kbalage

[VIDEO REVIEW] 42131 CAT D11T Bulldozer + Control+ profile test

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Very informative video - the basic setup does seem quite unusual. I've been wondering about the position encoding. Given that it's a four function gearbox, does the L motor controlling the selected function have four separate stored positions?

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5 minutes ago, Bartybum said:

Very informative video - the basic setup does seem quite unusual. I've been wondering about the position encoding. Given that it's a four function gearbox, does the L motor controlling the selected function have four separate stored positions?

It's very similar to the gearbox of 42114. There's a physical endpoint and the gearbox have 4 positions for the 4 functions, you can see it in action here.

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7 hours ago, kbalage said:

It's very similar to the gearbox of 42114. There's a physical endpoint and the gearbox have 4 positions for the 4 functions, you can see it in action here.

Sorry no, I meant the motor that controls the activated function, not the motor that controls the gearbox.

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I can say that I have controled my Lego 1% or less that the time I spent building it so for me all those advances are irrelevant but I do not know how many people usually play, I have to admit that it is cool but I still won´t pay for something I will not use, maybe the best part of the entire dozer.

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7 hours ago, Bartybum said:

Sorry no, I meant the motor that controls the activated function, not the motor that controls the gearbox.

You mean once it is calibrated, how it stores the endpoints for the different functions? That is an interesting question. Theoretically it can save the endpoints corresponding to each function and the last used position, so anytime it returns to a function it knows what the position is relative to the endpoints. I wonder how reliable it will be after a few dozen of switches.

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16 hours ago, Bartybum said:

Very informative video - the basic setup does seem quite unusual. I've been wondering about the position encoding. Given that it's a four function gearbox, does the L motor controlling the selected function have four separate stored positions?

Current delta and range of motion for each function should be stored in the C+ App, respectively in a file - like in the volvo.

That's one of the disadvantages of the PU-App compared to C+. Since you have no permanent but dynamic variable in PU, you have to define a 'parking position' or calibrate each time if you want to keep track of the real position.

Edit:

Filename of the Volvo is:  Hauler_stats.json

Edited by Gimmick

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55 minutes ago, kbalage said:

I wonder how reliable it will be after a few dozen of switches.

I'd imagine given that the LAs use worm gear actuation, you'd probably need to get quite a few full rotations of mismatch before it makes any meaningful difference.

But yeah @Gimmick that makes sense that it'd be stored in the app, not sure why I didn't think of that lol

Edited by Bartybum

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18 minutes ago, Bartybum said:

I'd imagine given that the LAs use worm gear actuation, you'd probably need to get quite a few full rotations of mismatch before it makes any meaningful difference.

If nothing stresses the LAs then theoretically the difference should not be significant even after a long time. But as my tests showed with the Liebherr and some custom code, if the LAs are under load (heavy lifting) then the calibration can get off very quickly. This might explain why the set is designed to avoid potential impacts, e.g. the ripper not touching the ground, as that could affect the calibration. 

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@kbalage The Liebherr lifts itself up in the calibration :D

For me, they thought a bit too much about scratches on the floor, but atleast that's something, that can be changed easily, even if someone wants to keep using C+. 

Someone posted a video about driving the real CAT under your review. The virtual 360° topview reminded me of the programming interface in the C+ App :D

Edited by Gimmick
Buged posting

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27 minutes ago, kbalage said:

If nothing stresses the LAs then theoretically the difference should not be significant even after a long time. But as my tests showed with the Liebherr and some custom code, if the LAs are under load (heavy lifting) then the calibration can get off very quickly. This might explain why the set is designed to avoid potential impacts, e.g. the ripper not touching the ground, as that could affect the calibration. 

Yeah, given that the functions for the CAT are generally done under minimal load (except for the ladder), I would expect that there's not much worry for going out of calibration.

I wonder what causes the encoders to skip? I assume it's generally something seen with encoded motors

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@Gimmick here is the function switching sequence. The motor driving the function does the shaking, meanwhile the gear selector rotates by ~45 degrees, then the shaking stops and the position according to the function is selected on the gearbox. A lot of extra stuff going on for safety before that actual gearbox switch :) 

 

 

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7 minutes ago, kbalage said:

here is the function switching sequence. The motor driving the function does the shaking, meanwhile the gear selector rotates by ~45 degrees, then the shaking stops and the position according to the function is selected on the gearbox. A lot of extra stuff going on for safety before that actual gearbox switch :) 

Seems like a very unusual thing to do. I would've thought that there'd be some conditional statements in the control profile, ensuring that the gearbox takes priority whatever function is being driven.

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42 minutes ago, Bartybum said:

Seems like a very unusual thing to do. I would've thought that there'd be some conditional statements in the control profile, ensuring that the gearbox takes priority whatever function is being driven.

Problem might be that the driveline is still undres stress, which would make the switching much harder under such load. This procedure makes sure that any pretension in the driveline is reduced before switching.

An analog is trying to pop a manual gearbox out of gear while accelerating hard. I'ts possible, but it takes much more effort than when it's not loaded.

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Hmm, that's a weird solution.. Not sure I understand what the 45 dergee rotation does, and why it's done at the same time as the shaking. And why the 45 rotation is undone before switching again..

16 minutes ago, Zerobricks said:

Problem might be that the driveline is still undres stress

Just to understand the problem clearly, is it that the driving ring could be tightly engaged with the clutch gear, and it would be hard to move the driving ring out of the clutch gear? In that case the 45 degree rotation happening in the beginning does not make sense to me. Or do you mean other parts of the driveline, such as tension around the LAs?

