On/Off Valve Based Position Control of a Hydraulic Cylinder

2007 ◽  
Author(s):  
Michael B. Rannow ◽  
Perry Y. Li
Keyword(s):  
Position Control ◽  
Hydraulic Cylinder ◽  
Conventional Technique ◽  
Hydraulic Systems ◽  
Hydraulic Actuator ◽  
Nonlinear Controller ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Averaged Model ◽  
Valve Control

A method of precisely controlling the position of a hydraulic actuator using an on/off valve is developed. Since valves exhibit little power loss when they are fully open or fully closed, the proposed system is more efficient than throttling valve control and can achieve flow variation without the expense or bulk of a variable displacement pump. Mating a pulse-width-modulated (PWMed) on/off valve with a fixed displacement pump and a smoothing accumulator creates a software enabled variable displacement pump. A drawback of using digital valve control for hydraulic systems is that the relatively low speed of the currently available switching valves results in a significant ripple in the pressure and flow rate. We propose a solution to this problem by using a throttling valve to shield the actuator from the ripple in the output. This creates an effective load sensing system with the throttling valve used only to provide a small known pressure drop between the supply and the load. This approach is significantly more efficient than the conventional technique of using throttling to vary the full flow. This paper presents an averaged model of the system, a nonlinear controller to achieve position control of an actuator and a simulation based study of the effectiveness of the controller.

Passivity Based Backstepping Control for Trajectory Tracking Using a Hydraulic Transformer

2015 ◽  
Author(s):  
Sangyoon Lee ◽  
Perry Y. Li
Keyword(s):  
Trajectory Tracking ◽  
Good Control ◽  
Hydraulic Systems ◽  
Hydraulic Actuator ◽  
Nonlinear Controller ◽  
Control Approach ◽  
Displacement Pump ◽  
Trajectory Tracking Controller ◽  
Regenerative Energy ◽  
Common Pressure Rail

Throttling loss is a major contributor to the low system efficiency in hydraulic systems. Hydraulic transformers can potentially be an energy efficient, throttle-less control approach for multi-actuators systems powered by a common pressure rail (CPR). The transformer transforms the input CPR pressure to the desired pressure of the actuator instead of throttling it. Regenerative energy can also be captured. For transformers to be useful, they must also have good control performance. This paper presents a a passivity based trajectory tracking controller for a hydraulic actuator driven by a transformer consisting of two mechanically coupled variable displacement pump/motors. In addition to controlling the motion of the actuator, the transformer speed can also be regulated at the most efficient operating speed. The nonlinear controller is designed using a Lyapunov function that is based upon a recently discovered natural energy storage function for hydraulic actuators. Experimental results validate the efficacy of this controller.

Simulacija i odstranjivanje stick-slip efekta servosistema sprovodnog aparata hidraulične turbine

2021 ◽  
Vol 23 (1) ◽  
pp. 37-41
Author(s):  
Darko Babunski ◽  
◽  
Emil Zaev ◽  
Atanasko Tuneski ◽  
Laze Trajkovski ◽  
...  
Keyword(s):  
Hydraulic Cylinder ◽  
Friction Model ◽  
Slip Effect ◽  
Hydraulic Systems ◽  
Hydraulic Actuator ◽  
Stick Slip ◽  
Hydro Turbine ◽  
Servo Mechanism ◽  
The Mathematical Model ◽  
Slip Phenomenon

Friction is a repeatable and undesirable problem in hydraulic systems where always has to be a tendency for its removal. In this paper, the friction model is presented through which the most accurate results are achieved and the way of friction compensation, approached trough technique presented with the mathematical model of a hydraulic cylinder of a hydro turbine wicket gate controlled by a servomechanism. Mathematical modelling of a servo mechanism and hydraulic actuator, and also the simulation of hydraulic cylinder as a part of a hydro turbine wicket gate hydraulic system where the stick-slip phenomenon is present between the system components that are in contact is presented. Applied results in this paper and the theory behind them precisely demonstrate under what circumstances the stick-slip phenomenon appears in such a system. The stick-slip effect is simulated using Simulink and Hopsan software and the analysis of the results are given in this paper. Removal of the stick-slip effect is presented with the design of a cascade control implemented to control the behaviour of the system and remove the appearance of a jerking motion.

Nonlinear Position Control of Digital Hydraulic Cylinder Despite Disturbance

2014 ◽  
Vol 998-999 ◽  
pp. 638-641
Author(s):  
Shi Jie Xu ◽  
J.F. Xing ◽  
Li Kun Peng
Keyword(s):  
Control System ◽  
Lyapunov Function ◽  
Linear Matrix Inequality ◽  
Nonlinear Model ◽  
Position Control ◽  
Hydraulic Cylinder ◽  
Linear Matrix ◽  
Matrix Inequality ◽  
Nonlinear Controller ◽  
Position Control System

A nonlinear controller is presented for a digital hydraulic cylinder against disturbance. We first establish the nonlinear model of digital hydraulic cylinder position control system. Then a Lyapunov function and a nonlinear controller are presented. The controller designing problem is translated into the problem of solving a linear matrix inequality. The experiment results show that the controller proposed by this paper has much better performance than traditional one.

