Weird Routing Behaviour (2)

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jfheath
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Re: Weird Routing Behaviour (2)

Post by jfheath »

mad-dawg wrote: 01 Dec 2022 10:24 This Alien Via Point thing makes a lot of sense after the issues I had in September, I will have a look into this and try and replicate it.
It is crazy if the XT starts making routing decisions based on some algorithm when you are forced to change direction due to road conditions.

It seems like Garmin have added loads of features and scuppered the one benefit!
Certainly when I noticed the new XT Via Point, a lot of things fell into place, and I had a lightbulb moment which seemed to account for a few odd behaviours. I'll keep those thoughts to myself, see if anyone comes up with the same theories.

I'm in conversation with one of the support officers, who seems to be more intrigued than usual about the behaviours that I have observed. She is actually addressing the issue of the broken track log that I get when this weird behaviour happens. The technical team have been unable to replicate the broken track behaviour, so they want to issue me with a replacement XT so that they can take mine and see if they can get it to happen on my current one.

If you can add anything extra to the routing behaviour or replicate what I have found - I would be most grateful if you would share it in this thread.
Note - at present, my belief is that this happens when I deviate from a route that the XT has already recalculated. I have observations that suggest that it doesn't do it when deviating from the original route. But this is all new information, so it is a belief that isn't fully tested.
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Oop North John
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Re: Weird Routing Behaviour (2)

Post by Oop North John »

jfheath wrote: 30 Nov 2022 23:56 You seem to be saying you get a new point inserted when you first deviate, and then another when you deviate from the recalculated route. Is that correct ? I'm not sure what you mean by the last 4 words "and when it isn't" ?
What I'm trying to say is that the new via point happens irrespective of the u-turn madness.

Easily seen as if you were routing, then the magenta line goes from behind to in front of you. If you go off route, then the magenta line starts from the point of the "new" routes calculation. I think that the new via point will be the point the magenta line starts,
jfheath
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Re: Weird Routing Behaviour (2)

Post by jfheath »

Ah. Yes - I have seen the new magenta line in those situations. I'd just never spotted that it involved a new Via Point.

I am thinking that the new via point happens - and then sometimes the madness begins.

But those are things that I can now investigate.
Have owned Zumo 550, 660 == Now have Zumo XT2, XT, 595, 590, Headache
Use Basecamp (mainly), MyRouteApp (sometimes)

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Re: Weird Routing Behaviour (2)

Post by Fxwheels »

One would think that after buying the unit, it will be fully trusted and functioned as you'd expect it to. Unfortunately it is not the case. After the software change (2014?), they made it so complicated that it was not possible to fully test it out. Therefor we consumers are testing it in "production". Granted I understand that some bugs in any new software algorithm can get out especially in a new device, but Garmin doesn't look like acting upon it when users are pointing that out. For one how long ago is the via-to-shaping point conversion repositioning problem was reported? Nothing is done yet. Strange "Nearest entry point" calculation, detours and now this. I'm not blaming Garmin for these problems per se, I'm blaming them for not resolving them.

On my LD trips I always take the old Nuvi 1490 as backup. It sure has much less features/options than the XT or 396 but is one I can trust (maybe cas it it simpler).

I'll try to create this problem on the XT and 396 and will report the result.
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Re: Weird Routing Behaviour (2)

Post by Fxwheels »

The XT is not in my possession yet (my son-in-law is using it), but used the 396 today. I think it has the same navigating software. Went off route, it recalculated, went off again and recalculated again. No new via point. Have done it several times. At one time it asked for a U-turn. I proceed forward and it continued to navigate. To be sure that I was on the planned route I had the track showed on the map.
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Re: Weird Routing Behaviour (2)

Post by jfheath »

The behaviour that you describe for the 396 is consistent with how the 590 and 595 behave.

The XT also behaves like this if it is given just a destination. Also if the route has not been recalculated by the Zumo itself - eg after a skip or after an earlier deviation. I'm still working out the precise circumstances. But my XT is with Garmin now. They think some of my issues with the broken track log, which I get when it demonstrates the weird routing, are hardware related. That was a refurbished unit after my original died. They have been unable to reproduce the broken track log issue, so they are sending out a brand new one so that I can repeat the tests that I sent to them, see if it still happens.
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guiri
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Re: Weird Routing Behaviour (2)

Post by guiri »

Hmmmm Garmin!