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2 minutes ago, gyenesvi said:

Hmm, that's a weird solution.. Not sure I understand what the 45 dergee rotation does, and why it's done at the same time as the shaking. And why the 45 rotation is undone before switching again..

Just to understand the problem clearly, is it that the driving ring could be tightly engaged with the clutch gear, and it would be hard to move the driving ring out of the clutch gear? In that case the 45 degree rotation happening in the beginning does not make sense to me. Or do you mean other parts of the driveline, such as tension around the LAs?

Driveline could be winded up in case the last function reached its limit.

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@gyenesvi the 45 degree rotation helps to move the driving rings to an intermediate position meanwhile the shaking happens. All this helps to avoid tension building up in the gearbox before actually switching it to a new position. I'll demonstrate it in a video soon. 

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@kbalage Thx =)

I might be wrong, but it looks like in the first test the driving motor turns in the same direction as you turned it with the last command. I do not think that this would help to release any tension that has been build up :D The shaking myabe does. Looks funny either way x)

I'm still almost ~some% sure that such effort is not neccessary and it only needs a very small backwards rotation of the drive motor to disengage the driving ring enough for a smooth gear switch. But on the other hand: You have the model and a PU Profile -> Fullpower in the actuator limit -> release power -> switch ^^. I will try this with the hauler later, iirc the motor was not strong enough to make the actuators 'slip'.

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@Gimmick I'm doing the tests right now and the shaking seems to make sense in certain scenarios :) The hauler is different, as it had a single function where it was moving the actuators and unless you pushed the bed against something there wasn't much resistance. Here you can push the blade below "surface level" with both functions operating it so there can be potentially a much higher load on the driven axle. 

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4 hours ago, Gimmick said:

I'm still almost ~some% sure that such effort is not neccessary and it only needs a very small backwards rotation of the drive motor to disengage the driving ring enough for a smooth gear switch.

This is what I thought too.

@kbalage, are you planning to test it with the PU app too? It would be nice to see what happens if you implement manual switching, without releasing the tension. And the same thing with the slight backwards rotation before the switch.

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8 minutes ago, gyenesvi said:

 

@kbalage, are you planning to test it with the PU app too? It would be nice to see what happens if you implement manual switching, without releasing the tension. And the same thing with the slight backwards rotation before the switch.

If there is tension in the system then the orange wave selector might not be able to move all DBG drive rings. Simple backwards rotation might be not be enough as the situation might happen and both ends or the movement range, so it's either slight backward or forward rotation. If we do both, then we get the Control+ profile's shaking as a result :) Of course you might cut half a second here and there in the PU app, but I assume the folks at TLG did some testing to see how much shaking is required to avoid most of the jams.

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2 hours ago, kbalage said:

slight backward or forward rotation

I meant backwards relative to the last direction of the motor (I guess @Gimmick meant the same), that should release the tension in all cases. Seems easy to test a few cases manually.

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@kbalage With "backwards" we obviously meant the opposite direction :tongue:

After a bit of testing it seems like the clamping happens between the white driving ring connector and the driving ring and not between the gear and the driving ring as I thought. That's unfortunate :laugh: because you cannot apply an opposite force on the ring. But I'm still a bit skeptical if the wiggle realy helps. But since my first assumption was wrong anyway... :

Pushing the bed against the actuator limit works perfectly fine for simulation :D

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On 9/10/2021 at 7:07 AM, M_longer said:

Way too pricey for functions you get. For same price 42100 offered 7 functions with separate motors for each of them.

Best thing to do if you want to have a decent Dozer is buying 42100 and rebuilding it:
 

 

I hope you will be blessing us with more of your amazing B models using the 42131 set :classic:

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15 hours ago, Gimmick said:

@kbalage With "backwards" we obviously meant the opposite direction :tongue:

After a bit of testing it seems like the clamping happens between the white driving ring connector and the driving ring and not between the gear and the driving ring as I thought. That's unfortunate :laugh: because you cannot apply an opposite force on the ring. But I'm still a bit skeptical if the wiggle realy helps. But since my first assumption was wrong anyway... :

Yes I understood what you mean thank you :grin:

In the case of the CAT the tension seems to be between the red gear and the driving ring, as the driving ring can become stuck in the gear and the orange wave selector slides out of the driving ring. Simply reversing the output for a second might help, but there are cases when it is not enough. I did a few tests and apparently the slight rotation of the orange wave selector and the wiggly movement together is definitely more effective then a simple short opposite movement of the output. A video will come this afternoon.

16 hours ago, gyenesvi said:

I meant backwards relative to the last direction of the motor (I guess @Gimmick meant the same), that should release the tension in all cases. Seems easy to test a few cases manually.

Since we are talking about Powered Up, how would the system know in all cases what was the previous direction to drive it the opposite way? :) Btw as I tested, this simple opposite movement does not remove the tension in all cases. In some cases it helps, but apparently the movement performed by the Control+ app is more effective.

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@kbalage I tried some manual gears from other sets, too. They bascially all stuck if there is some load on the system, it's just not recognizeable that much if you switch by hand. Are you realy sure about the stuck gears? I switched the direction for testing and since there was a delay between the motor and gear rotation I assumed, that the red gear is not stuck but the driving ring is. And the wave selector turns a bit to give the driving ring some space to move.

Maybe it's both x) But the conclusion is clear: We need new and better driving rings/connectors :D

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