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Reversing MiniPro Steering sensor


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Thanks;)

 

So.. no way at now to have a full working mini pro for 25kph lights included...:unsure:

 

Well, just get the notice by a mini clone retailer called i-Walk that their forthcoming new version will be 550w each motor and 28kphB)

Due I don't like clones. .. will wait to see if will be possible to mount that motors and motherboard on my 2 miniProB)

I strongly doubt that Ninebot will ever comes out with a same dimensions and weight BUT faster machine. .....:crying: due they have other aims and targets in Security and Certifications. ..:innocent1:

Edited by zugu
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13 hours ago, Ozpeter said:

 

Impressive work.  We clearly have some expert members here!

That's for sureB):clap3::whistling:

Anyway,  Imho, the best thing in order to have a full working mini with lights and all as normal,  would be to intercept the speed limit written in the firmware for the forward direction and remove it rewriting that piece of shit. ...:laughbounce2::thumbup:

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On ‎07‎/‎06‎/‎2017 at 8:26 PM, FreeRide said:

Step Nine: reevaluate sensor bias significance.  In Progress

I did a few basic tests of the steering on a smooth surface rather then carpet and there is a offset still in the lag between left and right as one direction require more of an offset of the control arm to activate any motion.  This indicates to me that although the output of the sensor for the center position was not enough to cause the minipro to turn on it's own it was enough to affect the dead zone for the steering.  This would have affected the steering of the device when the surface was tilted as keeping the device going straight when have been more complicated and sensitive to which side was tilted.  This may be the answer, but certainly needs to be resolved first before other experiments.  The main problem here may have been having to bust the magnet out of its epoxy which distorted the housing and chipped the magnet.  Back to the lab for a day or two.

 

I appreciate you trying this out and all, but to be fair you just did a very long winded and dragged out version of what we already did weeks ago and what we explained in this very thread in much more to-the-point posts - ie. reverse the magnet polarities and discover that the steering doesn't work properly as the unit steers to one side all the time.

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@donaldduck8 I am amazed at what you have created.  I congratulate you on your technical skill and creativity.  This is amazing work.  Thank you for sharing it with us and for posting the circuit diagram and photos of the circuit.  Just amazing!

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On ‎17‎/‎06‎/‎2017 at 2:11 PM, zugu said:

I'm almost sure that next official firmware release will have the check of the speed either in reverse. ...:pooping: :innocent1:

I agree.  Thanks to this forum, Segway are probably aware of the 25kph reverse speed and it won't be long before they fix it in a firmware update.  Having said that, in my experience dealing with their technical support, they don't know much about the product and they talk some major BS. 

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hi Guys,
I have still found an interesting thing.

I originally assumed that the offset was programmed in the Factory, and the values are fixed
After the magnets with me were turned around, I had to file the mounting holes of the Hall sensor board for the adjustment.
Also other people have their problems with the maladjusted offset.

Now I have figured out how to calibrate the offset without mechanical intervention.
1. Turn the Ninebot on the back
2. Press the on / off switch - wait until both wheels turn alternately left and right - switch off
3. Turn around and smile - Ninebot no longer turns left or right - calibration completed

I could not believe how easy it was. :)
Anyone who does not believe, this can simply perform the procedure with dejustated (slightly angled) steering wheel, and see what happens then.

Greeting Donald

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2 hours ago, donaldduck8 said:

hi Guys,
I have still found an interesting thing.

I originally assumed that the offset was programmed in the Factory, and the values are fixed
After the magnets with me were turned around, I had to file the mounting holes of the Hall sensor board for the adjustment.
Also other people have their problems with the maladjusted offset.

Now I have figured out how to calibrate the offset without mechanical intervention.
1. Turn the Ninebot on the back
2. Press the on / off switch - wait until both wheels turn alternately left and right - switch off
3. Turn around and smile - Ninebot no longer turns left or right - calibration completed

I could not believe how easy it was. :)
Anyone who does not believe, this can simply perform the procedure with dejustated (slightly angled) steering wheel, and see what happens then.

Greeting Donald

I just tried it and you are right!  It enters a mode in which the lights flash red, then it calibrates the steering.  Dude, you are a legend!  I am going to try the magnet reversal again and then calibrate the steering and see if it is rideable that way in reverse.

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@donaldduck8 I did the magnet reversal, put everything back together and followed your instructions.  The lights flashed red in a sequence of 1 flash, then 8 flashes. It repeated this several times but the wheels did not move. The Minipro still always turns to the left.

