Servo Unit Research Articles

Application of the Gray Wolf Optimization Algorithm in Active Disturbance Rejection Control Parameter Tuning of an Electro-Hydraulic Servo Unit

A valve-controlled hydraulic cylinder system has the characteristics of uncertainty and time-variance, and the electro-hydraulic servo unit encounters shock, vibration, and other external interference when working, which seriously affect the stability of the valve-controlled hydraulic cylinder system. Therefore, it is necessary to introduce an active disturbance rejection controller (ADRC) into the electro-hydraulic servo control. However, there are many ADRC parameters, and it is difficult to set these only with expert experience. Therefore, we propose applying the gray wolf optimization algorithm (GWO) to the ADRC, to auto-tune the parameters and find the optimal solution. In addition, the advantages of the GWO in ADRC parameter tuning are proven and analyzed. The simulation and experimental results showed that the GWO algorithm had a faster mean time for parameter tuning and the smallest fitness value (integrated time and absolute error), compared to the particle swarm optimization algorithm and genetic algorithm. Moreover, a valve-controlled cylinder system, after parameter tuning by the gray wolf optimization algorithm, could accurately adjust the parameters of the auto-disturbance rejection controller, with a faster response speed, smaller overshoot, and better anti-disturbance ability.

ROBUST AND FEEDFORWARD CONTROL FOR A NONLINEAR PNEUMATIC SERVOMECHANISM SYSTEM

The actuator of the vane servo unit epitomizes the control operator of force in systems of missile control, where the character of its dynamic and static plays a significant role in the missile behavior. Therefore, improving the dynamic behavior for the vane servo actuator is of main interest for designing control and guidance system. The article describes a new method of analyzing the mathematical model of the nonlinear pneumatic servo with different design parameters and designing a controller with these parameters. The robust control regulates the system with different parameters, and it is the first controller to attempt this technique. A servo actuator of nonlinear and linear simulators was constructed by MATLAB software package. Feedback controllers with PI and PID were designed and tested theoretically. The setting time and the behavior of the dynamic will be improved. The robust feedforward control was applied to the system to improve the stability and zero steady-state error and compare the results with PI and PID controller. Their tests showed that robust control is the best control for stability among the others.

Симуляционная модель системы адаптивного управления сегментами составного зеркала космического телескопа и ее метрологическая аттестация

The paper concerns a measurement problem of identifying inadequacy in a mathematical model of an adaptive control system driving segments of a deformable mirror in a large telescope. This is necessary to assess the validity of this model. A dual-axis servo drive unit utilising permanent magnet synchronous machines controls the mirror segments. The servo unit rotates each segment of the deformable mirror with respect to its axis of symmetry and tilts each segment relative to the fixed central reference segment. The paper provides general descriptions of the model structure and the feedback in the current control loop employing phase current measurement and coordinate transformations. We present initial data sets for metrological certification of the model. We used the MMK-stat M software to perform the metrological certification so that we could check empirical equations, determine the scope of application for the model and validate it. The metrological certification allowed us to confirm that the model of an adaptive control system for a segmented deformable telescope mirror is valid, and to find the model structure that ensures a more accurate description of the measurement problem that concerns controlling the spatial position of the object simulated

A Test-Bed For Measuring UAS Servo Reliability

Extant literature suggests minimal research on the reliability of Commercial off-the-shelf (COTS) components used in fabricating non-military Unmanned Aerial System (UAS). Stochastic failures of components during operational cycles over time poses a safety hazard to flight operations. The purpose of the study was to critically assess the operational performance standards (reliability) of a laboratory designed UAS component test-bed operated using real-world data collected from a Boeing Scan Eagle® UAS aileron servo unit via a flight data recorder. The study hypothesized that the test-bed’s reliability, in terms of a measured encoder output of commanded servo positions, will not be significantly different after double and triple periods of time for continuous operations compared to a base-line mean position. Results suggested that test-bed operated within reliability criteria for a baseline period but there were significant differences in the mean of the reliability after the operational cycles were doubled and tripled in time. This study adds to paucity of extant research on UAS COTS reliability and recommends further studies on reliability of other small UAS components within periods of time.

