Gain Tuning Method Research Articles

Output Voltage Regulation for Harmonic Compensation under Islanded Mode of Microgrid

This study examines a P+multi resonant-based voltage control for voltage harmonics compensation under the islanded mode of a microgrid. In islanded mode, the inverter is defined as a voltage source to supply the full local load demand without the connection to the grid. On the other hand, the output voltage waveform is distorted by the negative and zero sequence components and current harmonics due to the unbalanced and nonlinear loads. In this paper, the P+multi resonant controller is used to compensate for the voltage harmonics. The gain tuning method is assessed by the tendency analysis of the controller as the variation of gain. In addition, this study analyzes the slight voltage magnitude drop due to the practical form of the P+multi resonant and proposes a counter method to solve this problem by adding the PI-based voltage restoration method. The proposed P+multi resonant controller to compensate for the voltage harmonics is verified through the PSIM simulation and experimental results.

一般化最小分散評価に基づく定値制御データからのデータ駆動型PIDゲイン調整

This paper considers a PID gain tuning method based on generalized minimum variance evaluation. The method derives the PID gains for reducing the variance of the generalized output from regulatory control data disturbed by colored noise. Advantages of the method include the use of normal operating data with no additional experiment for PID tuning. Numerical examples for a CARIMA (Controlled Auto-Regressive Integrated Moving Average) model and a liquid level control model show the proposed method is effective for not only colored noise but also stochastic disturbances combined with periodical rectangular deterministic signals. The simulation results demonstrate that the proposed approach has robustness to model mismatch of disturbance characteristics.

Self-Tuning Geometric Control for a Quadrotor UAV Based on Lyapunov Stability Analysis

A Lyapunov-based self gain tuning geometric nonlinear controller for a quadrotor UAV has been developed on SE(3) in this paper. By designing an adaptive law with Lyapunov stability analysis for the controller gains, the proposed control system can asymptotically follow an attitude and position command while tuning the PID gains online, and it is extended to guarantee boundedness of tracking errors in the presence of unstructured disturbances. This introduce an unprecedented algorithm to autonomously tune the controller gains without need of extra effort or introducing boundary conditions. Proposed controller considers all the coupling effects between rotational and translational dynamics, and it is developed in a coordinate-free fashion to avoid complexities and ambiguities associated with other attitude representations such as Euler angles or quaternions. The desirable features of the proposed controller are illustrated by numerical simulations and juxtaposed with a well-known offline gain tuning method. The proposed algorithm is ultimately validated with an experimental example.

Adaptive Sliding-Mode Observer Design for a Selective Catalytic Reduction System of Ground-Vehicle Diesel Engines

In this work, we investigate the adaptive sliding-mode observer design problem for the selective catalytic reduction (SCR) system in diesel-engine aftertreatment systems. First, an uncertain three-state model is obtained. Two kinds of uncertainties are considered: uncertainties with slow variations and uncertainties with fast variations. For the uncertain model, an adaptive sliding-mode observer is proposed. Then, the observer gain tuning method is developed based on the stability analysis of the estimation error system. The proposed observer design method is applied to an SCR system of a medium-duty diesel engine. Experimental results and comparisons are provided to illustrate the advantages of the designed observer according to the proposed algorithm. Compared with the open-loop SCR model and the Luenburger-like observer, the proposed adaptive sliding-mode observer can achieve better performance.

Terminal area guidance for reusable launch vehicles

In this paper, a ranging-capability-estimation approach and an adaptive guidance law are developed for reusable launch vehicle during the terminal area energy management. The reference trajectory is planned within the neighborhood of the center of ranging capability. To estimate the ranging capability, a group of algebraic formulas are derived to compute its upper boundary, and an iteration logic is investigated to compute the lower boundary. This approach is simple and potential to be used on-board. A more precise range prediction and the consideration of bank angle and normal acceleration constraints improve the feasibility of the planned Shuttle-based ground track. In the longitudinal guidance, a new dynamic-pressure tracking scheme is designed to combine with the tracking of a reference altitude profile. This combination strategy guarantees the controlling of altitude, velocity, and flight-path angle. Finally, an automatic gain-tuning method, based on the feedback linearization technique, is developed for the proportional and derivative gains in the trajectory-tracking law. Numerical simulations of the X-33 demonstrate that the proposed ranging-capability-estimation approach has high precision, and its computation time is short; the new guidance law can automatically deliver the reusable launch vehicle to the desired approach and landing interface state even when there are initial-state dispersion and flying disturbances.

