class 12 - mathematical modeling of hydraulic system
TRANSCRIPT
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
July – December 2008 prv/System Modeling Coursework/MIT-Manipal 2
WARNING!
•
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.
•
For best results, it is always suggested you read the source material.
•
Of late, this has becoming supplement to what is taught in the class. So BEWARE! You are on two tracks!
July – December 2008 prv/System Modeling Coursework/MIT-Manipal 3
Contents
•
Description of a hydraulic system•
Model of the hydraulic system
•
Some questions.
July – December 2008 prv/System Modeling Coursework/MIT-Manipal 4
Hydraulic devices
•
They are used in hydraulic feedback systems and in combined electro-mechanical-hydraulic systems.
•
In hydraulic devices, power is transmitted through the action of fluid flow under pressure and the fluid is incompressible.
•
The fluid used are petroleum based oils and non – inflammable synthetic oils.
July – December 2008 prv/System Modeling Coursework/MIT-Manipal 5
Classification of hydraulic devices
•
Hydraulic devices used in control systems are generally classified as hydraulic motors and hydraulic linear actuators.
•
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.
•
Applications are power steering and brakes in automobiles, steering mechanisms in large ships, control of machine tools etc.
July – December 2008 prv/System Modeling Coursework/MIT-Manipal 6
Advantages of hydraulic devices
•
Hydraulic fluid acts as a lubricant and coolant•
Comparatively small sized hydraulic actuators can develop large forces or torques
•
Hydraulic actuators can be operated under continuous, intermittent reversing and stalled conditions without damage
•
Hydraulic actuators have a higher speed of response. They offer fast starts, stops and speed reversals.
July – December 2008 prv/System Modeling Coursework/MIT-Manipal 7
Advantages of Hydraulic devices
•
With availability of both linear and rotary actuators, the design has become more flexible.
•
Because of low leakages in hydraulic actuators, when loads are applied the drop in speed will be small.
•
Hydraulic components are more rugged than their counterparts
July – December 2008 prv/System Modeling Coursework/MIT-Manipal 8
Disadvantages of hydraulic devices
•
Hydraulic power is not readily available compared to electric power
•
Inherent problems of leaks and sealing them against foreign particles
•
Operating noise•
Costs more compared to electrical system
•
Fire and explosion hazards exist•
Hydraulic lines are not flexible as electric cables
•
Highly non linear response
July – December 2008 prv/System Modeling Coursework/MIT-Manipal 9
Find the transfer function of this system
July – December 2008 prv/System Modeling Coursework/MIT-Manipal 10
Description of the system
July – December 2008 prv/System Modeling Coursework/MIT-Manipal 11
July – December 2008 prv/System Modeling Coursework/MIT-Manipal 12
Try the rest!
July – December 2008 prv/System Modeling Coursework/MIT-Manipal 13
References
1.
Advanced Control Systems Engineering, Ronald Burns
2.
Modern Control Engineering, Ogata3.
Control Systems, Nagoor
Kani
…amongst others
July – December 2008 prv/System Modeling Coursework/MIT-Manipal 14
And, before we break…
•
Life is ten percent what you make it and ninety percent how to take it
Thanks for listening…