Showing papers on "Proportional control published in 2022"

A Case Study of Open- and Closed-Loop Control of Hydrostatic Transmission with Proportional Valve Start-Up Process

Abstract: This paper concerns the start-up process of a hydrostatic transmission with a fixed displacement pump, with particular emphasis on dynamic surplus pressure. A numerically controlled transmission using a proportional directional valve was analysed by simulation and experimental verification. The transmission is controlled by the throttle method, and the variable resistance is the throttling gap of the proportional spool valve. A mathematical description of the gear start-up process was obtained using a lumped-parameters model based on ordinary differential equations. The proportional spool valve was described using a modified model, which significantly improved the performance of the model in the closed-loop control process. After assuming the initial conditions and parameterization of the equation coefficients, a simulation of the transition start-up was performed in the MATLAB–Simulink environment. Simulations and experimental studies were carried out for control signals of various shapes and for various feedback from the hydraulic system. The pressure at the pump discharge port and the inlet port of the hydraulic motor, as well as the rotational speed of the hydraulic motor, were analysed in detail as functions of time. In the experimental verification, complete measuring lines for pressure, speed of the hydraulic motor, flow rate, and temperature of the working liquid were used.

Single-Phase Uninterruptible Power Supply Control: A Model-Free Proportional-Multiresonant Method

Abstract: Uninterruptible power supply (UPS) is an electronic power device that delivers voltage to critical loads and whose application must satisfy standardized performance requirements. Usual control techniques demand the UPS model. In this article, we propose a simple, model-free procedure based on the generalized forced oscillation method to design the control system of a UPS output stage. The procedure involves the design of an inner current loop with a proportional gain and a proportional-multiresonant controller in the output voltage loop. We also compare the closed-loop results obtained in a single-phase 3.5 kVA UPS with the IEC 62040-3 performance criteria and show that the results are equivalent to model-based approaches.

Design of Embedded Control System for Open Circuit Axial Piston Pump

Abstract: The article presents a developed embedded control system for variable displacement axial piston pump designed for hydraulic drive systems with open circuit. The regulation of displacement volume of the pump is carried out by means of an electro-hydraulic proportional valve, in parallel to which a conventional hydraulic pressure controller is connected. The control of the proportional valve is realized by a selective electronic amplifier. Unlike conventional systems with this type of pump control, this electronic amplifier receive a reference that is formed by an industrial controller with an embedded control algorithm. This makes it possible to implement advanced control techniques for control the basic energy parameters in hydraulic drives - pressure and flow. Presented experimental results show the operational capacity of the developed system.

Design of decentralized proportional–integral proportional–retarded controllers in discrete-time domain for two-input two-output processes

Abstract: In this paper, a decentralized proportional–integral proportional–retarded (PI-PR) controller design method is proposed for two-input two-output (TITO) systems in discrete-time domain. The well-known dominant pole assignment (DPA) approach is used as the basis of the proposed approach. The controller design starts with the decoupling of a given TITO system into two sub-systems and continues with the design of proportional–integral–retarded (PIR) controllers for each sub-system, respectively. The feasible discrete PIR controller parameter set is obtained through the Nyquist stability criterion by considering the desired closed-loop performance specifications. The obtained PIR controllers are then implemented using a PI-PR control structure to avoid poor performance of the closed-loop system (CLS) transient response, which can be caused by the controller zeros. Moreover, a case study is presented to show the performance of the PI-PR controller in a simulation environment. It is shown that the proposed control structure provides a satisfactory performance when compared with the other proportional–integral–derivative (PID) control methods from the literature.

Modeling, Analysis and Proportional Resonant and Proportional Integral Based Control Strategy for Single Phase Quasi-Z Source Inverters

Abstract: This paper proposes a proportional resonant and proportional integral based control strategy for single phase quasi-Z-source inverters (qZSIs) which is able to operate in buck and boost modes. Switching signals of the qZS inverters can be generalized as shoot through and non-shoot through states. The dc-link voltage of the qZSIs can be controlled by generating proper shoot through signals. The control strategy for qZSIs should be able to control both dc and ac-sides at the same time. First, the average state–space model of qZSI is obtained for closed loop control in this paper. Thereafter, the proportional resonant control is designed to achieve ac-side voltage control. Also, voltage control of dc-side capacitor is achieved by using proportional integral control method. Finally, the switching signals are obtained by applying the control outputs to modulation strategy. Experimental results are presented to demonstrate the effectiveness of the control method. The results verify that the proposed control strategy successfully regulates both dc and ac-side control variables.

Comparative Study of Controller Scheme and Tuning Methods

Abstract: The adjustment of a control parameter to produce a sufficient response to the processing system is known as tuning a control loop. Control procedures are frequently tweaked during running conditions rather than startup conditions to ensure that the process variable is stable at an operating point. Proportional Integral Derivative (PID) are the extensively used controllers to compensate for a wide range of industrial processes due to their simplicity and resilience. The effectiveness of tuning procedures has been compared using time response characteristics. This study shows how to adjust the gains of the Proportional Integral (PI), Proportional Integral Derivative (PID) and Fractional Order Proportional Integral (FOPI) controllers by using various tuning methodologies. The method involves calculating the Controller Gain (Kc), Integral Time Constant (T I ), and Derivative Time constant (T D ) for a PID-controlled system with a First-Order Plus Time Delay (FOPTD) process. MATLAB / SIMULINK platform is used to investigate and evaluate the performance of various PID tuning procedures in this study.

