View Full Version : Dream Servo

07-09-2009, 11:05 AM
Ok, we've had lots of discussions over the past few days about servos, both serial and PWM. There's clearly a ton of servos out there, but we never seem to be happy about them! We got into a discussion about this here on campus, but of course the people on this board have a lot more experience than the noobs in my lab. I'm wondering what "your dream servo" would be? What sort of size, features, etc would you want?


07-09-2009, 11:40 AM
Personally, I'd go for an AX-12+ style servo, as in maximum size constraints. Higher torque would be nice, RX-64-ish or so.

Firmware-wise I'd like to see internal S-curve calculation, and a decent load indication.
Ability for a multi-master bus would be nice too, or at least a way to alert the master that there's an issue with the servo, or when it's reached it's position or so. Then again, if it's a multi-master system, you could build a snake bot with nothing but servo's (token passing)

Due to some recent brainstorms, I'd also like the ability to set the servo's position according to an analog voltage. Eg. 0v = 0°; 5v = 90°. That'd make for some interesting analog robots.. although it's not too hard to do in analog hardware, the amount of chips piles up fast.

07-09-2009, 12:50 PM
The RX-64 for $25. Done. :)

07-09-2009, 12:57 PM
Personally I really think Robotis is on the right track, only thing that could be improved is the cost.

I'd love to see an AX-12 that was compatible with the RX/DX series RS485 as well, maybe with a built in voltage reg.

DC Robotic
07-09-2009, 01:29 PM
Robotis type, with 360 deg. positioning feedback encoder-style. And interchangable gearboxes that fit right to the servo horn and face (like the ServoCity models). This would allow simple choice of speed vrs. torque. As long as we are talking ultimate lets also have a full bearing opposite the servo horn. I think that right now the AX-12 is a good value for the money. The gearboxes wouldn't be that expensive if they were built in quantity.

07-09-2009, 01:45 PM
DC Robotic has a great idea with interchangeable gear boxes. I think that walkers need lower speed and higher torque than many other servo applications, for example. The ServoCity models are very large, however. The gearbox interchangeablility needs to be designed into the servo system and not an after-market item.

I'd be very happy with a less expensive version of the RX-64 having a beefier gearbox, lower gear ratio, and a slower speed than the existing device.

07-09-2009, 02:30 PM
The funny thing about super-low gear ratios - they're kinda hard to squeeze into a standard size case and keep them from exploding, unless you build them from unobtanium...

07-09-2009, 04:54 PM
good point.

I would like to correct: I'd like an AX12 sized servo with a built-in hydraulic system instead of just a dc motor. No sugar with that please.

Incidentally: does anyone know of the AX12 FW being available anywhere? I don't mean the hex files, but the actual code.

07-09-2009, 07:51 PM
The RX-64 for $25. Done. :)

In a perfectly symmetrical square case(not cube) with the shaft centrally located.

07-09-2009, 10:42 PM
My dream servo would have a reasonably high torque, good linearity, strong gearbox and decent cost.

But, manny's suggestions for a square servo is not bad either.

07-10-2009, 04:11 PM
Linear servos might be nice, mini-leadscrew devices. Firgelli stuff but a little bigger/stronger with internal electronics. And reacivity programability, a to maintain a particular force on an object, or introduce springiness ( for all types, linear or rotary).

Cheap is good, $25 price point a good goal.

07-10-2009, 04:14 PM
Well a $25 pricepoint on something comparable to an RX-64 is certainly a "Dream" :p

(I'll eat my words in 5 years)

07-10-2009, 04:35 PM
You want some salt to go with that? :P

I came up with another one, actually.

A servo with potential energy, like a true muscle. Just imagine bipeds hopping around..

Oh, and for 25$; offcourse

07-13-2009, 09:04 AM
At least 1500 oz.in of torque in a Hitec 5990 case made of Adamantium.

Seirously thought, I guess it would be the EX-106 in smaller format.


08-05-2009, 10:32 AM
Servos sold as three separate components..
Motor controller