A robust speed controller for induction motor drives

A speed controller considering the effects of parameter variations and external disturbance for indirect field-oriented induction motor drives is proposed in this paper. First a microprocessor-based indirect field-oriented induction motor drive is implemented and its dynamic model at nominal case is estimated. Based on the estimated model, an integral plus proportional (IP) controller is quantitatively designed to match the prescribed speed tracking specifications. Then a dead-time compensator and a simple robust controller are designed and augmented to reduce the effects of parameter variations and external disturbances. The desired speed tracking control performance of the drive can be preserved under wide operating range, and good speed load regulating performance can also be obtained. Theoretic basis and implementation of the proposed controller are detailedly described. Some simulated and experimental results are provided to demonstrate the effectiveness of the proposed controller     

Robust performance of the multiloop perturbation compensator

A novel perturbation attenuation method is proposed for robust performance of mechanical systems. First, we give a unified view on a class of existing perturbation observers and define the residual perturbation. In terms of the view and the definition, a new perturbation compensator with multiloop structure is developed. It effectively compensates the perturbation (i.e., model uncertainty and external disturbance) to the plant in a hierarchical and recursive fashion. In the multiloop perturbation compensator (MPEC) proposed, as the number of loops increases, the external disturbance condition for system stability is greatly relaxed and the perturbation attenuation performance is gradually enhanced but the robust stability margin on the modeling error becomes more strict. A recursive algorithm for general n-loop case of the MPEC is derived. By combining the developed robust perturbation compensator with a nominal feedback controller, a robust motion controller is synthesized. Experimental results for XY positioner and 2-DOF robot arms demonstrate the excellent robust tracking performance in spite of arbitrary large perturbation inputs     

Control of indirect field-oriented induction motor drivesconsidering the effects of dead-time and parameter variations

A speed controller that considers the effects of system dead time and parameter variations is presented. An indirect field-oriented induction motor drive is implemented, and its dynamic model is found, using a stochastic approach. A two-degree-of-freedom speed controller is designed to match the prescribed speed command tracking and load regulating specifications. Since the performance of the closed-loop controlled plant is greatly influenced by the presence of the inherent system dead time and parameter variations during wide-range operations, a dead-time compensator and a model-following controller are proposed to enhance the robustness of the two-degree-of-freedom speed controller. The simulated and experimental results show that good control performance both in speed command tracking and load regulating characteristics is achieved     

Robust motion controller design for high-accuracy positioningsystems

This paper presents a controller structure for robust high speed and accuracy motion control systems. The overall control system consists of four elements: a friction compensator; a disturbance observer for the velocity loop; a position loop feedback controller; and a feedforward controller acting on the desired output. A parameter estimation technique coupled with friction compensation is used as the first step in the design process. The friction compensator is based on the experimental friction model and it compensates for unmodeled nonlinear friction. Stability of the closed-loop is provided by the feedback controller. The robust feedback controller based on the disturbance observer compensates for external disturbances and plant uncertainties. Precise tracking is achieved by the zero phase error tracking controller. Experimental results are presented to demonstrate performance improvement obtained by each element in the proposed robust control structure     

A VSS speed controller with model reference response for inductionmotor drive

This paper is mainly concerned with the development of a variable-structure system (VSS) controller with model reference speed response for an induction motor drive. An indirect-field-oriented (IFO) induction motor drive is first implemented, and its dynamic model at a nominal operating condition is estimated from measured data. Then, a two-degrees-of-freedom linear model-following controller (2DOFLMFC) is designed to meet the prescribed tracking and load regulation speed responses at the nominal case. As the variations of system parameters and operating condition occur, the prescribed control specifications may not be satisfied further. To improve this, a VSS controller is developed to generate a compensation control signal to reduce the control performance degradation. The proposed VSS controller is easy to implement, since only the output variable is sensed. The existence condition of sliding-mode control is derived, and the chattering suppression during the static period is also considered. Good model-following tracking and load regulation speed responses are obtained by the designed VSS controller. Effectiveness of the proposed controller and the performance of the resulting drive system are confirmed by some simulation and measured results     

Robust control of induction motor with a neural-network load torqueestimator and a neural-network identification

