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trevmar

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Everything posted by trevmar

  1. 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).
  2. @ir_fuelI am currently milling microwave circuits on Rogers 5880 microwave laminate, which is PTFE-based and only 7mil (.2mm) thick. At millimeter-microwave frequencies I can use nothing else (20mil FR4 stops working at about 20GHz). I haven't been able to find a Chinese (or local) PC house interested in making me prototypes. Most of them do not have the microwave substrate available, let alone the paper-thickness boards.. @esaj Yes, I center the origin on the double sided artwork, and then drill four perimeter holes equidistant just off the edge of the board. Then I only have to worry about reversing the artwork for the back. I found it helps if you drill via holes (etc) before flipping, as then you can instantly see if you are cutting the backside in the wrong places. I use 0.8mm copper rivets for the through-hole vias
  3. Esaj, I have been using (and tuning) my 2418 for over a year now. Yet there were still things you covered that I had missed (Z axis accuracy/step size, for example). This is an absolutely brilliant tutorial, and I am looking forward to the double-sided tips and tricks, too. When I get my new 52mm low-runout spindle-motor-mod finished I will make sure I post that here.
  4. Yes, I changed the resistors but saw no difference because it is the firmware controlling the speed and load. I am waiting for Alexandre's modified firmware to fix the problem I have with small obstacles (1" gutters, pebbles, pinecones). Meanwhile I did buy a set of tyres from China which is soft and works out well. Ninebot.run sells them too, I believe. I paid $24 each for mine, but I see them advertised at half that now. It is the 85/65-6.5 off-road vacuum tire" like the ones from this seller: https://www.ebay.com/itm/332852828998 They are very wide, hard to squeeze onto rims, but I have been very happy with the way they handle obstacles. Almost the same as the knobblies, but a much lighter tire with no noise or vibration on bitumen. They have soft bouncy walls, rather than the stiff walls of the Ninebot OEM tires. I am heavy, like you, and the Ninebot was designed for riders less than 85Kg. Have you read the blog written by a member of the design team? They give a lot of info about the design philosophy. Google translate it from here: http://bbs.ninebot.cn/forum.php?mod=viewthread&tid=4100&extra=page%3D1%26filter%3Dtypeid%26typeid%3D43 1/23
  5. With the knobblies, there is a resonance on a bitumen road once the tire starts acting like the balloon it should be. Actually, there is always a resonance, but high pressure shifts it up above the riding speeds you normally use. Thus the "roughness" depends on both pressure and speed. In fact, you can use the "rough feeling" or "vibration" to ensure that the knobblies are properly inflated if you ride. Lower pressures mean "vibration" at a lower speed. Interesting that the MiniPRO doesn't seem to be bothered as much as the rider by this (relatively) high frequency "vibration".
  6. Handlebars off-road can be quite dangerous if you rely too much on them to steady you. The MiniPro is not designed to be firmly anchored in space by a heavy weight (a rider firmly holding handlebars), nor is a rider able to trust the minor and major motions a miniPRO transfers to a handlebar when it hits an obstacle (eg a 1" gutter). If you look at my avatar you can see that I made my own soft-handlebars out of plastic pipe. They give a reference-in-space, enough to assist rider balance, but yet compliant ('bendy') enough to absorb the shocks when hitting pine cones, etc. They are also light enough to balance upright without needing a stand.
  7. In dry off-road conditions I use 10-15psi for those tyres. Have gone as low as 6psi without separation.
  8. I use a phone with my MiniPROs that does not have 2G/3G/4G installed so that it is not easy for the Segway app to automatically update, or do anything else to my machines I connect that phone via Ethernet (Android 6+ works via a USB ethernet dongle for data). I never connect the phone to the Internet and to a MiniPRO at the same time. If your Swallowbot app needs online data could you please ensure that it takes data from all Android sources: cell, WiFi and Ethernet Thanks
  9. It isn't any special time of the year to have a sale, so I was surprised to see that Amazon has the MiniPRO for $420 today. This price is for the "US 2018" model with the smaller 4300maH battery, "ships from and sold by Amazon.com"
  10. Oh no! I am sorry to hear that! I fell off my own Minipro several months ago and it twisted my ankle badly by running over me!. But the good news is that the ankle has healed slowly but perfectly! So be encouraged that the body has amazing healing powers! I and my family are so grateful for what you have done for this community, and for us in particular, we will keep you in our prayers this New Year. Looking forward to meeting you when we next travel to Moscow!
