Servo Amplifier Research Articles

Development and testing of a discrete coil magnetostrictive actuator

Active combustion control (ACC) technology is an effective measure for suppressing the combustion oscillation of aero-engines. The magnetostrictive actuator is the most suitable choice for the ACC actuator due to its excellent high-frequency characteristics and high-temperature resistance. In order for the magnetostrictive actuator to produce high-frequency displacement, the constant current driver must have sufficient power, which results in a larger mass of the driver. A solution is to use multi-channel and low-power constant current driver. Therefore, the coil of the magnetostrictive actuator is axially dispersed and driven by two four-channel servo amplifiers. The driver’s mass is significantly reduced while maintaining the same electromagnetic conversion effect. In addition, an analytical model of a discrete coil magnetostrictive actuator is established, and a series of experiments are conducted. The maximum hysteresis error of output displacement at 200 Hz is reduced by 15.2%. Furthermore, under PID closed-loop control, the root mean square (RMS) error is less than 2% when tracking a 10 Hz sinusoidal displacement with coil switching drive.

Servo kontrollü maliyet etkin bir aktif kuvvet duyargası tasarımı ve denenmesi

In this work, the computerized control of a hydraulic system with analog characteristics is examined, and within this scope, a novel force sensor is designed. The system consists of two main structures: an analog subsystem comprising a four-way servo valve, hydraulic piston, servo amplifier, and the designed force sensor, and a digitizing subsystem responsible for comparison and control, composed of a desktop computer. Throughout this work, a cost-effective force sensor was designed by integrating a compression spring, guides, a support frame and a linear variable differential transformer (LVDT). In this integrated system, the force applied at a specific magnitude and frequency from an external force measurement and feedback unit is converted into electrical signals by horizontal motion of the LVDT core. These electrical signals from the force sensor are digitized and fed back to the computer and data acquisition card. The digitized data transferred to the software developed in this study continuously compare with the reference data, enabling position-dependent force control. Experiments conducted with the force sensor placed between two hydraulic pistons controlled by a servo valve revealed that it caused the pistons to move right and left, providing the desired control of the system with the reference force input. The system was observed to operate much more stably, especially for high-frequency signal inputs.

Developments of Prototype Automatic Transportation Lines with a Direct Electric Drive

The increasingly demanding requirements for the production capacity, accuracy and repeatability of industrial production require the development of fully automated transportation lines in which a workpiece is mounted once and passes all stages of the technological process. To solve these problems, the leading manufacturers of machinery construction equipment offer, instead of conveying systems with belt or roller drive, modular automatic transportation lines based on direct drives with permanent-magnet linear synchronous machines. A specific feature of using a linear machine in a transportation line is an inverted mutual layout of the primary part (the armature) and the secondary part (the magnetic way) in which the magnetic way segment moves over a number of modules distributed along the line with a set of armatures and sensors controlled by individual servo amplifiers interconnected by a digital bus. With such solution, a workpiece is attached to the passive moving part that does not require the connection of electrical cables – to ensure its free and independent movement within the entire production line. The modularity of the design provides flexibility of the transportation systems. The article gives a review of solutions offered by various manufacturers, shows the specific features of using linear synchronous machines and sensors in such systems, and proposes the authors’ own developments of prototype transportation lines.

