Showing papers on "Open-loop controller published in 2005"

A fixed-frequency pulsewidth modulation based quasi-sliding-mode controller for buck converters

Abstract: This paper presents the design and analysis of a fixed-frequency pulsewidth modulation (PWM)-based quasi-sliding-mode voltage controller for buck converters from a circuit design perspective. A practical design approach that aims at systematizing the procedure for the selection of the control parameters is presented. In addition, a simple analog form of the controller for practical realization is provided. The resulting controller exhibits the same structure as a PWM proportional derivative (PD) linear controller, but with an additional component consisting of the instantaneous input voltage and the instantaneous output voltage. Simulation and experimental results show that the performance of the converter agrees with the theoretical design.

A novel motor drive design for incremental motion system via sliding-mode control method

Abstract: This paper proposes a particular motor position control drive design via a novel sliding-mode controller. The newly designed controller is especially suitable for the motor incremental motion control which is specified by a trapezoidal velocity profile. The novel sliding-mode controller is designed in accordance with the trapezoidal velocity profile to guarantee the desired performance. A motor control system associated PC-based incremental motion controller with permanent-magnet synchronous motor is built to verify the control effect. The validity of the novel incremental motion controller with sliding-mode control method is demonstrated by simulation and experimental results.

On-line adaptive model predictive control in a process control system

Abstract: A method of creating and using an adaptive DMC type or other MPC controller includes using a model switching technique to periodically determine a process model, such as a parameterized process model, for a process loop on-line during operation of the process. The method then uses the process model to generate an MPC control model and creates and downloads an MPC controller algorithm to an MPC controller based on the new control model while the MPC controller is operating on-line. This technique, which is generally applicable to single-loop MPC controllers and is particularly useful in MPC controllers with a control horizon of one or two, enables an MPC controller to be adapted during the normal operation of the process, so as to change the process model on which the MPC controller is based to thereby account for process changes. The adaptive MPC controller is not computationally expensive and can therefore be easily implemented within a distributed controller of a process control system, while providing the same or in some cases better control than a PID controller, especially in dead time dominant process loops, and in process loops that are subject to process model mismatch within the process time to steady state.

Digital current-mode controller for DC-DC converters

Abstract: This paper introduces a digital average current-mode controller architecture based on a low-resolution current A/D converter and a simple digital controller realization. The proposed approach combines advantages of practical digital realization and current-mode control for DC-DC converters operating at high switching frequencies. An experimental test circuit includes an experimental prototype current A/D converter, a controller implemented on an FPGA, and a 6 V-to-1.8 V, 10 A synchronous buck power stage operating at 200 KHz. Experimental verification results are described.

Joint angle control by FES using a feedback error learning controller

Abstract: The feedback error learning (FEL) scheme was studied for a functional electrical stimulation (FES) controller. This FEL controller was a hybrid regulator with a feedforward and a feedback controller. The feedforward controller learned the inverse dynamics of a controlled object from feedback controller outputs while control. A four-layered neural network and the proportional-integral-derivative (PID) controller were used for each controller. The palmar/dorsi-flexion angle of the wrist was controlled in both computer simulation and FES experiments. Some controller parameters, such as the learning speed coefficient and the number of neurons, were determined in simulation using an artificial forward model of the wrist. The forward model was prepared by using a neural network that can imitate responses of subject's wrist to electrical stimulation. Then, six able-bodied subjects' wrist was controlled with the FEL controller by delivering stimuli to one antagonistic muscle pair. Results showed that the FEL controller functioned as expected and performed better than the conventional PID controller adjusted by the Chien, Hrones and Reswick method for a fast movement with the cycle period of 2 s, resulting in decrease of the average tracking error and shortened delay in the response. Furthermore, learning iteration was shortened if the feedforward controller had been trained in advance with the artificial forward model.

Recurrent-neural-network-based adaptive-backstepping control for induction servomotors

Abstract: This study is concerned with the position control of an induction servomotor using a recurrent-neural-network (RNN)-based adaptive-backstepping control (RNABC) system. The adaptive-backstepping approach offers a choice of design tools for the accommodation of system uncertainties and nonlinearities. The RNABC system is comprised of a backstepping controller and a robust controller. The backstepping controller containing an RNN uncertainty observer is the principal controller, and the robust controller is designed to dispel the effect of approximation error introduced by the uncertainty observer. Since the RNN has superior capabilities compared to the feedforward NN for dynamic system identification, it is utilized as the uncertainty observer. In addition, the Taylor linearization technique is employed to increase the learning ability of the RNN. Meanwhile, the adaptation laws of the adaptive-backstepping approach are derived in the sense of the Lyapunov function, thus, the stability of the system can be guaranteed. Finally, simulation and experimental results verify that the proposed RNABC can achieve favorable tracking performance for the induction-servomotor system, even with regard to parameter variations and input-command frequency variation.

System for determining overall heating and cooling system efficienies

Abstract: A computer readable medium with instructions stored on the medium. When the instructions are executed by a processor, they cause the processor to calculate overall efficiency. A system for determining the overall efficiency for a building. The system comprises: an environment system controller with a processor used to calculate overall efficiency; a plurality of indoor temperature sensors in communication with the environment system controller; an outdoor temperature sensor in communication with the environment system controller; an efficiency monitoring device in communication with the environment system controller; and a chronograph configured to time stamp sensor readings.

