[Dprglist] Fwd: LF intersection angle rule

David Anderson davida at smu.edu
Sun Dec 10 08:49:36 PST 2017

Thanks Doug,

I'm not sure I follow your examples (pun intended!).

For the segmented S curves, the difference between following the arc and 
following straight line approximations of that arc are pretty small, and 
likely to be indistinguishable from Ron's robot's path, for example.   
Similarly, each of the stains on the published "challenge" course is on 
a straight line segment between the entry point and exit point, so the 
paths would be identical in both cases.

For a robot with a base the size of the tiles, I'm not sure there would 
be any difference at all, unless the rules require that the "exact 
center" of the robot must remain on the line, in which case I don't see 
how either Carl's approach or Ron's would qualify.

This is just an intellectual exercise, I'm not planning on fielding such 
a 'bot.


On 12/10/2017 10:06 AM, Doug Paradis wrote:
> David,
>       Going from entry point to exit point is not considered enough. 
> You have to follow the line. For example, the segmented S curves, the 
> robot needs to follow the curve and make an S type movement. Another 
> example is the stain elements, the robot needs to follow the line 
> across the stain not follow the outside edge of the stain.
> Regards,
> Doug P.
> On Sun, Dec 10, 2017 at 1:11 AM, David Anderson <davida at smu.edu 
> <mailto:davida at smu.edu>> wrote:
>     Great meeting today.
>     Doug, I have a question based on Ron and Carl's presentations,
>     perhaps it has already been answered, to wit:
>     As I understand, the line following course consists of an assembly
>     of square tiles, each of which has an entry and exit point.
>     Is it sufficient for the robot to just identify the entry and exit
>     points, and drive directly from one to the other?
>     That is, it would not follow the line per se, though with
>     sufficiently large robot the differences would probably be pretty
>     negligible, but it would follow the course.
>     thanks,
>     dpa
>     On 12/09/2017 08:18 AM, Doug Paradis wrote:
>>     John,
>>         Currently, the intersecting lines are always straight and all
>>     intersections are 90 degrees. Curves lines at an intersection
>>     would be a possible addition to further challenge courses
>>     (interesting idea). The link to the course layout is at
>>     https://www.dprg.org/wp-content/uploads/2017/11/DPRG-Roborama-2011b-Challenge-Level-LF-Course.pdf
>>     <https://www.dprg.org/wp-content/uploads/2017/11/DPRG-Roborama-2011b-Challenge-Level-LF-Course.pdf>
>>     If you have any additional questions, let me know. I would love
>>     to see your work on the tests that you are developing.
>>     Regards,
>>     Doug P.
>>     On Sat, Dec 9, 2017 at 12:36 AM, John Swindle
>>     <swindle at compuserve.com <mailto:swindle at compuserve.com>> wrote:
>>         Doug,
>>         I'd say the crossing in your drawing was about either 30
>>         degrees or 150 degrees, and since it could come in on either
>>         side, I'd have to look for both. I am not asking that the
>>         rules state which side the angle is measured from. My issue
>>         is that I am developing a two-step test that covers all the
>>         conditions in the Challenge, but in the steps I need to
>>         include something that rejects the intersections. I am OK
>>         with rejecting any line that is 70 degrees to 110 degrees on
>>         either side. If the intersecting line is straight, the test
>>         is a bit more robust. If each side is 70 to 110 degrees (a
>>         bent intersecting line), my two-step test might fail.
>>         Doing it "that's just wrong" way,
>>         John Swindle
>>         -----Original Message-----
>>         From: Doug Paradis <paradug at gmail.com <mailto:paradug at gmail.com>>
>>         To: John Swindle <swindle at compuserve.com
>>         <mailto:swindle at compuserve.com>>
>>         Cc: DPRG <dprglist at lists.dprg.org
>>         <mailto:dprglist at lists.dprg.org>>
>>         Sent: Fri, Dec 8, 2017 11:52 pm
>>         Subject: Re: LF intersection angle rule
>>         John,
>>             In the challenge course, all the intersections are 90
>>         degrees. The rule was written to allow crossing variations in
>>         the future. I'm thinking that  70-90 degrees would represent
>>         the smallest angle of the intersection. I not sure that is
>>         right, just the way I would interpret the angle.
>>         if you saw an intersection that was like this:
>>                    |   /
>>                    | /
>>                    /
>>                  / |
>>                 /  |
>>                /   |
>>         What angle would you say the intersection was?
>>         Regards,
>>         Doug P.
>>         On Fri, Dec 8, 2017 at 9:03 PM, John Swindle
>>         <swindle at compuserve.com <mailto:swindle at compuserve.com>> wrote:
>>             Doug,
>>             The Line Following Challenge rules say "Intersections may
>>             cross with angles of 70 - 90 degrees." Doesn't that
>>             really mean 70 to 110 degrees? Is the intersecting line
>>             straight, or can it bend at the intersection?
>>             Thanks,
>>             John Swindle
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