  11. I was thinking the same "Thank You Ninebot" last night, as my wife and I cruised our MiniPROs around our district to see all the Christmas light displays which homeowners have put up. We still have a few neighborhoods to tour this evening... A Merry Christmas to all, even if its a bit early for our friends in Russia (Incidentally, those holiday lights and festivities in Moscow looked really nice)
  12. Great News! Just to clarify, you have posted earlier that you bought a new control board from @Ninebot.run yet you seem to be talking here about having sent your own original control board to Russia to have it programmed, and reporting that this approach was the one which worked.
  13. No, I disagree, from a design engineer's point of view you are simplifying the situation too much. The Ninebot design team wrote an excellent blog detailing the safety margins upon which the MiniPRO was built. You can find it with Google Translate in the Chrome Browser at http://bbs.ninebot.cn/forum.php?mod=viewthread&tid=4100&extra=page%3D1%26filter%3Dtypeid%26typeid%3D43 1/23 Truth is that the current firmware still has flaws which can, and do, result in the rider being thrown forward and run over. It happened to me. After reading the designer's blog I formed the opinion (as a design engineer) that many of the current speed and weight limitations were based on requirements by the various country's safety authorities, rather than on limitations of the platform. Additionally, when Ninebot was forced to used high-quality LG batteries by the hoverboard-fires scandal, the amount of power the motors had available was actually increased significantly (see my post on battery peak-power testing). This was never exploited to improve the carrying ability of the platform, and hence its safety margin. All firmware versions have the same balance capabilities, that is how they were designed. Finally, in answer to your question, the current being drawn, and rotational speeds of the motors are what the firmware uses to regulate the power it delivers.The current sensing resistors can be clearly seen at the top of the control board (R004 or R008 SMD power-resistors) If you want to explore this further, MRN76 has produced an app which allows any of the major Ninebot firmware revisions to be programmed into any MiniPRO, and the original firmware replaced after testing. Search here for "JTAG" to find my posts on implementing those changes. You can learn a heck of a lot about the device by looking at the progression of the designers' thought-processes as the device went to market, and was changed through to its current state (v1.4.1) Hope that helps...
  14. Nope. No news. Except for those few trusted dealers who were given a copy of the JTAG firmware, and are programming customers' units with that, none of the rest of us have gotten anything working. My excitement at the news of this potential breakthrough has faded...
  15. When you have ridden 50Km several limits are removed from maximum speed and maximum torque. That made a big difference for me...
  16. It was designed to keep lawyers and bureaucrats happy. Here is the chinese blog written by its design team. View it in Chrome, or run it through Google translate. It explains each of the steps of the designers. The executives, bureaucrats and lawyers then crippled it to provide the "safety margins" http://bbs.ninebot.cn/forum.php?mod=viewthread&tid=4100&extra=page%3D1%26filter%3Dtypeid%26typeid%3D43 1/23
  17. @ChriullFor me the speed increase is not important. Two other things make the MiniPRO critically unsafe 1. When you get to a point where the MiniPRO thinks you are pushing it too hard it slows down by pushing you backwards, which does result in me falling and crashing (turning off the track). It also beeps, but there is no way to tell it you are a responsible driver, and that beeping is all it needs to do (and 'please don't push me off'). This pushback occurs at varying speeds dependent on terrain, and on the streets around my home it occurs at 10-12Kph which is not much faster than a walking pace. It is very,very hard to keep your balance at these slow speeds when the pushback occurs. This is a safety problem, not a speed problem. Better to manually ride slow than get pushed off without warning, but the Ninebot firmware doesn't give you this choice. 2. As the battery empties the speed at which you can move is reduced by the controller firmware. The batteries can actually supply just as much current at low charge levels, yet the machine pushes me back at even lower speeds than the 10-12Kph mentioned above. I think this behavior allows Ninebot to use cheaper Lithium Ion cells than the LG cells they actually ended up using. My suspicion is that they were forced to drop the cheaper cells, for which this firmware was written, due to their propensity to catch fire. The Swallowbot software allows more of the LG battery to be used, if necessary, only slowing you down when the charge is almost gone (and charge has therefore become a safety issue). This forum is being used to share thoughts about these issues, and others, and is a HOT TOPIC because these are REAL PROBLEMS Does the Swallowbot software do what it is supposed to do? What about the Chinese firmware hack, does it work properly? These are the topics you will find in this forum, along with the "How do I get this to try on my MiniPRO" which is such a focus at this point in time.