An experimental study on vertical motion control of a high-speed planing vessel using a controllable interceptor in waves

This paper aims to construct an active control system using an interceptor and to verify the performance through towing tests to improve seakeeping performance of a high-speed planing vessel. The full-scale vessel is an unmanned surface vessel with a length of 8 m and the model ship is made with the scale ratio of 1/5.333. The interceptor servo unit is designed using the rack and pinion type. An embedded control system is developed based on a single board computer. The motion control algorithm is designed based on the differential control. The performance of the designed system and is verified by the calm water test and the seakeeping test in Seoul national university (SNU). The trim and the rise of center of gravity tend to decrease as the interceptor stroke increase. An improvement in the resistance by the interceptor is seen at the speed of less than Froude number 1.16. The pitch motion is decreased by 41.3% in the regular wave and 32.4% in the irregular wave by the controllable interceptor system.

Design and test of robotic harvesting system for cherry tomato

Harvesting of fresh-eating cherry tomato was highly costly on labor and time. In order to achieve mechanical harvesting for the fresh-eating tomato, a new harvesting robot was designed, which consisted of a stereo visual unit, an end-effector, manipulator, a fruit collector, and a railed vehicle. The robot configuration and workflow design focused on the special cultivating condition. Three key parts were introduced in detail: a railroad vehicle capably moving on both ground and rail was adopted as the robot’s carrier, a visual servo unit was used to identify and locate the mature fruits bunch, and the end-effector to hold and separate the fruit bunch was designed based on the stalk’s mechanical features. The field test of the new developed robot was conducted and the results were analyzed. The successful harvest rate of the robot was 83%, however, each successful harvest averagely needed 1.4 times attempt, and a single successful harvesting cycle cost 8 s excluding the time cost on moving. Keywords: cherry tomato, harvesting robot, visual servo, configuration design, field test DOI: 10.25165/j.ijabe.20181101.2853 Citation: Feng Q C, Zou W, Fan P F, Zhang C F, Wang X. Design and test of robotic harvesting system for cherry tomato. Int J Agric & Biol Eng, 2018; 11(1): 96–100.

Realizacija servosistema za vođenje rakete zasnovanog na primeni mikrokontrolera i beskontaktnog senzora položaja krila rakete

This paper describes the procedure for the realization of servo systems for the guided missiles. The realized servo system consists of four servo units for driving the missile wings. The servo units are independent of the each other and they are controlled by a 32-bit microcontroller STM32F407. Contactless high resolution magnetic encoders are used as the position sensors of the missile wings. The communication between the microcontroller and the magnetic encoders is realized via the serial port using the SPI protocol. DC motors are used as actuators. The actuator's energy converters are realized in a Hbridge configuration. These converters are controlled by the corresponding pulse width modulation (PWM) signal from the microcontroller. This servo system with four independents servo units makes possible to rotate the missile wings according to the guidance algorithm and at the same time according to the algorithm for the missile rolling control. The steering structures of the servo units are based on the application of the PI controllers.