This paper presents a control scheme for an induction motor drive which consists of a compensator, neural network identification (NNI), and neural network load torque estimator (NNLTE) based on the conventional proportional-integral controller. The NNI is a two-layer neural network which uses a projection algorithm to estimate the parameters of the induction motor and to regulate the gain of the compensator such that the response of the induction motor follows that of the nominal plant. The NNLTE is a two-layer neural network which uses the steepest descent algorithm to estimate the load disturbance and forward feed, resulting in equivalent control such that the speed response of the induction motor is robust against the load disturbance. Computer simulations and experimental results demonstrate that the proposed control scheme can obtain a robust speed control     

机电系统自适应控制仿真

针对机电伺服系统中存在的不确定因素和多余力扰动问题,提出一种自适应比例－积分－微分(PID)控制策略。该自适应控制器由最优PID控制器和小脑模型关节控制器(CMAC)组成,最优PID控制器用来整定系统的标称模型,CMAC控制器用来克服系统中含有的不确定项和多余力扰动,自适应PID控制器能确保系统跟踪误差和CMAC权值误差收敛到零。仿真结果表明,本文提出的控制器具有令人满意的跟踪性能,对系统中的不确定因素和多余力扰动具有一定的鲁棒性。     

Robust and precision motion control system of linear-motor direct drive for high-speed X-Y table positioning mechanism

In this paper, design and implementation of an H/sub /spl infin//-based precision motion control system is presented for a high-speed linear-motor direct-drive X-Y table positioning mechanism in semiconductor wire-bonding applications. The system works with a cascaded robust feedback control, which has an inner loop velocity controller and an outer loop position controller, and an autotuning feedforward compensator. The design aim is to achieve high and consistent tracking performance even in the presence of considerable resonance uncertainties and external disturbances. Toward this aim the velocity controller is designed using H/sub /spl infin// optimization technique, based on reduced-order modeling that considers three significant resonance modes and neglects all other resonance modes having an insignificant amplitude and/or too high frequency. These neglected modes and variations of the three resonance modes from machine to machine (due to manufacturing tolerance) and/or with different operating conditions are taken care of by appropriate additive uncertainty representation in the design phase. The resulting system is validated and implemented with a profile motion of a maximum acceleration of 5.2 g (1g=9.81 m/s/sup 2/) on mass-produced wire bonding machines.     

Development of new training algorithms for neuro-wavelet systems on the robust control of induction servo motor drive

A robust wavelet neural network control (RWNNC) system is proposed to control the rotor position of an induction servo motor drive in this paper. In the proposed RWNNC system, a wavelet neural network controller is the main tracking controller that is used to mimic a computed torque control law, and a robust controller is designed to recover the residual approximation for ensuring the stable control performance. Moreover, to relax the requirement for a known bound on lumped uncertainty, which comprises a minimum approximation error, optimal network parameters and higher order terms in a Taylor series expansion of the wavelet functions, an RWNNC system with adaptive bound estimation was investigated for the control of an induction servo motor drive. In this control system, a simple adaptive algorithm was utilized to estimate the bound on lumped uncertainty. In addition, numerical simulation and experimental results due to periodic commands show that the dynamic behaviors of the proposed control systems are robust with regard to parameter variations and external load disturbance.     

A Globally Stable High-Performance Adaptive Robust Control Algorithm With Input Saturation for Precision Motion Control of Linear Motor Drive Systems

This paper focuses on the synthesis of nonlinear adaptive robust controller with saturated actuator authority for a linear motor drive system, which is subject to parametric uncertainties and uncertain nonlinearities such as input disturbances as well. Global stability with limited control efforts is achieved by breaking down the overall uncertainties to state-linearly-dependent uncertainties (such as viscous friction) and bounded nonlinearities (such as Coulomb friction, cogging force, etc.), and dealing with them via different strategies. Furthermore, a guaranteed transient performance and final tracking accuracy can be obtained by incorporating the well-developed adaptive robust control strategy and effective parameter identifier. Asymptotic output tracking is also achieved in the presence of parametric uncertainties only. Meanwhile, in contrast to the existing saturated control structures that are designed based on a set of transformed coordinates, the proposed saturated controller is carried out in the actual system states, which have clear physical meanings. This makes it much easier and less conservative to select the design parameters to meet the dual objective of achieving global stability with limited control efforts for rare emergency cases and the local high-bandwidth control for high performance under normal running conditions. Real-time experimental results are obtained to illustrate the effectiveness of the proposed saturated adaptive robust control strategy     

