Showing papers on "Proportional control published in 2004"

A modular control scheme for PMSM speed control with pulsating torque minimization

Abstract: In this paper, a modular control approach is applied to a permanent-magnet synchronous motor (PMSM) speed control. Based on the functioning of the individual module, the modular approach enables the powerfully intelligent and robust control modules to easily replace any existing module which does not perform well, meanwhile retaining other existing modules which are still effective. Property analysis is first conducted for the existing function modules in a conventional PMSM control system: proportional-integral (PI) speed control module, reference current-generating module, and PI current control module. Next, it is shown that the conventional PMSM controller is not able to reject the torque pulsation which is the main hurdle when PMSM is used as a high-performance servo. By virtue of the internal model, to nullify the torque pulsation it is imperative to incorporate an internal model in the feed-through path. This is achieved by replacing the reference current-generating module with an iterative learning control (ILC) module. The ILC module records the cyclic torque and reference current signals over one entire cycle, and then uses those signals to update the reference current for the next cycle. As a consequence, the torque pulsation can be reduced significantly. In order to estimate the torque ripples which may exceed certain bandwidth of a torque transducer, a novel torque estimation module using a gain-shaped sliding-mode observer is further developed to facilitate the implementation of torque learning control. The proposed control system is evaluated through real-time implementation and experimental results validate the effectiveness.

High-performance induction motor speed control using exact feedback linearization with state and state derivative feedback

Abstract: This paper presents a novel nonlinear speed/position control strategy for the induction motor utilizing exact feedback linearization with state and state derivative feedback. The speed/position and flux control loops utilize nonlinear feedback which eliminates the need for tuning, while ordinary proportional-integral controllers are used to control the stator currents. The control scheme is derived in rotor field coordinates and employs an appropriate estimator for the estimation of the rotor flux angle, flux magnitude, and their derivatives. The overall control scheme can be easily implemented with a microprocessor-based control platform. An error sensitivity analysis is included which proves the system to be robust to parameter variation and even more, immune to rotor resistance variation. Simulation and experimental results validate the theoretical part of the paper and reveal the high performance and advantages of the novel control scheme.

Adaptive fuzzy sliding mode control design: Lyapunov approach

Abstract: An adaptive fuzzy sliding mode control algorithm is proposed for a class of continuous time unknown nonlinear systems. In contrast to the existing sliding mode control (SMC) design, where the presence of hitting control may introduce problems to controlled systems, the proposed adaptive fuzzy logic controller takes advantages of both SMC and proportional integral (PI) control. The chattering action is attenuated and robust performance can be ensured. The stability analysis for the proposed control algorithm is provided. Two nonlinear system simulation examples are presented to verify the effectiveness of the proposed method.

Minimizing air consumption of pneumatic actuators in mobile robots

Abstract: This paper introduces a new control method for pneumatic actuators, called "Proportional Position and Stiffness (PPS)" controller. The PPS method provides both position and stiffness control for a robot joint driven by a pneumatic cylinder with four ON-OFF valves. In addition, the proposed control system consumes much less compressed air than comparable strategies. These features make the PPS method highly suitable to application in mobile robots.

Analysis and control of a flywheel hybrid vehicular powertrain

Abstract: Vehicular powertrains with an internal combustion engine, an electronic throttle valve, and a continuously variable transmission (CVT) offer much freedom in controlling the engine speed and torque. This can be used to improve fuel economy by operating the engine in fuel-optimal operating points. The main drawbacks of this approach are the low driveability and, possibly, an inverse response of the vehicle acceleration after a kick-down of the drive pedal. This paper analyzes a concept for a novel powertrain with an additional flywheel. The flywheel plays a part only in transient situations by (partly) compensating the engine inertia, making it possible to optimize fuel economy in stationary situations without loosing driveability in transients. Two control strategies are discussed. The first one focuses on the engine and combines feedback linearization with proportional control of the CVT ratio. The CVT controller has to be combined with an engine torque controller. Three possibilities for this controller are discussed. In the second strategy, focusing on control of the vehicle speed, a bifurcation occurs whenever a downshift of the CVT to the minimum ratio is demanded. Some methods to overcome this problem are introduced. All controllers are designed, using a simple model of the powertrain. They have been evaluated by simulations with an advanced model.

