Saturday, 26 February 2011

The robotic arm

Unlike the left arm, the robotic arm has no joints in it whatsoever.  This arm is a piece of machinery, and was required to act accordingly.  Therefore this arm would move with a very straight, pivotal motion as opposed to a more organic motion.
The modeller modelled the arm in separate pieces, in order to facilitate the robotic movement.  The arm is also a separate model to the rest of the body.  In order to make this arm possible to animate adequately,  I parented each part of the arm to the next, starting from the fingers and ending with the shoulder.  I then created curves in for each part of the arm that rotates (i.e. the elbow pivots, the fingers, etc.), which are very like FK handles.  I then constrained each curve to their respective part of the arm.  This means that the animator just needs to rotate the arms, either on the Y or Z axis.

Here is a basic animation I did to show the robotic arm in action.

When it came to binding this arm to the rest of the body, I was faced with several problems.  I had initially only parented the curves to the chest controller, meaning that when I rotated the body (after binding the rig to the model, the robotic arm would move out of it's socket.  I tried to solve this by combining the shoulder with the rest of the model and keeping the rest of the arm separate, but I was faced with the same problem.

I solved this problem, by trying out an idea, which was to create a new joint from the chest that would go to the right shoulder.  I then constrained both the first curve of the arm and the arm itself to the new joint.  Now when I rotated the monster's upper body, the arm kept in place.

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