Recurrent-Fuzzy-Neural-Network-Controlled Linear Induction Motor Servo Drive Using Genetic Algorithms

A recurrent fuzzy neural network (RFNN) controller based on real-time genetic algorithms (GAs) is developed for a linear induction motor (LIM) servo drive in this paper. First, the dynamic model of an indirect field-oriented LIM servo drive is derived. Then, an online training RFNN with a backpropagation algorithm is introduced as the tracking controller. Moreover, to guarantee the global convergence of tracking error, a real-time GA is developed to search the optimal learning rates of the RFNN online. The GA-based RFNN control system is proposed to control the mover of the LIM for periodic motion. The theoretical analyses for the proposed GA-based RFNN controller are described in detail. Finally, simulated and experimental results show that the proposed controller provides high-performance dynamic characteristics and is robust with regard to plant parameter variations and external load disturbance     

Left atrial pressure controller design for an artificial heart

This paper describes the application of a dynamic compensator technique to the left atrial controller design for use with a portable artificial heart drive system. The compensator is designed using a method in the field of multivariable control. This controller design is based on the physical models of the actuator and blood pump system. The analysis shows that there exists a minimal compensator with a dimension of one. The computer simulation demonstrates the acceptable, robust control performance of the left atrial pressure for a relatively small parameter variation of the vascular system model when all the poles of the closed-loop system are assigned to appropriate values.     

Lie compensator design for exact linearization of inverter-fed induction machines

Differential-geometry methods enable the design of a Lie compensator that exactly linearizes the total system including the nonlinearities of an induction motor. The aim of this work is to prove under which circumstances the five equations of the induction motor are exactly linearizable and to figure out the linearization unit details as a basis for a linear controller. The use of computer-algebraic procedures facilitates the evaluation of the complex calculations. Simulations and the comparison with measurements of practical plants show that the linearization is successful and that the over-all system including induction motor, linearization circuit and controller obeys optimal tracking performance.     

Robust adaptive tracking control of uncertain electrostatic micro-actuators with H-infinity performance

A novel adaptive robust tracking control scheme is proposed for a class of single-degree-of-freedom (1DOF) electrostatic micro-actuator systems in the presence of parasitics, parameter uncertainties and external disturbances. This method integrates the adaptive dynamic surface control and H-infinity control techniques. Based on this method, both the design procedure and the derived tracking controller itself are simplified, and the controller guarantees that the output tracking error satisfies the H-infinity tracking performance. In addition, the tracking accuracy can be adjusted by an appropriate choice of the design parameters of the controller. Simulation results show that prescribed transient output tracking performance can be achieved, and the closed-loop system exhibits good robustness to system uncertainties.     

Continuous variable structure controller for BLDDSM positioncontrol with prescribed tracking performance

The continuous, accurate, and robust sliding mode tracking controller based on a disturbance observer for a brushless direct drive servo motor (BLDDSM) is presented. Although the conventional sliding mode control (SMC) or variable structure control (VSC) can give the desired tracking performance, there exists an inevitable chattering problem in control which is undesirable for a direct drive system. With the proposed algorithm, not only are the chattering problems removed, but also the prescribed tracking performance can be obtained by using the efficient compensation of the disturbance observer. The design of the sliding mode tracking controller for the prescribed, accurate, and robust tracking performance without the chattering problem is given based on the results of the detailed stability analysis. The usefulness of the proposed algorithm is demonstrated through the computer simulations for a BLDDSM under load variations     

Control of High-Speed Solid-Rotor Synchronous Reluctance Motor/Generator for Flywheel-Based Uninterruptible Power Supplies

A hybrid controller, consisting of a model-based feedforward controller and a proportional–integral feedback compensator, for a solid-rotor synchronous reluctance motor/generator in a high-speed flywheel-based uninterruptible power supply application is proposed in this paper. The feedforward controller takes most of the control output of the current regulator based on the machine model, and the PI controllers compensate the possible inaccuracies of the model to improve the performance and robustness of the complete control system. The machine current tracking error caused by parameter inaccuracy in the model-based controller is mathematically analyzed and utilized to dynamically compensate the estimated flux linkage to eliminate the steady-state error in current regulation. Stability analysis is also presented, and it can be seen that the regulation performance and robustness of the system are improved by the proposed hybrid controller. Simulation and experimental results consisting of a flywheel energy storage system validates the performance of the controller.      

