MIT's Smartphone Laser Scanner Is Totally Decent and Costs $49
To do capable and useful things, your robot needs capable and useful sensors, which is just another way of saying that your robot needs you to spend a lot of money on it. This is really too bad, because hardware cost is enormously restrictive for robots, especially ones that are intended to be affordable by people who haven’t co-founded a robotics startup or something (I think there are a few people left who have yet to do this). In particular, distance sensors that allow your robot to detect and avoid obstacles tend to be both very useful and very expensive, but if you want one that works reliably outdoors, start saving, because they cost thousands of dollars.
At MIT, a group of researchers led by Professor Li-Shiuan Peh designed a phone-based laser rangefinder that costs a total of $49, plus a smartphone that you’re not using anymore. Is it the greatest laser rangefinder ever? Not even close. But for less than $50, it’s pretty darn great anyway.