Speed Control Of Servo System Research Articles

Model-free PZC filter-based multi-loop speed controller for servo drives

Model-free PZC filter-based multi-loop speed controller for servo drives

Hydrostatic bearing groove multi-objective optimization of the gear ring housing interface in a straight-line conjugate internal meshing gear pump

The lubrication performance of a straight-line conjugate internal meshing gear pump is poor under the low-speed, high-pressure operating conditions of the volumetric servo speed control system, and it is difficult to establish a full fluid lubricating oil film between the gear ring and the housing. This leads to significant wear and severe heating between the gear ring and the housing. The lubrication performance of the interface moving pair of the electro-hydraulic actuator pump gear ring housing can be improved by designing a reasonable lubrication bearing structure for the gear ring housing. In this study, a multi-field coupling multi-objective optimization model was established to improve lubrication performance and volumetric efficiency. The whole model consists of the dynamic model of the gear ring components, the fluid lubrication model of the gear ring housing interface, the oil film formation and sealing model considering the influence of temperature, and the multi-objective optimization model. The comprehensive performance of the straight-line conjugate internal meshing gear pump was verified experimentally using a test bench. The results show that the lubrication performance is improved, the mechanical loss is reduced by 31.52%, and the volumetric efficiency is increased by 4.91%.

Reinforcement Learning and Optimal Control of PMSM Speed Servo System

This article proposes a novel model-free optimal speed tracking control scheme for permanent magnet synchronous motors (PMSMs) through reinforcement learning (RL). To achieve the speed servo control, we formulate the linear quadratic regulator associated with the reduced-order model in the outer-loop controller design. Such a model is obtained in terms of singular perturbation theory, which enables the separation of slow and fast time-scale dynamics. Moreover, we develop an off-policy RL algorithm to iteratively approximate the ideal value of solution to the linear quadratic regulator without requiring any knowledge of model parameters of the PMSM and the measurement of the load torque. Both simulation and experimental tests are carried out to justify that the proposed control scheme realizes precision speed tracking performance and shape transient response in the presence of unknown model parameters.

최적 절환 초평면을 갖는 슬라이딩 모드에 의한 DC모터의 강인한 속도제어

This paper deals with robust speed servo control for DC motors based on a sliding mode control (SMC). SMC is well known for its robust control performance against external disturbances including motor parameter variations. An optimum switching plane, a key issue for SMC, is designed to minimize control error and input energy in a state space model. Voltage command which is an output of the sliding mode controller is induced to satisfy the Lyapunov’s second method for critical stability. The robust control performance of the suggested sliding mode control is evaluated by two experiments such as a load test and parameter variation test. The external load test was conducted by applying 100% and 80% of the rated torque using a powder brake. The parameter variation experiment was conducted by increasing nominal parameters of the motor used in the controller by 3 times. Moreover, the effectiveness of SMC is clarified by comparing with the PI control experimental results. The experimental results showed that SMC has stronger control performance against the disturbance and parameter changes than the PI controller.

Design of Remote Hydraulic Teaching System

In this paper, a set of remote hydraulic teaching experiment system is designed and developed based on the demand of teaching experiment of hydraulic related courses in colleges and universities, which can enable teachers or students to conduct experiment operation on the field hydraulic testing platform at the remote client, so as to facilitate teachers and students to carry out hydraulic teaching experiment and research. The main contents of this paper are as follows: according to the requirements of hydraulic servo control system related to the teaching experiment, the experimental project of remote hydraulic teaching experiment system is determined. Through the analysis and comparison of C/S and B/S software system architectures, the remote monitoring scheme based on B/S mode is determined. Completed the design of the hydraulic circuit of the hydraulic test bench, developed the field measurement and control system based on LabVIEW, and built the remote monitoring system based on B/S mode. The development of the remote hydraulic teaching experiment system was completed. The input signal response experiment and load characteristic experiment of the valve-controlled motor electro-hydraulic speed servo control system were carried out on the remote client to the field hydraulic experiment platform, and the experimental results were analyzed. The experimental process and results have reached the expected target and meet the demand of remote hydraulic experiment.