マイクロサーボユニットの構造バリエーション検討

マイクロサーボユニットの構造バリエーション検討

단일채널 모노펄스시스템의 구현 및 성능 검증

본 논문에서는 일반적인 3채널 구조의 모노펄스수신기와 대비해서 비용, 크기, 무게 및 소모전력 측면에서 유리한 단일채널 구조의 모노펄스수신기를 적용한 추적시스템에 관한 연구를 진행하였다. 안테나, 모노펄스수신기, 구동체, RF 신호처리기 및 전원분배기를 제작 및 통합하여 단일채널 모노펄스시스템을 구현한 후, 지향오차각 산출정확도와 포인팅 손실을 측정하여 기본 추적성능을 확인하였다. 그리고 야외환경에서 실제 이동하는 목표물에 대한 추적성능을 검증하였다. 시험결과 분석을 통해 단일채널 모노펄스시스템이 일반적인 3 채널 모노펄스시스템과 동등 이상의 추적성능을 가지면서 시스템의 구현측면에서 이점이 있음을 확인하였다. 또한, 이 연구로 향후 모노펄스 추적시스템 개발 시 제작비용 및 제품 소형화에 유리한 단일채널 모노펄스수신기 적용이 가능함을 확인하였다. In this paper, we have studied the tracking system with a single channel monopulse receiver that has a comparative advantage of costs, size, weight, and power consumption over the general 3-channel monopulse receivers. After the single channel monopulse system was composed of an antenna, a monopulse receiver, a servo unit, a RF signal processor unit and a power supply unit, we analyzed the basic tracking performance of the tracking error angle and the pointing loss. And we proved the tracking performance to a moving target in the outdoor environment. On the Analysis of the tracking test results, the single channel monopulse system shows a equal or higher performance over the general 3-channel monopulse system and also has advantages of the system implementation. Also, it is concluded that this study is useful to apply a single channel monopulse receiver with benefits of production price and miniaturization when the monopulse tracking systems will be developed in the future.

Operational requirements to STA-5ZhO replaceable technological superstructure for transportation and subsoil application of liquid organic fertilizers based on Ural-432065 vehicle chassis

The development of Ural-432065 specialized all-wheel vehicle chassis with STA-5ZhO replaceable technological superstructure complies with agrotechnical, safe operation and maintenance requirements. Safety requirements and warning descriptions are reflected in the service manual in both text and graphical forms. It is important to study the service manual before using. The relevant symbols are represented on the equipment in locations of working organs and servo units. The Ural-432065 chassis with STA-5ZhO replaceable technological superstructure is intended for transportation and subsoil application of liquid organic fertilizers. The assembly can also be used for community facilities on all types of roads and terrain. The STA-5ZhO superstructure is designed in the form of tank equipped with auxiliary mechanisms with hydraulic drive from the base vehicle chassis. General view of STA-5ZhO superstructure, its specifications, composition, principle of operation, operator control, hydraulic circuit description, electrical schematic diagram, features of operation and service are presented. The adjustment of organic fertilizer consumption at the input of distributor is provided by the installation of plain washer that allows to change the passage area of distributor pipe. Organic fertilizer consumption depends on its density and on the size of plain washer. Operation of STA-5ZhO replaceable technological superstructure for transportation and subsoil application of liquid organic fertilizers based on Ural-432065 vehicle chassis is provided by performance and technology standards, regulated by relevant documents, available and handy to the operator. Design capabilities and used constituent parts allow to increase the operating efficiency of the replaceable superstructure as a part of technological complexes with rise in labor productivity.

Flight Reliability of Multi Rotor UAV Based on Genetic Algorithm

The UAV system has been widely applied in various military and civil fields. This technology mainly is applied to radar positioning, wild fire management, agricultural monitoring, environmental monitoring, aerial photography and search and rescue mission. It conducts real-time monitoring and control on the inclination angle, inclination angle speed and accelerated speed of inclination angle based on the flight attitude control of the multi rotor UVA. Secondly, it controls the swing deflection of rotor, motor speed, inclination angle control and speed based on the optimal solution ability to overall search of the genetic algorithm to achieve the real time optimization of parameters. Then, it establishes the servo unit with direct torque current which will be combined with the sliding mode controller to reconfigure the sliding mode variable structure controller with direct torque to carry out control on the motor balance in advance. The experiment results show that the servo unit with direct torque current together with genetic algorithm realizes the error correction of the hovering rotor of UVA; during the dynamic control of the UAV fight, the gyroscope is sensitive to the change of the aerial carrier attitude and then the correction to the drift of gyroscope can be realized to provide stable reliability control for the whole UAV flight.

