scholarly journals Simulation and Experimental Studies on Perfect Tracking Optimal Control of an Electrohydraulic Actuator System

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
R. Ghazali ◽  
Y. M. Sam ◽  
M. F. Rahmat ◽  
Zulfatman ◽  
A. W. I. M. Hashim
Keyword(s):  
Optimal Control ◽  
Discrete Time ◽  
Tracking Control ◽  
Phase Error ◽  
Experimental Studies ◽  
Phase System ◽  
Nonminimum Phase ◽  
Gain Error ◽  
Feedforward Controller ◽  
Electrohydraulic Actuator

This paper presents a perfect tracking optimal control for discrete-time nonminimum phase of electrohydraulic actuator (EHA) system by adopting a combination of feedback and feedforward controller. A linear-quadratic regulator (LQR) is firstly designed as a feedback controller, and a feedforward controller is then proposed to eliminate the phase error emerged by the LQR controller during the tracking control. The feedforward controller is developed by implementing the zero phase error tracking control (ZPETC) technique in which the main difficulty arises from the nonminimum phase system with no stable inverse. Subsequently, the proposed controller is performed in simulation and experimental studies where the EHA system is represented in discrete-time model that has been obtained using system identification technique. It also shows that the controller offers better performance as compared to conventional PID controller in reducing phase and gain error that typically occurred in positioning or tracking systems.

Concurrent Design of Continuous Zero Phase Error Tracking Controller and Sinusoidal Trajectory for Improved Tracking Control

1998 ◽  
Vol 123 (1) ◽  
pp. 127-129 ◽  
Author(s):  
Hyung-Soon Park ◽  
Pyung Hun Chang ◽  
Doo Yong Lee
Keyword(s):  
Continuous Time ◽  
Phase Error ◽  
Phase System ◽  
Pass Filter ◽  
Nonminimum Phase ◽  
Tracking Controller ◽  
Feedforward Controller ◽  
Gain Errors ◽  
High Pass ◽  
Zero Phase

A trajectory control strategy for a nonminimum phase system is proposed. A continuous-time version of the Zero Phase Error Tracking Controller (ZPETC), which is a well-known discrete-time feedforward controller, is considered. In the continuous-time case, the overall transfer function consisting of the ZPETC and the closed-loop plant exhibits high-pass filter characteristics. This introduces serious gain errors between the desired and actual output if the desired output is made directly as the ZPETC’s input. This paper proposes the use of a specially designed sinusoidal trajectory to compensate for the gain errors. The sinusoidal trajectory imparts a synergic effect to tracking performance when combined with the continuous ZPETC. Continuous ZPETC with sinusoidal trajectory is evaluated successfully by applying to a nonminimum phase plant, single link flexible arm.

Multi-Rate Feedforward Tracking Control for Plants With Nonminimum Phase Discrete Time Models

1999 ◽  
Vol 123 (3) ◽  
pp. 556-560 ◽  
Author(s):  
Yuping Gu ◽  
Masayoshi Tomizuka
Keyword(s):  
Discrete Time ◽  
Tracking Control ◽  
Performance Enhancement ◽  
Feedforward Control ◽  
Phase Error ◽  
Sampling Rate ◽  
Time Model ◽  
Rate System ◽  
Control Scheme ◽  
Feedforward Controller

This paper is concerned with performance enhancement of tracking control systems by multi-rate control. The feedback controller is updated at the same rate as the sampling rate of the output measurements. The feedforward controller processes the desired output signal for high accuracy tracking, and its output is updated at a rate N-times faster than the sampling rate of the output measurements. The discrete time model of the controlled plant may possess unstable zeros, and the zero phase error tracking controller (ZPETC) is used as a feedforward controller. Inter-sample behavior of the plant is included in evaluating the tracking performance of the multi-rate system. Illustrative examples are given to show advantages of the proposed multi-rate feedback/feedforward control scheme.

