Interesting idea. Seriously over-engineered though.

If you want a ‘human washer’ you don’t need a $350k fancy chair with heart rate monitors. Just take a page out of the automatic car wash.

Human stands in a stall. Shower allows human washing of hair and face. Then just hold arms out making a diamond in front of you (think TSA body scanner position, but with arms forward instead of upward) and a 360° robotic sprayer starts at the neck and goes down spraying soapy water, then back up again with a slight up angle to get the groin and armpits. Shower comes back on to de-shampoo hair, then the same 360 robot does two passes with clean water to rinse everything off.

If you get fancy with machine vision and body position sensors, the 360 wand could flip 90° to do the hair and would be angled backward a bit so it doesn’t get water or soap in your face.

You could build this for a lot less than $350k. And instead of $1500 worth of body sensors you have a $50 waterproof emergency stop button.