Rapid Returns

[RobotLady]

What has been everyone's experience with rapid returns?  We've used the dimensions in the manual, but unfortunately they do not seem to work reliably.  Has anyone gotten it to work consistently?

[RoyMercer]

I have not tried this yet but I am planning on it as soon as I get a chance. The came from someone else last year:

After a lot of work and frustration trying to make a rapid return work for the 3500, I think I finally got it, and wanted to share my experience.

Here is the layout that seems to work every time:

Straight run of at least six feet
Turn right for 28.5 inches
Turn left for 26 inches
Travel straight for five feet.
Measure the distance from the first right turn peg to the next turn right peg , it should be 21 inches.

What this does is cause the bot to abruptly turn right and then go a short distance, and then abruptly turn left actually more than 90 degrees, because it always overshoots a change of direction, and then travel on that line, and then abruptly turn right, and then go on a straight line for about five feet.

After experimenting with setting this up, and dozens of trial and error runs, this one seems to work every time.

I hope this helps out those who have been frustrated trying to use what is in the manual that does not work.  The real key here seems to be making a very sharp turn to the left beyond 90 degrees, after the first right turn.

In the drawing below, 1, 2, and 3 are pegs.  The dashed line is the wire.

- - - - - - -  1<------21"--   --->3 - - - - - - - -
                  -                           -
                    -                       -
                      -                     -
                        28.5"            26"
                          -               -
                            -             -
                              2

So, to make it clearer, distance from 1 to 2 is 28.5 in, distance from 2 to 3 is 26 in, distance from 1 to 3 is 21 in.  In actuality, the angle between 1 and 3 is more acute than my crude drawing would imply.

I hope this helps you create a rapid return.  Sorry for the botched up attempt at drawing, what you see is NOT what you get when you post!  Hope this is clear enough.

I have a very large yard, and need to use rapid returns.  I will try to post a video of it working later.

[RoyMercer]

Here is another one:

The only feedback path the bot has to determine what "pattern" the bot has followed is the magnetic pulse encoders on the drive wheel motors.  Those are on the motor end, ahead of the gear reduction, uneven ground, slopes, wheel slippage, etc.  The software probably comes down to this: in the past X seconds did the left and right wheel go forward at equal speed fo A seconds, opposite directions (right turn) for B seconds, forward together for C seconds, etc.  If the ground is uneven one or more of the timings are simply off.  If the grass is wet and a wheel slips, those timings are off.  If the play is too much in the gearbox, those timings are off.  All of this can be compounded by the fact that there are 3 different motor assemblies that can go in the bot... those of us with the older model have the Dunker motors.  The newer bots have the IMS motors.  I've never heard of a bot with the Automec motors, but aparently they can go in there as well.  Some out there have a combination of two due to warranty replacements!  While the service menu setting tries to make up for this, determining where the bot has been isn't an exact science even without the extra variables.

My bot came with an addendum sheet in the manual saying the triangles belong a different size than the manual says.  Was that due to a hardware change or a software change?  If software, has it or will it change again invalidating the manual once again?  I don't know.  The presence of the addendum sheet and the consistency of reports of failed triangles makes me suspect this probably is an old issue (a design defect) that isn't going to be solved anytime soon.

The only way to know for certain what causes a triangle to fail would be to know what the bot "saw" when it passed the triangle and to adjust the shape such that the bot sees the right thing (and that may not even look like a triangle to us anymore).  Since we can't get inside the mind of the robot, it is just guesswork that we have left to work with.

IMO, I'm afraid the best answer is to not rely on them except for islands where they are absolutely necessary.  It's very rare that I find Oscar out of battery on the return wire, so, except for the one island, I just don't worry about the triangles anymore.

[Bill S]

What a coincidence, I just added another triangle today with 16" sides. The original triangle does not work anymore. I will report back.

[prb238]

I have tried the instructions from last year with the layout mentioned above:

Straight run of at least six feet
Turn right for 28.5 inches
Turn left for 26 inches
Travel straight for five feet.
Measure the distance from the first right turn peg to the next turn right peg , it should be 21 inches.

and, it works every time.  I have a 3200 and the guy that had posted this originally has a 3500 so it definitely works well on both models.  I put in two rapid returns and both have been working every time the robot goes through trying to return for a charge.

[Bill S]

The 16" sided triangles I added the other day for the rapid returns both work (for now).  Also, both wheel motors have very little backlash at this time.

[Radjack]

I tried this with my 2150...does not work for me.
The bot simply makes a really tight turn and follows the wire...
The darn thing is smarter than i gave it credit for.

[jzawacki]

The darn thing is smarter than i gave it credit for.

Wouldn't "smarter" mean it knows you want it to take the rapid return?

[Radjack]

Could i be testing the rapid return incorrectly?
I was reading somewhere that when the bot is travelling to the 2nd zone it does not follow the rapid return, it stays on the wire.
My bot was never leaving the wire...
I was simply pressing the charge button and aiming the bot at the wire before the rapid return. Is that a correct way of testing the rapid return?
Thanks

[jzawacki]

Sounds correct.  Pressing the charge while it is "out and about" and it "searching charge" is for when it's going home.  If it was going to a second zone, it would be coming out of the garage, circling around, finding the wire, and heading on it's way to another zone.

[shep874]

Could i be testing the rapid return incorrectly?
I was reading somewhere that when the bot is travelling to the 2nd zone it does not follow the rapid return, it stays on the wire.

Radjack
That is how my 3200 works, I have a return just before it enters my front yard if going to the front yard by program it will disregard the quick return. however if I want to take Billie to the front yard or one of the other zones, I need to use the remote to bypass the quick return. If going to charge it uses all quick returns.   It sounds as though you have hit on the problem..

[Radjack]

Hey J, how are your rapid returns configured?
Are they the same as described above?
I cannot get that to work for me and am looking for other things to try.
Thanks

[RobotLady]

Radjack, check the dimensions carefully.  We also found they have to be exact.