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# How to develop electronic differential for articulated rear drive e-trike using the steering angle in Matlab/Simulink? Answered

one wheel at the front and two wheels at the rear,steering mechanism

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As most things today you can actually calculate the speed difference for the wheels.
Each turns at a given and different angle resulting in a different radius.
The circumfence of this radius together with the wheel diameter gives you the speed for each wheel.
Put that into a nice table, let's call it table A.
Next use a sensor and measure the corresponding steering wheel angle for the points you used before.
Map this into table B.
Consider the different motor load while cornering and use that for compensation, maybe in table C.
Last table would be your set speed from the handle or lever.
Table B is used to assing the values from table A and the result is linked to table C to get the correct max speed.

Migt be easier with a mechanical diff and torsio sensors but then again you would not need that with a mechanical diff ;)

The speed difference you want is a difference in frequency from the encoders on the wheels, which is directly proportional to wheel angle. You could probably adjust the gain on that difference with a pot somewhere until it feels right.

Thank you. I need to model an electronic differential using Matlab/Simulink by tracking the steering angle. So which steering mechanism can I use for this e-trike to calculate the difference in rear wheel speed while cornering.

If you use ordinary PMDC motors, and wire them in series, you get a differential action for free.

From your minimum turning radius, wheel angle and vehicle track, calculate the worse case Delta V between the wheels - the straight line case, the wheels are at the same speed:easy. I think the relationship is then simply linear.

Tricky. Are these BLDC or conventional motors ?

1. No need for a diff on a bike. simple drive a single wheel.

2. The only way I could see you doing this unless you have excellent electronics development skills (and you have asked the question so I suppose not) is to use a microprocessor which is going to need programming/

3. Your going to have to find or devise sensors to measure the inputs and transducors to effect the output.

4. It will add considerable weight and be complicated to what advantage?

Thank you for your answer. But it is a articulated-frame 3 wheeler. So how should I calculate the difference in rear wheel speed while cornering with respect to the steering angle.