Minipro intermittently LIFE-THREATENING unsafe, veering right

[Rider222]

I've seen [only] one old thread kind of discussing this, without satisfaction, so thought I would start up a new thread, as I can't be the only one with this safety issue.

Bought my white Mini-pro brand new about 6 months ago off Amazon.  Actually bought two, the black Mini-pro isn't showing any signs of problems.

After the first couple weeks of running the one in question, on dirt/gravel road of being 100% stable, while driving straight, the Minipro made a quick right turn (veering right) throwing me forward off, twisting me (right), landing on my back, banging my head, knocking me out for who knows how long.  Took me several weeks to recoup.  I immediately bought a bike helmet and never road again without the bike helmet.  To this day, I don't know what caused that event.

Very stable riding since then.

Except, about a month later, while riding straight on a city sidewalk, feeling the vibrations connecting each sidewalk slab, and being completely stable at all times, the Minipro instantly veered right, throwing me off forward again, this time I caught myself and landed on my feet.  The Minipro shooting across 6 lanes of  heavy commute traffic, before coming to rest, on the other side embankment. Luckily nobody was killed, and no accidents as cars were slamming brakes, swerving everywhere.

Upon internet researching and found that one other forum thread, I took the whole thing apart and reseated all connectors, and, checked everything including traces and solder joints with a magnifying glass, could see no issues anywhere, every thing looks good.  Yes, the steering magnets are secured, and all screws tight.   And, yes, I've updated the firmware/software, and factory reset everything multiple times, and, I'm an experienced hardware/software techie, and, not stupid.  I re-assembled everything and all looks good, and rides extremely stable nearly 100% of the time.

I've ridden it very slowly for many hours, and twice I "felt" hints of it wanting to dart to the right after hitting slight bumps.

I currently have this Minipro in pieces, and will keep it for spare parts, but can no longer trust it.  Maybe once I eventually swap out all the pieces I can track down the errant part, but other than spare parts I don't the interest to try to figure this out, and, how could I ever be certain?  The intermittent problem could be life threatening, is so rarely random, it just is not repeatable.

I'm not asking for anybodies help.

I'm asking to see if YOU have experienced this exact intermittent and extremely unsafe issue.  And, if this issue is solely with the Ninebot Mini-pro only.

 

Edited February 25, 2019 by Rider222

[jojo33]

Hello @Rider1289 at my beginning i had this issue but for me it was my fault, I had stupidly removed and put the pad back.
Normally everything must be disassembled and reassembled properly, the pads have several notches
There was no more precise contact between the joystick and the circular iron plate under the pad
I think the joystick under the pad is your problem, maybe it's defective, compare a joystick photo with yours,

Check both motor wheels, do they have the same logo, serial numbers, are they identical?

Edited March 25, 2022 by jojo33

[Rider222]

I appreciate the reply and will of course look into it, but this doesn't "feel" right to me as being the problem.  I often practice riding on just one foot, and then the other foot, so I know what exactly "normal" feels like.  I'm basically an expert at riding on/off road (forward and backwards) so I know normal.   Doesn't make sense to me that the foot sensors would cause an emergency/immediate 90deg veering to the right.  As you can imagine, a random unplanned 90deg turn while cruising straight 10mph can only end up in disaster.   Worse part is at such an abrupt turn while going fast, your body gets spun around so when you get thrown off forward, your body is spun backwards, so it's nearly impossible to land on your feet.  My opinion, is when hitting a "bump" and when the rare malfunction occurs, that it gets a fake sensor glitch input to make a quick veer right, and then to continue go straight (Minipro doesn't continue spinning right)  If I continue to try to trouble shoot, I would probably first switch the wheel motors, and then the foot sensors, but would be very surprised if this makes any difference.  My guess is there is an intermittent direction control sensor circuit problem, which seems to probably be triggered by a very rare physical bump/vibration.  I've tried to purposely trigger problem by random vibrations, bumps, etc, and it rarely can be triggered (I've never been able to purposely trigger it), and is extremely intermittent.  What make this so scary since there is no way that I could ever be certain that it got fixed.  Also, I want to make it absolutely clear that it has never veered left; only right.  Also, for additional info battery level is irrelevant.

[68bugboy]

I had the exact same problem. It was intermittent and only happened when hitting

a bump or crack in a sidewalk. It would just full turn hard to the right.

It turned out to be a cold solder joint on the circuit board for the hall sensor.

Re-soldering the pins on that board cured the problem.

