system
Given the following post, respond as if you're commenting on Reddit:
human
[Marvel] What are Tony Stark's arms doing in the Hulkbuster armor?

The iron man suit is fascinating technology, and although it's never entirely clear how it functions, it seems reasonable to assume that Mr. Stark's extremities fit within the suit, thus dictating it's humanoid shape.

however, the Hulkbuster suit is different. It's barely in a human shape, and certainly not to human proportions. The shoulders are too broad and the arms are too long. Even if you assume that the arms just don't reach all the way to the end, the shoulder joints are in the wrong place. So, how does it get piloted? Is the main body just all inside of the chest cavity?
gpt
Ever hear of something called a Waldo?

it's a puppetry interface. You move your hand, and the movement is read by a small computer, turned into precise movement data (joint moves 32 degrees, 2nd joint moves 22 degrees, etc), and transmitted to a motor to move whatever it's connected to. 

Stark operates the hands by waldo controls. Chances are, the entire suit's run that way. Since Stark implanted all those microsensors under his skin, technically, his body IS the waldo controller. 

Technically, for the hulkbuster, he doesn't even have to be IN the suit.