Time-delay Compensation Controller Research Articles

Pulse-Width-Modulation-Based Time-Delay Compensation Control for High-Speed On/Off Valves

The dynamic characteristics of high-speed on/off valves (HSVs) are a key factor in measuring their performance, and determining the control accuracy of valve-controlled systems. Furthermore, the hysteresis characteristics of HSVs can seriously affect their dynamic characteristics. This study evaluated the hysteresis characteristics of HSVs in a valve-controlled hydraulic control system, and considered the pressure changes in front of the valve during the opening and closing process of the valve core. A time-delay compensation control (TDCC) based on pulse-width modulation (PWM) was proposed. The reference PWM signal was used to control the opening and closing time of the HSV, while the loading signal was composed of an opening compensation PWM, an excitation PWM, an opening holding PWM, and a closing compensation PWM. Using an opening compensation PWM to start the initial current, combined with current feedback and pressure changes in front of the valve, the amplitude and duty cycle of different PWM signals were determined in real time. This reduced the time delay and working current of the HSV during opening and closing. A simulation comparison analysis was conducted, with a single PWM control and a pre-excitation control algorithm (PECA). The results showed that, compared to a single PWM control, the TDCC can reduce the overall opening and closing time delay by 78.1%, and the energy consumption by 64.7%. Compared with PECA, the overall opening and closing time delay was reduced by 10.9%, and the energy consumption was reduced by 28%. At the same time, the frequency response of the valve core displacement increased by 70%, compared to the single PWM control.

Design of Hypersonic Vehicle Time-Delay Compensation Controller based on Dynamic Surface Control

vehicles with input delays is described in this paper. Due to high dynamic characteristics of hypersonic vehicle, the strong uncertainties, high nonlinearity, strong coupling and control input time delays are challenging problems in the design of its control system. Therefore, it is necessary to design a control method that can handle input time delays. Finally, in this paper, the mathematical expression of the altitude nonlinear control theory problem of an aircraft with input time delay is given. Secondly, based on the backstepping method, the time delay compensation controller is designed. Thirdly, the backstepping method and dynamic control surface are used to design altitude angle control law. The stability and time delay compensation effect are proved. Finally, simulation results show that the suggested method can improve the stability and disturbance rejection performance for the system effectively, which has certain actual application value.

Time delay compensation control using a Taylor series compound robust scheme for a semi‐active suspension with magneto rheological damper

AbstractTime delay significantly degrades the control performances of semi‐active magneto rheological damper. However, the robust control approaches combined with the Taylor series are difficult to perform time delay compensation because it has strict application conditions. In this study, two Taylor series compound robust control schemes are presented to address the robust control and time delay compensation problems for the semi‐active magneto rheological damper with time delay. The formulation of a quarter vehicle model with a magneto rheological damper is described by a hyperbolic tangent model. Given the mechanical characteristics, an experimental test was conducted to fit the hyperbolic tangent model parameters. As a prototype, the Taylor series‐H2/H∞ control approach is proposed through establishing a first‐order Taylor series‐delay equation in augmented state equation and using the H2/H∞ norms to constrain the predictive control force. Moreover, the Taylor series‐H2/H2 controller is proposed to reduce the conservatism and suppress the predictive control force amplification. Simulation results corroborate the efficacy of both control strategies. Specifically, compared with the Taylor series‐H2/H∞ control, the Taylor series‐H2/H2 control can obtain a better control effect for time delay compensation.

Adaptive Control of a Piezo-Positioning Mechanism With Hysteresis and Input Saturation Using Time Delay Estimation

In this paper, based on backstepping technique and time delay estimation (TDE) technique, an adaptive time delay compensation control scheme is developed for a class of piezoelectric positioning mechanical systems with Bouc-Wen hysteresis and input saturation constraint. The nonlinear part of the Bouc-Wen model is estimated online by TDE, and the TDE error introduced by TDE is compensated online by an adaptive law. Furthermore, an auxiliary variable system is used to deal with the input saturation constraint. Based on the Lyapunov method, the stability of the closed-loop system is analyzed and proved. Two simulation examples are given to demonstrate the effectiveness of the proposed control scheme.

