Parametric PID controller tuning for a fast steering mirror

Compact high performance hybrid reluctance actuated fast steering mirror system

Fast steering mirror (FSM) is one of the most important components in electro-optical tracking system and access to FSM model is the basis for controlling and fault diagnosis. This paper presented a correlation identification method based on Invert-Repeated m-sequence which can be used in the electro-optical tracking system to achieve the model of FSM under low sampling rate. Firstly, this article discussed the properties of the Invert-Repeated m-sequence and program implemented in matlab language, then analyzed the principle of correlation identification method based on Invert-Repeated m-sequence by utilizing Wiener-Hopf equation which is simple to achieve with strong anti-jamming capability and small perturbations on the system. Finally, a FSM model with the experiment data got by Dynamic Signal Analyzer was built in Matlab/Simulink and identified by the method mentioned in the paper. The experiment showed that correlation identification method which has certain actual application value, based on Invert-Repeated m-sequence can obtain more accurate recognition results even if the FSM system’s output signal contained large variance noise.

In this paper the mechanical structure and the operating principle of a fast steering mirror (FSM) are introduced, and a novel FSM based on magnetostrictive actuators is designed. The modal analysis of the FSM is carried out with the help of the finite element method, and relative experiments are also conducted. The experimental results and that of simulation are given and in good qualitative agreement with each other. This paper pays attention to ameliorating the FSM structure for higher mechanical natural frequency and perfect control performance. The experimental results would be helpful for the construction design of the FSM.

A simple tuning method for multiloop PID controllers will be presented in this article. The method is suited for PID algorithms with no proportional and derivative kick. This tuning method is derived from a controller synthesis method with a control performance specification of 5% overshoot on servo response. Depending on the interaction natures of the multiloop systems, tuning based on the diagonal elements of the model or further detuning may be necessary. For systems with a relative gain array [RGA(λii)] < 1, a detuning factor based on this information is proposed. The information needed for controller tuning purposes is the dynamic model parameters of the diagonal elements and the process gain information of the off-diagonal elements. The tuning method procedure is very simple and straightforward, utilizing only nth identification tests with n as the number of the interacting control loops. The tuning method can easily be applied to various industrial situations with almost no need for a priori process knowledge.

One of the most common control algorithms in process control is the Proportional-Integral-Derivative (PID) controller, which could be very efficient if well tuned. The aim of this paper is to discuss the optimal tuning of the PID controller using extremum seeking (ES). Two ES algorithms, Perturbation Based Extremum Seeking (PBES) and Sliding Mode Based Extremum Seeking (SMBES), will be used to tune the PID parameters by searching for the optimal parameters that minimize a certain performance index. The Continuous Stirred Tank Reactor (CSTR), with irreversible first-order reaction, has been considered as a case study. The two algorithms have been implemented with two choices of Performance-Index (PI), Integral Absolute Error (IAE) criteria, and a combination of IAE with the integral of absolute of control signal. With the later choice of PI, both the algorithms show an improvement in the performance over the Internal Mode Control (IMC) tuning method, with good control behavior. The cost in the PBES tuning algorithm has converged to an ultimate bound around the optimal value within a lower number of iteration than the SMBES tuning algorithm. However, the speed of the SMBES algorithm can be increased but with the drawback of increasing the chattering effect produced in the PID parameters.

The adjustment of a control parameter to produce a sufficient response to the processing system is known as tuning a control loop. Control procedures are frequently tweaked during running conditions rather than startup conditions to ensure that the process variable is stable at an operating point. Proportional Integral Derivative (PID) are the extensively used controllers to compensate for a wide range of industrial processes due to their simplicity and resilience. The effectiveness of tuning procedures has been compared using time response characteristics. This study shows how to adjust the gains of the Proportional Integral (PI), Proportional Integral Derivative (PID) and Fractional Order Proportional Integral (FOPI) controllers by using various tuning methodologies. The method involves calculating the Controller Gain (Kc), Integral Time Constant (T <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</inf> ), and Derivative Time constant (T <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</inf> ) for a PID-controlled system with a First-Order Plus Time Delay (FOPTD) process. MATLAB / SIMULINK platform is used to investigate and evaluate the performance of various PID tuning procedures in this study.