ANALYSIS OF BRAKE SYSTEMS IN MOTOR VEHICLES USING PRACTICAL EXAMPLES FROM THE ASPECT OF THEIR DIAGNOSTICS

The part of the braking system that has the task of transmitting the command activated by the driver to thebrakes is called the transmission mechanism. The transmission mechanism itself can be different depending on howit is constructed and conceptually executed. As for the conceptual solution, the question arises as to whether thetransmission method itself must be such that the driver's command is only transmitted to the brakes or the driver'scommand itself is handed over to a separate energy system. The energy system itself can be such that it additionallyhelps the activation of the brakes (servo brake force boosters) or completely takes over the activation of the brakes,with the creation of a certain braking force on the wheels, and these are the so-called mechanisms with full servoaction. Today we have the following transmission mechanisms in use: Mechanical transmission, hydraulic with orwithout servo amplification, hydraulic with full servo action, pneumatic with full servo action, hydro-pneumaticwith servo amplification or with full servo action. The very choice of these systems depends on a large number offactors, but the main one is - how much energy must be delivered to the brakes. Each of these systems is explainedseparately in the paper. A mechanical transmission mechanism is a system that does not have any additional servoamplification, but the command of the driver or the person operating the machine is directly transmitted to thebrakes. Based on this, we can conclude that the application of this transmission mechanism in brake systems is quitelimited. Today, this transmission mechanism is only used as a service brake on some slower trucks and tractors. Thehydraulic transmission mechanism is the system that is most common in brake systems of passenger, light cargo anddelivery vehicles. In the case of vehicles weighing up to 1000 kg, the driver alone is sufficient to develop thenecessary energy for braking, so it is not necessary to additionally support the braking force with servo boosters. Butthat's why smaller trucks and delivery vehicles need additional help from a servo booster to activate the brakingforce. Servo amplifiers have become an integral part of the equipment in passenger vehicles primarily due to thesafety, security and comfort of passengers. In contrast to the mechanical transmission, this system is morecomplicated in terms of performance and its operation is based on the transmission of pressure through the brakefluid from the main brake cylinder to the brake cylinder in the brakes. The pressure created by the brake fluid actson the pistons in the cylinder itself and in this way force is created and the brakes are activated. The main advantageof this system is the very safety and safer braking, because with the hydraulic system it is possible to make adistribution in several independent branches to the cylinders on the brakes, and this is one of the basic satisfactoryrequirements in the ECE regulation that the brakes must also have an auxiliary braking system in case dismissal ofthe principal. The system itself consists of: the pedal, which is activated by pressing the foot on the pedal itself, themain brake cylinder, the distribution system, the working brake cylinders in the brakes and the brake itself.

Parametric Analysis of Variable Stator Vane System in Gas Turbines Based on Cosimulation of its Refined Model and System Dynamic Performance Model

AbstractThe variable stator vane (VSV) system is a key component of gas turbine supercharged rotor components for anti‐surge, and its performance directly affects the working stability and economy of the gas turbine. The effect of the VSV system on the dynamic characteristics and control performance of the gas turbine cannot be known. Then a refined model of the VSV system refined to design parameters established and studied to explore the effect of gas turbine dynamic performance based on co‐simulation. The effects of key parameters on the performance of the gas turbine system are analyzed by embedding the refined VSV model into the engine model. The simulation results prove that servo amplifier gain, viscous friction coefficient and dead band are sensitive structural parameters that affect the dynamic performance of the gas turbines. In the proposed appropriate interval, the optimal sensitive parameters can reduce the overshoot and adjustment time by about 51% and 7%. The gain of the servo amplifier is positively correlated with the maximum opening of the VSV. When the dynamic performance of the control system has been exerted to its extreme, some nonlinear parameters of the actuator can greatly improve the overall performance of the complex system.

Closed-Loop Control of a Helmholtz Coil System for Accurate Actuation of Magnetic Microrobot Swarms

Magnetic microrobot swarms have attracted lots of research interests in the robotics field. Since the remote actuation of swarm can be affected by the accuracy of the external magnetic field, electro-magnetic systems capable of generating precise magnetic fields have great value. In this work, we propose a closed-loop control scheme for 3-axis Helmholtz coil system to improve the field generation performance. Each coil is connected to and driven by a commercial servo amplifier, and the mathematical model of the system is obtained by the sweeping frequency method. With the identified model, a current controller based on the model predictive control (MPC) is presented, the states of the system and the lumped disturbance are observed by a 4th-order super-twisting sliding mode observer (STSMO) for control input calculation and disturbance compensation. To evaluate the effectiveness of the proposed control scheme, we conduct experiments on a lab-made 3-axis Helmholtz coil system. Results indicate that the bandwidth of the system can be increased to 50 Hz, and the settling time can be reduced to 0.9 ms and 0.83 ms for the outer coil and middle coil, respectively. Moreover, rotating fields with different frequencies are generated with and without the proposed scheme to actuate magnetic vortex-like microswarms. The swarm deforms to an ellipse with shape ratio equals to 0.45 as the frequency increases in the open-loop condition, in contrast to which with the proposed control scheme shows a more accurate and controllable circular pattern.

