Liver Retractor Control

The first complaint that I got from the surgeon when I let him test the prototype retractor shown in the previous post was that the interface didn't make any sense. He moved the joysticks while watching the retractor, expecting it to imitate the motions of his fingers, while I had designed it so that the joysticks themselves were representations of the retractor fingers and the movements of the retractor would mimic the position of the joysticks.

The interface just wasn't set up for the kind of control that the surgeon wanted. He was correct though, the surgeon wouldn't be looking at the joysticks when he was working, he would be watching the retractor inside the patient. The interface would have to translate his hand motions into motions of the retractor. So I set out to make a new interface that would hide the joysticks and just focus on getting the surgeon's hand into a natural position.

This diagram shows a part of the new interface, the joysticks that control the finger portion of the retractor. It is shown upside down in an attempt to make the joysticks recognizable for what they are. The surgeons hand would wrap around the top (bottom in this diagram) of the shell containing the joysticks and his fingers would rest in a series of loops protruding from the shell. Each loop stem would pivot around a pin in a slot, allowing side to side and forward and backward motion. These motions would be transferred to tiny joysticks inside the shell which were wired to the motors that controlled the retractor. I tried to get at least the basic idea of this across in this section view which was drawn based on a CAD model I used to fabricate the shell.

However, I didn't show this diagram to the surgeon as that would have defeated the entire purpose of my redesign: to hide the joysticks so that he didn't have to think about them. When I let him control the retractor, it was much more intuitive for him. He did complain that the range of motion for each finger was too limited, but at least it was a step in the right direction!