That is where I would check.

Hope you find it.

[trevmar]

I also was thrown by a small 1" pebble on a dirt track, miniPRO veered to the right, caught my left foot under it. No broken bones, just an ankle which took a month before I could walk on it again, and several months to heal fully.

I have been wearing a helmet since day 1, after once coming off a motorcycle on bitumen at 35mph speed (where the helmet no doubt saved my life).

I am convinced this is a firmware problem, as resoldering the hall sensor and careful reassembly had already been done before I was hurt. We have a 1" high gutter at the end of our driveway which had also occasionally been giving the same problem since we first bought the miniPROs. All 4 of my miniPROs fail in the same way at that obstacle, except that my weight (90Kg) and my wife's weight (50Kg) make the difference between a unit working nearly all the time, and not navigating the bump at all... I think a firmware limit is running awry, maybe a stray CPU interrupt, or something similar.

I have had no further trouble since I reached the 50Km "boost" mileage on the miniPROs, changing to soft tyres, and soft handlebars. I had been carelessly resetting the mileage without realizing that the firmware does different things once you have driven 50Km :(  I made a set of PVC-tubing handlebars (see my avatar) which help to decouple my control-inputs quite a lot (soften the ride). Additionally, soft tyres made a huge difference. I ended up with the Knobblies on two units and 85/65-6.5  'off-road' on the other two (discussed in another topic).

[Rider222]

The solder joints look perfect.  I'm very good at electronics, and have much experience with lead tracing, board inspections, etc.   My concern is even if I re-solder, I just can't trust my life on that one, since I can't be certain problem got fixed.  If I can't actually trace down the problem, then I can't consider it fixed.  My gut feeling is there is problem of a glitch with the steering sensor circuit.  I may eventually replace that whole circuit and try again. Also I've taken it apart so many times, I've broken a connector pin off the main board to the tail light assembly; that's when I gave up and decided I had enough and  I was done with that unit.  Unfortunately this problem is what I would call a life or death, worst case type of issue (having your body mass twisted around then ejected forward at 10mph).  The black Minipro I ride daily ever since, never showed any signs of safety problems.  I just got a brand new white Minipro yesterday and road for 4 hours yesterday and so far that one feels solid/safe, no problems but obviously I'm gun-shy and will be constantly keeping an eye on ANYTHING that feels odd.  The black Minipro is the one my wife uses and I feel that one is stable so will continue to let her to only use that one for now.  And my wife has also confirmed that she has never felt any odd issues.  I've told my wife to tell me if when ANYTHING feels odd, no matter how small.  The errant white Minipro every now and then, would have a "hint" of oddity; an occasional hint/feeling at jumping right especially going over sidewalk bumps/off-roading.  I would ask myself did I just feel an oddity, or, was it trying to correct/overcorrecting/slip, and would just be unsure.  But that time that it did a complete unsafe right veer at 10mph ejecting me  (per my description in above previous post) I knew 100% for certain that something was wrong.

[Zephyrzone]

This is a very timely thread.

I bought a factory refurbished Mini-Pro (first mistake) last month. Much like you @Rider222, occasionally I’d detect something odd in the ride but figured it was just me. Also, my mini makes a very subtle whining noise when powered on- not sure if that’s normal or not?

Anyway, I’ve put many miles on my mini using it for commuting to and from the train station. Just today, I was going slowly- maybe 5mph, thank God- down a declining sidewalk, when I rode over a very minor bump and the mini just shot off to the right. It was terrifying...

I thought I must have accidentally hit the knee bar, so I got back on.

A few meters later, exactly the same thing happened a second time. Then, once I was too scared to ride it and decided to “trolley” it, it did the same thing a third time. I have no idea what’s going on, but I can no longer trust it, which really sucks.

[Rider222]

What Zephyrzone is describing, is exactly how I would describe the issue.  The difference, in my case, the issue was extremely intermittant, making it impossible for me to repeat/track down.  In YOUR case, the problem is showing itself much more repeatable, so you might actually have a chance to locate the problem.  It's a very eerie and gut wrenching feeling to have this otherwise stable unit, randomly veer out from under you.  You can't ride what you can't trust.

 

[mrelwood]

Scary reading about this issue! I’ve ridden my MiniPro for about 200km, most of it on extremely uneven and shaky packed snow surfaces (with the off-road tires at 0.6-0.8 bars). No issues, other than the darn thing trying to slow me down the second I start to move.