Position controlling of Sun Tracking System using optimization technique

The prime objective of this paper is to devise optimization technique for the position control of Sun Tracking System (STS). In order to control the position of this system, PID controller tuned by different methods such as Genetic Algorithm (GA), Particle Swarm Optimization (PSO) and Teaching Learning Based Optimization (TLBO) is used. These methods have been carried out to determine the most optimized and robust one for the position control. The simulated results for nominal and perturbed value of servo amplifier gain show that the PID controller tuned with TLBO technique gives most optimized and robust performance in comparison to other tuning techniques.

Учет аппаратных ограничений при построении систем управления сервопривода

In designing a servo drive operating in a high-precision tracking mode, its motion trajectory should be shaped so that none of the specified drive state variables exceeded the preset constraints. This is one of the most important factors essential for securing the required accuracy and stability of system operation. On the other hand, if the drive operation parameters are kept far from the constraints, the drive equipment is underused; it will have excessive capacity and overall dimensions and, hence, excessive capital cost. Therefore, from the economic point of view it is important to set up the drive operation close to the constraints imposed on it. The article considers the constraints imposed on a direct servo drive equipped with a permanent-magnet synchronous machine (either a linear or rotary one). A constraint consideration concept is presented, according to which the constraints are conditionally subdivided into internal (constraints relating to the servo drive components) and external ones (constraints connected with the technological process and environment). Dedicated software for analyzing the constraints is presented, and its underlying principles are described. By using this software, it is possible to determine the permissible coordinates of a servo drive composed of the preset components (electrical machine, servo amplifier, position sensor, etc.) subject to the specified external constraints. Proceeding from the servo drive components (a synchronous machine, control unit, position sensor) selected from an editable library and the process installation parameters specified by the user as the input data, the software produces the domain of static mechanical characteristics individually for the electrical machine, for the machine together with the control unit and position sensor, and for the servo drive with taking into account the constraints specified by the user. As a result, the following positive aspects become available. First, the compatibility of the selected components is checked, and the possibility of using the selected equipment for implementing the required motion law is determined. Second, the components limiting the servo drive performance indicators are revealed. And third, the possibility of improving the servo drive performance characteristics in the case of using sophisticated control algorithms is analyzed. In particular, it has been shown that weakening of the field does not always make it possible to broaden the servo drive speed range. By using the proposed constraint consideration concept, a direct drive and its control systems can be designed and optimized much more rapidly, so that the newly developed drive can become commercially available within a shorter period of time.

Feeding Apparatus Directly Driven by Optimal Topology Flux Switching Permanent Magnet Linear Motor

For both magnets and coils are arranged in motor primary, short primary, and long secondary flux switching permanent magnet linear motor (FSPMLM) is extremely appropriate to long distance applications. A novel FSPMLM is developed to construct a feeding apparatus in this article. The magnetic field is analyzed by equivalent magnetic circuit (EMC), which indicates that the longitudinal end effect can be weakened by adjusting the width of the end-PMs. Then finite element analysis (FEA) and response surface methodology (RSM) are applied to optimize the force performance. The whole construction of the proposed FSPMLM feeding apparatus is designed and the prototype is manufactured. A commercial servo amplifier is used to control the prototype and the experiment setup is built to demonstrate the prototype performance. 500 mm feeding distance is conducted with the rated speed 1.5 m/s and the acceleration 10.0 m/s2, which indicates the high speed and high acceleration capacity. Then 10 kg and 20 kg weights are loaded on the prototype with the speed 200 mm/s and 100 mm/s, respectively. Well force response performance is exhibited, and the position error is sufficient low. It can be seen that the proposed FSPMLM feeding apparatus can be employed competitively in various machine tools.

