A microprocessor‐based electrohydraulic servo system

Abstract

A microprocessor‐based electrohydraulic servo system has been constructed and tested. It is implemented with an 8‐bit single‐chip microcomputer to control a hydraulic motor. The control algorithm is based on variable structure control principles. The experimental results show that the system is under good control and possesses a great potential for electrohydraulic servo control.     

Robust controllers design and efficiency analysis for a brushless servo system

Abstract

This paper investigates the design of robust controllers for a class of ac servo drives, the brushless servo motor drive, and presents the efficiency and power factor analysis of the drive system. Robust PI, H ², and H ⁸ control techniques are applied to the design of servo controllers. A fully digital control system is constructed to experimentally verify the controller performance. The steady‐state characteristics of the servo drive are derived and are measured on‐line by a microcomputer‐based efficiency measurement system. The theoretical development is validated by the experimental work.     

Adaptive model following control with variable structure control system

Abstract

The adaptive model following bang‐bang control (BB‐MFC) and variable‐structure model following control (VSS‐MFC) have the advantage of no tracking error. However, they are impractical in mechanical application. They will excite the mechanical resonance due to the high‐frequency switching of control signal. Therefore, we use the “modified VSS”. By theoretical analysis, simulations and experiments, the “modified, VSS” effectively modifies the control signal. There was no mechanical resonance in the experiments of DC motor position control.     

Speed Control of Motor Based on Improved Glowworm Swarm Optimization

To better regulate the speed of brushless DC motors, an improved algorithm based on the original Glowworm Swarm Optimization is proposed. The proposed algorithm solves the problems of poor robustness, slow convergence, and low accuracy exhibited by traditional PID controllers. When selecting the glowworm neighborhood set, an optimization scheme based on the growth and competition behavior of weeds is applied to a single glowworm to prevent falling into a local optimal solution. After the glowworm’s position is updated, the league selection operator is introduced to search for the global optimal solution. Combining the local search ability of the invasive weed optimization with the global search ability of the league selection operator enhances the robustness of the algorithm and also accelerates the convergence speed of the algorithm. The mathematical model of the brushless DC motor is established, the PID parameters are tuned and optimized using improved Glowworm Swarm Optimization algorithm, and the speed of the brushless DC motor is adjusted. In a Simulink environment, a double closed-loop speed control model was established to simulate the speed control of a brushless DC motor, and this simulation was compared with a traditional PID control. The simulation results show that the model based on the improved Glowworm Swarm Optimization algorithm has good robustness and a steady-state response speed for motor speed control.     

An experimental study of on‐line computer control techniques applied to a double pipe heat exchanger

Abstract

Three different on‐line computer control methods, namely the identification and optimizing control technique, the direct design method and the digital form of P‐I‐D control, are applied to control the response of a double pipe heat exchanger. The relative merits of the methods are studied and discussed.

The experimental work is accomplished by the use of a HP‐1000 model 5L microcomputer. A digital voltmeter; the HP‐3456A, is used for reading and transferring data from the process to the computer. A data acquisition system, the HP‐3497A, contains a thermocouple relay and a D/A converter which can read input data from a thermocouple and also convert digital outputs to 4–20 mA signals required by control elements.

Results indicate that the identification and optimizing control technique gives superior performance in most cases, but requires longer computation time. Digital form of the P‐I‐D control requires the least computation time but yields poor performance and is limited in its potential for application to multivariable systems or to tracking problems.     

DSP控制直流电动机的嵌入式软件设计

自DSP出现以来,电机控制就是DSP主要应用领域之一。特别是随着控制理论的发展和高性能控制的需求,一般的单片或多片微处理器不能满足复杂而先进的控制算法时,更使得DSP成为这种应用场合的首选器件。随着计算机进入控制领域,以及新型的电力电子功率元器件的不断出现,使采用全控制的开关功率元件进行脉宽调制(Pulse Width Modulation,简称PWM)控制方式已经成为绝对主流。这种控制方式已作为直流电动机数字控制的基础。     

A high performance step up/down three phase AC to DC converter

Abstract

In this paper, a new three phase AC to DC converter is proposed to achieve a sinusoidal current waveform and the unity power factor at the input, and clean DC at the output. Control of the converter is so simple that only one PWM control circuit with fixed switching frequency is required. In addition, the new converter has both step‐up and step‐down capabilities. Also, no current sensor is required for the current control. The small signal model and some design considerations are also presented. Finally, some experimental results are provided for the purposes of demonstration.     

