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 Author Topic: Ejs Open Source 3 Dimensional Rotational Gimbal lock Model java applet  (Read 16460 times) 0 Members and 1 Guest are viewing this topic. Click to toggle author information(expand message area).
lookang
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 « Embed this message on: July 17, 2011, 01:53:04 pm » posted from:SINGAPORE,SINGAPORE,SINGAPORE

Ejs Open Source 3 Dimensional Rotational Gimbal lock Model java applet by Fu-Kwun Hwang and lookang
3 Dimensional Rotational Model
as a response to http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=2084.0

reference: http://en.wikipedia.org/wiki/Gimbal_lock
Gimbal lock is the loss of one degree of freedom in a three-dimensional space that occurs when the axes of two of the three gimbals are driven into a parallel configuration, "locking" the system into rotation in a degenerate two-dimensional space.
The word lock is misleading: no gimbal is restrained. All three gimbals can still rotate freely about their respective axes of suspension. Nevertheless, because of the parallel orientation of two of the gimbals axes there is no gimbal available to accommodate rotation along one axis.

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3 Dimensional Rotational Model
Flight dynamics is the science of air vehicle orientation and control in three dimensions. The three critical flight dynamics parameters are the angles of rotation in three dimensions about the vehicle's center of mass, known as pitch, roll and yaw.

Description:
The 3 Dimensional Rotational Model is a setup that resembles an actual real life demonstration set using to illustrate and allow exploration of the meaning of pitch, roll and yaw. There are 2 possible frames to choose from cylinder rings or rectangles.
The independent axes when selected allows independent axes to be rotated without affecting the others 2 axes, while when independent is not selected allows a couple rotational model that could be used to explore the concept of gimbal lock.
In simple Java, the is no object rendered in the model, just the frames to explore pitch, roll and yaw.
In Java 3D, a aeroplane (in wrl) is rendered inside the model for better association to aeroplane pitch, roll and yaw angles in 3D.

Exercises:
Engage:
Have you wondered how do airplane pliots communicate to each other about the angles that the airplane makes with a defined equilibrium state?
Do you know that what you learn here can be applied to boat and ships angles too?

Set the sliders to roll = 90 , pitch 90 and yaw = 0 degree.
explore the roll slider and verify whether the following statement is appriopriate.
"The equilibrium roll angle is known as wings level or zero bank angle"
Discuss and suggest a value of roll for this zero bank angle to occur.
hint: roll = 90 degree

Similarly, explore the sliders pitch and yaw and visit http://en.wikipedia.org/wiki/Flight_dynamics_(aircraft) and other websites related to draw sketches and describe in sentence(s) the meaning of
i) roll
ii) pitch
iii) yaw
hint:

According to http://en.wikipedia.org/wiki/Gimbal_lock
Gimbal lock is the loss of one degree of freedom in a three-dimensional space that occurs when the axes of two of the three gimbals are driven into a parallel configuration, "locking" the system into rotation in a degenerate two-dimensional space.

Explore the model and discuss with your classmates what this means?

Please submit your remix model that model features that are not available in the existing virtual lab and share your model with the world through NTNUJAVA Virtual Physics Laboratory http://www.phy.ntnu.edu.tw/ntnujava/index.php?board=28.0. Impacting the world with your model now.
Credits:

The 3D rotational Model was created by Fu-Kwun Hwang (original model found here http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=2084.0) , customized by Loo Kang WEE (newer model found here http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=2237.0) using the Easy Java Simulations (EJS) version 4.3.3.3 authoring and modeling tool. An applet version of this model is available on the NTNU website < http://www.phy.ntnu.edu.tw/ntnujava/ >.

You can examine and modify this compiled EJS model if you run the model (double click on the model's jar file), right-click within a plot, and select "Open EJS Model" from the pop-up menu. You must, of course, have EJS installed on your computer. Information about EJS is available at: and in the OSP comPADRE collection .
 gimbalwithvrml.png (27.9 KB, 520x508 - viewed 927 times.) « Last Edit: November 17, 2011, 10:54:14 pm by lookang » Logged
lookang
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 « Embed this message Reply #1 on: July 17, 2011, 01:56:03 pm » posted from:SINGAPORE,SINGAPORE,SINGAPORE

naming convention change to suit airplanes as in picture
set initial values to all zero all blanks
range of slider -180 to 180 degree
re-design the implementation to suit the physical Gimbal with support structures represented by cylinders using the 3D group method to ease the need to program in the codes as it is the outer ring's motion is automatically translated to the middle ring and the middle ring motion translation to inner ring.
add cylinders to aid the visualization of the support of the Gimbal

added rectangles from Prof Hwang's version 6
customized to my version 4 dimensions
added an independent axis control checkbox for egabev mention something about no dependency of each axis of rotation, without the structures and in rectangle shapes, the rectangles do overlap
consistent the color with Prof Hwang's version 6
vrml files
render is JAVA3D is the only trick!
think there is a bug in Ejs 4.3.3.2 , it works in the download standalone jar but not VRMLfile cannot show up in web deploy applets.
reference:
http://www.fho-emden.de/~hoffmann/gimbal09082002.pdf
Enjoy! egabev
 gimballock.png (308.19 KB, 901x558 - viewed 1134 times.) « Last Edit: July 17, 2011, 02:01:30 pm by lookang » Logged
lookang
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 « Embed this message Reply #2 on: October 04, 2011, 02:02:46 pm » posted from:SINGAPORE,SINGAPORE,SINGAPORE

strange error in mac

java.lang.NullPointerException
at users.sgeducation.lookang.glimbal8wee02_pkg.glimbal8wee02View.reset(glimbal8wee02View.java:1516)
at org.colos.ejs.library.Animation.reset(Unknown Source)
at users.sgeducation.lookang.glimbal8wee02_pkg.glimbal8wee02Simulation.(glimbal8wee02Simulation.java:23)
at users.sgeducation.lookang.glimbal8wee02_pkg.glimbal8wee02.(glimbal8wee02.java:140)
at users.sgeducation.lookang.glimbal8wee02_pkg.glimbal8wee02Applet.init(glimbal8wee02Applet.java:26)
at sun.plugin2.applet.Plugin2Manager\$AppletExecutionRunnable.run(Plugin2Manager.java:1640)

but run perfectly in Windows.
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lookang
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 « Embed this message Reply #3 on: November 19, 2011, 11:05:18 am » posted from:SINGAPORE,SINGAPORE,SINGAPORE

i managed to fix the java in m iMac and the model run well in MacOSX 10.6.8

but the Java 3D is still not working
 Screen shot 2011-11-19 at PM 12.06.47.png (114 KB, 1056x621 - viewed 1814 times.) Logged
ilua
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 « Embed this message Reply #4 on: November 27, 2011, 11:51:22 pm » posted from:,,Satellite Provider

exactly it goes with my thinking.-*-
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alansholto
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 « Embed this message Reply #5 on: August 29, 2012, 07:46:34 pm » posted from:,,Satellite Provider

Sadly, my computer won't let me run the applet as it says it can't trust the source.
Do you have a solution to my problem?
Thanks.
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lookang
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 « Embed this message Reply #6 on: August 29, 2012, 07:53:20 pm » posted from:SINGAPORE,SINGAPORE,SINGAPORE

U need to download the applet and run it as a standalone.