Let’s say it’s recycling day and you’ve got a bunch of empty boxes, cans, bottles, and containers next to some new cans of beer. Your personal robot of the future will be able to sort them out for you without accidentally throwing out your precious stash even if its cameras and laser scanner can’t tell the difference just by looking at them. It’s all thanks to a new project that alerts the PR2 to the mechanical effort exerted when lifting or pushing objects. It’s like when you reach for a carton of milk, only to find that it’s too light – and you instantly know that the carton is virtually empty. After implementing and refining the model, the PR2 was able to sort empty bottles from full ones with 100% accuracy. They then taught the PR2 how to sort boxes by the amount of force required to push them around.
This kind of thing seems like common sense to us, and could be determined by other means, but what’s cool about this method (called proprioception) is that the PR2 can sense relatively minute differences in the physical efforts of its joints.
[source: Willow Garage]