Evolving controllers for simulated car racing

Abstract: This paper describes the evolution of controllers for racing a simulated radio-controlled car around a track, modelled on a real physical track Five different controller architectures were compared, based on neural networks, force fields and action sequences The controllers use egocentric (first person), Newtonian (third person) or no information about the state of the car (open-loop controller) The only controller that able to evolve good racing behaviour was based on neural network acting on egocentric inputs

A wavelet-based multiresolution PID controller

Abstract: A novel controller based on multiresolution decomposition using wavelets is presented. The controller is similar to a proportional-integral-derivative (PID) controller in principle and application. The output from a motion control system represents the cumulative effect of uncertainties such as measurement noise, frictional variation, and external torque disturbances, which manifest at different scales. The wavelet is used to decompose the error signal into signals at different scales. These signals are then used to compensate for the uncertainties in the plant. This approach provides greater expanse over the degree of control applied to the system. Through hardware and simulation results on motion control systems, this controller is shown to perform better than a PID in terms of its ability to provide smooth control signal, better disturbance, and noise rejection.

Low voltage power line communication for climate control system

Abstract: A system for controlling one or more components of a climate control system is provided that includes one or more controllers in connection with low voltage power lines for powering the one or more controllers. The controllers are further capable of transmitting one or more communication signals via the low voltage waveform. The system includes a thermostat controller, at least one system controller for a heating or cooling system, and a controller for a circulating air blower. The thermostat controller, system controller and circulating air blower controller are connected to each other only through each controller's individual connection to the hot and common low voltage power transmission lines. Each controller is capable of transmitting one or more signals that are superimposed onto the low-frequency low-voltage waveform and include information identifying a destination controller that the signals are intended for.

Model-based multirate controllers design

Abstract: In many industrial control applications the control action updating can be faster than the output measurement, leading to multirate controllers. In this paper, some dual rate operations are used to model the controller as well as the controlled plant. The controller design is model-based and depends on the input to be tracked. The controller is split into two parts acting at different sampling rates and its design is approached based on the characteristics of each available sampling rate. The control target is to reach the similar performances to those the faster single rate controller would achieve. Model-based cancellation controllers are designed using this approach and promising results are obtained.

H/sup /spl infin// control and estimation with preview-part I: matrix ARE solutions in continuous time

Abstract: Preview control and fixed-lag smoothing allow a noncausal component in the controller/estimator. Time domain variational analysis is used in a reduction to an open loop differential game, leading to a complete, necessary and sufficient characterization of suboptimal values and an explicit state space design, in terms of a parameterized (nonstandard) algebraic matrix Riccati equation in a general continuous time linear system setting. The solution offers insight into the appropriate structure of the associated Hamiltonian, where the state and co-state are not the usual state of the original dynamic system and that of its adjoint. Rather, the state and co-state are selected to capture the respective lumped effects of initial data and future input selection in the allied game.

Control by interconnection of mixed port Hamiltonian systems

Abstract: In this note, the regulation problem for mixed finite and infinite dimensional port Hamiltonian systems (m-pH systems) is discussed. A m-pH system results from the power conserving interconnection of finite and infinite dimensional systems in port Hamiltonian form. In particular, the system given by the interconnection of two finite dimensional systems, one of which is the controller, by means of an infinite dimensional connection is studied. The proposed control methodology is a generalization to the infinite dimensional case of a well-established passivity-based control technique for finite-dimensional port Hamiltonian systems, the control by interconnection and energy shaping, according to which the open-loop energy function is shaped so that a minimum in the desired configuration is introduced. This procedure is possible once the state variable of the controller is related to the state variable of the plant by constraining the state of the closed-loop system on a structural invariant (defined by a set of Casimir functions). In this way, the energy function of the controller, which is freely assignable, becomes a function of the configuration of the plant and, then, it can be easily shaped in order to solve the regulation problem.

Application of neural networks and State-space averaging to DC/DC PWM converters in sliding-mode operation

Abstract: A novel output feedback neural controller is presented in This work for the implementation of sliding-mode control of dc/dc converters. The controller, which consists of a multilayer perceptron, has been trained in order to be robust for large variations of system parameters and state variables. Fast dynamic behavior is the other main advantage of the proposed controller, which allows realization of all beneficial features of the sliding-mode control technique. Other advantages of the controller are simplicity and low cost. Computer simulations have been carried out to investigate the effectiveness of the controller in voltage regulation for a relatively complex dc/dc converter topology of the Cuk converter. Simulation results confirm the excellent performance of the control system in response to large signal variations. In order to verify the simulation results, a controller prototype has been designed and built using analog components. The controller is applied to regulate the output voltage of the Cuk converter. Experimental results confirm the analytical and simulation achievements.