Step-Signal-Injection-Based Robust MTPA Operation Strategy for Interior Permanent Magnet Synchronous Machines

In various applications that utilize maximum torque per ampere (MTPA) operation of interior permanent magnet synchronous machines (IPMSMs), there exist unexpected perturbations in electrical parameters and operating environment, which deteriorate the accuracy and efficiency of the MTPA operation. This paper establishes a step-signal-injection-based robust MTPA operation strategy for the IPMSM drives. The method works by injecting a step signal into the current vector angle and observing the response in the current magnitude, followed by a proportional-integral controller which returns the system to optimal operation. The stability of the proposed algorithm is established using the Lyapunov theory. A speed-servo control system of IPMSM is considered, where a disturbance detection unit is designed to switch operation between optimal current angle updating mode and steady-state MTPA operation mode. Since the optimal current angle updating is independent of machine parameters, the impact of system perturbations on the MTPA operation can be effectively suppressed. Extensive experimental results for IPMSM and hardware-in-the-loop-based machine are presented to validate the effectiveness and robustness of the proposed method.

A new reliability analysis method for repairable systems with closed‐loop feedback links

AbstractA new reliability analysis method for repairable systems with closed‐loop feedback link (CLFL) is proposed based on GO methodology. A method for creating new function GO operators is used to describe the CLFL. Next, methods for deducing the formulae of the new GO function are proposed. In addition, a 2‐level GO model is proposed for the GO operation of repairable systems with CLFL. And then, quantitative and qualitative analysis methods for repairable systems with CLFL based on the GO method are proposed, and a process for analyzing repairable systems with CLFL based on the new GO method is formulated. Finally, we used this new GO method to analyze the reliability of an electro‐hydraulic servo speed control system and a power‐shift steering transmission control system for a heavy vehicle. To verify the feasibility, advantages, and reasonability of the new GO method, we compared our results with those obtained by fault tree analysis, Monte Carlo Simulation, and an existing GO method using serial and parallel structures to represent the CLFL. All in all, the proposed method overcomes the limitations of the existing methods as well as increasing its applicability. And it provides a new approach for reliability analysis of repairable systems with CLFL.

Disturbance observer control for AC speed servo with improved noise attenuation

The paper deals with a noise attenuation design of a modification of the disturbance observer (DO) based PI control for an AC servo drive with the dominant first-order dynamics. The achieved results are compared with the traditional PI control. The DO based filtered PI (DO-FPI) controller consists of the P control with adjustable filter. It is augmented with an integral action based on load reconstruction using equally filtered plant dynamics inversion. The availability of broadly scalable filters requires a simple one-parameter based tuning. In looking for a possibly good noise attenuation, it allows changing the filter order and time constants by keeping nearly the same speed of disturbance responses as in the PI control. An application to the speed servo control with an incremental position sensor brings to light interesting properties of the compared solutions. The DO FPI and PI control give nearly equally robust solutions. However, in case of PI control it is at the expense of significantly increased torque ripple.

Artificial Immune System based PID Tuning for DC Servo Speed Control

Artificial Immune System based PID Tuning for DC Servo Speed Control

Robust 2DOF fuzzy gain scheduling control for DC servo speed controller

This paper proposes a new design method called “robust 2DOF fuzzy gain scheduling control” for a DC servo speed control system. The proposed technique utilizes the basic concept of 2DOF robust loop shaping, whose time‐domain specifications are combined during the controller design using a reference model. In addition, the local controllers are fixed‐ structure robust controllers whose structure can be specified as for a simple controller. A fuzzy approach is adopted in both system identification process and global control structure to accomplish an entirely robust system. Although the design of robust control in a fuzzy system is not easy, genetic algorithms (GAs) simplify the control design problem to design the fuzzy controller such that the average stability margin is minimized. Implementation of a DC servo speed control was adopted to investigate the effectiveness of the proposed controller. As seen from the results, the proposed controller has more robust performance and can be adopted in applications with a wide operating range. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Magnetic Gear Pole-Slip Prevention Using Explicit Model Predictive Control

