This is a laser cannon robot. It has the animation that you can see here, already in the file. There are 3 action constrained bones for the feet and one for the cannon.

For the head opening, I would recommend moving the bones 0.5 or so to the sides. 0.5 up/down, and 2.7 back. Those are the settings that are in the animation.

Also, for the cannon's animation, I would recommend moving the bone for at least 100 frames. Otherwise, it opens too fast. You should also set the interpolation in the graph editor to 'Vector'. The cannon has a separate armature from the rest of the robot.

I hope you guys enjoy this piece of work. :)

https://www.youtube.com/watch?v=DGDUo9-MrnE