I took the XT for it's maiden voyage today, and whilst the overall experience was positive, I got this weird routing behaviour near home.

There were a few different triggers maybe...

I'd already started navigation half way into the route (after a coffee stop).
I restarted the navigation having decided against the final coffee stop of the day (and skip waypoint didn't work as expected).
I didn't follow the suggested rerouting due to traffic and stuck to my original plan (I had recalculate on automatic though).

I got u turn request after u turn request. I got the impression that it was trying to take me back to where it thought I should go due to the traffic, rather than just reroute from my current position (because it didn't seem to realise that I was getting closer to home and was on a sensible road).

I didn't think to check the edit list, I'll do that next time!
jfheath
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Re: Weird Routing Behaviour (2)

Post by jfheath »

guiri wrote: 08 Jan 2023 17:55 Hmmmm Garmin!

I took the XT for it's maiden voyage today, and whilst the overall experience was positive, I got this weird routing behaviour near home.

There were a few different triggers maybe...

I'd already started navigation half way into the route (after a coffee stop).
I restarted the navigation having decided against the final coffee stop of the day (and skip waypoint didn't work as expected).
I didn't follow the suggested rerouting due to traffic and stuck to my original plan (I had recalculate on automatic though).

I got u turn request after u turn request. I got the impression that it was trying to take me back to where it thought I should go due to the traffic, rather than just reroute from my current position (because it didn't seem to realise that I was getting closer to home and was on a sensible road).

I didn't think to check the edit list, I'll do that next time!
This is a behaviour that I have reported twice - and which I have mentioned on this site a few times. The 1st attempt resulted in someone senior dealing with it who was very helpful. I gave a lot of evidence, convinced them of the fault and it was passed ont o software development. Nothing since then.

That was about a year ago, I guess. The I discovered another fault - that of the broken track log. I use the track logs a lot as a historical record of where we have been, stayed and roads that we have ridden and to have them broken into sections of a minute or less was really irritating. So this time I have someone who seems much more determined to sort it out. I think mainly because of the quality of evidence that I have sent - but also they were intrigued by its apparent association with the 'Go back to Old Kent Road' behaviour - which was apparently something new. They must get a lot of people who blame the XT, blame Garmin, blame the maps. I don't I look at it as a problem that I don't know the answer to and until I do I'm quite happy to consider myself as one of the causes.

Whatever, they have latched onto this, partly becasue the evidence I have sent is complete and explained - but they couldn't reproduce it. So in order to elimintae my XT as the issue, the wanted mine in their hands to see if they could get it to do it. They sent me a bran new unit in its place, and the first thing that I did was to go out and get it to go wrong again. That was 22 December, pouring rain but not icy. It is amazing how much grip there is aon a wet road when you have ridden on icy roads.

I've discovered a few things from which I have a hypothesis. But it is far from complete.

The use of the Skip facility to remove a via or shaping point from the list certainl has an effect. That causes the entire route to recalculate. (Beware MyRouteapp users who export the route using GPX v1.2 format - as it strips the shaping points from the route, so the recalculation will not go through them).

Uisng Closest Entry Point also seems to have an effect.

In most of my tests if I have done anything that causes the XT to recalculate the route on the fly, any subsequent deviation seems to result init refusing to calculate a new way to get to the the next route point, and it insists on going back.

On the other hand, if I choose simply a destination having selected Where To ?, then the route behaves perfectly sensibly. So far anyway - I haven't tested that a great deal yet.

But I've seen other odd behaviour too.

There are a few things that you can do:

Simple things first:

Turn off automatic Recalculation. That means if you deviate, the XT will not change your route. It will go quiet until you rejoin the route.
Make a track of your route (you can do that in Basecamp quite easily. Transfer both. Show both on the map. The track will not alter.
Create a track and ask the XT to navigate it. (with / without auto recalc turned on) . The XT will navigate you along the magenta line. If you deviate it will plot a straight line to show you where the nearest point on the route is. Its up to you to get there.

A bit harder.

Create a track and ask the XT to convert it to a trip. This navigates like a route, but if you deviate it will do what the XT does when navigating a track and find the closest point from your current position to the route and then find a way to get you to that point.

Neither of these methods show any route points.

A bit different.

Think about where you might want to force the XT into taking a particular road. It isn't very helpful adding lots and lots of shaping points as they can become more restrictive if you are forced to deviate. But adding a couple which are strategically placed will certainly help.

