For belt 4WD, does anyone ever use a different spec motor, ESC, or even different settings when adding a drivetrain to the other end of the board?
Also, is it possible for one end to push or pull more than the other? Couldn’t you regulate with pulleys to get close? A front/back torque asymmetry should be ok or dare I say… possibly desirable to have more watts put to the ground in the back? Let’s say you can’t perfectly sync speed, but you get pretty close. Wouldn’t a minor speed difference just translate to disproportionate rolling resistance? (assuming all rpm limits are setup in a way that’s deemed save)
Nuther question:
Can one go sensorless and maybe use cheaper ESCs on one set? Wouldn’t the FOC torque on ramp up get the ball rolling and the sensorless BLDC kick in a bit later?
I know a lot of you normies are gonna be like “Get two Unities, connect via can bus, and drive 4 x TB6374/190kv and use sensored FOC.” Maybe you have to do it this way. I’m just wondering what oddities you’ve seen.
Yes it is. And if your motor specs/gearing are way off, then you could he generating a lot of back-emf on the slower drivetrain, which would translate into braking force (and possibly cook your ESC)
Uh. Maybe? Depends on how close you can get it. If you are gonna try this, I would recommend actually measuring the kv of each motor, rather than trusting the manufacturer numbers.
Yes yes and yes. Push different amounts of amps all you want. Its volts and kv and gearing thats going to fuck you on this lol.
Yeah probably. I would be interested to see this actually. The cogging unsensored motors might try to fight the sensored motors. Maybe increase the positive ramping time for the unsensored ones so that they dont kick on until the sensored ones get you rolling?
I’m going to think this over after seeing what y’all have to say and post my proposed configuration if you don’t talk me out of it. I’m sure there are scenarios that might work better than others. I have a lot of spare parts, but no perfect set of four ESCs & motors. I can design/print pretty sweet pulleys tho. I think I can get that ratio within 1%. I may have some mismatched motors (6354 / 6374) with the same KV rating.
Risk mitigation:
Safe to say running these on two different battery packs may reduce the risk of something like this? PPM signal mapping gonna be important? Maybe disable braking on the smaller pair? What other obvious risks need to be accounted for?
I’ve run one sensored and one unsensored — and one unsensored and one HFI — a lot. It works fine.
I’m not sure about this. It shouldn’t be any different than a rider with a different weight. The ESC is controlling current, not speed. They should work together just fine.
Although mismatches on the left and right side can cause torquesteer and instabilities related to that. But generally I really don’t think it’s a big deal.
Isn’t the objective of a wizard to simplify configuration? Maybe advise the user on optimal pulley size(s) for the supplied motors. Additional inputs such as weight is relevant. Also maybe the mix of -Amps for braking would be part of the formula. The objective is to let them use their stuff… or maybe advise they shouldn’t. I don’t think the use case is that radical.
To clear this up. Motor size difference wasn’t by design. These were what I had on hand to make the board run. Just did Gibraltar Road run with @RipTideSports In Santa Barbara, Ca last Sunday. 7mile +2000’ incline on this setup.
As for sensored motors, our stuff is non sensored. They cog on take off but still launch like no other. The guy on the left, SRB rider Mario Chacon. 2nd on takeoff was AWD sensored 12kw.