Development and tuning of fuzzy controller for a conical level system

Abstract: A real-time control of liquid level in a conical tank is studied. System identification of this nonlinear process and tuning of the fuzzy system are undertaken. Genetic algorithms are used to tune the membership functions of the fuzzy system. The results of the tuned fuzzy controller are compared to a proportional integral controller to evaluate the performance of the genetic algorithm tuned fuzzy controller.

Motor control device

Abstract: A speed controller includes a speed integration compensation low-pass filter, an integral control system, a proportional control system, and a multiplication device 134 . The speed integration compensation low-pass filter has a transfer function corresponding to a delay of a speed control system. The integral control system 136 is multiplied by an integral gain by a multiplier and integrated by a speed integrator before being supplied to an adder. The adder adds an output of the proportional control system and an output of the integral control system and outputs the result to the multiplier, which in turn multiplies the output of the adder by a proportional gain and outputs the result as a torque command. The multiplication means multiplies the output of the integral control system and the output of the proportion control system by a speed proportional gain and outputting the value of the torque command.

Modeling and control for smart Mesoflap aeroelastic control

Abstract: This paper introduces a novel concept termed Smart Mesoflaps for Aeroelastic Recirculation Transpiration (SMART) to render mass and momentum transfer for controlling shock/boundary-layer interactions in supersonic jet inlets. The SMART concept consists of a matrix of small flaps designed to undergo local aeroelastic deflection to achieve proper mass bleed or injection when subjected to shock loads. To optimize the performance of this system, NiTi shape memory alloy is used as an actuator for the flaps to control the amount of recirculation. The focus of this paper will be the subsystem modeling and control of a single flap. After a relatively detailed model is developed, a simpler model is generated, and it is experimentally shown that this approximation is adequate for control purposes. Next, the control strategy for this subsystem, subject to hysteresis and actuator saturation, is presented. A basic proportional integral derivative (PID) controller is enhanced using a hysteresis compensator (HC) and an error governor (EG). A generalized error governing scheme for PID controllers to compensate for actuator saturations is also developed. This EG method is generalizable to any stable process controlled by a PID. Finally, the PID with HC and the error governing method is experimentally applied to a benchtop SMART subsystem.

Signals and Signal Processing for Myoelectric Control

Abstract: This chapter explains the way in which the myoelectric signal is used to control powered upper limb prostheses. This first part of the chapter covers the acquisition of the signal and the problems associated with electrodes that can occur in practice.This is followed by a brief description of some signal processing that must be performed to derive a useable control signal. The second part of this chapter describes the various strategies employed to control the terminal device and differentiates between ON-OFF and proportional control. In this part, concepts are explained using examples of some of the currently available technology.

Regularization of Linear Discrete-Time Periodic Descriptor Systems by Derivative and Proportional State Feedback

Abstract: In this paper, we consider the regularization problem for the linear time-varying discrete-time periodic descriptor systems by derivative and proportional state feedback controls. Sufficient conditions are given under which derivative and proportional state feedback controls can be constructed so that the periodic closed-loop systems are regular and of index at most one. The construction procedures used to establish the theory are based on orthogonal and elementary matrix transformations and can, therefore, be developed to a numerically efficient algorithm. The problem of finite pole assignment of periodic descriptor systems is also studied.

Classical control theory applied to OPC correction segment convergence

Abstract: Model based Optical Proximity Correction work is currently performed by segmenting patterns in a layout and iteratively applying corrections to these segments for a set number of iterations This is an open loop control methodology that relies on a finely tuned algorithm to arrive at a proper correction A goal of this algorithm is to converge in the fewest number of iterations possible As technology nodes become smaller, different correction areas tend to correct at different rates, and these correction rates are diverging with process node This leads to more iterations being required to converge to a final OPC solution, the consequence of which is an increased runtime and tapeout cost The current solution to this problem is to use proportional damping factors to attempt to bring different structure types to a solution Classical control theory provides tools to optimize the convergence of these processes and to speed up convergence in physical systems Introducing derivative and integral control while continuing use of proportional control should reduce the number of iterations needed to converge to a final solution as well as optimize the convergence for varied configurations