Features of operation of STA-5TM replaceable technological superstructure for application of solid mineral fertilizers based on Ural-432065 vehicle chassis

The development of Ural-432065 specialized all-wheel vehicle chassis with STA-5TM replaceable technological superstructure for application of solid mineral fertilizers complies with the agrotechnical, safe operation and maintenance requirements. Safety requirements and warning descriptions are reflected in the service manual in both text and graphical forms. It is important to study this manual before starting. The relevant symbols are represented on the equipment in locations of working organs and servo units. The Ural-432065 chassis with STA-5TM replaceable technological superstructure is intended for agricultural and municipal works, such as application of dry granulated fertilizers and spreading of earth-moist lime, sand, broken stone, salt and mixtures. General view of the STA-5TM superstructure, its specification, composition, principle of operation, operator control, hydraulic circuit description, electrical schematic diagram, features of operation and service are presented. Amount of fertilizer is controlled by the principal slide gate. Under transportation mode, the slide gate should be occluded. Distribution of granular fertilizers is carried out by the spreading discs. Distributing width is 10-36 m. The adjustment is made on the basis of table of application rate or by means of passing of measuring distance, taking into account the grain size, volume weight, surface structure and moisture. Operation of the STA-5TM replaceable technological superstructure for application of solid mineral fertilizers based on Ural-432065 vehicle chassis is provided by the performance and technology standards, regulated by relevant documents, available and handy to the operator. Design capabilities and used constituent parts allow to increase the operating efficiency as a part of technological complexes with rise in labor productivity.

Virtual line‐shafting control for permanent magnet synchronous motor systems using sliding‐mode observer

This study presents a novel observer-based electronic line-shafting control strategy for permanent magnet synchronous motor systems. Adopting the sliding-mode variable structure technology, the proportional–integral speed controller for every servo unit is designed, followed by design of two cascades connected observers, in order to improve the system synchronisation performance when a large load disturbance occurs. The load torque observer transmits the observed load torque value instead of the calculated one back to the virtual shafting, which reflects the dynamic relationships of all the virtual or slave shafts more accurately. Another load torque derivative observer feeds the observed value forward to the corresponding sliding-mode controller for reducing the switching gain. The proposed control system is proved stable by Lyapunov stability theory, and simulation results show the strategy is effective on reducing sliding-mode chattering and achieving higher synchronisation precision.

Research of journal bearings for using in agricultural mobile machines

The competitive environment forces producers in agricultural machine industry to decrease the costs. Producers as well as sub-suppliers need to find possible savings. The paper presents results of laboratory experiments with real journal bearings made of bimetallic alloy performed to find out possible replacement of a rolling bearing by a journal bearing. An important correlation between the results of laboratory experiments with a model of tribological system and the real journal node can be achieved by a maximum approach of simulation features by real running conditions. Thus, the given experiment conditions result from the chosen application, i.e. a steering servo unit in mobile machines. The experiments were performed on the Tribotestor M'06'' testing machine.

Driver steering model for closed-loop steering function analysis

In this paper, a two level preview driver steering control model for the use in numerical vehicle dynamics simulation is introduced. The proposed model is composed of cascaded control loops: The outer loop is the path following layer based on potential field framework. The inner loop tries to capture the driver's physical behaviour. The proposed driver model allows easy implementation of different driving situations to simulate a wide range of different driver types, moods and vehicle types. The expediency of the proposed driver model is shown with the help of developed driver steering assist (DSA) function integrated with a conventional series production (Electric Power steering System with rack assist servo unit) system. With the help of the DSA assist function, the driver is prevented from over saturating the front tyre forces and loss of stability and controllability during cornering. The simulation results show different driver reactions caused by the change in the parameters or properties of the proposed driver model if the DSA assist function is activated. Thus, the proposed driver model is useful for the advanced driver steering and vehicle stability assist function evaluation in the early stage of vehicle dynamics handling and stability evaluation.