Ultra-compact, high performance motor controller and method of using same

Abstract: Featured is a controller for a motor that is ultra-compact, with a power density of at least about 20 watts per cubic cm (W/cm 3 ). The controller utilizes a common ground for power circuitry, which energizes the windings of the motor, and the signal circuitry, which controls this energization responsive to signals from one or more sensors. Also, the ground is held at a stable potential without galvanic isolation. The circuits, their components and connectors are sized and located to minimize their inductance and heat is dissipated by conduction to the controller's exterior such as by a thermally conductive and electrically insulating material (e.g., potable epoxy). The controller uses a single current sensor for plural windings and preferably a single heat sensor within the controller. The body of the controller can also function as the sole plug connector.

Current-error space-vector-based hysteresis PWM controller for three-level voltage source inverter fed drives

Abstract: A current-error space-vector-based PWM hysteresis controller is proposed for three-level voltage source inverter fed induction motor drive applications. A hexagonal boundary for the current-error space vector is formed by sensing the current-error space vector along three different axes, which are 120 degrees apart and are orthogonal to machine phase axes. Only the adjacent inverter voltage vectors forming a triangular sector, in which tip of the machine voltage vector lies, are switched to keep the current-error space vector within the hexagonal boundary. Selection amongst the three nearest voltage vectors is done by a simple region detection logic in all the sectors. Calculation of the machine voltage vector is not needed and information of the same is indirectly derived from the direction of current-error space vector. The controller uses a self-adaptive sector identification logic, which provides smooth transition between sectors (voltage levels), including over modulation region up to 12-step mode of operation. Inherent advantages of current hysteresis controller are retained with the added advantage of adjacent voltage vector selection for hysteresis PWM control. Simple look-up tables are only needed for sector and vector selection, based on the hysteresis controller output, for the proposed hysteresis PWM controller. Experimental verification is provided by implementing the proposed controller on a 1.5 kW open-end winding induction motor drive. The proposed controller can be extended for further levels of multi-level inverters for high-performance drives by constructing suitable look-up tables.

Robust PID controller design for hydroturbines

Abstract: The design and analysis of a robust proportional, integral, derivative (PID) controller for a hydraulic turbine generator governor using a frequency-response technique is presented. The approach uses data from literature on the turbine and on the interconnected system in various modes of operation through a model in the literature to design a single PID controller to guarantee stability and performance over the entire operating range. To ensure stability of the loop for as yet unanticipated operating situations, gain margin, and phase margin, constraints are imposed during the design of the controller. The new PID governor is compared with a high-order controller designed by the H/sub /spl infin// method.

Optimal mixing enhancement in 3-D pipe flow

Abstract: We design a Lyapunov based-boundary feedback controller for achieving mixing in a three-dimensional (3-D) pipe flow governed by Navier-Stokes equations. We show that the control law maximizes a measure related to mixing (that incorporates stretching and folding of material elements), while at the same time minimizing the control effort and the sensing effort. The penalty on sensing results in a static output-feedback control law (rather than full-state feedback). We also derive a lower bound on the gain from the control effort to the mixing measure. Furthermore, we establish input-output-to-state-stability properties for the open-loop system. These results show a form of detectability of mixing in the interior of the pipe from the chosen outputs on the wall. The effectiveness of the optimal control in achieving mixing enhancement is demonstrated in numerical simulations.

Stability and feedback control of wireless networked systems

Abstract: This study analyzes data losses and their effect on wireless networked system stability/performance using a simple communication scheme and a stochastic 2-state Markov network model. An architecture utilizing event-driven control and clock-driven, co-located sensing and actuation serves as the base framework. Data losses are treated in a switched system scheme where two discrete dynamics are available. When the network transmits data successfully, the closed loop dynamics are active; when packets are dropped, zero control is applied and open loop dynamics exist. Using analysis tools for stochastic stability of Markov jump linear systems, operating conditions in a probability space can be identified for given plant dynamics that ensure second moment stability (SMS). Additionally, switched system H/sub /spl infin// norms can be used to identify regions of network operation in the probability space with expected levels of performance. Results from these tools and experiments involving wireless hardware suggest a scheme for decentralized controller variation that rebalances network loading for the control loops when communication disturbances occur in the network. This scheme varies the sampling period of the individual loops based on network condition measurements, system stability/performance requirements, and computation/bandwidth limits of the hardware.

A Space Phasor Based Current Hysteresis Controller Using Adjacent Inverter Voltage Vectors with Smooth Transition to Six Step Operation for a Three Phase Voltage Source Inverter

Abstract: In this paper, a space phasor based current hysteresis controller for a three-phase voltage source inverter is proposed. The current errors are determined along three axes, which are orthogonal to the A, B, C phases, and the current error space phasor is held within a hexagonal boundary. The proposed controller does not require any computation of machine voltage vector and uses only those inverter voltage vectors, which are adjacent to the machine voltage vector for the entire range of operation. The region detection logic employed in the proposed controller ensures that, the vector (among the three adjacent vectors), which has the largest deviation in the opposite direction, is selected, for all the regions of the hexagonal boundary. A simple self-adapting logic is used to effect sector changes and smooth transition to six-step mode of operation is achieved. The proposed controller is implemented for a 5hp induction motor drive.