Optimal Control for Hydraulic System with Separate Meter-In and Separate Meter-Out

Rath, Gerhard; Zaev, Emil

doi:10.3384/ecp17144125

Cited by 5 publications

(3 citation statements)

References 9 publications

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“…The theory of optimal control has existed for several centuries [1]. When applied to a hydraulic system, it dampens all vibrations at the end of the motion and still achieves the desired values [2]. However, due to the extremely nonlinear dynamics its use in hydraulics is a challenge [3].…”

Section: Introductionmentioning

confidence: 99%

Multidimensional Trajectory Tracking for Numerically Stiff Independent Metering System

Stojanoski¹,

Ninevski²,

Rath³

et al. 2021

Linköping Electronic Conference Proceedings

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This paper presents a new approach for solving an optimal control problem in a hydraulic system, using a variational calculus method. It uses a path tracking method of two different states with different units and of different magnitude. To ensure the uniqueness of the solution, two regularization terms were introduced, whose influence is regulated by regularization parameters. The system of differential equations, obtained from the Euler-Lagrange equations of the variational problem, was solved by a mass matrix method and discretized with linear differential operators at the interstitial points for numerical stability. This enabled the calculation of the control variables, despite the stiffness of the numerical problem. The results obtained show an energy-efficient performance and no oscillations. Finally, a Simulink model of the hydraulic system was created in which the calculated control variables were inserted as feed-forward inputs, to verify the results.

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Section: Introductionmentioning

confidence: 99%

Multidimensional Trajectory Tracking for Numerically Stiff Independent Metering System

Stojanoski¹,

Ninevski²,

Rath³

et al. 2021

Linköping Electronic Conference Proceedings

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“…On the other hand, load oscillation appears during movement using separate meter-in separate-meter out (SMISMO) system, precisely when the load stopping after moving. An optimal approach based on Hamiltonian method was developed in[101].…”

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confidence: 99%

A review of electrohydraulic independent metering technology

et al. 2020

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The subject of this paper is the review of advanced technology used in hydraulic systems. The technology in question is termed Independent Metering (IM); this is used in hydraulically driven mobile machinery, such as agricultural, construction, municipal, and forestry vehicles. The idea behind the concept is to modify the connection between the actuator, which could be a cylinder or a motor, and a flow control valve. Traditionally, spool hydraulic valves were used to control the fluid flow into and out of hydraulic actuators. This keeps the meter-in and the meter-out of the actuator mechanically connected due to the construction of these valves. This connection makes the control system blind to pressure changes in one of the hydraulic chambers in the actuator. This, in turn, reduces the overall system controllability. It also increases energy losses, especially under an overrunning load. These two main weaknesses led researchers to break this mechanical connection and get into a new technology with different characteristics. The proposed technology was called Independent Metering. New and more complex control techniques can now be applied to the hydraulic systems using this technology that were not possible before or could be applied to more conventional servo design. This paper reviews Independent Metering (IM) and the technologies used or developed in this field to date. The paper reviews the state of art hydraulic technologies and indicates the links between them and IM. It also reviews the different types of hydraulic valves used when implementing IM. This review also discusses some control algorithms, IM layouts, IM challenges, and identifies where further improvements may be achieved.

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“…An example of valves following both trends is the IndependentMetering Mobile Valve from Eaton [EatonCMA200]. Independent-metering valves can for example be used to improve the control performance [RZ17] or to improve the energy efficiency [KW16].…”

Section: Hydraulic Actuationmentioning

confidence: 99%

On Motion Control of Linear Incremental Hydraulic Actuators

Hochwallner¹

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Linear Incremental Hydraulic Actuators combine one or more short-stroke cylinders, and two or more engaging/disengaging mechanisms into one actuator with long, medium, or even unlimited stroke length. The motion of each single short-stroke actuator concatenated by the engaging/disengaging mechanisms forms the motion of the linear incremental hydraulic actuator.The patterns of how these motions are concatenated form the gaits of a specific linear incremental hydraulic actuator. Linear incremental hydraulic actuators may have more than one gait. In an application, the gaits may be combined to achieve optimal performance at various operating points.The distinguishing characteristic of linear incremental hydraulic actuators is the incremental motion. The term incremental actuator is seen as analogous to the incremental versus absolute position sensor. Incremental actuators realize naturally relative positioning. Incremental motion means also that the behavior does not depend on an absolute position but only on the relative position within a cycle or step.Incremental actuators may realize discrete incremental or continuous incremental motion. Discrete incremental actuators can only approach discrete positions, whereby stepper drives are one prominent example. In contrast, continuous incremental actuators may approach any position. Linear electric motors are one example of continuous incremental actuators.The actuator has no inherent limitation in stroke length, as every step or cycle adds only to the state at the beginning of the step or cycle and does not depend on the absolute position. This led to the alternative working title Hydraulic Infinite Linear Actuator.Linear incremental hydraulic actuator provides long stroke, high force, and linear motion and has the potential to• decrease the necessary resource usage, • minimize environmental impact, e.g. from potential oil spillage, • extend the range of feasible products: longer, stiffer, better, etc. iThis thesis presents an analysis of the characteristics and properties of linear incremental hydraulic actuators as well as the gaits and possible realizations of some gaits. The gait for continuous, smooth motion with two cylinders is comprehensively studied and a control concept for the tracking problem is proposed. The control concept encapsulates the complexity of the linear incremental hydraulic actuator so that an application does not have to deal with it. One other gait, the ballistic gait, which realizes fast, energy-efficient motion, enabling energy recuperation is studied.ii Sammanfattning (SV)Linjära inkrementella hydrauliska aktuatorer (engelska: linear incremental hydraulic actuators) kombinerar en eller flera korta cylindrar och två eller fler ingrepps-/ urkopplingsmekanismer till ett manövrdon med långa, medellånga eller till och med obegränsad slaglängd. Förflyttningen av varje enskilt slag sammanfogas av ingrepps-/ urkopplingsmekanismerna som utgör rörelsen av den linjära inkrementella hydrauliska aktuatorn. En specifik kombination av dessa rör...

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Optimal Control for Hydraulic System with Separate Meter-In and Separate Meter-Out

Cited by 5 publications

References 9 publications

Multidimensional Trajectory Tracking for Numerically Stiff Independent Metering System

Multidimensional Trajectory Tracking for Numerically Stiff Independent Metering System

A review of electrohydraulic independent metering technology

On Motion Control of Linear Incremental Hydraulic Actuators

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