Belt Driven Industrial Robotic Concept

[Sicilian Engineer]

Hi All,

I'm looking for some advice on this robotic design I'm working on.

Mostly with the transmission. The motion of the system is as shown in my little vid below.

For reference the links are approx. 1.5m, and one can say there is a 600N point load in the centre of the horizontal link.

I want to mount the motors as proximally as possible (because they are quite big) so I need to figure out the optimal transmission to achieve this.

To me a cable driven system makes sense (high stiffness, no backlash (minimal I guess), great for systems with under 360 deg rotation). But for assembly it essentially isn't feasible with what we can use.

I think chain and sprocket are not usable due to backlash, lubrication, and repeatability concerns.

Which brings me to belts. I have never used a sync/timing belt for such a high torque application (base motors experience up to 700Nm) and essentially want to know if is feasible to use them, what to consider (double belts?, some non polyurethane advanced material (would prefer not to for cost)?, Multiple stages for further reduction? (speed is no issue)).

Also would it be insane to drive the first stage with a timing pulley fixed on the shaft AND have a timing pulley on a bearing on the same shaft, drive this with a separate motor and transfer from this shaft to the final stage?

Literally any help / thoughts /critique are welcome

can provide drawings to clarify any & everything

Thanks

 

[mfgenggear]

Here's a lead
Harmonic drives have three components, a wave generator, a flex spline, and a circular spline. These drives reduce the gears on a robotic system, ultimately saving you increased maintenance costs. For more information on harmonic drives, contact Robots.com experts today. Harmonic gears are a type of strain wave gear.

 

[XR250]

Maybe contact Gates. Some Harleys had belt drives and I imagine the torque was getting near that amount after the transmission gear reduction.

 

[Sicilian Engineer]

Here's a lead
Harmonic drives have three components, a wave generator, a flex spline, and a circular spline. These drives reduce the gears on a robotic system, ultimately saving you increased maintenance costs. For more information on harmonic drives, contact Robots.com experts today. Harmonic gears are a type of strain wave gear.

I can't afford harmonic drives unfortunately

 

[Sicilian Engineer]

Maybe contact Gates. Some Harleys had belt drives and I imagine the torque was getting near that amount after the transmission gear reduction.

Thanks for this I'll give it a go.

In the gates power design soft When I input my parameters it comes out with options (most with ridiculous pulley sizes or belt widths) but then gives me the "no products available" indicator which is somewhat worrying tbh.

 

[3DDave]

Check this:

 

[Sicilian Engineer]

Check this:

Thanks boss, I have actually seen this one but I'll take a closer look. I am somewhat worried about fabrication for something so complex (honestly even machining for the capstan looks non-trivial)

Either way if this has to be done it has to be done

Cheers

 

[dgeesaman]

Thanks for this I'll give it a go.

In the gates power design soft When I input my parameters it comes out with options (most with ridiculous pulley sizes or belt widths) but then gives me the "no products available" indicator which is somewhat worrying tbh.

I was going to suggest the Gates power design software, so I'm glad you're already trying it.

In my industry we use gearing or synchronous belts (Gates GT4, Contitech (Goodyear Eagle) herringbone). Our task is speed reduction / torque increase not robotic movement.

Gears are better for high torque. Belts only have so much torque capacity, at which point they need to get wider to achieve a linear increase in torque capacity. Also with gears you can do ratios higher than 5:1 but with synchronous belts it gets less practical and generally and stops at 6:1.

While it's true that Harley motorcycles use synchronous belts, they are large and the torque is not. If there was construction machinery that used synchronous belts instead of hydraulic levers, *that* would be a very high torque belt system.

 

[mfgenggear]

I was contemplating string would be very light. Duty. Second would be belt, most robust of course are gears. How ever
3d plastics may suffice for this application.
There is a guy on youtube that designed
And 3D printed harmonic gears for a test run.

 

[Sicilian Engineer]

I was contemplating string would be very light. Duty. Second would be belt, most robust of course are gears. How ever
3d plastics may suffice for this application.
There is a guy on youtube that designed
And 3D printed harmonic gears for a test run.

Thanks, I'll look into this, key issue will be keeping time and cost down as much as I can (but you can't always have cheap, fast AND quality)

 

[XR250]

While it's true that Harley motorcycles use synchronous belts, they are large and the torque is not.

85 ft-lbs +/- at the crank, 9.5 final drive/ approx 2:1 belt sprocket ratio = about 400 ft.-lbs at the small sprocket in first gear - pretty close to what he needed.
1 1/8" belt.
Seems like there are better ideas though.