RenaissanceMan Posted October 31, 2016 Share Posted October 31, 2016 I wonder, has anybody every tried to build a weight sensor into an EUC? That together with a weight-sensitive firmware should enable much more precise warnings related to all kinds of maneuvers and maybe even optimize the motor driver for best performance!? Or even just have the possibility to enter weight via the app and have the firmware work on that, maybe just in 3 classes light (<70kg), medium (70kg < W < 90kg), heavy (>90kg)? That should enable much better adjusted performance characteristics. Link to comment Share on other sites More sharing options...
Greg Spalding Posted October 31, 2016 Share Posted October 31, 2016 I can imagine if I were teetering on the edge of two different categories and rode my EUC and OVERATE... The performance deficit on my way home would be exaggerated Link to comment Share on other sites More sharing options...
RenaissanceMan Posted October 31, 2016 Author Share Posted October 31, 2016 45 minutes ago, RenaissanceMan said: I wonder, has anybody every tried to build a weight sensor into an EUC? That together with a weight-sensitive firmware should enable much more precise warnings related to all kinds of maneuvers and maybe even optimize the motor driver for best performance!? Or even just have the possibility to enter weight via the app and have the firmware work on that, maybe just in 3 classes light (<70kg), medium (70kg < W < 90kg), heavy (>90kg)? That should enable much better adjusted performance characteristics. @tinawong Hi Tina, thanks for making the KS16, I love that wheel (even if it has its quirks)! Has KingSong been thinking about weight-dependant motor control?! This should not be too difficult to build into your current firmware, should it? Link to comment Share on other sites More sharing options...
HEC Posted October 31, 2016 Share Posted October 31, 2016 While weight sensors are cheap and easy to implement in the (stationary) devices it would be a bit tricky in the moving device with dynamic forces being applied during the ride. And even if that problem would be addressed there is more factors to be taken in the consideration by the "smart" FW like the wind speed / resistance and so on. I do agree though that at least some weight category selectable via mobile app could improve some of the security options like speed limitation during depleted batteries and so on. I'd much more though prefer to have really smart FW which will be monitoring the consumption trends based on the speed and direction of the movement (in "3D" is the gyro sensors can also detect riding on the incline / decline) and based it's security features on that instead. That would involve a zero input from the user and will be much more safer. Necessary HW is already present in the EUC - waste majority of current models is capable of measuring the momentary voltage and current used and the only change needed might be different wiring of gyro chip. Link to comment Share on other sites More sharing options...
RenaissanceMan Posted October 31, 2016 Author Share Posted October 31, 2016 5 minutes ago, Greg Spalding said: I can imagine if I were teetering on the edge of two different categories and rode my EUC and OVERATE... The performance deficit on my way home would be exaggerated Indeed, it would , but you'd still have the chance to change your weight (class) at any stop, e.g. after having lunch . Link to comment Share on other sites More sharing options...
Greg Spalding Posted October 31, 2016 Share Posted October 31, 2016 Just now, RenaissanceMan said: Indeed, it would , but you'd still have the chance to change your weight (class) at any stop, e.g. after having lunch . As long as I was riding near a place which had adult diaper changing stations... Link to comment Share on other sites More sharing options...
RenaissanceMan Posted October 31, 2016 Author Share Posted October 31, 2016 18 minutes ago, HEC said: (1) While weight sensors are cheap and easy to implement in the (stationary) devices it would be a bit tricky in the moving device with dynamic forces being applied during the ride. (2) And even if that problem would be addressed there is more factors to be taken in the consideration by the "smart" FW like the wind speed / resistance and so on. (3) I do agree though that at least some weight category selectable via mobile app could improve some of the security options like speed limitation during depleted batteries and so on. (4) I'd much more though prefer to have really smart FW which will be monitoring the consumption trends based on the speed and direction of the movement (in "3D" is the gyro sensors can also detect riding on the incline / decline) and based it's security features on that instead. That would involve a zero input from the user and will be much more safer. (5) Necessary HW is already present in the EUC - waste majority of current models is capable of measuring the momentary voltage and current used and the only change needed might be different wiring of gyro chip. (1) Yes, agreed. However, you could have two different modes, "ride" and "weigh" and have the weigh mode on for only the first 100 ms after a halt. (2) Yes, but let's tackle one issue at a time, starting with adding weights to the equation. (3) (4) Again, that's further down the road and certainly desirable, but I think the weight factor alone could improve riding behavior a lot, since it is such an important parameter. (5) Perhaps there could even be a way to reverse calculate the rider's weight from measuring voltage drop, current and speed (on a flat surface). That woulld be a short "calibrating run", optionally activated via the app. Link to comment Share on other sites More sharing options...
Mono Posted October 31, 2016 Share Posted October 31, 2016 The Uniwheel has a detector to know whether a rider is present, but IIRC they don't use a weight sensor. Link to comment Share on other sites More sharing options...