This paper considers the phenomenon of “pole slipping” in magnetic gears and couplings as a result of torque overload. Specifically, previously reported work on optimized servo speed control and pole-slip detection in magnetic gears is extended through the development of a new control scheme to prevent pole slipping due to combined controller and load torque overload. By utilizing a model predictive control (MPC) strategy, the controller's principal objective is to prevent the magnetic gear from pole slipping by invoking hard constraints on the amount of controller torque that can be applied for a given steady-state load torque. A custom demonstrator drivetrain incorporating a magnetic coupling (1:1 magnetic gear) is used to experimentally verify pole-slip prevention using an implementation of explicit MPC via multiparametric quadratic programming (mp-QP). It is shown that while conventional MPC is restricted to systems with relatively low sample rates, due to the need to solve the constrained optimization problem in real time, an alternative explicit form of MPC can be readily utilized at sample rates more typically found in electrical drive applications. The underlying principles and benefits afforded by the proposed techniques are validated using simulation and experimental measurements from the drivetrain test facility, using only motor-side sensor measurements and load-side state estimates via a discrete-time observer.

Blowers of Vacuum Cleaners Utilizing Coreless and Sensorless Axial-Flux Motors with Edge-Wire Coils

Axial-flux motors (AFM) generally have higher torque and power densities, smaller volume and weight, larger diameter to length ratio, and compact construction for the same power level than radial-flux motors (RFM). Hence, AFM are attractive alternative to conventional RFM for applying in low torque and speed servo control systems. Additionally, magnetic Hall-effect sensors and commutation circuits are unsuitable for environment with high temperature and restricted space, so sensorless driving control method of AFM by detecting zero-crossing of back-EMF signals has been achieved. Furthermore, coreless design can reduce motor total weight, normal attractive force and torque pulsation and can increase efficiency of machines as compared with conventional design with cores. Thus, this study focuses on sensorless AFM design applying for blowers in vacuum cleaners to follow the concepts of axial-flux, edge-wire with high space-utilization factors, and stators without ferromagnetic cores. The closed-loop velocity controller designs by adopting proportional-integral-derivative (PID) and fuzzy logic control (FLC) algorithms have been demonstrated effectively for the design sensorless AFM of blowers in vacuum cleaners. As a result, the settling time of velocity closed-loop control methods can be converged within 1.0 second; i.e. the vacuum cleaners can switch and operate in various speeds with different operational environment rapidly. Therefore, the system characteristics and lifetime of the designed sensorless AFM have been enhanced and satisfied the demands of blowers to employ in vacuum cleaners.

Controller Design Methods for Driving Systems Based on Extensions of Symmetrical Optimum Method with DC and BLDC Motor Applications

The paper gives design methods dedicated to speed control of Direct Current (DC) and Brushless Direct Current (BLDC) motors in the framework of servo systems. Two design approaches are offered for position and speed control of servo systems with inner current control loops. The PI and PID controllers in these approaches are tuned on the basis the Extended Symmetrical Optimum method and of the double parameterization of Symmetrical Optimum method. Cost-effective features are ensured by simple controller designs and easy implementations, and they are illustrated by means of a case study that includes simulation results. A two-degree-of-freedom interpretation is given. A BLDC motor application applied to mechatronic systems is presented.

Combines Speed Servocontrol Based on RBF

In order to let the combine working in the best condition, it is necessary to control its speed according to the crop conditions in the field. The walking office of combine is analyzed in this paper. It is a high order system, some parameters will change during its working, and it is impacted by external disturbance. Then a servocontroller based on RBF neural network is designed. The model is simplified, and there are 2 parameters in it. Then a RBF neural network is established. The speed of combine, its integral value and differential value are inputted to identify the parameters. The inverse controller is established base on the simple model. The result of simulation and real vehicle tests shows that the controller can effectively adapt to changes in the internal parameters, overcome the external disturbance, and achieve the purpose of tracking a given speed.

Servo speed control of travelling-wave ultrasonic motor using digital signal processor

In this study a novel servo speed control system for travelling-wave ultrasonic motor (TWUSM) has been presented. A drive system has been built based on two-phase high-frequency inverter using mechanical resonant frequency of the ultrasonic motor. The TMS320F243 digital signal processor (DSP) is adapted to ultrasonic motor drive system. The speed control of ultrasonic motor has been implemented with driving frequency in the range of 41.3–43.3 kHz. The improved speed characteristics realised by the proposed drive and control system have been demonstrated and validated by experiments.