ABR traffic control over multi-source single-bottleneck ATM networks

Abstract: The problem of flow control in fast, connection-oriented communication networks supporting the traffic generated by multiple sources is considered. A novel sampled time strategy governing the behaviour of the sources is proposed. The strategy combines the Smith principle with the conventional sampled time proportional controller. It guarantees an equal resource allocation between various users, full bottleneck link utilisation and no cell loss in the controlled network. Consequently, the need for cell retransmission is eliminated and a high throughput is ensured. Furthermore, transmission rates generated by the algorithm are limited. This property permits a direct implementation of the proposed strategy in the network environment. A simulation example confirms favourable performances of the proposed control scheme.

A Fed-Batch Fermentation Process Identification and Direct Adaptive Neural Control with Integral Term

Abstract: A nonlinear mathematical model of a feed-batch fermentation process of Bacillus thuringiensis (Bt.), is derived. The obtained model is validated by experimental data. Identification and direct adaptive neural control systems with and without integral term are proposed. The system contains a neural identifier and a neural controller, based on the recurrent trainable neural network model. The applicability of the proposed direct adaptive neural control system of both proportional and integral-term direct adaptive neural control schemes is confirmed by comparative simulation results, also with respect to the (-tracking control, which exhibit good convergence, but the I-term control could compensate a constant offset and proportional controls could not.

A fed-batch fermentation process identification and direct adaptive neural control with integral term

Abstract: A nonlinear mathematical model of a feed-batch fermentation process of Bacillus thuringiensis (Bt.), is derived. The obtained model is validated by experimental data. Identification and direct adaptive neural control systems with and without integral term are proposed. The system contains a neural identifier and a neural controller, based on the recurrent trainable neural network model. The applicability of the proposed direct adaptive neural control system of both proportional and integral-term direct adaptive neural control schemes is confirmed by comparative simulation results, also with respect to the λ-tracking control, which exhibit good convergence, but the I-term control could compensate a constant offset and proportional controls could not.

Iterative learning control for position tracking of a pneumatic actuated X-Y table

Abstract: The iterative learning control (ILC) learns the unknown information from repeated control operations. The tracking error from previous stages is used as the correction factor for the next control action. Therefore, the ILC controller can make the system tracking error converge to a small region within the limited numbers of iterations. A proportional-valve controlled pneumatic X-Y table system is built to perform the position tracking control experiments. The ILC controllers are implemented in the experiments and the results are compared. The P-type updating law with delay parameters are used for both the x and y axes in the repetitive trajectory tracking control. Experimental results show that the ILC controller can effectively control the system to track the given circular trajectory at different speeds. The controller parameters are varied for studying their effects. Inertial disturbance is also added to show the learning performance of the ILC controller.

A proportional plus extended time-delayed feedback controller for a PWM inverter

Abstract: PWM current-mode single phase inverters are known to exhibit bifurcations and chaos when parameters vary. Our aim in this paper is to show how to apply a control method issued from chaos theory, in order to extend the stability range of a commonly used linear controller. To accomplish this aim, an extended time-delayed feedback controller (ETDFC) is used in conjunction with the proportional controller. An obvious advantage of this method is the robustness and ease of implementation because it does not require the knowledge of an accurate model but only the period of the target unstable periodic orbit (UPO).

Proportional poppet valve

Abstract: In order to provide proportional control of a poppet valve or a gate valve, adapted for fluid power applications, an electrical voice coil is used to move the gating element. Further, a preferred embodiment includes a feedback means for detecting and regulating the position of the gating element, for example to compensate for any perturbing mechanical vibrations. The result is a valve which closes securely, is infinitely variable within a range, and can make up to a full stroke, from fully closed to fully open, within 3 to 10 milliseconds, compared to the 15 milliseconds needed by a solenoid. Due to its fast response time, the improved valve mechanism provides much faster tracking of any changes in an applied command signal. Suitable applications are mechanical testing devices, and other repetitive motions situations, such as industrial automation and animatronics.

