animating avatar by m3g

[meshoooo]

I am an it student. My graduation project is talking about translating Arabic text to Arabic Sign Language on mobile phone. I face a problem on animating the avatar of the System who's represent the Sign language. I create the avatar via blender this avatar is moven by skeleton. I exporte it to m3g file and load it on my application. When I want to animate it I face a problem. the movement is not smooth and clear for user e.g when I move the arm bone to become longer. And I don't know how to get the xyz-axis for the represented avatar to move it easily. I use the methods: Postrotate that rotate selected bone but the rotated bone is not move smoothly, so I use also translate to set its place. The xyz values for these methods are set rendomly until I get the right position for the bone becuase I don't know the axis( it is not like the m3g axis or blender axis it seems different). My questions are:

- How to get the right axis for my avatar?

-Are the used methods are enough or I have to use another methods?

-Are my solution to solve animation problem are correct?

Please give me your advices for this problem.

Best regards.