光雷一体化测量系统的谐振特性及组合补偿

To overcome the adverse effect of complicated resonant vibration resulting from the OE-radar integrative measuring system on a servo unit, a hybrid compensating method combined an adaptive notch filter and the feedback of observer filtering was proposed to restrain the resonant vibration. Firstly, the resonant characteristics of the system were analyzed according to the mechanical structure and tested frequency properties. It indicates that there are three kinds of primary resonant modes in the system, which is the radar antenna resonance, radar cabin resonance and the antenna high-order and bearing coupling resonance. The rule of resonant characteristics varying with an elevation angle was also obtained. Then, a compensating method to the complicated resonant vibration was discussed. The adaptive notch filter in series was applied to compensation of the radar antenna resonance and the radar cabin resonance, and the feedback of the Kalman observer filtering was used to restrain the antenna high-order and bearing coupling resonance. Experimental results indicate that all kinds of resonances are restrained effectively by the hybrid compensating method, the velocity close-loop bandwidth of servo unit is up to 115 rad/s, and the transient time of step response is 0.35 s. The method proposed can satisfy the system requirements for high bandwidth and stabilization.

Development of Derived CNC System for Ship Engine Piston Turning

Based on the principle of derived CNC, a NC lathe system is redesigned for cutting ship engine pistons which have a non-circular middle-convex and varying oval (NMVO) profile in the skirt. With an attached high-speed linear motor servo unit, a new derived CNC lathe system based on a normal NC lathe system is developed to machine non-circular section. Using this method, the development cost is reduced. A moving magnet voice coil motor is designed as the actuator to provide sufficient stroke and driving force for the cutting. The controller of the derived unit is designed based on digital signal processor (DSP) TMS320F28335, and a method of pre-interpolating data on main computer is employed in the software development. By doing this, the real-time performance of the system is satisfied.

An Experimental Analysis of Brake Efficiency Using four Fluids in a Disc Brake System

This paper studies drum brake failure in Mini-buses using an experimental analysis to test the viscosities and the maximum braking force when different fluids such as clean, less dirty, dirty and soapy water solution were used in the braking system. The effects of each of these fluids when successive increments in pedal force were applied at hot and cold conditions for drum brakes were studied. The results of the Thepra Universal Brake Testing Equipment used for the braking efficiency test indicated that a pedal force of 110 kN produce a brake force of 0.61 kN for clean fluid, 0.56 kN for less dirty, 0.51 kN for dirty and 0.92 kN. The value of 0.92 kN which was achieved when the soapy water solution was used indicated a positive braking force and that soap water solution could be used to produce a high pedal force within a very short time (10-30 min) and can therefore be used only in case of emergency. It was observed that the clean brake fluid gave the best braking force followed by the less dirty and finally the dirty brake fluid. In a situation where air has been trapped in the system under hot condition with or without a servo unit, clean brake fluid performed much better at least three times better than the other three fluids. For soap solution, braking was effective only when it was operated at cold condition but less effective when the system was hot. Soap solution is therefore not reliable when used for a very long time but effective only for emergency situations.

Pitch Attitude Control Design of Unmanned Aerial Vehicle via Hardware-in-the-Loop Simulation

This paper describes an investigative hardware-in-the-loop simulation (HILS) effort through virtual instrumentation on longitudinal control of an unmanned aerial vehicle (UAV). The proportional-integral-differential (PID) controller and fuzzy logic controller (FLC) are designed for the pitch angle hold mode of autopilot; moreover, they are implemented by an embedded real-time control system as a prototype autopilot and tested by hardware-in-the-loop simulation. The hardware configuration of HILS is composed of a personal computer, an embedded real-time control system, several data acquisition devices, servo and sensor unit. The real-time control and data acquisition tasks in HILS is carried out by virtual instruments that is developed by graphical programming language LabVIEW. HILS provides a platform for researchers to correct and improve their design efficiently. The closed-loop performance between PID controller and FLC is evaluated in HILS. The results demonstrate that in the presence of unmodelled dynamics and nonlinear saturation the FLC has an excellent robust performance.

Research on Technology of Variable Spindle Speed Noncircular Turning

To improve the stability and precision of noncircular manufacture process, the variable spindle speed turning is applied to noncircular turning process. The variable spindle turning system is designed. The character of variable spindle speed is analyzed. The linear servo unit available for variable speed noncircular turning process is designed. An active disturbance rejection control technique is applied to servo unit. The experiment results show that surface quality and tracking error of variable spindle speed noncircular turning are better than constant speed machining. The linear servo unit is able to track the desired trajectory of cutting tool motion.