[quote author=Fu-Kwun Hwang link=topic=2084.msg8298#msg8298 date=1310566183]
You can download EJS source and open it with EJs,
or download jar file , double click to run it, right click then select open ejs model.

What you need to modify is "[b]Fixed relation[/b]" Page: you will fins the following line

mat3="y:"+c3;
mat1="z:"+c1+" & y:"+c3;
mat2="x:"+a2+" &y:"+c3;

where c1,a2 and c3 are angle for row, pitch and row.
// for outer most ring
mat3="y:"+c3; // mean rotate around y axis with angle c3
// for inner most ring
mat1="z:"+c1+" & y:"+c3;// mean mean rotate around z axis with angle c3, then  rotate around y axis with angle c3
// mat2 is for middle ring

Click green triangle to generate new simulation when you finish your modification.

You can find the jar file,at [b]export[/b] directory under ejsworkspace

You will find "Upload new EJS jar file" at the same line where you submit the message , click the checkbox
then select your jar file with button, then submit your message.
Your simulation will be shown automatically follow the end of your message.
[/quote]

Thank you very much for your very useful advice. Before I start to use your instructions and to try to modify the applet (I did not sleep for 25 hours working in my lab and will start with the applet tomorrow) I would like to beg you to look at the attachment or at the  http://www.fho-emden.de/~hoffmann/gimbal09082002.pdf Isn't it possible for you to change the ring shaped gimbals with the one having rectangular shape as in the attachment file. This will give  more clear vision on the rotational axes of the rectangular frames (gimbals) as well as the pivoted points than the circular one  and as a whole (on my humble opinion) is easier to work with it both for you and for me. Waiting for your answer (any time day or night) I am with best regards. The model of gimbal  given at the attachment is exactly what I need. Meanwhile, please ignore the text about quarterions. egabev.