Precision Tracking Control of Discrete Time Nonminimum-Phase Systems

1993 ◽  
Vol 115 (2A) ◽  
pp. 238-245 ◽  
Author(s):  
Chia-Hsiang Menq ◽  
Jin-jae Chen
Keyword(s):  
Discrete Time ◽  
Tracking Control ◽  
Tracking Performance ◽  
Nonminimum Phase ◽  
Nonminimum Phase Systems ◽  
Control Scheme ◽  
Feedforward Controller ◽  
Precision Tracking ◽  
Phase Systems ◽  
Precision Tracking Control

In this paper, a precision tracking control scheme for linear discrete time nonminimum-phase systems is proposed. This control scheme consists of a preview filter, a tracking-performance filter, a command feedforward controller, and a feedback controller. A command feedforward controller, whose design is based on the minimal order inverse model of the plant being controlled, will result in a completely decoupled system. The preview filter is introduced to compensate the phase and gain errors induced by the nonminimum phase zeros or lightly damped zeros of the system. Using the command feedforward controller along with the proposed preview filter, the tracking performance of the proposed control scheme can be characterized by the frequency response of the tracking-performance filter. For the design of the preview filter, a generalized Nth order preview filter and its associated penalty function that quantifies the tracking error of a design are defined. It is shown that, given the desired bandwidth and the order of the preview filter, the optimal solution for the design of the preview filter can be obtained explicitly. The proposed control scheme together with the optimal preview filter is shown to be very effective in achieving precision tracking control of discrete time MIMO nonminimum phase systems. It is also shown that the tracking performance is improved as the order N of the preview filter is increased.

Pseudo-Causal Tracking Control of a Nonminimum Phase System

2009 ◽  
Author(s):  
Pengfei Wang ◽  
M. Necip Sahinkaya ◽  
Sam Akehurst
Keyword(s):  
Transfer Function ◽  
Test Facility ◽  
Phase System ◽  
Hardware In The Loop ◽  
Nonminimum Phase ◽  
Software Models ◽  
Continuously Variable Transmissions ◽  
Future Value ◽  
Novel Method ◽  
Feedforward Controller

A novel method is described to implement noncausal feedforward compensators causally, i.e. without requiring any future value of the reference input trajectory. A hardware-in-the loop test facility developed for continuously variable transmissions is utilized in this paper. The test facility includes two induction motors to emulate engine and vehicle characteristics. Software models of an engine and vehicle, running in real-time, provide reference torque and speed signals for the motors, which are connected to a transmission that is the hardware in the loop. Speed control of the output motor that emulates the vehicle dynamics is used to demonstrate an application of the proposed technique. A feedforward compensator, based on transfer function inversion, is used to compensate for the nonminimum phase motor and drive system dynamics. The vehicle model cannot be run ahead of time to provide the future values required by the noncausal inversion technique because it requires the current torque at the output of the transmission. Therefore, the feedforward controller has to be applied causally. A frequency domain estimation technique and a multi-frequency test signal are utilized to estimate, within the frequency range of interest, a low relative order transfer function of the closed loop system incorporating a manually added delay in the feedback loop. A noncausal feedforward controller is designed for the delayed output of the system based on the identified transfer function. It has been shown experimentally that this compensator offers excellent tracking performance of the motor when subjected a multi-frequency speed demand signal.

scholarly journals Discrete-Time Sliding Mode Control Coupled with Asynchronous Sensor Fusion for Rigid-Link Flexible-Joint Manipulators

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Guangyue Xue ◽  
Xuemei Ren ◽  
Kexin Xing ◽  
Qiang Chen
Keyword(s):  
Sensor Fusion ◽  
Discrete Time ◽  
Tracking Control ◽  
Sliding Mode ◽  
Estimation Error ◽  
Tracking Error ◽  
Sampling Rate ◽  
Experimental Studies ◽  
Flexible Joint ◽  
Rigid Link

This paper proposes a novel discrete-time terminal sliding mode controller (DTSMC) coupled with an asynchronous multirate sensor fusion estimator for rigid-link flexible-joint (RLFJ) manipulator tracking control. A camera is employed as external sensors to observe the RLFJ manipulator’s state which cannot be directly obtained from the encoders since gear mechanisms or flexible joints exist. The extended Kalman filter- (EKF-) based asynchronous multirate sensor fusion method deals with the slow sampling rate and the latency of camera by using motor encoders to cover the missing information between two visual samples. In the proposed control scheme, a novel sliding mode surface is presented by taking advantage of both the estimation error and tracking error. It is proved that the proposed controller achieves convergence results for tracking control in the theoretical derivation. Simulation and experimental studies are included to validate the effectiveness of the proposed approach.