I only started wearing a helmet when there were dry snowless patches for me to go faster. But unlike when unicycling, I haven’t worn supports or pads on my wrists, elbows and knees. I think I will now that I read about this issue!

[Rider222]

Please wear helmets. I guarantee you will NEVER have an accident; that is, until you do. 

I will never again ride any segway without a helmet.

A good analogy to give you to relate concerning this veering issue:   If you are driving your car down a road, or freeway, and instantly your steering wheel (and all controls) randomly disconnect, and your car makes an abrupt hard right turn...  Very scary. 

[trevmar]

Scary, but very common in Interrupt-driven firmware designs. I have my driveway bump which allows repeatability, and it is definitely not a limitation of the platform, but an overload warning the software calculates which is incorrect... I am keen to get my hands on a copy of MRN76 & Alex's hacked firmware. Which may well no longer have the problem, if we are lucky (it may be in the 'pushback' or 'battery saver' code somewhere)

[Rider222]

I certainly kept wondering at first if the veering problem was caused by an edge case, sensor/algorithm issue, but as it only happened with that one Minipro unit (so far), and have not yet experienced with either of my other two Minipro's; I'm pretty sure that one errant Minipro was (or became) defective.  I'm hyper sensitive to the issue, so if I ever feel that again (or any oddity no matter how small) I will not ignore it.  I'm not talking of course about normal/odd algorithm concerning wheel slippage on unstable sand, or rocks.

[68bugboy]

I still think it is a hardware issue.

Has to be something to do with the hall sensor.

[trevmar]

All our miniPRO (4 of them) fail in the same way at this ledge, but the heavier the rider the worse the problem.

But here is the main reason why I believe it is a firmware issue: When we put knobbly tyres on the miniPRO the problem goes away, it can negotiate the 3cm ledge with knobblies, but not with the stock tyres. Yet the load on the miniPRO motors is higher due to the larger radius of the knobblies, so we are not dealing with a motor-strength issue.. When I put the 85/65-6.5 (soft) tyres on the miniPRO the problem largely disappears, but it still fails occasionally. It may be something to do with impact sensors, but I suspect timing is the culprit. Two unexpected signals are hitting the CPU at once, and it has not been programmed to cope with that occurrence.

I have been programming microcomputer firmware since the 2650, 6805 and 8048, and have seen this type of intermittent failure happen many times before.

Edited March 1, 2019 by trevmar

[SegwayMiniPro]

On 2/25/2019 at 8:43 AM, Rider222 said:

I've seen [only] one old thread kind of discussing this, without satisfaction, so thought I would start up a new thread, as I can't be the only one with this safety issue.

Bought my white Mini-pro brand new about 6 months ago off Amazon.  Actually bought two, the black Mini-pro isn't showing any signs of problems.

After the first couple weeks of running the one in question, on dirt/gravel road of being 100% stable, while driving straight, the Minipro made a quick right turn (veering right) throwing me forward off, twisting me (right), landing on my back, banging my head, knocking me out for who knows how long.  Took me several weeks to recoup.  I immediately bought a bike helmet and never road again without the bike helmet.  To this day, I don't know what caused that event.

Very stable riding since then.

Except, about a month later, while riding straight on a city sidewalk, feeling the vibrations connecting each sidewalk slab, and being completely stable at all times, the Minipro instantly veered right, throwing me off forward again, this time I caught myself and landed on my feet.  The Minipro shooting across 6 lanes of  heavy commute traffic, before coming to rest, on the other side embankment. 

 

I had the oringinal Ninebot Mini before my Segway and this happened to me. No bumps or cracks, cruising at 8-10 mph all of a sudden it just swerved right and I hit the ground hard. Couldn’t understand what happened as the sidewalk was level and nothing was loose. I was also going in a straight line. 

It didn’t ever happen again either. It had about 100 miles on it and another 300 after the incident. I have well over 1500 miles on my minipro and it has never once swerved. I believe it can be either hardware or software or a combination of the two that causes this. 

Now if your minipro is prone to this, it has to be hardware related. The swerving is very sudden and unstoppable and if these minipro s were prone to this they would be out of business.

Edited March 1, 2019 by SegwayMiniPro

[trevmar]

1 hour ago, SegwayMiniPro said:

 The swerving is very sudden and unstoppable and if these minipro s were prone to this they would be out of business.