Decentralized adaptive partitioned approximation control of high degrees-of-freedom robotic manipulators considering three actuator control modes

Partitioned approximation control is avoided in most decentralized control algorithms; however, it is essential to design a feedforward control term for improving the tracking accuracy of the desired references. In addition, consideration of actuator dynamics is important for a robot with high-velocity movement and highly varying loads. As a result, this work is focused on decentralized adaptive partitioned approximation control for complex robotic systems using the orthogonal basis functions as strong approximators. In essence, the partitioned approximation technique is intrinsically decentralized with some modifications. Three actuator control modes are considered in this study: (i) a torque control mode in which the armature current is well controlled by a current servo amplifier and the motor torque/current constant is known, (ii) a current control mode in which the torque/current constant is unknown, and (iii) a voltage control mode with no current servo control being available. The proposed decentralized control law consists of three terms: the partitioned approximation-based feedforward term that is necessary for precise tracking, the high gain-based feedback term, and the adaptive sliding gain-based term for compensation of modeling error. The passivity property is essential to prove the stability of local stability of the individual subsystem with guaranteed global stability. Two case studies are used to prove the validity of the proposed controller: a two-link manipulator and a six-link biped robot.

Novel AC Servo Rotating and Linear Composite Driving Device for Plastic Forming Equipment

The existing plastic forming equipment are mostly driven by traditional AC motors with long transmission chains, low efficiency, large size, low precision and poor dynamic response are the common disadvantages. In order to realize high performance forming processes, the driving device should be improved, especially for complicated processing motions. Based on electric servo direct drive technology, a novel AC servo rotating and linear composite driving device is proposed, which features implementing both spindle rotation and feed motion without transmission, so that compact structure and precise control can be achieved. Flux switching topology is employed in the rotating drive component for strong robustness, and fractional slot is employed in the linear direct drive component for large force capability. Then the mechanical structure for compositing rotation and linear motion is designed. A device prototype is manufactured, machining of each component and the whole assembly are presented respectively. Commercial servo amplifiers are utilized to construct the control system of the proposed device. To validate the effectiveness of the proposed composite driving device, experimental study on the dynamic test benches are conducted. The results indicate that the output torque can attain to 420 N·m and the dynamic tracking errors are less than about 0.3 rad in the rotating drive. the dynamic tracking errors are less than about 1.6 mm in the linear feed. The proposed research provides a method to construct high efficiency and accuracy direct driving device in plastic forming equipment.

Development of Hydraulic Servo Amplifier with Single Supply

Development of Hydraulic Servo Amplifier with Single Supply

Design and Characteristic Analysis on Servo Amplifier

With the rapid development of the electro-hydraulic servo control technology, the application of electro-hydraulic servo valve has become more and more widely. Servo amplifier is an important part of the electro-hydraulic servo control system to drive and control servo valve. This essay introduces the principle and the function of servo-amplifier, and designs a servo amplifier with the functions of proportional amplifier, zero adjustment, feedback and current limitation. The performance analysis and validation for the servo amplifier are carried out by using simulation software EDA .On the basis of the simulation, the servo amplifier is fabricated, and its performance is tested. The results indicate that the servo amplifier has features of stable current output, good linearity, rapid response, and fully meet designing requirements.

Performance and Flow Field Evaluation of a Savonius Rotor Tested in a Wind Tunnel

A renewed interest on Vertical Axis Wind Turbines (VAWTs) arose from their great capacity for integration within urban areas and for applications of distributed generation. In order to be able to highly improve their performance, making them competitive with respect to the more consolidated Horizontal Axis Wind Turbines (HAWTs), it is fundamental to have a deeper comprehension of their fluid dynamic behavior. In order to reach this goal, a two-bucket Savonius rotor has been designed, built from a PVC pipe with a nominal diameter of 200mm, and tested in the wind tunnel of the Department of Mechanics, Mathematics and Managment (DMMM) of the Politecnico di Bari. The Savonius rotor is connected to an AC brushless servo motor, able to control either the braking torque or the rotational speed. This paper describes the experimental evaluation of the unsteady flow field downstream the rotor by means of a Constant Temperature hot wire Anemometer (CTA). Whilst, for performance analysis, the torque measurements have been obtained directly from the Servo Amplifier torque monitor.