Development of intelligent position control system using optimal design technique

This paper addresses the application of an intelligent optimal control system (IOCS) to control an indirect field-oriented induction servo motor drive for tracking periodic commands via a wavelet neural network. With the field orientation mechanism, the dynamic behavior of an induction motor is rather similar to a linear system. However, the uncertainties, such as mechanical parametric variation, external load disturbance and unmodeled dynamics in practical applications, influence the designed control performance seriously. Therefore, an IOCS is proposed to confront these uncertainties existing in the control of the induction servo motor drive. The control laws for the IOCS are derived in the sense of the optimal control technique and Lyapunov stability theorem, so that system-tracking stability can be guaranteed in the closed-loop system. With the proposed IOCS, the controlled induction servo motor drive possesses the advantages of good tracking control performance and robustness to uncertainties under wide operating ranges. The effectiveness of the proposed control scheme is verified by both simulated and experimental results. Moreover, the advantages of the proposed control system are indicated in comparison with the sliding-mode control system.     

Dual-stage HDD head positioning using an H∞ almost disturbance decoupling controller and a tracking differentiator

We adopt in this paper a novel control scheme to achieve fast and accurate head positioning for dual-stage actuated hard disk drive (HDD) servo system with actuator saturation and disturbances. This control scheme consists of a tracking differentiator (TD) to avoid actuator saturation as large as possible and an H_∞ almost disturbance decoupling controller to deal with disturbances and improve the tracking performance. More specifically, the TD aims to provide a smooth reference signal in a feedforward way so as to reduce the system error, and further decrease the control inputs to both the VCM actuator and the micro-actuator such that the saturation problem can be effectively avoided. The H_∞ almost disturbance decoupling controller, when it is applied to control the micro-actuator, is able to almost decouple the disturbance and the controlled output such that satisfactory tracking performance can be achieved. Furthermore, the VCM actuator is controlled by a notch filter in series with a lead compensator so as to stabilize the servo loop. Finally, simulation results in time domain and frequency domain verify the effectiveness of the proposed control scheme.     

On-line fuzzy tuning of indirect field-oriented induction machinedrives

This paper presents an on-line fuzzy tuning scheme for indirect field-orientation (IFO)-controlled induction machine drives. A fuzzy controller is used to regulate the speed, and another two fuzzy compensators are combined to correct detuning of field orientation. Since detuning effects of the IFO induction machine drive is minimized by the new fuzzy control scheme, the induction machine can achieve good performance in terms of overshoot, steady-state error, torque disturbance, and variable-speed tracking. Efficiency and torque/ampere capability are also enhanced. The results obtained by laboratory implementation are presented to verify the effectiveness of the proposed on-line fuzzy-tuning scheme     

Development of Robust Current 2-DOF Controllers for a Permanent Magnet Synchronous Motor Drive With Reaction Wheel Load

This paper develops robust 2-DOF current and torque control schemes for a permanent magnet synchronous motor (PMSM) drive with satellite reaction wheel load. A DSP-based experimental PMSM-driven reaction wheel system is established, and the key motor parameters are estimated for realizing the proposed control schemes. In the proposed current control schemes, the traditional 2-DOF controller is augmented with an internal model feedback resonant controller or a robust tracking error cancellation controller (RECC). Comparative performance and error analyses of these two proposed control schemes are given. Accordingly, an improved robust 2-DOF current control scheme combining the resonant controller and the RECC is further proposed. The resonant controller enhances the transient and steady-state tracking of the sinusoidal current, simultaneously rejecting the back electromotive force. A similar robust tracking control for the observed torque can be designed, which exhibits quick transient response. Effectiveness of the proposed controls and the driving performance of the whole reaction wheel are evaluated experimentally.