Variable PID Gain Tuning Method Using Backstepping Control With Time-Delay Estimation and Nonlinear Damping

Proportional-integral-derivative (PID) controllers with constant gains seldom meet desired performance when system dynamics rapidly changes due to unknown disturbances. A gain tuning method for variable PID controllers is presented in this paper. First, the equivalence relationship between a discrete PID control and a discrete backstepping control with time-delay estimation and nonlinear damping is clarified, and the variable gains of the PID controller are automatically tuned with a nonlinear damping component. The nonlinear damping terms directly affect system performance and make PID gains vary. The system performance of a variable PID controller with the proposed method is compared with that of a constant PID controller. The experimental results show that the proposed method is adaptive, robust, and effective.

A Torque Measuring Method for Robot Joints with Harmonic Drives

To meet the demand of joint torque measurement for a modular reconfigurable robot, a harmonic drive built-in torque measuring method was proposed. The robot and its joint module and the torque measuring principle were introduced. Based on the two-order ripple model, strains on the flexspline were then analyzed. A new measuing method based on double compensations was proposed. This method cancels out the first order ripples by individual channels, and then cancels out the remain ripples by weighted stacking the signals. The relationship between output signal and torque was given, and a new gain-tuning method was presented. Finally, a simulation was conducted. The simulation proves that the proposed torque measuring method is correct and of high accuracy.

Design and Evaluation of Simple Ship's Automatic Maneuvering System Using Sliding Mode Controller

In this paper, we present a simple automatic ship's maneuvering system using sliding mode controller. In this system, the input chattering in sliding mode control is reduced by introducing the gain scheduling method and the adaptive gain tuning method. Moreover, the ideal target course is generated using the Hermite interpolation method based on the minimum-time maneuvering solution. In order to evaluate the performance of the proposed system, computer simulation and actual sea tests carried out using small training ship Shioji-Maru under various conditions. As a result, we can see that the control performance is improved under all experimental conditions by comparing the proposed two systems and PID control which has been used traditionally to automatic maneuvering of the ship.

A Direct PID Gain Tuning Based on FRIT Method Using Optimal Filter in the Frequency Domain

The paper gives a PID gain tuning method using a Fictitious Reference Iterative Tuning (FRIT) approaches in the frequency domain. The proposed method obtains the PID gains that optimize a performance index, which evaluates the difference between the closed loop output and the reference model output in the frequency domain. The performance index is calculated using the Fourier transformation of one-shot experimental input-output data. The paper shows that a bandpath filter plays an important role in the Fourier transformation of the one-shot input-output data, and the optimal pre-filter, which well approximates the performance index to the original performance index, can be easily calculated in the frequency domain, and contributes to deriving a better PID gains improving the closed loop response through numerical examples.

An online self-gain tuning method using neural networks for nonlinear PD computed torque controller of a 2-dof parallel manipulator

Parallel manipulators have advantages like high accuracy, high stiffness, high payload capability, low moving inertia, and so on. In this paper, a detailed study to apply an online self gain tuning method using neural networks for nonlinear PD computed torque controller to a 2-dof parallel manipulator is presented. A novel nonlinear PD computed torque controller is achieved by combining conventional computed torque controller and auto tuning method using neural networks which has advantages such as flexibility, adaptation and learning ability. The proposed controller has a simple structure and little computation time while securing good performance in tracking trajectories of parallel manipulators. To verify the control performance, various simulations of a 2-dof parallel manipulator are conducted. Simulation results show the effectiveness of the proposed method in comparison with the conventional computed torque controller.