Mono Posted October 31, 2016 Share Posted October 31, 2016 1 hour ago, RenaissanceMan said: Again, that's further down the road and certainly desirable, but I think the weight factor alone could improve riding behavior a lot, since it is such an important parameter. Is it really? Compare a 60kg rider on a 10% slope with a 120kg rider on a 5% slope, both at the same speed. The voltage and current and measurements will look similar. Now, is there really a relevant difference we ask from the wheel in both scenarios, such that weight needs to be factored in for how it drives? Other than the runaway situation (and maybe the max speed setting), I fail to see any specific example where knowing the weight would help to make the right decision by the controller, that is, knowing the weight would change the decision we would anyway ideally make based on load measurements. Do you have a striking example of it? Link to comment Share on other sites More sharing options...
zlymex Posted October 31, 2016 Share Posted October 31, 2016 4 hours ago, MoNo said: Is it really? Compare a 60kg rider on a 10% slope with a 120kg rider on a 5% slope, both at the same speed. The voltage and current and measurements will look similar. The current spikes may be larger for heavier rider. Because the road is not perfectly smooth, the rider is constantly adjusting the feet and put pressure on the pedals front/rear in order to keep balance, heavy rider will put more force on the pedals, thus the current change will be larger. This current spikes will reflect the torque, and a torque margin must be provided in order to stay below the speed-torque curve. This means a larger torque margin(and speed margin) for heavier rider. I've tested the similar situation myself, measure the current by installing a precision current sensor. Part A is my normal riding at speed of 20kph(orange curve) back and forth on a straight line. I'm 75kg. The blue curve is the current measured. Part B is the preparation of a 25kg backpack. It is very heavy that I have difficulty standing up with it on. Part C is a 100kg person(me and the backpack) riding, again back and forth on the same line at speed of 20. Now you can see that the current spikes of part C is larger than part A. Considering the total weight of part A is 96kg and part B is 121kg(my V3 is 21kg with expanded battery), the increase from A to B is 26%. If the rider is changing from 60kg to 120kg, the spikes will be much more. Link to comment Share on other sites More sharing options...
RenaissanceMan Posted October 31, 2016 Author Share Posted October 31, 2016 Accelerating a heavier rider requries more force and hence more energy than a lighter rider ceteris paribus. I think there must be an easy way to infer the weight or at least the relative weight of the rider from data collected during a short sprint starting from 0 km/h to say 10km/h and back to standstill on a flat surface. My basic idea is that the force of acceleration is dependent on the riders (plus EUCs) weight and at the same time is also a function of the energy spent (Ampere x Volt x seconds) by the wheel. Now equating the integrals of those terms over time (during a quick sprint) one should be able to derive a relative measure of weight of the rider, ceteris paribus. And that would be all that is needed to get the weight factor into the motor control equations. In fact, it seems so simple, I wonder if it hasn't been done already?! Maybe mathematically experienced members of this forum could please comment on this proposal? Link to comment Share on other sites More sharing options...
Mono Posted October 31, 2016 Share Posted October 31, 2016 1 hour ago, zlymex said: Now you can see that the current spikes of part C is larger than part A. Honestly, the difference seems rather small. We also don't know how much of the difference were due to not being used to ride with a backpack. 31 minutes ago, RenaissanceMan said: Accelerating a heavier rider requries more force and hence more energy than a lighter rider ceteris paribus Sure, but in any and all cases the wheel must try to keep upright and that is all there is to it. It can't be more relaxed about staying upright because the rider is light. It must stay up right whatever happens, if necessary with all it has to give. So I can see why weight is relevant to know the limits where this job becomes impossible to do, but I still don't see a reason why knowing the weight would be relevant to do this job, other than setting a different speed limit. 37 minutes ago, RenaissanceMan said: In fact, it seems so simple, I wonder if it hasn't been done already?! The simplest explanation is that it is not needed or not even useful. Link to comment Share on other sites More sharing options...
RenaissanceMan Posted October 31, 2016 Author Share Posted October 31, 2016 3 minutes ago, MoNo said: So I can see why weight is relevant to know the limits where this job becomes impossible to do, but I still don't see a reason why knowing the weight would be relevant to do this job, other than setting a different speed limit. And that should mean a lot for the rider: to know the safety speed limit at the actual, current circumstances, including battery level and weight. I'd even say, such variable and "personalized" safety speed limit could prevent many accidents - unless, of course, the rider chooses to ignore those warnings (but that cannot be helped anyway). Link to comment Share on other sites More sharing options...
volavoile Posted November 2, 2016 Share Posted November 2, 2016 I fully agree. I just make a topic on that before I read your's. speed limit HAS TO consider the weight. My experience? A broken shoulder with no alarm, so no time to slow down! Link to comment Share on other sites More sharing options...
Vik's Posted November 2, 2016 Share Posted November 2, 2016 On 31.10.2016 at 0:02 PM, MoNo said: The Uniwheel has a detector to know whether a rider is present, but IIRC they don't use a weight sensor. what Uniwheel? Link to comment Share on other sites More sharing options...
Mono Posted November 2, 2016 Share Posted November 2, 2016 http://forum.electricunicycle.org/forum/50-uniwheel Link to comment Share on other sites More sharing options...
Vik's Posted November 3, 2016 Share Posted November 3, 2016 11 hours ago, MoNo said: http://forum.electricunicycle.org/forum/50-uniwheel Ah, you mean vaporware! And if it existed, it could have some pressure-sensors... Link to comment Share on other sites More sharing options...
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