Experimental research of the operational characteristics and control study of a high-flow proportional valve

Abstract: Self-regulated control of the flow of oxygen, air, or other gases plays an important role in the design of new high-end medical products. High-flow proportional valves are the main component in determining their overall performance as they influence operating and transient conditions. Therefore, it is important to control the value of the flow through the proportional valve by means of a non-linear model that guarantees precision and above all a control model that allows to deal with the hysteresis effects of solenoid valves. The article presents a methodology for testing a miniature high-flow proportional valve, with a description of the operational characteristics of the elements involved and design of an experimental prototype for the proportional valve control study. The results of the experimental activities are shown, both the conditions of use, operability, and assembly of the components, with special attention to the current controller, Flow Sensor and Analog Digital Converter. For the analysis and identification of the system, MATLAB and Simulink tools are used, which through the use of the ARX and ARMAX approximation methods, the model of the plant to be controlled was identified, making use of the experimental data set of both inputs and outputs of the system in question and two plant models were obtained due to the presence of valve hysteresis. Once the control models were obtained, the implementation of a PI/PID controller was carried out and the validity of the proposal was validated experimentally.

An Experimental Study on Position Control of Pneumatic Cylinder Using Programmable Logic Controller and Pneumatic Proportional Valves

Abstract: This paper evaluates experimentally the position control ability of a pneumatic cylinder by using pneumatic proportional valves and a programmable logic controller. An experimental system consisting of a double acting pneumatic cylinder, two pneumatic proportional valves and a programmable logic controller is considered. A proportional-integral-differential controller is applied to control the cylinder position. The controller is evaluated by experimental system with step and square wave input signals. The evaluation results show that the used control method can provide good control performances with the absolute position accuracy less than 3% and the rise time less than 3 s.

Comparison of PID and Fuzzy Controllers in an Omnidirectional Robot to Follow People

Abstract: In this work we are interested in evaluating the response of proportional-integral-derivative and fuzzy con-trollers. The controllers are implemented in an omnidirectional robot for the purpose of tracking a person. A kinect device is used to detect the person and the distance between the person and the visual sensor is obtained. To follow the person to a set distance, the speed of the motors is controlled. The proportional-integral-derivative controller parameters are optimized with a genetic algorithm. Experiments were performed in a simulated environment CoppeliaSim. The results obtained suggest that the response of the controllers evaluated are comparable. Therefore, it is shown that the use of a genetic algorithm is a good strategy to improve the response of the proportional-integral-derivative controller.

Improved Adaptive Controller Design Scheme to Attenuate the Noise Amplification Effect of Differentials

Abstract: Adaptive control is widely used in nonlinear systems, and is under active research. Although the conventional adaptive control guarantees the asymptotic stability, it may yield limited performance in real experiments due to many factors, such as noise and hardware limitations. In this paper, a proportional-integral adaptive controller with a proportional-integral-derivative update law is proposed to attenuate the effect of measurement noise and improve the performance of the closed-loop system. Two more improvements, dividing differential signals into two smoother signals and facilitating additional estimations to weight different components of the same signal, are used in addition to the proportional-integral-derivative-type update law. The stability is proved theoretically and the performance is verified by simulation tests.

Research on magneto-hydraulic proportional control strategy for single degree of freedom supporting system of magnetic-liquid double suspension bearing.

Abstract: Compared with the traditional active electromagnetic bearing, the additional hydrostatic supporting concept is imported to form magnetic-liquid double suspension bearing (MLDSB) without affecting the support performance. Therefore, the bearing carrying capacity and stiffness are greatly increased and the operational stability and reliability of MLDSB are also improved. The controlling strategy and the regulating mode have the major impact on the safe and stable operation of MLDSB, which directly determines the performance quality. MLDSB adopts the magnetic-liquid coupling supporting mode with electromagnetic suspension as the main and hydrostatic supporting as the supplement, which greatly increases the complexity and difficulty of MLDSB. Therefore, the proportional control strategy and the magneto-hydraulic coupled nonlinear controller of MLDSB are explored in this paper. First, the regulation mechanism of the single degree of freedom (DOF) supporting system is revealed, and the proportional-integral-differential controller of the electromagnetic and hydrostatic closed-loop is designed. Then, the fuzzy control idea is introduced into the single DOF supporting system to design a magnetic-liquid variable proportional fuzzy controller, and the difference between the proportional/variable proportional control modes is compared. Finally, the rotor displacement following characteristics and anti-interference characteristics in the proportional/variable proportional control mode are compared on a magnetic-liquid double suspension test bench. The results show that compared with the proportional control method, the variable proportional control method combines the advantages of fast regulation speed of the electromagnetic system and the stable and reliable advantages of the hydrostatic system. In the same step signal, the rotor can achieve unbiased following under two control modes of proportional/variable proportion, and the adjustment time of the variable proportional control mode is shorter. In two control modes, the rotor can be restored to the original equilibrium position. The maximum offset under the variable proportional control mode is smaller, and with the continuous increase of the displacement, the performance of the variable proportional control method is more obvious. The stability control of MLDSB is provided on the theoretical basis in this article.

A Simplified Hardware Proportional-Integral-Derivative Controller Using Power-of-2 Multiplication

Abstract: This paper proposes a simplified digital proportional-integral-derivative (PID) controller with a power-of-two multiplication operation. The power operation of the circuit is realized by the barrel shift register, which can quickly calculate the proportional control gain Kp, the integral control gain KI and the differential control gain KD. The implemented and verified controller is in the 180 nm CMOS process. Under the verification of a fully digital switching DC-DC buck converter, when the input voltage is 3.3 V, and the operating frequency is 1 MHz, the controller stabilizes the voltage at the set 1.5 V within 65 µs, which is ten times faster than turning off the PID controller. Compared with traditional PID controller, the area is reduced by 70 %.