Hi here!
For quite sometime I was following the forum but only recently I decided to join the club. Anyway, i bought a bunch of Lynxmotion brackets, ordered servos from china (DRF15MG - cheap with lots of torque) and a Mini Maestro from Pololu as servo controller.
I got the BRAT up and running and slowly i’m trying to learn how to make it work. Got the idea and ignoring the clumsy moves is really walking!
My problem is now this: in some positions the servos will start to vibrate and make the legs shake non stop unless i hold on them for few seconds. I understand that the servos are the problem and some suggest that may be not enough torque (which is not the case as are rated for 14 Kg/cm torque). Actually some of them will start to oscilate even when just connected to the servo controller, not even attached to any bracket.
Does anyone have any suggestion on what servos to use not to make a huge hall in my pocket but also not to have to throw them away anytime soon? Is HD 1501MG any good? Plolu sells them for 17.95 a piece if buy 10…
Also, one more thing, maybe silly, but… anyway: any way to reduce the amount of slip during the walk? My floor is made from tiles, shiny tiles :-S
You can check my post about my custom BRAT inspired biped, I decided to use Power HD 1501 MG.
I don’t know how they will evolves with time but for now they are really great.
Made from tough hard plastics, the cases and hardware are really well molded (not like TowerP… ). They have plentiful of torque (rated at 17 kg.cm, but I’ve not mesured it) and they don’t jitter when assigned to a position (again, not like common cheap chinese servos).
Hi Robot Dude, thank you
I’m using a 6V ni-mh battery pack, similar with the one Lynxmotion sell. While some of the the china made ones are shaking the ones I used for arms (5101) are working fine… I can try using 4.8V pack instead tonight and see how is it.
I took a short video few nights ago, not sure if can see the jittering
Hi bravach, should be fine, according to the published specs (40.7 x 20.5 x 39.5 mm) should be more “standard” then the one i’ve bought from China… Well, i should see in 1 week, hopefully everything will go fine.
Btw, your bot looks pretty cool, and the finishings are great! What controller are you planning to use?
I’m using a Picaxe-18X with the SD21 Servo controller. It’s not as performant as an Atom 28 + SSC32, but it’s more than enough for my bot (also, it didn’t take much place because the µcontroller is directly on the SD21).
The SD21 works with base registries commanded via the I2C bus.
Lovely setup you have there. Please do let me know how your servos cope. Mine will take probably another 1 week or more to reach here…
Playing with the current ones (China made), i can see that sometime can move up to 10 degree or more untill will try to correct the position. Guess for big projects using digital servos is the only way to keep all this under control. Anyway, I’ll give it a try as soon I get mine and let you know.
This is really good news for me. Btw, I just got my 209 with 4 DOF walking around pretty well even with the cheap servos. Can’t wait to see what the new servos can do. Really appreciate your feedback
I got my servos yesterday (very fast delivery ^^) and last night I’ve replaced the old ones. The difference is HUGE! Barrely can hear them, no jittering, etc… Thank you bravach, you make my bot happy ^^
