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.

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.

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.

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.

Six-phase motor drive supplied by four voltage source inverters with synchronized space-vector PWM

2011 ◽  
Vol 60 (4) ◽  
pp. 445-458 ◽  
Author(s):  
Valentin Oleschuk ◽  
Gabriele Grandi
Keyword(s):  
Continuous Phase ◽  
Power Sharing ◽  
Voltage Source ◽  
Motor Drive ◽  
Phase System ◽  
Space Vector Pwm ◽  
Space Vector ◽  
Voltage Source Inverters ◽  
Pulsewidth Modulation ◽  
Novel Method

Six-phase motor drive supplied by four voltage source inverters with synchronized space-vector PWMNovel method of space-vector-based pulsewidth modulation (PWM) has been disseminated for synchronous control of four inverters feeding six-phase drive based on asymmetrical induction motor which has two sets of windings spatially shifted by 30 electrical degrees. Basic schemes of synchronized PWM, applied for control of four separate voltage source inverters, allow both continuous phase voltages synchronization in the system and required power sharing between DC-sources. Simulations show a behavior of six-phase system with continuous and discontinuous versions of synchronized PWM.

scholarly journals A novel method for assessing cerebral autoregulation in preterm infants using transfer function analysis

2015 ◽  
Vol 79 (3) ◽  
pp. 453-459 ◽  
Author(s):  
Zachary A. Vesoulis ◽  
Steve M. Liao ◽  
Shamik B. Trivedi ◽  
Nathalie El Ters ◽  
Amit M. Mathur
Keyword(s):  
Transfer Function ◽  
Preterm Infants ◽  
Cerebral Autoregulation ◽  
Function Analysis ◽  
Transfer Function Analysis ◽  
Novel Method

l 1 Controller Design for a High-Order 5-Pool Irrigation Canal System

2003 ◽  
Vol 125 (4) ◽  
pp. 639-645 ◽  
Author(s):  
Pierre-Olivier Malaterre ◽  
Mustafa Khammash
Keyword(s):  
Time Domain ◽  
Controller Design ◽  
Mimo System ◽  
State Space Model ◽  
High Order ◽  
Irrigation Canal ◽  
Phase System ◽  
L1 Norm ◽  
Worst Case ◽  
Nonminimum Phase

The aim of this work is to present an application of recent methods for solving the l1 design problem, based on the Scaled-Q approach, on a high-order, nonminimum phase system. We start by describing the system which is an open-channel hydraulic system (e.g., an irrigation canal). From the discretization and linearization of the set of two partial-derivative equations, a state-space model of the system is generated. This model is a high-order MIMO system (five external perturbations w, five control inputs u, 10 controlled outputs z, five measured outputs y, 65 states x) and is nonminimum phase. A controller is then designed by minimizing the l1 norm of the impulse response of the transfer matrix between the perturbations w and the outputs z. Time-domain constraints are added into the minimization problem in order to force integrators into the controller. The numerical resolution of the problem proved to be efficient, despite of the characteristics of the system. The obtained results are compared in the time-domain to classical PID and LQG controllers on the nonlinear system. The results are good in terms of performance and robustness, in particular for the rejection of the worst-case perturbation.

Sign in / Sign up

Export Citation Format

Share Document