Swing device of construction machinery

Abstract: PROBLEM TO BE SOLVED: To enhance operability of an operation part by making a revolving superstructure smoothly start to move in the control and smoothly performing the accurate and fine control of a pressing force in pressing work SOLUTION: A controller 12 performs normal speed control for an electric motor 9 in accordance with revolving-superstructure speed command from an operation part, when a revolving-superstructure speed detected by a revolving-superstructure detector is equal to/exceeds a predetermine value The controller 12 performs proportional control wherein a proportional gain is set at a predetermined value or below and which is performed based on torque commensurate with a deviation between the revolving-superstructure speed command from the operation part 13 and the revolving-superstructure speed detected by the revolving-superstructure speed detector, in place of the normal control, when the revolving-superstructure speed detected by a revolving-superstructure detector is equal to/falls below a predetermine value COPYRIGHT: (C)2006,JPO&NCIPI

Motor speed controller

Abstract: PROBLEM TO BE SOLVED: To provide a speed controller of simple arrangement with excellent ability to suppress disturbance such that the rate of overshooting is low even at high speeds. SOLUTION: A speed control part 13 comprises a speed integration compensating low-pass filter 133 having a transfer function corresponding to the delay of a speed control system; an integration control system 136 including a speed integrator 132 which integrates a speed deviation between a delay speed command obtained by inputting a speed command to the low-pass filter 133 and a speed; a proportional control system 137 which outputs a command proportional to the deviation between the speed command and the speed; and a multiplying means 134 by which an output of the integration control system 136 plus an output of the proportional control system 137 is multiplied by a speed proportional gain and output as a torque command. A torque control part 4 controls the motor speed in accordance with the torque command output from the speed control part 13 so that the motor speed conforms to the speed command. A speed feedback low-pass filter 135 is provided having a transfer function that prevents a ripple resulting from the position detection of an encoder E from appearing in the torque command. COPYRIGHT: (C)2005,JPO&NCIPI

Computerized electro-hydraulic proportional control device

Abstract: of EP1413773The control of the actuator (H) used with such as a crane is based around four electro hydraulic proportional control valves (13-16) connected in a daisy chain. The pressure of the output and return lines (7,8) are monitored (9,10) and signals fed to a control unit (CU). This provides control inputs to the proportional valves to regulate the speed.

A unified nonlinear controller for a platoon of car-like vehicles

Abstract: This work presents a dynamics-based nonlinear tracking control scheme for a platoon of two car-like mobile robots. A unified controller is designed for both look-ahead and look-behind tracking. Look-ahead and look-behind tracking maneuvers require the following vehicle to follow the leading vehicle in two opposite directions: forward or backward, respectively. Furthermore, both steering control and driving control are also integrated in the unified controller. Tracking stability is ensured by proper design of a stable performance target equation. Simulation results show the control scheme work properly in both tracking cases. Simulations also investigate the influence of two important design parameters: the desired distance l and the desired steering angle ratio p. The results suggest that these parameters affect the system performance and require careful selection.

Decentralized robust h∞ controller design for a half-car active suspension system

Abstract: In this paper an H∞ controller is designed for a hydraulically actuated active suspension system of a half-modeled vehicle in a cascade feedback structure. Using the proposed structure the nonlinear behavior of actuator is reduced significantly. In the controller synthesis, a proportional controller is used in the inner loop, and a robust H∞ controller forms the outer loop. Two H∞ controllers are designed for this system. First unstructured uncertainty is not considered in the design procedure and secondly, the controller is designed considering uncertainty. Each of these controllers is designed in a decentralized fashion and the vehicle oscillation in the human sensitivity frequency range is reduced to a minimum. Statistical analysis of the simulation result using random input as road roughness, illustrates the effectiveness of the proposed control algorithm for both cases. Keyword: active suspension, cascade feedback, hydraulic actuator, nonlinear model, multiplicative uncertainty, robust H∞ controller, disturbance input, road random input, statistical analysis.