Servo Speed Control of Traveling-Wave Ultrasonic Motors Using Pulse Width Modulation

W ith the advantages of lightweight, compact size, fast response, power-off holding torque and high-torque low-speed characteristics, the traveling-wave ultrasonic motor (TUSM) is becoming attractive for servo application. This paper presents a new pulse width modulation (PW M) method for servo speed control of a TUSM. The key is to digitally control the pulse width, hence the fundamental value, of the bipolar 2-phase voltages feeding into the TUSM. This method takes a definite advantage of minimum audible noise compared with those available methods, such as phase-difference control, frequency control, and on-off PW M control. Experimental results confirm that the proposed speed controller can offer good steady-state and transient performances and can significantly suppress the audible noise occurred at speed variations.

High speed servo control of multi-axis machine tools

Advances in high-speed machining technology, including those in spindle speeds and cutters, are out-pacing advances in the servo control performance of machine tools. To close this gap, new machine tools and improved controls must be developed. Improvements to machine tools under development include special-purpose machine tools, the use of advanced materials, the replacement of ball screws and ways with linear motors and roller guides, and the use of parallel link actuators. This paper focuses on the control issues that will become increasingly important as these high-speed machining and high-speed machine tool advances are realized. The main issues in high-speed servo control are feed rate planning, and servo loop control laws. A method is developed in this paper which takes advantage of the full performance envelope of each axis in an arbitrary path. This near-complete usage of the servo capabilities of a machine tool results in reduced cycle time or reduced path error. A servo loop control law is then developed that uses the axis performance envelope as well as instantaneous position, velocity, and acceleration information of the target path and machine axis to improve servo performance in the presence of disturbances.

A robust nonlinear controller for induction motor

In this paper, a new method based on nonlinear auto-disturbance rejection controller (ADRC) has been developed for the induction motor drives. Via the use of ADRC, the stability is guaranteed for the speed servo control and insensitivity to uncertainties and disturbances are obtained as well. The proposed control system has been successfully tested by means of simulations and experiments. The results show that the controller performs quite robustly under modeling uncertainty and measurement noise, and the dynamic performances are improved as well.

Speed tracking servocontrol system with speed ripple reduction scheme for traveling-wave-type ultrasonic motor

Recently, as an area of application of ultrasonic waves to the energy-related subject, technical development of ultrasonic motors is expected. To date, the principles and characteristics of several types of ultrasonic motors have been reported. Components taking advantage of the characteristic features of the ultrasonic motor have been in part reduced to practice. Further, several methods have been reported on the driving control method for the ultrasonic motor. In the speed tracking servocontrol system using the ultrasonic motor, the effect of the load torque and the control characteristics of the speed tracking are only partly reported and are insufficient for practical applications. Further, the fluctuation of the speed, or the speed ripple, caused by the manufacturing process of the ultrasonic motor has not been studied carefully. In this paper, a new speed servocontrol system is proposed in which the speed ripple reduction, load torque characteristics, and speed tracking are taken into consideration. The proposed system uses two control loops. A speed control loop using a variable gain is constructed in the driving frequency control section. Further, only the speed ripple is extracted from the revolving speed detection signal and is used for feedback compensation to the constant voltage control loop in the applied voltage control section. A test experiment is carried out and the experimental results are used to determine the effectiveness of the proposed speed servocontrol system. © 1998 Scripta Technica, Electron Comm Jpn Pt 3, 81(9): 1–9, 1998

Speed tracking servo control system incorporating traveling-wave-type ultrasonic motor and feasible evaluations

A variety of ultrasonic motors (USMs) have attracted special interest as a new type of actuator in servo motion control systems. For practical applications, the speed servo control system incorporating the ultrasonic motor developed in Japan has some special unique features. However, this system has several significant problems, such as the inherent speed ripple characteristics, the speed regulation characteristics under the condition of applied disturbance load torque, and the speed tracking characteristics. In order to solve these practical problems, some control schemes of ultrasonic-actuated motor systems have been proposed and discussed theoretically, which include fuzzy reasoning control, adaptive control, repetitive learning control, and neural-network-based learning control. However, it is considered that these control strategies mentioned above have not been sufficiently substantiated from a feasible experimental point of view. This paper presents a newly proposed precise speed tracking servo control system using the compact traveling-wave-type ultrasonic motor. Its proposed control scheme is composed of both the driving frequency control loop with the variable-gain strategy and the applied voltage control loop with the speed ripple reduction strategy of the USM. The improved speed characteristics realized by this proposed control system are demonstrated and evaluated in experiments.