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Comment by 3apo | Hacker News Reader

From an economic standpoint, I would be interested to see how many OTC parts this system. That is, does it need a $1000 lidar or would it get a similar performance with a cheap $100 sensor? From a technical point of view, 25mph is very limiting IMO. You probably do not need a very sophisticated controller to navigate at 25. If you reach speeds of 60-70MPH with varying road curvatures, the controller design gets trickier.

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I disagree. City driving at 25 mph is a lot more complicated and needs a lot more computing power than highway driving at 60-70 mph. City driving involves: handling the "dead zone" of intersection (square of pavement with no marking), poorly marked roads, pedestrians/cyclists/cars getting in your way, complex turn lanes, etc. By comparison highway driving is a piece of cake: clearly marked lanes, no sharp turns, no intersections, clear entry/exit ramps, all vehicles moving in the same direction, no pedestrians.

On city roads, if your car gets confused it can just stop, even without pulling over. This will annoy a lot of people but nobody will die.

On a highway, you can't safely just stop. And there are still difficult driving situations. For example, construction zones often have poorly marked lanes (or multiple, contradictory lane markings), construction workers to watch out for, and nowhere to pull over. Exit and entry ramps may be clear, but merging at speed and in traffic is a difficult and unsafe problem. And any failure at highway speeds is far more dangerous than at 25mph.

What you say is true - city driving is complicated with too many decisions to make, but it does not need a very optimized controller to control the car through those scenarios. Changing a lane at 15-25MPH is far more easier than on a turning highway with merging traffic at 55-60MPH. At that speed the controller would not only need to safely execute the maneuver but also stabilize the vehicle in the event it needs to come to a halt or take an evasive action.

Moreover if there is say some uncertainty in the sensor readings at 25mph, that is multiplied by many factors at higher speeds and becomes very significant. Control at higher speeds has more stability issues and can deal with less uncertainty and than at lower speeds.

The 25 m/h speed limit is a regulatory hack. The converted normal cars already drive on the freeway (with human back-up drivers in them).

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