Adaptive Learning Based Current Control of Active Filters Needless to Detect

Abstract: This paper proposes a new current control method suitable for an active power filter (AF). It requires only detecting the source current. It requires neither detecting AF output current nor extracting a harmonic component from the source current. Thus, the current control system can be greatly simplified compared to conventional load current detection AF. This paper introduces an adaptive digital filter (ADF) with a synchronized filtered-x (SFX) algorithm. An SFX-ADF based current controller exhibits high gains only at fundamental and harmonic frequencies that the load current contains. It automatically adjusts its transfer function to minimize the mean-square error. The proportional controller is also used to improve the dynamic performance of the current control system. Simulation and experimental results demonstrate that almost the same excellent filtering performance can be achieved as conventional load current detection AF. I. INTRODUCTION

Modeling and simulation of a three-phase four-leg inverter based on a novel decoupled control technique

Abstract: Three-phase four-leg inverters are developed to power unbalanced/nonlinear three-phase loads. This paper presents a decoupled control scheme for three-phase four-leg inverter via an inner current regulator based on space vectors cascaded with an outer synchronous frame PI controller. Firstlya circuit model in abg coordinate system for three-phase four-leg inverter is established; then the three-dimensional space voltage vectors of four-leg inverter in dqo space are analyzed and an inner current regulation method implementedby two three-level hysteresis comparators and a two-level hysteresis comparator is presented accordingly. Outer voltage loop employs a synch-ronous frame PI controller. A simple proportional controller can be applied to three-phase output voltages to obtain zero steady-state error in theory, ensuring excellent steady-state perfor-mance. Control models of the whole system are established in dqo frame and a decoupled control of d, q, and o-components is realized. Simulation results verify the validity of the presented control scheme.

Multi-region fuzzy tracking control for a pneumatic servo squeezing forces system

Abstract: A multi-region fuzzy tracking control approach was used to control a pneumatic servo squeezing forces system with unknown non-linearity and frequently changing process dynamics in this paper, using the E/P proportional pressure valve as the electro-pneumatic converter in constructing the electro-pneumatic automatic squeezing pressure servo system. The squeezing pressure process is firstly divided into different fuzzy regions according to the operating behavior of the system. Then, using a process auxiliary variable to detect the squeezing pressure operating region, the fuzzy controller is designed based on the regional information. The results of this test show that this scheme can effectively overcome unknown nonlinear influence of the system, and has high control precision and robustness.

Authors' reply to comments on "variable-structure PID control to prevent integrator windup"

Abstract: For comments by R.J. Mantz and H. De Battisa see ibid. (vol. 51, p736-38, June 2004) . For original paper by A. S. Hodel and C. E. Hall see ibid.(vol.48, p442-51, April 2001).

A study on multiple models predictive control for superheated steam temperature based on local neural network models

Abstract: Based on the characteristics of superheated steam temperature of a boiler, a new cascade control system is designed. The master regulator adopts multiple models predictive control based on local neural network models, namely, at the different operating points specified according to the flux of main steam, local dynamic models are built with neural networks, based on which a set of local neural network predictive controllers are constructed, then the final control signal is synthesized by weighting. The secondary regulator adopts weighting synthesized proportional control based on several proportional controllers. This control strategy combines the characteristics of neural network, multiple models control, and predictive control. The simulation shows that the control system can maintain better performance when the load changes within a large range and has a strong robustness.

Design of Digital High-Gain PD Control Systems Using Analytical Approach

Abstract: It is known that a continuous stable high-gain PD control system may become unstable when the controller is implemented digitally. Recent works consider this problem and determine the stability regions of such systems. In most cases the stability regions are obtained numerically. This work introduces a new analytical approach for obtaining the stability criteria for digital systems. The approach is based on the critical constraints of simplified version of Jury test and makes use of the capabilities of MATLAB software. The approach is applied to digital PD control systems. Here, the effect of computation time in addition to that of sampling period are considered. The resulting stability criteria are presented in closed forms that are suitable for design purposes and make it possible to map the stability region for various control design parameters. This versatile capability is illustrated via design examples. To the contrary of previous knowledge, the results show that, in certain cases, the stability is obtained through increasing the proportional gain or computation time rather than by decreasing them. A comparison with the literature shows that this approach is straightforward, versatile and even corrects some of the stability regions that have been reported.