전기 피드백 직동형 서보 밸브에 관한 역 분석

Mechanical and electrical properties of a DDV(Direct Drive servo Valve) with electric feedback are analysed via reverse analysis technique in this work. The DDV is disassembled and mechanical parameters, such as spool mass, spring stiffness and port size are identified. The servo amplifier, which is built in the valve, is reversely analysed and the control scheme and gains for several control actions are also identified. The electrical feedback for spool displacement improves much better the valve performance, such as hysteresis and dynamic bandwidth frequency, than an ordinary mechanical feedback valve. Integrating control action with very large gain was adopted in the valve amplifier, and it seemed to give high performance.

A Gluing Device Based on PLC for Manufacturing Flap-Disks

The gluing control system designed for production plants to manufacture flap-disks was investigated using programmable logic controller (PLC) and servo. The system has been mainly developed to achieve efficient gluing for the back cover. It is implemented by a PLC, a human-machine interface (HMI), a positioning module and sensors, as well as servo amplifiers and motors. Issues was discussed in this paper, such as connection of the hardware, working mechanism design, capacity selection of servo motors, high-speed and uniform gluing, means of pre-opening and delayed-shutoff for the needle valve and etc. Hardware and software was developed for the system and high-precision gluing was achieved. The device has been provided for industrial applications, which has greatly improved the production quality and efficiency.

Design and Implementation of Motion Control System with Precise Driving Mechanism

In this paper, a motion control system based on 2-axis gimbal system is designed and implemented to drive a high speed and precision. The proposed system consists of the RS-422 interface, 2-axis gimbal platform, SCU (servo control unit) integrated with a high speed DSP chipset, SAU (servo amplifier unit), potentiometer sensor unit, and resolver sensor unit. The SCU using the DSP firmware is designed to get a fast response without an overshoot with step input and a RMS error of low probability with ramp input. The SAU using a voltage control is designed to resolve the zero-crossing distortion for precise motion. To verify the performance and stability of the implemented system, experiments are performed through a measurement of the time and frequency domain response in a laboratory environment by using a PXI (PCI extentions for instrumentation).

정밀구동메커니즘 적용 모션제어시스템 설계 및 구현

In this paper, a motion control system based on 2-axis gimbal system is designed and implemented to drive a high speed and precision. The proposed system consists of the RS-422 interface, 2-axis gimbal platform, servo control unit integrated with a high speed DSP chip-set, servo amplifier unit, potentiometer sensor unit, and resolver sensor unit. The servo control unit using the high speed DSP firmware is designed to get a fast response without an overshoot with step input and a RMS error of low probability with ramp input. The servo amplifier unit using a voltage control is designed to resolve the zero-crossing distortion for precise motion. To verify the performance and stability of the implemented system, experiments are performed through a measurement of the time and frequency domain response in a laboratory environment by using a PXI(PCI eXtentions for Instrumentation).

Electro-Hydraulic Servo Road Simulation System Based on Fuzzy Control

The indoor road simulation test system test cycle is short, good reproducibility of the test results, confidentiality, etc., more and more attention in the vehicle industry. Analyzed by electro-hydraulic servo system of road simulation servo amplifier, electro-hydraulic servo valve, hydraulic cylinder and countertops and displacement transducer, The mathematical model of the system is established. The fuzzy model that comply with control law is designed. By unit step response simulation experiments, it is to be verified that the fuzzy control electro-hydraulic servo road simulation system is able to work better. It is a new attempt in roads simulation control strategy.

Modeling and Stability Analysis of Hydraulic System for Wave Simulation

This thesis put forward a hydraulic wave simulation system based on valve-controlled cylinder hydraulic system, which simulated wave movement on the land. The mathematical model of valve-controlled symmetric cylinder was deduced and the mathematical models of servo valve, displacement sensor and servo amplifier were established according to the schematic diagram of the hydraulic system designed, on the basis of which the mathematical model of hydraulic wave simulation system was obtained. Then the stability of the system was analyzed. The results indicated that the system was reliable.