A New Electric Hydraulic Actuator Adopted the Variable Displacement Pump

2015 ◽  
Vol 18 (1) ◽  
pp. 178-191 ◽  
Author(s):  
Wei Shen ◽  
Yunfei Mai ◽  
Xiaoyu Su ◽  
Jinbao Zhao ◽  
Jihai Jiang
Keyword(s):  
Hydraulic Actuator ◽  
Displacement Pump ◽  
Variable Displacement

Software Enabled Variable Displacement Pumps: Experimental Studies

2006 ◽  
Author(s):  
Michael B. Rannow ◽  
Haink C. Tu ◽  
Perry Y. Li ◽  
Thomas R. Chase
Keyword(s):  
Experimental Studies ◽  
Check Valve ◽  
Design Parameters ◽  
Duty Ratio ◽  
System Response ◽  
Experimental Apparatus ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Valve Control ◽  
Variable Displacement Pumps

The majority of hydraulic systems are controlled using a metering valve or the use of variable displacement pumps. Metering valve control is compact and has a high control bandwidth, but it is energy inefficient due to throttling losses. Variable displacement pumps are far more efficient as the pump only produces the required flow, but comes with the cost of additional bulk, sluggish response, and added cost. In a previous paper [1], a hydromechanical analog of an electronic switch-mode power supply was proposed to create the functional equivalent of a variable displacement pump. This approach combines a fixed displacement pump with a pulse-width-modulated (PWM) on/off valve, a check valve, and an accumulator. The effective pump displacement can be varied by adjusting the PWM duty ratio. Since on/off valves exhibit low loss when fully open or fully closed, the proposed system is potentially more energy efficient than metering valve control, while achieving this efficiency without many of the shortcomings of traditional variable displacement pumps. The system also allows for a host of programmable features that can be implemented via control of the PWM duty ratio. This paper presents initial experimental validation of the concept as well as an investigation of the system efficiency. The experimental apparatus was built using available off-the-shelf components and uses a linear proportional spindle valve as the PWM valve. Experimental results confirm that the proposed approach can achieve variable control function more efficiently than a valve controlled system, and that by increasing the PWM frequency and adding closed-loop control can decrease system response times and of the output ripple magnitude. Sources of inefficiency and their contributions are also investigated via modeling, simulation and are validated by experiments. These indicate design parameters for improving inefficiency.

scholarly journals Classification and Review of Pump-Controlled Differential Cylinder Drives

Energies ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1293 ◽  
Author(s):  
Søren Ketelsen ◽  
Damiano Padovani ◽  
Torben Andersen ◽  
Morten Ebbesen ◽  
Lasse Schmidt
Keyword(s):  
Small Volume ◽  
Hydraulic Cylinder ◽  
Future Research ◽  
Hydraulic Systems ◽  
Hydraulic Circuit ◽  
Variable Speed ◽  
Electric Drives ◽  
Variable Displacement ◽  
Oil Tank ◽  
Pump Controlled Cylinder

Pump-controlled hydraulic cylinder drives may offer improved energy efficiency, compactness, and plug-and-play installation compared to conventional valve-controlled hydraulic systems and thus have the potential of replacing conventional hydraulic systems as well as electro-mechanical alternatives. Since the late 1980s, research into how to configure the hydraulic circuit of pump-controlled cylinder drives has been ongoing, especially in terms of compensating the uneven flow requirements required by a differential cylinder. Recently, research has also focused on other aspects such as replacing a vented oil tank with a small-volume pressurized accumulator including the consequences of this in terms of thermal behavior. Numerous references describe the advantages and shortcomings of pump-controlled cylinder drives compared to conventional hydraulic systems or electro-mechanical drives. This paper presents a throughout literature review starting from the earliest concepts based on variable-displacement hydraulic pumps and vented reservoirs to newer concepts based on variable-speed electric drives and sealed reservoirs. By classifying these drives into several proposed classes it is found that the architectures considered in the literature reduce to a few basic layouts. Finally, the paper compares the advantages and shortcomings of each drive class and seek to predict future research tasks related to pump-controlled cylinder drives.

The Swashplate Angle Control of a Variable Displacement Pump with an Electro-Hydraulic Proportional Valve

2008 ◽  
Vol 594 ◽  
pp. 389-400 ◽  
Author(s):  
Ming Hwei Chu ◽  
Yuan Kang ◽  
Yi Wei Chen ◽  
Yeon Pun Chang
Keyword(s):  
Angular Displacement ◽  
Mathematic Model ◽  
Hydraulic Systems ◽  
Displacement Pump ◽  
Type Variable ◽  
Hydraulic Servo ◽  
Simulation And Experiment ◽  
Variable Displacement ◽  
Servo Controller ◽  
The Stability

In this paper, the mathematic model of the swashplate type variable displacement axial piston pump (VDAPP) is established. The VDAPP applied to an electro-hydraulic servo control system usually induces unstable performance, so that a servo controller is designed and analyzed to control the swashplate angular displacement and improve the stability and transient response of pump performance. The flow and pressure variations of pump with the proposed controller are investigated and analyzed by mathematic simulations and experiments. The simulation and experiment results show that the proposed controller can improve the stability of swashplate angular displacement, and easily applied to the energy saving hydraulic systems.

