Hoist motor suggestions?

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ProgramThyself

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Can anyone recommend a BLDC motor and gears for a personal hoist application? I use it for wheelchair transfers and it needs to pull about 200 lb. Speed is not so important. Low noise and compact are desirable. Now I'm using this GRIN motor with a VESC controller which is maybe overkill and runs rough. On the plus side, it has voice control via Raspberry Pi / picovoice. That keeps the hands free to help transfer.

Attached pix are incomplete, but the motor winds a rope on the rim and the rope passes through some pulleys, also allowing lateral motion. More details here.

Edit: The GRIN motor has a lot going for it (high torque of 100 Nm at 30A, strong build, nice mounting HW) and the roughness may actually be due to controller issues. Nevertheless, brushless drill drivers can make 50 Nm of torque or more in a comparatively tiny package. Here is a teardown video that shows internals and highlights the risk of stripped gears.
 

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Does it need to be BLDC? The whole setup seems to be overkill tbh, DC (brushed) with a worm drive would be cheap and readily available and have the advantage of self-braking. Are there other criteria that led to using a BLDC? Also, is it a mobile application? AC with variable frequency drive would be the conventional route for something along those lines if stationary but I'm guessing you need DC.
 
I chose BLDC for torque control, which translates to force control at a connected shoulder harness. It's like a helper grabbing me under the arms and lifting to give a boost. Torque control allows finding a good strength and makes the system more nimble than speed or on/off control would. It's not mobile, but useful enough that I've setup two (bed and bath). I'm thinking of putting up one or two more and want a smoother-running motor.
Other solutions involve a full-body harness to carry all of the body weight in a more mechanized way. This would be more complicated to use without an assistant.
 
Would worm drive give the wrong kind of lift, torque control might work ok going up but immovable at rest and probably just fixed speed going down, no springyness? Sounds interesting, I doubt anything like that is commercially available because safety, it's not a path manufacturers would think of taking but it's not all that hard to make safe, something like the centrifugal clutches in seatbelts would work.

Can you get parts engineered? A smaller diameter pully attached to the cassette splines or brake disk mounting would probably be enough but it might need a carrier bearing if it's more than a couple of inches wide. Chain reduction probably wouldn't be noisy and would be simple to source, still needs some kind of pulley though. Block and tackle would be the simplest route, plenty of boat parts available and could be very compact with dyneema line.

You've got the VESC dialed in well? I'm guessing the roughness is just because the motor is mostly at near zero speed but there have been a few posts on tweaking VESC's for hub motors lately.
 
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Chain reduction and dyneema line are interesting. It's true that the VESC may not be perfectly dialed in yet. Thank you for the good suggestions.
Worm drive would certainly have a different behavior but I haven't tried. Experiments are hard and this is not funded research. Controlled torque/force seems the most human-like, and so I built it.
I sometimes design parts for CNC machining or laser cutting, but I'm not a mechanical engineer by training. Custom adapter plates are okay but I try to keep it simple and use off the shelf parts if possible.
Block and tackle probably takes more space than I want.
This link has a picture and video of a bedroom setup.
Project Hercules (lifting shoulder harness)
It's running in a slow speed (fixed duty cycle) mode there, just for positioning. But on the way down there are audible knocking noises. Up is quieter. For actual use I would put one belt under each shoulder and say keywords to activate torque mode which pulls faster, more aggressively and noisily. The shelf brackets are attached to wood studs in a condo building so this probably travels to other floors.
 
I'd be wary of using a drill, I've used the motors and gearboxes a few times for other jobs and they're not quiet! They're also not great when it comes to heat dissipation, they've got a lot shorter duty cycle than you'd expect when they're reving and the fan is drawing air through them but I wouldn't be surprised they overheated in less than 30 seconds under medium load in stall or near stall conditions.

That's definitely a big plus with the motor you're using, it'll put out masses of torque at very low speeds without overheating. The only problem I see is gearing, if the motor was spinning faster it would be a lot smoother and quieter and after seeing your setup I'd definitively use pulley blocks to achieve it. 3mm dyneema cord has a breaking strain of 1.4 tons, you could go down to 1mm and still be well within safe limits but getting pulley blocks that small with a high enough load rating wouldn't be easy, it's tricky enough at 3mm but there are some triple row ones on amazon for less than $10 that come very close. Good quality triple pulley ones (I doubt those on amazon have bearings fit for daily use) for 3mm line shouldn't be much over an inch square. Tangling might be a concern, mostly they're used for boat rigging and resist it well, guided housings, close tolerances, ballrace swivels etc. Dyneema isn't necessary btw, 6 rows (triple pulleys) would have a breaking strain of over 8 tons! Decent braided 3mm cord would be more than adequate, stuff for boat rigging would be ideal but it's is usually way overpriced, much cheaper sources available but quality can be variable.

Dyneema could come in if you can get gearing or a smaller puller attached, single row 3mm would allow for a very narrow pulley, something that would fit in place of the cassette. It wouldn't be a big job for any machine shop, gut a cassette to get the splines and press and weld it into a turned bit of bar, hopefully not too pricey. 3d printing could possibly work but it's a very risky "possibly". Thin cord causes a concentrated load and successive turns concentrate it even more, aluminium can't cope with those kind of loads sometimes and I wouldn't be surprised if even a solid regular quality 3d print popped like a cork as the layers split. Wedges may work, printed segments for the drum so the layers are going the right way with big steel washers either end drilled for some decent sized through bolts... might work but I wouldn't like to be the test hamster.
 
lnanek said:
There's off the shelf solutions out there, aren't there:
auxx-lift.com

Overhead Garage Storage Lift Systems - Motorized | Auxx-Lift

Maximize your space with our motorized storage lift systems. Auxx-Lift's range of overhead storage solutions brings efficiency and organization to your garage.
auxx-lift.com auxx-lift.com
Click to expand...
That one is cool. Our ceiling is not for load-bearing which adds another wrinkle. Hence the shelf construction. Still, a smaller drum like in the video would help.
 
I've narrowed the noise problem down to gear backlash that occurs near zero load.

With constant drive duty cycle, the motor goes back and forth between speeding up and slowing down the geared wheel, which has its own inertia and experiences a very small external speed-up force due to gravity. The resulting back-and-forth gear backlash is rather loud.

Maybe a ramped duty cycle/speed can help…
 
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