In the precise pointing system of satellite laser communication, the piezoelectric fast steering mirror (FSM) is used in the system. In the free state, the hysteresis between the input voltage and the output displacement of FSM is obvious, which has a serious impact on the precision positioning accuracy. Therefore, aiming at the hysteresis problem of the fast steering mirror in satellite laser communication, a phenomenal hysteresis mathematical model based on Bouc-Wen operator is established by analyzing the hysteresis mechanism of the piezoelectric fast steering mirror. An improved nonlinear particle swarm optimization (PSO) parameter identification method is proposed, which greatly improves the optimization efficiency of particle swarm optimization. On this basis, a feedforward inverse compensation linearization method is proposed. In order to verify the effectiveness of the proposed model, a fast steering mirror system experiment is established. The experimental results show that the improved PSO parameter identification method proposed in this paper can accurately identify the parameters in the model, and the proposed feedforward linearization method can improve the linearity of piezoelectric ceramic actuator by more than 90%, which can meet the actual index requirements of the fast steering mirror.KeywordsFast steering mirrorHysteresisBouc-WenFeedforward linearization

The majority of the paper is devoted to debunking flawed methods proposed in the literature within the context of multiresonant control systems for grid-connected converters and then a novel approach is proposed. Several flawed approaches to grid tied power electronic converters (rectifiers and shunt active power filters) are discussed to initiate a critical discussion regarding some tuning methods reported in the topical literature. In this paper we analytically show that some of them are even erroneous from the control theory point of view or are based on mathematically erroneous derivations. That is especially prevalent for papers in which the Naslin polynomial method is employed to tune proportional-multiresonant controllers. Some authors recognize that the resulting control systems are not robust, i.e. not practical, and use obtained gains only as a starting point for further tuning using the trial and error method or evolutionary global optimization. Robustness of such systems is often not guaranteed and if it occurs at all, it is by chance or thanks to a combination of luck and expert knowledge of the engineer (not by deliberate design). Therefore, the absence of such a guarantee motivates the search for better ways to tune such controllers. As a result, a practical robust controller tuning method for multiresonant grid current controllers is proposed and verified experimentally. We are convinced that one of the solutions can be based on the disk margin stability analysis and a global search algorithm. The required robustness is expressed as stability margins. The design procedure is very user-friendly and the disk size is the key design parameter to be selected by an engineer. The practicality of the tuning method is demonstrated empirically in a 10 kVA physical grid-tied converter.

Quite recently, fractional calculus is extensively used in control engineering area. Several approaches of fractional controllers tuning has been considered. In this paper, a multi-input multi-output (MIMO) quantitative feedback theory (QFT) method is combined with a fractional order PD <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</sup> controller and a fractional prefilter to control multivariable systems. Each obtained sub-systems from the MIMO QFT procedure is controlled independently. A new tuning method of fractional order controller is developed in order to ensure stability and robustness. After the controller tuning, a fractional order prefilter is designed and optimized to satisfy the desired performances. The proposed technique effectiveness will be evaluated and tested via a real robot model.

