Is this RUT?

[gwilki]

Reporting back.

Thanks in no small part to all the help that I've gotten here, I managed to complete a loop route without the unit telling me make a u-turn.

There is one strange (to me, at least) thing, though. I am attaching a screencap. The arrow is pointing to where I selected the route and told the Zuno to go and start from the nearest point. You can see the start of the route to the left and down from that point. However, the first instruction the Zumo issued was to turn right at the first corner. This would have taken me in the opposite direction from the start point. I ignored the instruction and after a couple of bad instructions, it told me to turn left onto Terry Fox Drive, which is where the start point is.

I supposed that I should have followed the instruction to see where it would have taken me. If doing that will help with any advice you can give me, I can do that tomorrow.

In the meantime, can anyone tell me why the Zumo is taking me in the wrong direction?

Thank you

perth_ride.jpg (272.48 KiB) Viewed 1335 times

[Peobody]

I think I see an entrance ramp onto 417 at the upper right of the image. It that is indeed the case, I suspect that the XT2 was going to take you up to that access onto 417 and then down to the exit onto Terry Fox. I believe this would have been a certainty with the XT. I thought the XT2 was less exuberant about faster roads but maybe not less exuberant enough.

[jfheath]

Thanks for the update @gwilki .

Two thoughts.

I am not surprised by what you observed with Closest Entry Point. I don't know how the Zumo calculates it, but think about what the computer (XT2) might have to do. The shortest distance between any point and any straight line route is in the direction that meets the straight line route at a right angle. There are very easy mathematical ways that the equation for this line can be calculated, and where the point of intersection is.

Garmin's method of calculating will be much more sophisticated than that, but that thought might reveal the problem with your map. You cannot draw any line from your start that meets the route at a right angle. Some time back I was curious as to how it worked and noted that the only few occasions that I got weird results were when my position would not permit that perpendicular line to be drawn.

Most times the Zumo would come up with a solution. Sometimes it didn't. One time - that I have never been able to replicate - I was facing the wrong way, just before the start point, U turns not allowed. I used CEP and the map navigated me south to some roundabout 150 miles away, and then returned me to the start. At the time I did the tests, This type of error would happen more often if U turns were not allowed, and the Zumo thought that it was facing in the wrong direction. (It doesn't have a compass, so it only knows your direction if you are moving)

Rule of thumb. Expect a weird result with CEP if you are at a location that is before the route starts. Eg you are further East from the start point if the route is heading west-ish. If that is the case, then choose the start point as the next destination, rather than CEP. I'd be surprised if Garmin software did not make this check. But I have been surprised before.


Nb - I have not tested CEP for a very long time. Knowing from before that it could produce weird results, I avoid using it. But on odd occasions I have used it. I always check the preview map to see where is heading and it has always been Ok - but I never use it in situations where it was going wrong before - never to get to the start, never if the Zumo has not moved in the right direction, never with U turns disabled. Garmin may have addresses these issues. I wouldn't have noticed if they have.

Second thought. A query. Is your XT2 set to synchronise with the Explore database with the Tread App ?

Reason for asking - I was able to run my well tried and tested route when I first gave RUT behaviour its name. Previous observations had led me to think that the XT2 would never get into a RUT. I ran the XT and XT2 side by side. The results were pretty much identical - both getting stuck in a loop repeatedly wanting to go back to its last recalculated position behind me. The XT2 used more turn around loops than the XT and the XT2 plotted the route to the next route point when it was 1.3 miles away from it. The XT found it 0.2 miles later.

This was unexpected from what I had seen with an earlier route on the XT2. The only difference that I can think of is that I had been messing with the trip planner on the XT2 and it was still set to synch with the explore database.

[Oop North John]

Just bought an XT2 and this morning tried it on a route that the XT always went into a RUT if it wasn't "saved" etc.

Basically home to a via / way-point (ie announced) to work. Planned in Basecamp, transferred to a SD card, and then imported. Activated by starting it from the "routes option". "U-Turns" are not avoided in the settings.

So I Go along my road and then the route as calculated means turning left, I turn right as I know it's quicker and is my preference.
XT2 almost immediately calculates how to do a u-turn up ahead, which I ignore, and turn down what will be the fastest / my chosen route. XT2 almost immediately calculates how to get back to what was the "planned" route, which I ignore and continue on the same road. XT2 almost immediately calculates after I miss it's last instruction on the sensible option of continuing along the road I'm on. The XT would have tried on a few more times over the next few miles to get me to do a u-turn.

Once only test, but a vastly improved behaviour to the XT and an "un-saved" route.