 

EDIT: Ok I figured out that this will not work if pressure is applied to the foot pads when it's upside down. I tried it again making sure nothing was touching the pads and it worked!

Edited by RooMiniPro
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WARNING

I just got back from a test ride and discovered a very serious problem.  I would urge no one to try this mod from here on.  First of all, although the steering is straight now, it still does not behave correctly.  It is too sensitive at high speed and when travelling straight but along a lateral decline, such as at the edge of a road where it declines down to the gutter, the MiniPro tries to correct and keep straight (as it did before the mod) but now steers in the opposite direction than it should, doing the oppsite of what is needed to correct for the angle of the road. 

But what's even more dangerous is that when you hit the top speed tilt-back is now reversed to be tilt-forward.  I was riding along and when I got close to 25kph, suddenly the MiniPro tilted me forward and I almost fell off.  Quickly I was able to lean back (despite my toes being pushed closer to the ground) and slow down, at which point the tilt-forward stopped and it leveled out again.

It has been a fun and educational experience doing all this, but I will no longer pursue this riding backwards method.  The machine just cannot do it.

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@RooMiniPro

Really thanks so much for your tests

So, no way to use this walkaround .... better find a way to remove the 18kph limit in forward direction from the firmware if only someone will be able to "crack" this...:whistling:

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11 minutes ago, Ozpeter said:

Might be worth putting that warning in the first post or title, just in case...  I'm glad there was no blood on the road!

A shame the project has hit the buffers after all that hard work.

I would but I can't edit the first post.  There must be a time limit for how long a post can be edited.

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16 hours ago, RooMiniPro said:

But what's even more dangerous is that when you hit the top speed tilt-back is now reversed to be tilt-forward.  I was riding along and when I got close to 25kph, suddenly the MiniPro tilted me forward and I almost fell off.  Quickly I was able to lean back (despite my toes being pushed closer to the ground) and slow down, at which point the tilt-forward stopped and it leveled out again.

I am deeply frightened by this dangerous behavior.
Thank God, nothing bad happened to you.
I apologize to you for putting you in danger

If I had known this before, I would have stayed out of all things.
I do not want to be damaged by my contributions to people.

In my own tests I did not notice this dangerous behavior, because I always finished just before 25Kph the test.

A thoughtful Donald :(

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On 6/23/2017 at 3:37 AM, RooMiniPro said:

I would but I can't edit the first post.  There must be a time limit for how long a post can be edited.

The time limit was changed recently. Don't remember the actual times, but I think normal users are allowed to edit their posts only a couple of days after posting. I edited the first post to contain your warning.

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On ‎23‎/‎06‎/‎2017 at 9:46 AM, donaldduck8 said:

I am deeply frightened by this dangerous behavior.
Thank God, nothing bad happened to you.
I apologize to you for putting you in danger

If I had known this before, I would have stayed out of all things.
I do not want to be damaged by my contributions to people.

In my own tests I did not notice this dangerous behavior, because I always finished just before 25Kph the test.

A thoughtful Donald :(

No need for apologies, Donald.  Anything I do with these modifications is at my own risk.  The same should go for anyone else brave enough to experiment with such mods.  I too never went beyond 25kph in my previous tests and never rode on laterally slanted roads either, and so I thought it was all good apart from the

always turning left' issue.  When you figured out the steering calibration trick I thought we had this solved.  But it is extremely dangerous.  To be fair, some of this is Segway's error.  Fresh from the factory with no modification, the unit does 25-27kph in reverse and when hitting that speed limit tiltback tilts back instead of forward like it should.  It should not do that.  Now, granted, it's very unlikely that anyone will ever ride the unit backwards at that speed because the steering makes it too dangerous by default.  But I am just amazed that they let this slip through testing unnoticed. 

On ‎24‎/‎06‎/‎2017 at 6:03 AM, esaj said:

The time limit was changed recently. Don't remember the actual times, but I think normal users are allowed to edit their posts only a couple of days after posting. I edited the first post to contain your warning.

Thanks so much, that's really helpful!

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On 22.06.2017 at 7:35 PM, donaldduck8 said:

hi Guys,
I have still found an interesting thing.

I originally assumed that the offset was programmed in the Factory, and the values are fixed
After the magnets with me were turned around, I had to file the mounting holes of the Hall sensor board for the adjustment.
Also other people have their problems with the maladjusted offset.

