Highly modified Ninebot Mini Pro / S-Plus hybrid with 16" wheels

[xaveus]

Hi EUC community,  I'm building an ambitious custom PEV based on Ninebot-Mini donor units.  It's an off-roader with 16" wheels and ladder-frame chassis (Ducati Monster style), I'm using Ninebot's electrical components but all the PCBs are being relocated to fit around the suspension and hydraulics. Target weight is to be same as the Ninebot S-Plus.  I have a ton of questions and a ridiculous deadline to get it built before a family holiday on 9th August - I can only walk a few feet, so need this PEV for mobility.

Question 1: is there a gyro or accelerometer on the S-Plus main-board?  (posted a photo below). I need to find the balance sensor(s) so I can relocate the large 'board but put the sensors back in the location between the axles, I'd do this by unsoldering them and extending wires from the relocated components back to the (now vertically-mounted) main-board.

Question2: what do the footpad sensors do? I'm not going to use remote control feature, so can I wire the footpad sensors to make them permanently 'on' ?

Question 3: There is a small PCB and a tiny 'sensor' glued into the front, inner wall of the magnesium housing (it's covered in white sealant), I think this is a load cell or strain-gauge for detecting if there's too much weight on the Ninebot (it increases electrical resistance when the magnesium is flexed), someone on the forum referred to it as a 'gravity sensor' but I can't find anything outside of CERN labs that can measure gravity.  If it is a load-cell, can it be disabled by just leaving it disconnected (it would have zero electrical resistance), or would the 5v input (the red wire?) have to be connected directly to black (ground) to send a zero resistance (no weight, not flexing) signal?

I will post photos of the build once the major components are assembled, but I need to find answers to these three questions before I can finalise the location of the brackets and 3d printed casings.

https://prnt.sc/tsomhb   s-plus 'board - is there a gyro here?

https://prnt.sc/tsonad  strain gauge or gravity detector? (yes, the three hair-thin wires are removed).

[mrelwood]

On 8/2/2020 at 4:22 PM, xaveus said:

I'm building an ambitious custom PEV based on Ninebot-Mini donor units.  It's an off-roader with 16" wheels

Interesting project! I was going to make something similar from two EUCs, but so far the seated Airwheel A3 serves me well enough for the rare cases where an EUC is not suitable.

 Be sure to consider that the torque of a wheel will be greatly reduced, and the ride softness (chassis tilting forward during acceleration etc) is increased due to the larger tire size. The Mini is not a very powerful vehicle, so there isn’t much torque to spare.

On 8/2/2020 at 4:22 PM, xaveus said:

Question 1: is there a gyro or accelerometer on the S-Plus main-board?

Usually a MEMS chip that measures directional information is on board, yes.

On 8/2/2020 at 4:22 PM, xaveus said:

I'd do this by unsoldering them and extending wires from the relocated components back to the (now vertically-mounted) main-board.

I think the chip may have enough pins to make this not a viable solution. Besides, communication with the processor may require a short and noiseless connection. I would definitely remake the plan to support using the original board as a whole, in a horizontal position.

On 8/2/2020 at 4:22 PM, xaveus said:

Question2: what do the footpad sensors do?

They determine whether the rider is on board. If not, balancing is slow and motors only get a small amount of power and speed. Unfortunately the Mini can’t be powered on if the sensors sense weight on the pedals. You will have to put the sensors under a seat (if you plan on including one), or behind a ride mode switch.

 

On 8/2/2020 at 4:22 PM, xaveus said:

Question 3: There is a small PCB and a tiny 'sensor' glued into the front, inner wall of the magnesium housing (it's covered in white sealant)

It’s a lightness sensor that is used to control the headlight. You can leave it out.

 

On 8/2/2020 at 4:22 PM, xaveus said:

I can't find anything outside of CERN labs that can measure gravity.

The mentioned MEMS sensor can measure acceleration and also have a compass, and the data could be used to calculate gravity with a sufficient precision.

[xaveus]

Thanks for the detailed reply, very useful info.

I took a week off the project, but now with the new knowledge and fresh perspective, I can see what needs sorting.

Just bought a 3D printer which will enable me to make brackets and casings for the ‘tronics.

The battery pack is going to need reconfiguring to keep the weight of the cells balanced fore and aft of the CofG and allow the standard motherboard to be aligned as it was originally.