Design and implementation of an adaptive inverse controller for a micro-permanent magnet synchronous motor control system

An adaptive inverse controller design for a micro-permanent magnet synchronous motor control system is proposed. The adaptive inverse controller is constructed by using an adaptive model and an adaptive controller. The parameters of the adaptive model and adaptive controller are on-line tuned. By using the proposed adaptive inverse controller, the transient responses, load disturbance responses and tracking responses of the control system are improved. To detect the shaft rotor position, a micro-encoder is attached with the micro-permanent magnet synchronous motor. The micro-encoder provides only 100 pulses/revolution because of its space limitation. As a result, the resolution of the position signal and speed signal is not good enough. In order to improve the resolution, a state estimator is proposed here. By using the proposed state estimator, the control system can be operated from 1 to 25 000 r/min. The adaptive inverse control algorithm and the state estimation algorithm are executed by a digital signal processor, TMS320F28335. In addition, the proposed adaptive inverse control algorithm can be applied to the position control for the micro-permanent magnet synchronous motor as well. Several experimental results validate the theoretical analysis. The experimental results show that the proposed system has good performance including transient responses, load disturbance responses, and tracking responses.     

Application of variable‐structure system in dc‐motor velocity‐control

Abstract

The most important characteristic of variable‐structure system (VSS) is its insensitivity to parameter variations in the sliding mode. In this paper three methods of VSS are used to implement DC‐motor velocity‐control. The conventional VSS uses only a sliding line. The adaptive VSS uses multiple switching lines. The modern method uses a sliding curve. The modern method makes a system trajectory following the sliding curve which has been set up in the controller from the initial state to the origin in the phase plane. Hence it is insensitive to parameter variations from the initial state to the steady state. If parameter variations are the most critical factors, then the modern VSS is the right method to be considered to overcome the problem of parameter variations.     

Passivity‐based adaptive position control for an induction motor

Abstract

This paper presents a passivity‐based composite adaptive control scheme for the position control of an induction motor. First, the dynamics of the induction motor are proved to be state strictly passive by the passivity theorem. Then, a composite adaptive estimation algorithm is designed to control the position of the induction motor and the global stability of the overall position control system is proved based on passivity instead of Lyapunov‐type arguments. The approach is robust with regard to variations of motor mechanical parameters and external load disturbances. Experimental results are provided to show that good position tracking capability can be obtained without knowledge of the rotor flux.     

基于MSP430的神经网络控制器设计

采用具有自学习能力的神经网络与传统PID控制相结合的办法,实现直流电机双闭环调速。该算法简单,易于在微控制器中实现。试验证明该控制器具有较好的控制效果和应用前景。     

Multi‐rate digital control for a cascaded system consisting of two subsystems with different input time delays

Abstract

This paper presents a multi‐rate state‐space control scheme for digital control of a cascaded continuous‐time system with fractional time delays. First, a discrete‐time state‐space representation of a continuous‐time system with a fractional input delay is established. Based on the time‐delay digital modelling, an ideal state reconstructor is also presented such that system states are exactly reconstructed via the measurement histories of inputs and outputs without a state observer. Next, a time‐delay subsystem (designated subsystem 1) with a fast sampling rate is designed to form the inner loop of the overall system, then the designed closed‐loop subsystem 1 is cascaded with a time‐delay open‐loop subsystem 2 with a slow sampling rate. A digital modelling of the time‐delay open‐loop subsystem 2, based on a fast‐rate sampling, is also formed for obtaining the digital modelling of the overall cascaded continuous‐time system by using the block‐pulse function approximation. Then, the fast‐rate overall system is converted into a slow‐rate model via the newly developed model conversion technique. Furthermore, subsystem 2 is separated from the slow‐rate overall system via a linear transformation for achieving a reduced‐order subsystem design. As a consequence, a digital control law is determined on some specific goals for the overall system. The proposed method is suitable for digital control of a multivariable, multi‐rate, time‐delay system in which state variables are not accessible.     

New algorithms of interpolations for a computer numerical control system

Abstract

This paper presents new algorithms of linear interpolation and circular interpolation. These algorithms have the advantages of increasing speed and accuracy compared with the conventional algorithms. They are tested by some part‐programs in a microcomputer system with an X‐Y recorder.     

