[Dprglist] self driving trucks and the desert

[David P. Anderson]

Hello not Paul,

I think perhaps you missed the point I was attempting to make. Not to 
put words in your  mouth... :)   I have no objections to following a 
path or roadway, no matter how defined.   My robots can do that in 
several different ways, including following a closely spaced set of 
waypoints.  My point was more simply that the robots are not in fact 
operating unconstrained, as in a desert, as Paul's analogy suggests.   I 
think that greatly oversimplifies what they are doing.

Cheers!

-not Karim


On 10/23/21 1:14 PM, Karim Virani wrote:
>
> */[EXTERNAL SENDER]/*
>
> Try not to take this as putting words in Paul's mouth. My guess is 
> Paul was not trying to come up with a rigorously defensible analogy, 
> but accentuating a difference of constraints in the moment of that 
> conversation.
>
> In reality, we all place constraints on getting from here to there. A 
> path following constraint is just one example, but it's almost never 
> the only one. It's also not required. If you have constraints against 
> bumping into things instead of trying to plough through them, then you 
> probably have some sensors involved. If you have a path following 
> constraint there there are also sensors involved in determining how 
> far off the path you have travelled. It could be GPS outside, it could 
> be odometry - could be a dozen other kinds of sensors. The path could 
> be described in different kinds of coordinate systems. Paths may be 
> defined with a different stickiness - how tightly you have to cleave 
> to them. There may be a different stickiness per waypoint. A path can 
> be described without waypoints - could be formulaic.
>
> Adding path constraints may help with certain kinds of navigation 
> problems, could be unhelpful, or could be required. It'll almost never 
> be sufficient. Path planning can get you around known obstacles (a 
> building), less likely to encounter obstacles (lane keeping), but 
> won't be helpful in avoiding collisions with dynamic obstacles 
> (vehicles, people, donkeys). And for highly planned paths, you have 
> the burden of maintaining that definition's correspondence with 
> changing reality.
>
> Animals (including people) follow paths all the time. There are all 
> sorts of reasons to do so. There are also reasons to depart from a 
> path. It'll be a long time before robots can judge dynamically which 
> is the best approach in a given situation. Until then, they follow the 
> rules we lay out. But your robots are following a path even if they 
> only do it emergently. I'd like to see them emergently avoid driving 
> through a freshly planted flower bed.
>
> Path planning is just something in our toolbox. Why not learn how to 
> use it? Figure out where it works best and where it doesn't? The more 
> I discover about it, it's not a single kind of tool, it's a spectrum.
>
> -not Paul
>
> On Sat, Oct 23, 2021 at 11:44 AM David P. Anderson via DPRGlist 
> <dprglist at lists.dprg.org <mailto:dprglist at lists.dprg.org>> wrote:
>
>     Hi Paul,
>
>     I've been reflecting on your comments Tuesday evening about the self
>     driving trucks needing lots of waypoints to stay on the road, vs. the
>     robot demos shown that evening using more sparse waypoints.
>
>     In particular the observation that the robots are operating
>     essentially
>     unconstrained, as in a desert, except for the need to avoid
>     obstacles,
>     while the trucks need to stay centered on the roadway.
>
>     I'm not sure that is correct.  It seems that the long hallways
>     that my
>     robot had to navigate is the functional equivalent of the trucks'
>     roads.  So the robot is not in fact operating as in a desert,
>     unconstrained.  But must instead follow a fairly narrow and
>     constrained
>     path.
>
>     Now if that is the case, why does it not use hundreds waypoints to
>     accomplish that task?  Or more to the point, why the army trucks do?
>
>     So I pondered this for a while and it occurred to me that in the
>     robots'
>     case, the waypoint navigation is not responsible for keeping the
>     vehicle
>     on the "road," i.e., centered in the hallway.   Rather that is the
>     task
>     of a separate group of sensors and behaviors.   But for the
>     convoy, the
>     navigation behavior is responsible for navigation in the global
>     sense as
>     Chris was describing, and also in the local sense of staying
>     centered on
>     the road.
>
>     Now for the army trucks to do it the way the robots do would also
>     require a second suite of sensors and behaviors to stay on the
>     road ---
>     not trivial --- while the method you describe can all be done with
>     just
>     GPS, no other sensors required.   (Though I assumed or maybe you
>     told me
>     there are forward looking radar to keep from running into the
>     truck in
>     front of you.)
>
>     In any case, the desert vs. constrained roadway is perhaps not the
>     best
>     analogy for what the robots are doing.
>
>     cheers!
>
>     David
>
>
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