Optimal Tracking Control for Discrete-time Systems with Time-delay Based on the Preview Control Method

2019 ◽  
Vol 7 (5) ◽  
pp. 452-461
Author(s):  
Haishan Xu ◽  
Fucheng Liao
Keyword(s):  
Optimal Control ◽  
Time Delay ◽  
Discrete Time ◽  
Tracking Control ◽  
Control Method ◽  
Reference Signal ◽  
Control Law ◽  
Preview Control ◽  
Optimal Tracking ◽  
Delayed System

Abstract In this paper, the optimal tracking control problem for discrete-time with state and input delays is studied based on the preview control method. First, a transformation is introduced. Thus, the system is transformed into a non-delayed system and the tracking problem of the time-delay system is transformed into the regulation problem of a non-delayed system via processing of the reference signal. Then, by applying the preview control theory, an augmented system for the non-delayed system is derived, and a controller with preview function is designed, assuming that the reference signal is previewable. Finally, the optimal control law of the augmented error system and the optimal control law of the original system are obtained by letting the preview length of the reference signal go to zero.

Disturbance Rejection Through an External Model for Nonminimum Phase Systems

1994 ◽  
Vol 116 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Wei-Chi Yang ◽  
Masayoshi Tomizuka
Keyword(s):  
External Disturbance ◽  
Phase System ◽  
Control Input ◽  
External Disturbances ◽  
Nonminimum Phase ◽  
Nonminimum Phase Systems ◽  
External Model ◽  
Feedforward Controller ◽  
The Stability ◽  
Adaptive Feedforward

This paper considers the use of an external model for the cancellation of disturbances in a nonminimum phase system where disturbances can be regarded as the output of a stable (in the sense of Lyapunov) autonomous system. It is assumed that the parameters in the nonminimum phase system are unknown, but the orders of the numerator and denominator polynomials, and the delay steps are known. External model method is a kind of adaptive feedforward controller that the control input is the function of estimated external disturbance. In order to cancel the effect of disturbances, we use two consecutive recursive parameter identification algorithms to estimate external disturbances. The stability of the closed-loop system is proved.

Discrete-Time H2-Optimal Control for Hydraulic Position Control Systems

2007 ◽  
Author(s):  
Yang Lin ◽  
Yang Shi ◽  
Richard Burton
Keyword(s):  
Optimal Control ◽  
Control Systems ◽  
Discrete Time ◽  
Ad Hoc ◽  
Position Control ◽  
Experimental Studies ◽  
Design Procedure ◽  
Design Parameters ◽  
Practical Applications ◽  
And Control

Hydraulic position control systems play an important role in industrial automation. This paper explores the application of discrete-time H2-optimal control for a hydraulic position control system (HPCS). By minimizing the H2-norm of the system, the discrete-time robust H2-optimal control both stabilizes the plant and minimizes the root-mean-square of the servo position error simultaneously. The intuitive nature of this advanced approach helps to manage the selection of design parameters, whereas, classical methods provide less insight into strategies for parameter selection and control design. Additionally, the powerful ability to address disturbances and uncertainty in the robust H2-optimal design offers a more direct alternative to the ad hoc and iterative nature of classical methods for the hydraulic servo position system. Computer simulations illustrate the design procedure and the effectiveness of the proposed method. Experimental studies which employ the H2-optimal control on a hydraulic positioning system are also conducted and the results show that the method is suitable for practical applications.

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