System Modeling Coursework
P.R. VENKATESWARANFaculty, Instrumentation and Control Engineering,
Manipal Institute of Technology, ManipalKarnataka 576 104 INDIAPh: 0820 2925154, 2925152
Fax: 0820 2571071Email: [email protected], [email protected]
Web address: http://www.esnips.com/web/SystemModelingClassNotes
Class 12: Modeling of Hydraulic systems
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WARNING!
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I claim no originality in all these notes. These are the compilation from various sources for the purpose of delivering lectures. I humbly acknowledge the wonderful help provided by the original sources in this compilation.
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For best results, it is always suggested you read the source material.
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Of late, this has becoming supplement to what is taught in the class. So BEWARE! You are on two tracks!
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Contents
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Description of a hydraulic system•
Model of the hydraulic system
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Some questions.
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Hydraulic devices
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They are used in hydraulic feedback systems and in combined electro-mechanical-hydraulic systems.
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In hydraulic devices, power is transmitted through the action of fluid flow under pressure and the fluid is incompressible.
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The fluid used are petroleum based oils and non – inflammable synthetic oils.
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Classification of hydraulic devices
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Hydraulic devices used in control systems are generally classified as hydraulic motors and hydraulic linear actuators.
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The output of a hydraulic motor is rotary motion and that of linear actuator is translational. The hydraulic motor is physically smaller in size than an electric motor for the same output.
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Applications are power steering and brakes in automobiles, steering mechanisms in large ships, control of machine tools etc.
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Advantages of hydraulic devices
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Hydraulic fluid acts as a lubricant and coolant•
Comparatively small sized hydraulic actuators can develop large forces or torques
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Hydraulic actuators can be operated under continuous, intermittent reversing and stalled conditions without damage
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Hydraulic actuators have a higher speed of response. They offer fast starts, stops and speed reversals.
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Advantages of Hydraulic devices
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With availability of both linear and rotary actuators, the design has become more flexible.
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Because of low leakages in hydraulic actuators, when loads are applied the drop in speed will be small.
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Hydraulic components are more rugged than their counterparts
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Disadvantages of hydraulic devices
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Hydraulic power is not readily available compared to electric power
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Inherent problems of leaks and sealing them against foreign particles
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Operating noise•
Costs more compared to electrical system
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Fire and explosion hazards exist•
Hydraulic lines are not flexible as electric cables
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Highly non linear response
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Find the transfer function of this system
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Description of the system
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Try the rest!
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References
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Advanced Control Systems Engineering, Ronald Burns
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Modern Control Engineering, Ogata3.
Control Systems, Nagoor
Kani
…amongst others
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And, before we break…
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Life is ten percent what you make it and ninety percent how to take it
Thanks for listening…