ok...now
you ignored the fact that you must use

* time_step / 16;
...you should use that, and just use a number, instead of refering to a variable to make sure it works. If it does, define a variable(inside the top of the action/function) to keep it local, if it is global, you will end up with bots that are adding to their speed or other weird things.

Everybody Poops.
here are some tutorials I made.
http://www.acknexturk.com/blender/