  18. @Chriull Ah - I see the confusion now. There is no way this discussion has been an advertisement. It was started by a member alerting other members to the firmware 'Swallowbot.' There was much discussion before MRN76 joined in. In my opinion, MRN76 was very careful not to advertise his or Alexei's work. Recently MRN76 actually posted: " I do not know why this topic was created. I did not want to advertise it until the bluetooth application was made" Please allow us to continue formulate and test this major development. Push-back is so very unsafe when going up hills. When you are struggling up a slope, and pushback occurs at only 10Kph, it is very hard to avoid crashing. I myself could not walk on my left ankle for over a month after being thrown while going up a hill....
  19. Alex_from_NZ, I suspect it is all a big mistake - @Chriull not understanding the safety problems in the design of the Ninebot MiniPRO, and thinking that MRN76's motivation here was to sell something. I bet @Chriull doesn't even know MRN76 and Alexei have already produced a stream of totally free software to help those of us who are worried about the MiniPRO's safety. The discussion about those free programs was not curtailed, AFAIK. I think TPTB were attracted by the optics of Alexei wanting much-deserved recompense this time, which IMO is reasonable, considering the magnitude of what he has achieved. However, even a casual reader will note the discussion from our Taiwanese members about the Chinese attempts on TaoBao to work towards what Alexei and MTN76 have achieved. What is being done here is not so much related to 'firmware modification' as it is to 'solving a problem.' The discussions here have been technical and balanced. Hopefully the mistake will be corrected before it does too much more damage.
  20. *** YOU ARE SORRY???. Rubbish, you don't care about the hours I have spent participating in this thread, nor do you care about me losing contact with members who have only ever posted in this thread. You have made a decision that all this work will RETROSPECTIVELY disappear, without any warning to me, or the other participants. Please at least be honest with us...
  21. For the next 24hours the '2018 US Model' N3M260 MiniPRO (with the mini battery) is selling on Amazon for $335, including Prime shipping. https://www.amazon.com/Balancing-Transporter-10-5-Inch-Pneumatic-Customizable/dp/B0749956JC They obviously did not sell many at Black Friday's price of $479..
  22. An update, since I have been busy over the Thanksgiving holidays. I realized that one of the biggest problems I had with my CPU soldering was the surface coating Ninebot put over all components on the control board. Even though it had been dissolved by the methylene chloride, a semi-fluid residue (looking like water) was left around which my circuit board solvents were not removing. This stuff was interfering with the flux during soldering. All this only became visible when I used my binocular microscope, which I normally only use for really,really, small stuff. After two re-soldering of the Swallowbot CPU (and two more power MOSFETs, which blew each time I tried using the CPU) I decided it could have been damaged, and so I soldered a brand new STM32F103RCT6 CPU (STmicro, I usually buy them from from DigiKey to avoid the Chinese clones) onto the board. This time nothing misbehaved (by comparison with what I remember from previous experience with the MiniPROs, all the LEDs illuminated with an error code which beeped two long, nine short, error 29. I had this code once before when I had programmed the 1.1.7 firmware from a different MiniPRO into mine, and I knew it was a serial number mismatch (the Segway firmware is locked to a unique ID within each CPU chip). Darn - I had thought I had swapped in the new ID Anyway, MRN76 kindly sent me the specific patching instructions for the Binary files and I realized that I had thought the data would be little-Endian while it was actually literal. Oh well... After fixing Error 29 the MiniPRO rebooted to error 12, at which point I relaxed as I have fixed that one before (loose wires in the plug from the motor sensor). I will continue the debug after Thanksgiving, but am confident that I soldered the CPU in properly this time, using the Microscope on every lead, and am pretty confident everything will come back to life again from this point... And, on the plus side, those special Chinese Power-MOSFETs they use will be pretty neat for some of my other projects. I bought plenty of spares
  23. No. We were also taught how to design bridges, radars, etc Those were the days before microcomputers, when Engineers were just trained how to design stuff. Then came the microprocessor (late '70s) and everything changed... Getting back to pneumatic tyres, however, the job of the air is to act as a cushion, a balloon to absorb impact. The inflation of that balloon, and the rigidity of its 4-ply polymer walls (in the case of the INNOVA 90/65-6.5) is therefore important. A tyre is typically a key part of the resonant system involving machine/rider mass, and elasticity. Reducing inflation pressure, rather than building lighter tyres, does increase the resonance problem, it is much better to produce tyres specifically designed for the lighter loads it will be bearing. But in the case of miniPRO tyres we are repurposing tyres designed for pocket-bikes, lawnmowers etc. The stiff-wall-thin-web design approach taken by Ninebot was quite radical, since it departed from the 'balloon' concept in a quest (I assume) for perceived 'safety' and longer battery life.
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