DCS devices based non-linear process control system design for plants with distributed time-delay using particle filter

Remote control process system with distributed time-delay has attracted much attention in different fields. In this paper, non-linear remote control of a single tank process system with wireless network is considered. To deal with the distributed time-delay in a large-scale plant, the time-delay compensation controller based on DCS devices is designed by using operator theory and particle filter. Distributed control system (DCS) device is developed to monitor and control from the central monitoring room to each process. The particle filter is a probabilistic method to estimate unobservable information from observable information. First, remote control system and experimental equipment are introduced. Second, control system based on an operator theory is designed. Then, process system with distributed time-delay using particle filter is carried out. Finally, the actual experiment is conducted by using the proposed time-delay compensation controller. When estimating with the proposed method, the result is close to the case in which the distributed time-delay does not exist. The effectiveness of the proposed control system is confirmed by experiment results.

Time delay analysis and constant time-delay compensation control for MRE vibration control system with multiple-frequency excitation

Magnetorheological elastomer (MRE) vibration isolation method has attracted more attention in vibration engineering fields. Time delay in real time control system has an important influence on the control effect, especially for the vibration system with periodic excitations. For the phase difference between the response signal and controlled signal caused by time delay will reduce the vibration control effect or even make the vibration more intense. Therefore, the main purpose in this paper is to improve the vibration attenuation of the MRE vibration control system by analyzing the cause of the time delay and designing the time-delay compensator (TDC) based on the traditional fuzzy controller. The time delay in MRE vibration control system, may be generated by controller, actuator, filter and current driver, was analyzed in theory, and experimental test was carried out to estimate the value. Then a constant TDC was designed for the various vibration amplitude and frequency (single frequency and multiple frequencies). Finally, the real-time control experiments were conducted to verify the effectiveness of the proposed TDC, and the results illustrated that the acceleration RMS with TDC has been attenuated more greatly than that without TDC. Meanwhile, the lower energy consumption is another benefit.

A compensation controller based on a regional pole-assignment method for AMD control systems with a time-varying delay

Active mass damper/driver (AMD) control system has been proposed as an effective tool for high-rise buildings to resist strong dynamic loads. However, such disadvantage as time-varying delay in AMD control systems impedes their application in practices. Time-varying delay, which has an effect on the performance and stability of single-degree-of-freedom (SDOF) and multi-degree-of-freedom (MDOF) systems, is considered in the paper. In addition, a new time-delay compensation controller based on regional pole-assignment method is presented. To verify its effectiveness, the proposed method is applied to a numerical example of a ten-storey frame and an experiment of a single span four-storey steel frame. Both numerical and experimental results demonstrate that the proposed method can enhance the performances of an AMD control system with time-varying delays.

An improved DIM interface algorithm for the MMC-HVDC power hardware-in-the-loop simulation system

Power hardware-in-the-loop (PHIL) simulation has become the crucial means of research on modular multilevel converter based high voltage direct current (MMC-HVDC) devices. To deal with the stability and accuracy problems caused by the power interface, an improved damping impedance method (DIM) interface algorithm is proposed by real-time impedance matching in this paper. The trapezoidal integration method is used to disperse the sub-module capacitance, and the turn-off resistance of power device is set to infinity to simplify the calculation process of MMC equivalent impedance, which can realize the efficient impedance matching for the DIM. Moreover, based on the voltage signal reconstructed by a dq coordinate transformation, a time delay compensation control method is proposed for the uncertain interface delay to improve the accuracy of the PHIL simulation. To verify the excellent stability and accuracy performance of the improved DIM, the characteristics of the reference system, DIM and ideal transformer model (ITM) interface systems are compared by digital simulation. The start-up strategy of a practical MMC-HVDC PHIL test platform is designed, and the effectiveness and feasibility of the proposed methods are verified by simulation experiments.

