A lot of impact avoidance with other vehicles and pedestrians is done by communicating with looking at each other though. The easiest solution, car always yields, would just mean it will take forever to move because people will lose all respect and just treat it like a solid obstacle. Also, sometimes cars can and do pass within a few cms to humans (ok if everyone is aware of the maneuver and it's slow), would an automated system do that?

> The easiest solution, car always yields, would just mean it will take forever to move because people will lose all respect and just treat it like a solid obstacle.

I've often wondered how self-driving cars will deal with this. Imagine we reach the point where self driving cars are perceived as being guaranteed to stop before hitting a pedestrian.

This presents a lot of problems that need to be overcome. A car-jacker could rob you simply by getting an accomplice to stand in front of your car. Teenagers might start jumping in front of cars as a high-tech game of chicken. What happens when somebody steps into the road and the car brakes so hard it gives the occupants whiplash?

I'm sure all of these problems will be solved in time, but it's going to be interesting to see how!

There is a 500 m long street in front of my house where it is customary that people cross it everywhere and cars are just expected to stop for the people. There are no traffic lights or pedestrian crossing or any special rules, its just that people started doing this decades ago and now it is just tradition to do this.

So now you have a long street where tons of people are crossing every 10 meters during the day because it's a quite busy shopping district.

Although cars are driving slow, it must be very hard for autonomous cars because there are people everywhere running in every direction.

Don't forget computers have vastly faster response times than people. A car going 5mph with 10ms reaction times can stop in ~1 foot. http://www.random-science-tools.com/physics/stopping-distanc...

Do you want to be inside the car when it does that? It is not going to be much fun unless you are paying attention and bracing yourself, in which case I'm not sure I see the advantage of letting the computer do it for you.

You are probably overestimating the jerk from that. 5mph has (1/12)^2 = 1/144th the energy of 60mph. Passengers often don't pay attention to what's going on and breaking force is generally not enough to really mess with people.

That said, the default is not going to be stopping within 1-2 inches of pedestrians, rather it's going to gradually slow down to deal with pedestrians while trying to maintain forward progress. The point is a self driving car could be more aggressive than most people while staying safe instead of freaking out and just stopping because people are jaywalking.

You're right of course. It's hard to imagine any useful vehicle spending much of its time moving at only 5 mph, though, so I suppose I'm really imagining what such a stop would be like from a more normal travel speed like 20-25 mph.

I am picturing this more as an extreme edge case than anything else. If a person can safely do 20-25mph in an area then a self-driving car should be able to do the same thing.

It's the edge case where a car needs to cross a really high traffic area that's going to be an issue and people can't do 20mph right in front of a high traffic box store entrance etc. Further, going slow for a few hundred feet really does not take that long.

I would VASTLY prefer to be in that car than to be in a different car with a human driver and watch a person get killed by the vehicle I'm riding in.

Nobody is going to die from a 5 mph collision. It's not even likely to break any bones. At 30 mph, the chance of death is still only 5%!

There may still be reasons to prefer robot cars for low-speed environments but the probability of such a vehicle striking and killing a pedestrian is already very low, so that is not relevant to a discussion of a robot car's ability to stop very rapidly at very low speeds.

http://www.nhtsa.gov/people/injury/research/pub/HS809012.htm...

The "every direction" bit is actually something autonomous cars handle far better than humans since they can have eyes pointing in every direction. The hard part is noticing that someone waiting at a crosswalk wants you to stop so they can cross.

The problem is not necessarily "obstacles made of stone." Think about lanes in the countryside where you only see grass and the possibility of a ditch to either side... I guess that is really complicated for a self-driving car to manage in each and every case as well as human does.

Yes, walls are easily located. Holes not so much. Emptiness is quite difficult to see.

Except that it's much more likely for there to be pedestrians.