Comparative study of stabilising methods for adaptive speed sensorless full-order observers with stator resistance estimation

The full-order Luenberger flux (FOLO) observer combined with adaptive techniques is the most widely used method for sensorless vector-controlled drives in induction machines. These methods suffer inherently from an unstable regenerating region and the unobservable zero stator frequency operating point. Stator resistance estimation is also required in the low speed region leading to a complicated multiple-input multiple-output (MIMO) system, and a novel simplification of the MIMO system into a single-input single-output (SISO) system based on the two-time-scale approach is proposed for a simple stability analysis procedure. Four different stabilisation strategies are suggested for this comparison, based on the main stabilisation methods found in the literature. The `augmented error signal` and the `observer gains retuning' methods, based on the Routh-Hurwitz criterion, are used for the stabilisation of the motor speed estimator. The stator resistance stabilisation has been implemented using the `augmented error signal` method. This has been evaluated using two different gain tuning methods, one based on the Routh-Hurwitz criterion and the other on the averaging analysis technique. The different stabilising strategies are evaluated theoretically according to the simplified SISO system open-loop transfer function zeroes and compared by simulation and extensive experiments. The suggested observer is flexible for any vector controlled drive and results have been validated in a 7.5 kW experimental test bench for rotor flux-oriented vector control (RFOC) and indirect self-control drives. The stability and behaviour of the sensorless scheme are successfully verified for all operating conditions above 0.4 Hz stator frequency.

A Study on High Precision Temperature Control of an Oil Cooler for Machine Tools Using Hot-gas Bypass Method

This study aims at precise control of oil outlet temperature in the oil cooler system of machine tools for enhancement of working speed and processing accuracy. PID control logic is adopted to obtain desired oil outlet temperature of the oil cooler system with hot-gas bypass method. We showed that the gains of PID controller could be easily determined by using gain tuning methods to get the gain of PID controller without any mathematical model. We also investigated various gain tuning methods to design the gains of PID and compared each control performance for selecting the optimal tuning method on the hot gas bypass method through experiments. Moreover, we confirmed excellent control performance with proposed PI controller gain even though disturbances were abruptly added to the experimental system.

DEVELOPMENT OF A STEAM GENERATOR TUBE INSPECTION ROBOT WITH A SUPPORTING LEG

This paper presents details on a tube inspection robotic system and a positioning method of the robot for a steam generator (SG) in nuclear power plants (NPPs). The robotic system is separated into three parts for easy handling, which reduces the radiation exposure during installation. The system has a supporting leg to increase the rigidity of the robot base. Since there are several thousands of tubes to be inspected inside a SG, it is very important to position the tool of the robot at the right tubes even if the robot base is positioned inaccurately during the installation. In order to obtain absolute accuracy of a position, the robot kinematics was mathematically modeled with the modified DH(Denavit-Hartenberg) model and calibrated on site using tube holes as calibration points. To tune the PID gains of a commercial motor driver systematically, the time delay control (TDC) based gain tuning method was adopted. To verify the performance of the robotic system, experiments on a Framatomes 51B Model type SG mockup were undertaken.

Parameter optimization of 2-DOF-PID controller using genetic algorithm

This paper presents a gain tuning method to obtain optimal gains in designing a 2-DOF-PID controller. A 2 degree- of-freedom PID controller has been designed to compensate the effects of disturbance without degrading tracking performance. But it is not easy to get optimal gains and keep system stability during the tuning process with real-time tuning methods. Thus we suggest an offline tuning method by genetic algorithm. For the experimental system we consider a commercial sewing machine that requires high speed, robustness and accuracy. Modeling techniques based on neural networks have proven to be quite useful for building good quality models from measured data. So it is modeled by a neural network that is configured as an output-error dynamical system. Then using the model, we search optimal gains for 2-DOF-PID controller with genetic algorithm in offline simulation. Experimental results confirm that the model is a good approximation of sewing machine dynamics and that the proposed control methodology is effective.

An instantaneous photomultiplier tube gain-tuning method for PET or gamma camera detectors using an LED network

A photomultiplier tube (PMT) gain can change with many environmental factors, such as room temperature, patient load, short-term or long-term radiation exposure, and time. Unbalanced PMT gains degrade the image resolution and quality in a positron emission tomography (PET) camera or a gamma camera. This paper presented a new method to instantaneously recover the original manufacture PMT gain setting using a blue light-emitting diode (LED) network. Each LED shines directly into the center of a scintillation crystal block from the PMT side, and the light is collected by the surrounding PMTs. The gain tuning is done by changing the gains of these surrounding PMTs or their following amplifiers to have the same signal output. An LED has well-known problems of large light-yield varieties and is very sensitive to temperature. To overcome these problems, the light outputs of two neighboring LEDs are aligned first by a shared PMT. Each LED flashes at 250-KHz pulse rate, the data acquisition for the gain tuning can be finished within a very short time so the LED temperature effect can be ignored. The amount of LED light output is set as close as possible to the amount of scintillation light by programming the width or height of the pulses; therefore, the same electronics can be used for data acquisition and tuning. We estimated a 12 module PET camera with 924 PMTs in a PMT-quadrant-sharing design can be tuned in 1 min.

