. Additionally, there is provided a method of efficiently changing the media access controller from the active mode to the power-save mode, and vice versa.
7 Jun 2004
TL;DR: This paper implements the intelligent controller hardware such as a neural network controller with an FPGA based general purpose controller and a DSP board to solve nonlinear control problems.
Abstract: In this paper, we implement the intelligent controller hardware such as a neural network controller with an FPGA based general purpose controller and a DSP board to solve nonlinear control problems. The designed control hardware can perform a real time control of the backpropagation learning algorithm of a neural network. The basic PID control algorithms are implemented in an FPGA chip and a neural network controller is implemented in a DSP board. By using high capacity of an FPGA, the additional hardware such as an encoder counter and a PWM generator can be implemented in a single FPGA device. As a result, the controller is very cost effective. In order to show the performance of the controller, it was tested for controlling nonlinear systems such as an inverted pendulum.
Patent•
26 Jan 2004
TL;DR: In this article, an upper-level controller is adapted to automatically assign each lower-layer controller a unique communication address, which enables the upperlevel controller to send messages over the communication bus (146) to individual ones of the lower-level controllers.
Abstract: A conveyor system, and method of controlling the conveyor system, includes providing a conveying surface (58), at least one motor (52a) propelling the conveying surface and a plurality of lower-level controllers (106). At least one of the lower-level controllers adapted to control the at least one motor. An upper-level controller (108) is provided in communication with the plurality of lower-level controllers (106). The upper- level controller is adapted to send communications to the lower-level controllers for controlling the at least one motor (52a). A communication bus is provided that carries the communications between the upper-level controller and the lower-level controllers. The upper-level controller is adapted to automatically assign each lower-level controller a unique communication address. The unique communication address enables the upper-level controller to send messages over the communication bus (146) to individual ones of the lower-level controllers.