Did you note that in the MiniPRO specifications that they say the maximum obstacle height is 2cm. Yet it must easily take larger tree roots, and has to be able to recover from larger bumps without throwing the rider. I assume Segway know that this swerving is a real problem that they can't fix, and anybody who complains is just pointed at the legal disclaimer saying that hitting a 2cm bump is riding it beyond its capabilities.

By the way. Is the original design team still available to Segway/Ninebot to debug the problem? I heard that the original firmware writers had left the company. Indeed, at one point there was a rumor that the primary firmware developer was a high school student who had written all the key stuff in his holidays. That story is in line with my experience as to how these breakthrough products tend to come together...

[SegwayMiniPro]

2 hours ago, trevmar said:

Did you note that in the MiniPRO specifications that they say the maximum obstacle height is 2cm. Yet it must easily take larger tree roots, and has to be able to recover from larger bumps without throwing the rider. I assume Segway know that this swerving is a real problem that they can't fix, and anybody who complains is just pointed at the legal disclaimer saying that hitting a 2cm bump is riding it beyond its capabilities.

By the way. Is the original design team still available to Segway/Ninebot to debug the problem? I heard that the original firmware writers had left the company. Indeed, at one point there was a rumor that the primary firmware developer was a high school student who had written all the key stuff in his holidays. That story is in line with my experience as to how these breakthrough products tend to come together...

Not sure what you are trying to say, but like I said if you read the whole post it was a level even sidewalk.

[Rider222]

I'm glad other people are locating this thread, and discussing this issue.  The first time the veering happened to me (per my OP above), I was going full speed straight on my hard dirt/gravel driveway.  Something I had done hundreds of times previous to this accident, and many hundred times since.  I had never even came close to losing control at any other time. Sure, off-roading, you always feel a bit of highly controllable slippage, corrections, etc.  But from going to 99.999% of the time feeling safe being in complete control, to 0.001% of the time to absolute complete uncontrollable veering right fighting for your life, is a very strange and scary concept if you've never experienced it.  The first time you say "what the hell just happened".  The second time you say "that was not an accident and I'm not getting back on that crazy thing!"  You feel that somebody else just took control of the unit and is trying to kill you!

[SegwayMiniPro]

1 hour ago, Rider222 said:

I'm glad other people are locating this thread, and discussing this issue.  The first time the veering happened to me (per my OP above), I was going full speed straight on my hard dirt/gravel driveway.  Something I had done hundreds of times previous to this accident, and many hundred times since.  I had never even came close to losing control at any other time. Sure, off-roading, you always feel a bit of highly controllable slippage, corrections, etc.  But from going to 99.999% of the time feeling safe being in complete control, to 0.001% of the time to absolute complete uncontrollable veering right fighting for your life, is a very strange and scary concept if you've never experienced it.  The first time you say "what the hell just happened".  The second time you say "that was not an accident and I'm not getting back on that crazy thing!"  You feel that somebody else just took control of the unit and is trying to kill you!

It seems very uncommon ... but like I said it happened to me once and seriously threw me off and I hit the ground hard. It happened out of nowhere. And never happened again. 

[trevmar]

Uncommon? It happens on all four of my family's miniPROs,  better than one out of 4 times when we run over the ledge at the end of our driveway. I consider that 'replication', and certainly not 'uncommon'. The miniPRO takes larger obstacles OK, and smaller ones, but this particular size (and/or shape)  it doesn't like... There is an identical road-edge at the inlet to our local park. It threw me there, too. And the 1" pebble on the well-groomed dirt pathway (in the park) twisted my ankle for several months. I couldn't walk for a month. No, this is a very common problem. I only hope that the MRN76/Angel firmware modifications make it go away...

[Zephyrzone]

13 hours ago, trevmar said:

Uncommon? It happens on all four of my family's miniPROs,  better than one out of 4 times when we run over the ledge at the end of our driveway. I consider that 'replication', and certainly not 'uncommon'. The miniPRO takes larger obstacles OK, and smaller ones, but this particular size (and/or shape)  it doesn't like... There is an identical road-edge at the inlet to our local park. It threw me there, too. And the 1" pebble on the well-groomed dirt pathway (in the park) twisted my ankle for several months. I couldn't walk for a month. No, this is a very common problem. I only hope that the MRN76/Angel firmware modifications make it go away...

What is the MRN/Angel firmware and how does one get and install it? I sent a message to Swallbot (Alexy?) asking to purchase their mod but haven’t heard back. Also, I’m not so sure I actually want to speed the thing up now after this sudden swerving thing. I can’t imagine a sudden veer-off at 15mph. I was going a third that speed and almost landed in the ER. 