Now I have figured out how to calibrate the offset without mechanical intervention.
1. Turn the Ninebot on the back
2. Press the on / off switch - wait until both wheels turn alternately left and right - switch off
3. Turn around and smile - Ninebot no longer turns left or right - calibration completed

I could not believe how easy it was. :)
Anyone who does not believe, this can simply perform the procedure with dejustated (slightly angled) steering wheel, and see what happens then.

Greeting Donald

Hello.
After you know this information, will your circuit board change?

Diagram1.thumb.jpg.76b3a22702e3a7f5f74fe9cfc13bc336.jpg

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With this knowledge, two components (Poti 4.7KR and resistor 180KR) could be omitted.
The two 22Kr resistors are connected.
The positive input of the OP is permanently UB / 2 = 2.5V

Disadvantage:
The steering must always be calibrated after switching from normal to reverse and vice versa.
Who does not need the switch, can do so.

Advantage of this circuit:
No mechanical intervention in the steering sensor
Gain (steering sensitivity) from 1 to 0.5 Adjustable (1 = Hard 0.5 = soft)

Warning:
But the main problem remains. At maximum speed no tilt-back occurs but a tilt-forward.
The MiniPro is then difficult to control, an accident threatens.

 

Donald

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17 hours ago, donaldduck8 said:

With this knowledge, two components (Poti 4.7KR and resistor 180KR) could be omitted.
The two 22Kr resistors are connected.
The positive input of the OP is permanently UB / 2 = 2.5V

I will be very grateful if you create a new scheme taking into account these changes. :efeeec645d:

17 hours ago, donaldduck8 said:

Warning:
But the main problem remains. At maximum speed no tilt-back occurs but a tilt-forward.
The MiniPro is then difficult to control, an accident threatens.

Thanks for the warning I'll be careful as possible.

 

Please answer one more question.

Why does the board have a component to adjust the sensitivity of the steering?

1.jpg.6a9f190f54d9d60c55d009598b2d4374.jpg

2.jpg.9c082d90dffa605e8eedbc90b17a9cd7.jpg

If I'm not mistaken the adjustment of the steering sensitivity is available in the appendix.(Automatic adjust steering sensitivity)

Edited by xJlaIIax
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8 hours ago, xJlaIIax said:

I will be very grateful if you create a new scheme taking into account these changes. :efeeec645d:

 

LENKSE1.thumb.jpg.23c43a80cd467576ab3581fc9a63f817.jpg

 

8 hours ago, xJlaIIax said:

Please answer one more question.

Why does the board have a component to adjust the sensitivity of the steering?

 

8 hours ago, xJlaIIax said:

If I'm not mistaken the adjustment of the steering sensitivity is available in the appendix.(Automatic adjust steering sensitivity)

Because that is not enough when you drive backwards.
I have the automatic steering sensitivity off and the sensitivity set to minimum.
The steering at high speeds was still too strong.

If the gain setting is not desired, the potentiometer can be omitted (bridged).
For gain = 1 the resistance 10KR is to be increased to 22KR.

 

 

Donald

 

 

Edited by donaldduck8
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Donald, Why are you in the scheme removed the switch between the normal mode and reverse?

If I understand correctly, after each switching (normal and reverse) it will be necessary to repeat the calibration:

On 22.06.2017 at 7:35 PM, donaldduck8 said:

Now I have figured out how to calibrate the offset without mechanical intervention.
1. Turn the Ninebot on the back
2. Press the on / off switch - wait until both wheels turn alternately left and right - switch off
3. Turn around and smile - Ninebot no longer turns left or right - calibration completed

Can I make a switch like this?

4.thumb.jpg.22297c6db8c25233c8d14c2585c82794.jpg

Edited by xJlaIIax
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4 hours ago, xJlaIIax said:

Donald, Why are you in the scheme removed the switch between the normal mode and reverse?

This switch only makes sense with the offset calibration (4.7KR Poti) at the first circuit.

 After each switching (normal and reverse) you dont repeat the calibration.

Take a look at my video from 17 june

 

4 hours ago, xJlaIIax said:

If I understand correctly, after each switching (normal and reverse) it will be necessary to repeat the calibration:

On 22.6.2017 at 6:35 PM, donaldduck8 said:

Now I have figured out how to calibrate the offset without mechanical intervention.
1. Turn the Ninebot on the back
2. Press the on / off switch - wait until both wheels turn alternately left and right - switch off
3. Turn around and smile - Ninebot no longer turns left or right - calibration completed

Yes, with your circuit.

 

4 hours ago, xJlaIIax said:

Can I make a switch like this?

Yes, but this circuit must be recalibrated every time after switching.

 

 

Donald

Edited by donaldduck8
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