06-14-2015 12:11 PM

cad321

Re: pic: CGX-104 cycloidal versaplanetary external

I love the compact design. Perhaps designing a small coupler that goes from a versa planetary to this would be something people would find useful. Hope to see some CAD files soon.

06-14-2015 02:01 PM

Lil' Lavery

Re: pic: CGX-104 cycloidal versaplanetary external

My equations?

Thanks for the credit, but I don't think I ever got around to finding you any equations.

06-14-2015 03:36 PM

GeeTwo

Re: pic: CGX-104 cycloidal versaplanetary external

As I understand it, the advantage of cycloidal is the larger ratio of reduction available in a single stage, improving efficiency. Stacking gearboxes that match VP ratios would give up that advantage.

If you made cycloidal gearboxes at ratios of 36:1, 40:1, and 45:1 that could take a VP output as input, then with a single VP and a single "VC" (VersaCycloidal) stage, you could cover the range from 108:1 to 450:1 with no gaps larger than 12.5%.

Here's the table:

     Cycloidal Ratio
VP    45    40    36
-----------------------
 3   135   120   108
 4   180   160   144
 5   225   200   180
 7   315   280   252
 9   405   360   324
10   450   400   360

06-14-2015 03:42 PM

asid61

Re: pic: CGX-104 cycloidal versaplanetary external

Quote:

Originally Posted by Lil' Lavery My equations? Thanks for the credit, but I don't think I ever got around to finding you any equations.

06-14-2015 03:44 PM

asid61

Re: pic: CGX-104 cycloidal versaplanetary external

Quote:

Originally Posted by GeeTwo As I understand it, the advantage of cycloidal is the larger ratio of reduction available in a single stage, improving efficiency. Stacking gearboxes that match VP ratios would give up that advantage. If you made cycloidal gearboxes at ratios of 36:1, 40:1, and 45:1 that could take a VP output as input, then with a single VP and a single "VC" (VersaCycloidal) stage, you could cover the range from 108:1 to 450:1 with no gaps larger than 12.5%. Here's the table: Code: Cycloidal Ratio VP 45 40 36 ----------------------- 3 135 120 108 4 180 160 144 5 225 200 180 7 315 280 252 9 405 360 324 10 450 400 360 Of course, you must put the versaplanetary first because they couldn't take those large output torques.

06-14-2015 04:03 PM

cad321

Re: pic: CGX-104 cycloidal versaplanetary external

Another advantage to this over a vp to consider is that at the moment, from looking at the renders available, this might be machinable by a team with some cnc access. Whereas a vp is something you must buy. For some teams buying the cots item is easier, for others, getting the machine time is easier.

Quote:

Originally Posted by asid61 You distributed a solidworks model with the cycloidal gear generated from equations on a spreadsheet.

06-14-2015 04:40 PM

asid61

Re: pic: CGX-104 cycloidal versaplanetary external

Quote:

Originally Posted by cad321 Another advantage to this over a vp to consider is that at the moment, from looking at the renders available, this might be machinable by a team with some cnc access. Whereas a vp is something you must buy. For some teams buying the cots item is easier, for others, getting the machine time is easier. Could you share the link? I can't seem to find it on chief.

06-14-2015 04:49 PM

ajlapp

Re: pic: CGX-104 cycloidal versaplanetary external

Very nice. Glad I see others working on this technology.

FYI...from my own experience building these, the 0.030" eccentricity will be violent and rob efficiency.

It doesn't seem like much, but spinning at speed it's wicked.

06-14-2015 05:12 PM

asid61

Re: pic: CGX-104 cycloidal versaplanetary external

Quote:

Originally Posted by ajlapp Very nice. Glad I see others working on this technology. FYI...from my own experience building these, the 0.030" eccentricity will be violent and rob efficiency. It doesn't seem like much, but spinning at speed it's wicked.

06-14-2015 05:42 PM

ajlapp

Re: pic: CGX-104 cycloidal versaplanetary external

Everyone of these units I've ever seen has either had multiple wobble plates out of phase for balancing or a dedicated balance weight.

There's no free lunch.

It's no coincidence that you only see these types of drives in major industrial applications where a bit of extra mass and volume is worth some of the cycloid's benefits.

Here's an unbalanced unit designed to work with RS-550 and RS-775 motors built for the 2012 FRC season.

You can see that this unit is very polished and was even intended for production...however, its promise didn't match with its performance.

https://www.dropbox.com/s/mthooimzm0...42.02.jpg?dl=0

06-14-2015 05:46 PM

asid61

Re: pic: CGX-104 cycloidal versaplanetary external

Quote:

Originally Posted by ajlapp Everyone of these units I've ever seen has either had multiple wobble plates out of phase for balancing or a dedicated balance weight. There's no free lunch. It's no coincidence that you only see these types of drives in major industrial applications where a bit of extra mass and volume is worth some of the cycloid's benefits. Here's an unbalanced unit designed to work with RS-550 and RS-775 motors built for the 2012 FRC season. You can see that this unit is very polished and was even intended for production...however, its promise didn't match with its performance. https://www.dropbox.com/s/mthooimzm0...42.02.jpg?dl=0

06-14-2015 05:54 PM

ajlapp

Re: pic: CGX-104 cycloidal versaplanetary external

You must put the second and/or third plate must be on their own eccentricity that is also out of phase.

06-15-2015 08:59 AM

akoscielski3

Re: pic: CGX-104 cycloidal versaplanetary external

I have to say, this looks like a fun engineering challenge, and good on you for designing this.

In regards for a team machining this though, I always try and recommend buying as many parts as possible (of course this depends on your team's budget however), rather then machining them. The reason is, you can put that much more time into either designing, programming, or practicing with your robot.

In the first few years that I was on 772, we machined a lot of our own parts. However, when I started to design the robots we transitioned to buying more COTS parts. We focused on designing more, rather then machining. And we were "done" the robot a week earlier then normal, and had a lot more practice with it. The robot's level of performance went way up too.

Remember, your robot isn't going to become a great competitor because you custom built a transmission, but you can get better by designing the whole robot better, having a great strategy, having reliable parts (with easy to find replacements), and having more practice.

06-15-2015 09:55 PM

asid61

Re: pic: CGX-104 cycloidal versaplanetary external

Quote:

Originally Posted by akoscielski3 I have to say, this looks like a fun engineering challenge, and good on you for designing this. In regards for a team machining this though, I always try and recommend buying as many parts as possible (of course this depends on your team's budget however), rather then machining them. The reason is, you can put that much more time into either designing, programming, or practicing with your robot. In the first few years that I was on 772, we machined a lot of our own parts. However, when I started to design the robots we transitioned to buying more COTS parts. We focused on designing more, rather then machining. And we were "done" the robot a week earlier then normal, and had a lot more practice with it. The robot's level of performance went way up too. Remember, your robot isn't going to become a great competitor because you custom built a transmission, but you can get better by designing the whole robot better, having a great strategy, having reliable parts (with easy to find replacements), and having more practice.