Software Enabled Variable Displacement Pumps

2005 ◽  
Author(s):  
Perry Y. Li ◽  
Cassie Y. Li ◽  
Thomas R. Chase
Keyword(s):  
Feedback Control ◽  
Response Time ◽  
Low Cost ◽  
Hydraulic Systems ◽  
Ongoing Research ◽  
Throttle Valve ◽  
System Pressure ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Variable Displacement Pumps

Direct pump control of hydraulic systems is more energy efficient than throttle valve based methods to control hydraulic systems. This requires variable displacement pumps that are responsive and capable of electronic control. Such Electronic Displacement Controlled (EDC) pumps tend to be significantly larger, heavier and more expensive than fixed displacement counterparts. In addition, achievable control bandwidths are typically lower than throttle valve based control approaches. We have recently begun a project to achieve the functionality of a variable displacement pump by combining a fixed displacement pump, a pulse width modulated (PWM) on/off valve under closed loop feedback control, and an accumulator. The proposed topology is the hydro-mechanical analog of the DC-DC boost converter in power electronics. Since on/off valves have little loss in either the on or the off state, this approach is potentially more efficient than throttle valve based control approaches. It has the small size/weight and low cost advantages of a fixed displacement pump. Faster response can be expected by eliminating the intervening inertias of the swash plate control system. The pump’s functionalities can also be easily programmed by controlling the PWM on/off valve in different manners. This paper presents some preliminary results from this ongoing research program. While the PWM valve based approach provides desirable features, it also introduces undesirable ripples to the system pressure and flow rate. It is shown that increasing the accumulator pre-charge pressure and the accumulator volume can decrease ripple size at the expense of response time. This apparent trade-off can be alleviated by feedback control to achieve fast response time while keeping ripple small. Feedback control using PWM control must be implemented with care since the conventional “state-space” model may not be valid when the PWM frequency is low. On the other hand, increasing PWM frequency reduces ripple size and enables the system to achieve high control bandwidths.

Simulation of Position Control and Flow Rate Match of Integrated Hydraulic Actuator Unit

2010 ◽  
Vol 118-120 ◽  
pp. 640-644
Author(s):  
Jian Xin Liu ◽  
Yu Liu ◽  
Ping Tan
Keyword(s):  
Flow Rate ◽  
Position Control ◽  
Control Method ◽  
Hydraulic Systems ◽  
Hydraulic Actuator ◽  
External Disturbances ◽  
Heavy Load ◽  
Actuation System ◽  
Oil Tank

This paper presents a kind of all-digital integrated hydraulic actuator (IHA) unit to drive heavy load object without centralized oil tank. In order to improve the control quality of the actuation system while eliminating or reducing the disturbance, and also to solve the problem of flow rate mismatch existed in IHA with single-rod cylinder actuator, a fuzzy PID PWM controller is suggested. Simulations on the integrated hydraulic actuator unit are carried out to evaluate the effectiveness of the proposed control method when applied to hydraulic systems with various external disturbances encountered in real working conditions. Simulation results are discussed and some conclusions are given.

Dynamic Model and Control Design for a Nonlinear Hydraulic Actuator

2018 ◽  
Author(s):  
Carlos Borrás Pinilla ◽  
José Luis Sarmiento ◽  
Juan Felipe Ortiz
Keyword(s):  
Optimal Control ◽  
Dynamic Behavior ◽  
Pid Control ◽  
Nonlinear Dynamic ◽  
Feedback Linearization ◽  
Position Control ◽  
Settling Time ◽  
Hydraulic Systems ◽  
Hydraulic Actuator ◽  
And Control

Industrial hydraulic systems are complex, and show nonlinear dynamic behavior because of their nature. When it is not easy to deal with the nonlinear models, hydraulic systems are usually described by linear or linearized models around operating points. In this work a nonlinear dynamic and mathematic model for the position control of a double rod hydraulic actuator was developed. Three control strategies were implemented: PID control, optimal control (LQR) and control by Feedback Linearization. For the PID control and optimal control (LQR) strategies a linearized model of the hydraulic actuator was developed around a specific operating point, contrary to the Feedback Linearization control that have a wide operation range and the nonlinear model was used. These mathematical models were represented on Simulink environment, in order to compare and analyze the response and dynamic behavior. The optimal control (LQR) shows better settling time than the PID control, both without overshoot; and the Feedback Linearization show the best dynamic performance in terms of settling time with a little overshoot and disturbance tolerance.

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