Influence Analysis of a Higher-Order CSI Effect on AMD Systems and Its Time-Varying Delay Compensation Using a Guaranteed Cost Control Algorithm

A control-structure interaction (CSI) effect commonly exists between an active mass damper/driver (AMD) system with a DC motor and a controlled building. Additionally, its higher-order component leads to the fact that the actual control force acts behind its theoretical time; i.e., time delay. In this paper, the main influencing factors of a higher-order CSI effect are analyzed, including the input frequency of the control voltage, the structural parametric uncertainties, and the control gains. In addition, a new time-delay compensation controller based on a guaranteed cost control (GCC) algorithm is designed, to consider the higher-order CSI effect for multi-level steel frame structures. Experiments on a typical four-storey frame are conducted, to verify the performances of the proposed method. The results show that the proposed controller has an excellent control effect and stable control parameters, even under the situation of large parametric uncertainties and long time-varying delays.

Time-delay compensation method for networked control system based on time-delay prediction and implicit PIGPC

A network time-delay compensation method based on time-delay prediction and implicit proportional-integral-based generalized predictive controller (PIGPC) is proposed. The least squares support vector machine (LSSVM) is used to predict the current time-delay, the parameters of the least squares support vector machine are optimized by particle swarm optimization (PSO) algorithm, and the predicted time-delay is used instead of the actual time-delay as the parameters of the network time-delay compensation controller. In order to improve the compensation effect of implicit generalized predictive controller (GPC), this paper puts forward an implicit generalized predictive control algorithm with proportional-integral-based (PI) structure and designs the controller based on implicit PIGPC. Through the simulation results, the effectiveness of this design in the paper is verified.

Comprehensive control of networked control systems with multistep delay.

In networked control systems with multi-step delay, long time-delay causes vacant sampling and controller design difficulty. In order to solve the above problems, comprehensive control methods are proposed in this paper. Time-delay compensation control and linear-quadratic-Guassian (LQG) optimal control are adopted and the systems switch different controllers between two different states. LQG optimal controller is used with probability 1 − α in normal state, which is shown to render the systems mean square exponentially stable. Time-delay compensation controller is used with probability α in abnormal state to compensate vacant sampling and long time-delay. In addition, a buffer window is established at the actuator of the systems to store some history control inputs which are used to estimate the control state of present sampling period under the vacant sampling cases. The comprehensive control methods simplify control design which is easier to be implemented in engineering. The performance of the systems is also improved. Simulation results verify the validity of the proposed theory.

Smith fuzzy control of teleoperation rendezvous with variable time delay

The control methods of ground-based teleoperation rendezvous with variable time delay are surveyed. With the help of root locus method, the influences of time delay on the stability and performance of the control system are analyzed. Then, a time-delay compensator is designed to transfer the variable delay into a constant. A predictive model is established based on the relative dynamic equations. After that, a multivariable Smith predictor is designed based on the principle of Smith predictor, which makes the control input state variables independent of variable time delay. At the same time, the fuzzy control method is introduced to alleviate the uncertainties in the teleoperation rendezvous system. Finally, semi-physical simulations are carried out to verify the methods presented in this paper. Simulation results show that time-delay compensation and Smith-Fuzzy control are effective in alleviating the variable time delay and model uncertainties in the process of teleoperation rendezvous, and the success probability and control accuracy can be improved.

Time Delay Compensation Control Structure for a Robotic Teleoperation System

In this paper, a time delay compensation control structure for a robot teleoperation system is presented. The structure design was made considering 1.9-seconds time delay in the communication between the remote and local stations. The objective is to control both the remote manipulator's position and force. Force and position signals are fedback to the local station so that the human operator feels in his/her hand the force associated with the task being executed at the remote site. Simulations are carried out considering the dynamic model of the hwnan operator in the control loop. In this sense, simulations show a good perfonnance of the proposed compensation control structure.