Both of my sudden veers (henceforth known as SV’s) happened on the same day within minutes of each other. I was on a sidewalk, cautiously moving forward and rolled up and over a “dip”- I wouldn’t really call it a bump, it was like an undulation in the sidewalk. The second SV was also on an undulation- a smaller one. There’s no way the Segway shouldn’t be able to handle those, they’re not acute and pretty natural sidewalk irregularities. After the second SV, the MiniPro was turning in clockwise (right side) circles even after I hopped off and was using the trolly handle to pull it straight on even ground. 

I emailed Ninebot and they were responsive but didn’t really seem to know the root cause. The service rep suggested that I go through a recalibration process that involves a few steps and actually flipping the unit upside down to do it. I haven’t heard of this before and am really hoping it works, I have a difficult time trusting this thing now and that may end up being a dealbreaker if it happens again. That would be a shame because I love this thing for navigating around San Francisco. 

[SegwayMiniPro]

21 hours ago, trevmar said:

Uncommon? It happens on all four of my family's miniPROs,  better than one out of 4 times when we run over the ledge at the end of our driveway. I consider that 'replication', and certainly not 'uncommon'. The miniPRO takes larger obstacles OK, and smaller ones, but this particular size (and/or shape)  it doesn't like... There is an identical road-edge at the inlet to our local park. It threw me there, too. And the 1" pebble on the well-groomed dirt pathway (in the park) twisted my ankle for several months. I couldn't walk for a month. No, this is a very common problem. I only hope that the MRN76/Angel firmware modifications make it go away...

If it happens to all of them maybe it’s your riding style or lack thereof.

[SegwayMiniPro]

On 3/2/2019 at 7:42 PM, Zephyrzone said:

What is the MRN/Angel firmware and how does one get and install it? I sent a message to Swallbot (Alexy?) asking to purchase their mod but haven’t heard back. Also, I’m not so sure I actually want to speed the thing up now after this sudden swerving thing. I can’t imagine a sudden veer-off at 15mph. I was going a third that speed and almost landed in the ER. 

Both of my sudden veers (henceforth known as SV’s) happened on the same day within minutes of each other. I was on a sidewalk, cautiously moving forward and rolled up and over a “dip”- I wouldn’t really call it a bump, it was like an undulation in the sidewalk. The second SV was also on an undulation- a smaller one. There’s no way the Segway shouldn’t be able to handle those, they’re not acute and pretty natural sidewalk irregularities. After the second SV, the MiniPro was turning in clockwise (right side) circles even after I hopped off and was using the trolly handle to pull it straight on even ground. 

I emailed Ninebot and they were responsive but didn’t really seem to know the root cause. The service rep suggested that I go through a recalibration process that involves a few steps and actually flipping the unit upside down to do it. I haven’t heard of this before and am really hoping it works, I have a difficult time trusting this thing now and that may end up being a dealbreaker if it happens again. That would be a shame because I love this thing for navigating around San Francisco. 

How many miles do you have on your device?

[Zephyrzone]

On 3/5/2019 at 5:22 AM, SegwayMiniPro said:

How many miles do you have on your device?

About 40.

I let the unit sit for a few days and tried it again. Worked for a few meters then shot off to the right. Tire pressure is good, knee bar is tight and centered. I did the upside down calibration 4 times and as well as the software, sensor calibration. Now the unit spins to the right immediately after I turn it on, about half the time.

It’s thrown me off twice, I was lucky not to get hurt.

Ninebot customer service asked me to get a video and upload the black box data, which I did a couple of days ago. Supposedly the data is being reviewed by the engineering team now and I should hear back by the end of the week.

-edited to specify “right”

Edited March 10, 2019 by Zephyrzone

[trevmar]

I have been suggesting the veering right has all the hallmarks of a rogue CPU interrupt, but I was programming a DC-removal-digital-filter last night and it struck me that the firmware processing the miniPRO accelerometer data may overload at the precise ledge where this problem occurs, and that numeric overflow may be causing the veering (the accelerometer data has to have gravity filtered out of the miniPRO-induced accelerometer fluctuations). Further, any difference in the impact (for example, when we changed tyres) would mitigate the potential for overload. It will be interesting to take a closer look at the problem when the Russian Hack firmware is eventually delivered to us all. If momentary overflow is indeed the cause, I would expect the failure to be not changed much in the hacked firmware... One way or another we need to get this loss-of-control fixed..