The fast steering mirror is a commonly used image motion compensation device in space cameras. The mechanical properties of the support structure will directly affect the response speed and closed loop bandwidth of the fast steering mirror system. A fast steering mirror driven by voice coil motor in a low earth orbit space camera was taken as the research object, and a two-axis flexible support structure based on cross-shaped flexible hinges was designed, which had the advantages of compact structure and small center drift. According to the approximate differential equation of cantilever beam deflection, the mathematical model of the rotational stiffness of the two-axis flexible support was established. The main structural parameters of the flexible hinge were selected for the resonant frequency requirements of the fast steering mirror mechanism, and a modal analysis of the mechanism was performed by using the finite element software MSC.Patran. The analysis results show that the resonant frequency of the fast steering mirror mechanism in the two working directions is 18.6 Hz and 18.7 Hz, while the resonant frequencies in other non-working directions are above 292.2 Hz, which proves that the choice of flexible hinge structural parameters is reasonable. In order to test the correctness of the theoretical model, a prototype of the fast steering mirror was processed and the experimental platform was built. The rotational stiffness and resonant frequency of the mechanism were tested. The results of the test and the theoretical analysis are consistent within the allowable error range.

The proportional-integral-derivative (PID) controller structure is the most widely used one in industrial applications. The controller has three tuning parameters which are often tuned by trial and error. Over the past decades, several PID tuning methods have been developed for industrial use. Most of these tuning techniques are based on simple characterizations of stable process dynamics, for instance, the characterization by a first order model with deadtime. There is an extensive amount of literature on PID tuning methods. For a comprehensive survey on tuning methods of PID controllers, we refer the reader to [2] and the references therein. In this chapter, we give an introductory discussion of some well-known PID tuning formulas.

Design and wide-bandwidth control of large aperture fast steering mirror with integrated-sensing unit

This paper presents microcontroller based autotuning proportional-integral-derivative (PID) controller for an oven designed as an experiment set. Different types of autotuning PID controller methods have been examined. Proportional, P, control method has been applied first. Relay and integral square time error criterion (ISTE) tuning methods are used as autotuning PID method. For relay tuning method, proportional (P), proportional-integral (PI) and proportional-integral-derivative (PID) and for ISTE disturbance (PI, PID) have been used. These methods have been applied to the experiment set which is an FODPT (First Order Plus Dead Time) system. To be able to control this system a digital signal processing card is designed. PIC17C44 is used as microcontroller and ADS1212 is used as A/D converter. And the results are discussed to define which controller is the best for this experiment set.KeywordsAdaptive controlautotuning PID methodstemperature control

Proportional-Integral-Derivate (PID) controllers are widely used in industry because of their remarkable efficiency, simple structure and robust performance for a wide range of applications. Parameters tuning (Kp,Ki,Kd) of PID controller is necessary to satisfy the operation of the system. But many tuning methods such as Ziegler-Nichols methods do not work so perfectly as it is expected. Such methods have many disadvantages such as lack of precision, long run time and lack of stability. Therefore, Particle Swarm Optimization (PSO) algorithm and Genetic Algorithm (GA) are applied to system in order to optimize the PID controller parameters and improve the performance of PID controller system. The simulation results show that the PSO method is more effective in improving the step response characteristics such as: overshoot, rise time and settling time.

In this study, it was sought to implement a Proportional-Integral-Derivative (PID) controller in SIMATIC S7-1500 Programmer Logic Controller (PLC) with Open Platform Communications United Architecture (OPC UA) communication and tunable control from WinCC unified, in order to reduce the settling time of the temperature variable in the plant SO 3536-8T. Using the Ziegler-Nichols PID rule, adjustments were made to the Kp,Ti and Td coefficients of the PID controller. Initially set with values of Kp = 1.0, Ti = 20.00 s, Td = 0.1 s, and ess ≤ 2%. Without tuning, a maximum settling time of 193 s was achieved for a setpoint of 50 °C. After tuning from the WinCC unified interface, improved parameters (Kp = 6.05, Ti= 0.75 s, Td = 0.15 s) were obtained for ess ≤ 2%, presenting an underdamped response and a maximum settling time of 54 s. The tests present a reduction of the settling time of the variable higher than 60.25%, evidencing the effectiveness of the tunable PID controller in improving the system performance. Overall, the successful implementation of this tunable PID controller not only optimized the efficiency of the control system, but also provided a considerable reduction in the settling time of the temperature variable in the plant, representing a significant advance for the operation and overall efficiency of the process.