Only a suspicion, but I wonder if the algorithms have been tweaked so that going off an un-saved route the GPS tries to return you to the original route, say twice, and then does a full calculation? Sort of opposite to the SP3 was tweak as when it tried to do a full recalculation but was lacking in processor power so could spend minutes trying to work out the answer. That tweak was to try to get you to go back 3 times IIRC, and then it did the full recalculation.

I also wonder if the fastest roads bug in the XT made it even more likely that the answer it came up with was the least optional?

[jfheath]

Thanks @Oop North John

That was more or less my experience with my new XT2. I felt really positive about it. It is certainly different and better.
I too had the notion that there was a counting mechanism involved. 2 or 3 times, and then try something else. The 595 used to do something similar with its prompt to skip a point. After the third time it wouldn't prompt any more.

My test was really disappointing. I intend to post the results, but it wasn't my previous experience - which on a normal ride it 'eventually' gave in and navigated ahead. All the time, what it was suggesting I could make sense of - although it wasn't as good as the 'fixed' imported XT route.

[Oop North John]

My test was really disappointing. I intend to post the results, but it wasn't my previous experience - which on a normal ride it 'eventually' gave in and navigated ahead. All the time, what it was suggesting I could make sense of - although it wasn't as good as the 'fixed' imported XT route.

Could a traffic input, for example, have messed up the results?

[jfheath]

Possible, but I don't think so in this case. Normally a re-routing notice is given and a red circle shows up on the map. I came across that in Scotland - where they had put bollards across one road (blocking shortcut on a very tight left hand elbow junction) - but the map had that route open, and the main route blocked ! It recovered from that remarkably well.

I need to reinstate the XT as it was. Get rid of the link with the Tread App synchronising my account and try it again. If I don't - that will be a niggle in my head.

[gwilki]

@Peobody You hit it. I followed the instruction to turn right onto Campeau to see where it would take me. It took me east 1 km, south 500 metres to get on the 417 highway, then west 2km. Then, it took me off the 417 to turn south on Terry Fox and finally hit the start point. I can see the "logic" of this, but in this case, the route the XT2 takes me on is neither shorter nor faster.

I'll add @jfheath into this now.

My XT2 is not set to sync with Tread or anything else. I do not have Tread installed on anything.

As a further test, I did a very short route. This time, I made the start point north of the 417 ramp on Terry Fox. (The first routes' starting point is south of the ramp.) So, the "logic" of the first route would fail since I could not pick up the start point from the ramp. I would need to turn north on Terry Fox then make a uturn to hit the start point. This being the case, I thought the unit would simply have me turn left/west on Campeau, left on Terry Fox and start the route from there - the nearest point. Not so. Instead, the unit had me take the same directions as on the first route. Turn right/east onto Campeau, right/south again in 1km, then onto the 417 to go west. It took me off at Terry Fox as before. The problem now is that I am south of the start point. No worries for the XT2. It has me turn left/south on Terry Fox, then continue to my end point. This got me to the destination, but it completely ignored the start point and the first 200metres from it to the ramp.

Clearly, I am still confused. That start point is a Via point. I thought that I had to hit them. In this case, I could have done so easily by going the direct way. Instead, the XT2 took me out of my way to the east, then south on Terry Fox, completely ignoring the start/via point. What am I missing here?

Obviously, none of this is an issue when I am in my own backyard, so to speak. My concern is that, in my limited experience, when I am actually in need of its directions, it will fail.

As always, I am grateful for any thoughts.

[Peobody]

My concern is that, in my limited experience, when I am actually in need of its directions, it will fail.

That depends on your definition of "fail". The one thing you can rely on is that it will get you to the end point, so from that viewpoint it won't fail. Beyond that, it appears that the XT2, like the XT, requires us to try to out-think it. If I had created your route I would have placed the starting point near Kanala Ave on Campeau Dr in the hopes of minimizing the options the XT2 might consider. OTOH, may folks set their starting point well away from where they'll be mounting the bike. They can load the route, choose the starting point as the entry point, then ignore the device while they go get coffee, breakfast or whatever, eventually joining the route. All is well once they do.

You mentioned that when you started the route you told the XT2 to "go and start from the nearest point". If that means "Closest entry point" then it is understandable that the start point was skipped. IIRC, I don't think the XT cares if you miss the starting point. I navigates forward just fine when you join the route somewhere between it and the next Via.

[gwilki]

@Peobody thanks for this. Yes, I did mean "closest entry point".

I understand your advice to make the start point near Kanata on Campeau. That's good advice. I think I'm simply overreacting to my initial failures - those where I set the start point at my actual start point - my house.

I take your point that "failure" is relative. The GPS in my car often takes me on meandering trips with no discernible logic. However, to date, it has always delivered me to the final destination.

Rest assured that, thanks to all the help that I am getting here, I am learning. Slowly - but I am learning.