光电跟踪系统力矩波动的自抗扰控制

为解决光电跟踪伺服系统受电机力矩波动影响产生的速度波动问题,提出了一种改进的自抗扰控制策略进行力矩波动补偿。该算法主要由两部分组成:通过扩张状态观测器辨识出系统扰动,然后将该扰动前馈到系统控制量中去,构成复合校正系统;反馈通道中采用两参数的比例微分控制器,可以保证系统的稳定性和良好的动态特性。仿真分析和实验结果表明:与同等闭环控制带宽的PI控制器相比,自抗扰控制器可以提高系统对扰动力矩的抑制能力,采用自抗扰补偿时,速度误差的峰值由1.88%降低到0.65%,速度误差的均方根值由0.8%降低到0.2%。实验结果证明提出的方法能够有效降低电机力矩波动的影响,提高速度平稳性。     

基于FPGA和模糊PID的纸材上料机控制系统设计

采用FPGA芯片设计了纸材上料机直流调速控制系统,提出了预设运行速度曲线实现惯性分离的控制策略,设计了模糊PID双闭环算法,缩短速度上升的时间并提高稳态精度,RS232接口使系统可以多机协同工作,并且通过判断算法解决了卡纸、重张问题。在Quartus Ⅱ 6.0中设计了包括速度电流检测、模糊PID算法、调速给定和RS232的控制核心。试验表明,系统动作准确、反应快速、性能稳定。     

On the realization of multimemory block structure digital adaptive filter using distributed arithmetic

Abstract

In this paper, the hardware complexity and system performance of the two multimemory structures (parallel and cascade) of adaptive digital filters are studied. These structures are based on the use of a distributed arithmetic technique without a multiplier in the realization of the filter function. The results from computer simulations and implementations by an MC 68000 16‐bit microprocessor demonstrate that adaptive filters implemented by these two structures have comparable performances on the average. However, the hardware implementation of the parallel structure is simpler and can achieve higher operation speed with fewer IC components. A prototype of a 16‐tap parallel structure (divided into two blocks) adaptive filter is implemented by Schottky TTL circuits. Experimental result of this adaptive filter for noise cancellation has demonstrated its capability for high speed signal processing.     

AI-based adaptive control and design of autopilot system for nonlinear UAV

The objective of this paper is to design an autopilot system for unmanned aerial vehicle (UAV) to control the speed and altitude using electronic throttle control system (ETCS) and elevator, respectively. A DC servo motor is used for designing of ETCS to control the throttle position for appropriate amount of air mass flow. Artificial Intelligence (AI)-based controllers such as fuzzy logic PD, fuzzy logic PD + I, self-tuning fuzzy logic PID (STF-PID) controller and fuzzy logic-based sliding mode adaptive controller (FLSMAC) are designed for stable autopilot system and are compared with conventional PI controller. The target of throttle, speed and altitude controls are to achieve a wide range of air speed, improved energy efficiency and fuel economy with reduced pollutant emission. The energy efficiency using specific energy rate per velocity of UAV is also presented in this paper.     

Controller design and FPGA implementation of a speed‐sensorless vector‐controlled induction motor drive based on stability consideration

Abstract

The purpose of this paper is to determine the controller parameter tuning range for a speed sensorless vector‐ controlled induction motor drive from the system stability point of view. The tuning rules for conventional PI controllers are mostly based on experience. Trial‐and‐error procedures are used to tune the values of the controller parameters. The relationship between the tuned controller parameters and the stable operating range of the control system is generally not known. This paper starts from establishing complete dynamic models for a sensorless vector‐controlled induction motor drive. The nonlinear dynamic models are linearized around a chosen operating point. The characteristic equation is then derived, which is used to determine the values of the controller parameters corresponding to the marginal system stability. Based on these critical values, the tuning ranges of the controller parameters are obtained, which assures stable operation of the drive in the entire operating region and provides a reference for controller parameter tuning. The proposed method is further extended to include the effect of parameter sensitivity due to motor parameter variation. An experimental setup based on a DSP‐FPGA system is implemented. The simulation and experiments confirm the validity of the proposed approach.     

Sensorless interior permanent magnet synchronous motor drive system with a wide adjustable speed range

The authors propose a novel extended flux estimating method for an interior permanent magnet synchronous motor. By using the proposed method, an extended flux can be systematically derived. Then, the shaft position and speed of the motor can be obtained. Starting from a standstill and at a low-speed range control, a current-slope estimating method is used to replace the extended flux method because the estimating extended flux decreases as the motor speed is reduced. By combining the extended flux and the current-slope estimating methods, the interior permanent magnet synchronous motor drive system can be controlled in a wide range with satisfactory performance. The adjustable speed range is from 1 to 2000 r/min. In addition, the system performs fast transient responses and good load-disturbance responses. Moreover, a sensorless position control system has been well developed based on the speed control drive system. A TMS 320LF2407 digital signal processor is used to execute the rotor position estimation, rotor speed estimation, current-loop control, speed-loop control and position-loop control algorithms. The hardware circuit therefore is very simple. Several experimental results are provided to validate the theoretical analysis.