[Dprglist] self driving trucks and the desert

[Karim Virani]

Then we are per usual more in agreement than not.

-not dpa

On Sat, Oct 23, 2021, 1:22 PM David P. Anderson <davida at smu.edu> wrote:

> 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> 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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>
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