PArt of the problem is to do with the fact that when the XT recalculates, it doesn't find the fastest route. It finds a route which uses faster roads. Even if it takes longer and is a much greater distance.
So if you have a couple of Via Points that you know your really want to pass through (eg coffee stops) then putting a couple of shaping point in between will help. But don't put them on junctions. Put them part way along a road.

Example. If you have a nice 'A' road running in roughly the same direction as the a motorway, then you have to stop the XT from taking the motorway (don't say put an avoidance in, otherwise I will have to think of anothoer example, and this example is easier to understand !).

If you put one shaping point part way along the A road - to force the XT to go onto the A road rather than the motorway, then all the XT will do is come off the motorway at (say) Junction 123, visit your shaping point and then rejoin the motorway at the same junction - 124. So if you try to prevent that by putting the shaping point closer to junction 124 - it will simply stay on the motorway and come off at Jn 124, visit the point and then go back on the motorway.

So you think aha - and place the shaping point on the A road - roughly equal distance from two motorway exits 123 and 124 - then there is a pretty good chance that the XT will come off at one of the junctions visit the point and then go back to the motorway at the same junction. The lure of the faster road seems to be quite strong.

So a better strategy is two use 2 shaping points. Split the A road into 3 equal parts. Put a shaping point at each point. It has to visit the shaping points in turn, but now it is much harder for it to make the motorway a better option. It would have to come off at Jn 123, visit the first point, go back to Jn 123 up the motorway to Jn 124, off to visit the 2nd shaping point an then back to Jn 124. Much. much longer. It doesn't always work but it stands a better chance then the other two, and it is much better than adding a lot of shaping points - which are a real headache if a road is closed or there is an accident or a massive queue.

You have to look at the proximity of 'faster roads' - if there aren't any, then you might not need shaping points at all.


Things that don't help: Turning "Allow U turns" off. It just makes the XT go quiet for longer periods until it can find a road to take you back.
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guiri
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Re: Weird Routing Behaviour (2)

Post by guiri »

Some more info from today.

I had created the route in MRA with both via points and shaping points, and exported with 1.1. In the Trip Planner, the shaping points were blue dots as expected. I had Recalculation set to automatic.

My final two waypoints in the route were both via points; a coffee stop on a side street (waypoint 15), and then my home (waypoint 16).

I had a via point at waypoint 10, and had stopped for a coffee. On setting off from there, I selected Closest Entry Point for the route.

On getting close to waypoint 15, I decided to hit the skip symbol (which I am displaying on the map view), but weirdly it offered me to skip waypoint 10 from where I had set off (even though the time to waypoint 15 was being displayed correctly as the next one). I didn't go down the side street, but carried on along the main road. After skipping waypoint 11, 12, 13 and 14, the sat nav still didn't want to get back on route (it seemed to want to take me back somewhere). I pulled over, restarted the navigation and then selected Select Next Destination with my final waypoint 16 (expecting this to take me straight home).

I got notification about a traffic problem, which I ignored because the XT wanted me to stay on the motorway (a much longer and overall slower route). That ties in with the comment that the XT "doesn't find the fastest route. It finds a route which uses faster roads". At this point there were no more shaping points before my final via point. I carried on with my ride, with the Garmin insisting on trying to turn me back towards the motorway (until I exited the navigation).

I'm happy following a track (that's how I use Open Street Map offroad on my trail bike), but I thought I could use the Garmin with some via points (for essential coffee stops with a time countdown to the waypoint) and some shaping points to choose the roads.

Not sure if these are all manifestations of the same fault related to a Trip with both via and shaping points, or different issues that I just happened to experience on my first ride!
jfheath
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Re: Weird Routing Behaviour (2)

Post by jfheath »

Thank you for that detail. It ties in with other things that I have observed once. I have my notes, but haven't seen the same behaviour again. It will be useful to compare your sequence with mine.

What I do remember was that mine showed a very early route point that I had visited, but it was still in the route as being the next point to.skip.
The navigation was still taking me ahead though.

You are using MRA ? Do you have the gold version ? Are you using HERE maps ?
Have owned Zumo 550, 660 == Now have Zumo XT2, XT, 595, 590, Headache
Use Basecamp (mainly), MyRouteApp (sometimes)

Links: Zumo 590/5 & BC . . . Zumo XT & BC