Expert Skill-Based Gain Tuning in Discrete-Time Adaptive Control for Robots

This paper presents a gain tuning method based on the sampling period in discrete-time adaptive control for robots. Gain matrices of model-based adaptive control in a continuous-time system are allowed a high gain positive definite. The maximum of the gains depends on the sampling period, however, and gain tuning is very time-consuming. It is thus desirable to give a gain tuning rule in discrete-time adaptive control. The proposed gain tuning consists of two steps. The first is gain tuning at the basic sampling period by a skilful specialist by trial and error. The second step, executed if the sampling period changes, is a new gain calculation based on a new sampling period. The simulation and experiments with 1-dof and 3-dof robots demonstrate that the robot controller is stable at the large variance of sampling period changes and more accurate than a fixed gain controller.

Gain Tuning Method to Improve Sensor's Accuracy and Resolution

Sensing of physical quantities is often accompanied by generation of periodic error signals. Especially in the case of rotary type sensors, periodic error signals are difficult to be avoided. In this paper, we present a method to compensate periodic error signals by gain tuning in multiple pick-up sensors. A mathematical model of the periodic error signal and a method to compensate the error is presented. It is shown that gain adjustment in a minimum of three pick-ups is needed to compensate any frequency component of the error signal. Minimum number of pick-ups needed to compensate multiple frequency components of the error signal is also derived. The method is successfully demonstrated on simulated and experimental examples, where one and two frequency components of the error signal are successfully compensated. Reduced periodic error increases the sensors accuracy and allow higher resolution for digital sensors.

Development of Hoop Filament Winding System with Tension Control.

The purpose of this research is to establish the advanced filament-winding system by realtime sensing and control of the winding tension. In this paper, first, the design and the manufacture of the filament-winding machine is presented in order to be able to measure and control the winding tension in process, and the winding tension control method is proposed and implemented using PID, I-PD control and two-degree-of freedom PID control. Secondly, modeling of the Hoop-winding tension process (pattern) is studied in terms of a system identification technique, and the controller is designed by using Genetic Algorithm (GA). Finally, the effectiveness of the proposed approach is demonstrated via control experiments. Proposed tension control and its gain tuning methods respectively show good performance through the experimental results.

Real-time gain tuning of PI controllers for high-performance PMSM drives

In this paper, a new and practical real-time gain-tuning method for proportional plus integral (PI) controllers has been formulated and implemented, using the speed control of a permanent-magnet synchronous motor drive system as a testbed. While the novel strategy enhances the performance of traditional PI controller greatly and proves to be a completely model-free approach, it also preserves the simple structure and features of PI controllers. The essential idea is as follows: (1) according to the system dynamics to step variation, define a performance index to evaluate the system response; (2) based on the monotonous relationship between the performance index and an intermediate PI gain parameter, this latter parameter is estimated with a modified binary search algorithm in order to improve the performance index; and (3) finally, PI gains are calculated and renewed according to the estimated intermediate gain parameter. Experiments have been thoroughly carried out to test the proposed method under different conditions. Besides being simple and easy to implement for real-time applications, the proposed method also possesses features such as versatility, stability, and effectiveness.

ＮＣ工作機械補間運動時の過渡応答誤差

This paper deals with the dynamic motion errors with XY synchronous motions in NC machine tools in terms of gain tuning. By analytical calculations and computer simulations, it is shown that the differences of the velocity loop bandwidth as well as natural frequencies of feed drives cause the transient errors on linearly interpolated motions inclined from X axis by 45 degree. Compensation methods based on dynamical matching of each axis and the acceleration feedforward technique are proposed to avoid such kind of transient errors. Motion error traces are measured on several combinations of servo gains and found to be very close to the estimated ones, which suggests the effectiveness of the proposed gain tuning methods of velocity loop gains as well as acceleration feedforward gains.