POSITION DETECTION

摘要

How can a toothbrush know which part of your mouth it's cleaning? "That was one of the toughest nuts to crack," says Frank Kressmann, the P&G engineer who developed the Oral-B Genius 9000. Somehow the brush has to know where it is in your mouth. To solve this challenge, Kressmann and his team fitted the brush with a set of acceterometers that measure changes in motion in three dimensions and so calculate changes in brush angle of just a few degrees. That's just how smartphones detect whether they are vertical or horizontal.