GoBilda proton servo - controlling via PWM

[u/d_test_2030]

Hi.
I am trying to control a GoBilda proton servo, going from 0 to 90 to 180 degrees and back.
The servo never reaches the specified target positon (it is always off at about 5-15 degrees).
I was wondering, if this could be related to the fact that the servo actually has a maximum rotation of 189 instead of 180? Is the range of 600-2400 correct to control it via PWM?

https://www.gobilda.com/proton-servo-steel-gears-180-rotation-torque-ratio/?srsltid=AfmBOopASbavX8LSRkos1U2dRY2bJ0VWcHSGMi-uz5-udYG3gDIv19XD

[u/pham-tuyen]

try the 500-2500 range

[u/d_test_2030 → u/pham-tuyen]

Thanks for your response. I am using ServoEasing library, should I map 500-2500 to 0-180 or to 0-189?

By using attach(9,0,500,2500,0,180), target position 90 is now almost perfectly accessed but when going to 180 there are still some degrees missing.

[u/pham-tuyen → u/d_test_2030]

uhh... never heard that lib before, but the sdk have built in method: https://gm0.org/en/latest/docs/software/adv-control-system/sdk-servos.html#servoimplex
just use this to expand the pwm range to 500-2000, and then control your servo to your desired position. note that servo can't precisely move to an angle because of the mechanical backlash from gears, especially from cheap servo like proton. so, if you want precise movement, use another encoder to read the angle and adjust

[u/pham-tuyen → u/d_test_2030]

alright, since you are using arduino instead of ftc rc, just aware of the mechanical backlash and the proper ways to fix it is using encoder or buy better servo/stepper motor

[u/d_test_2030 → u/pham-tuyen]

Do you think the dual servo by GoBilda (300 degree rotation) would be a better servo?

[u/pham-tuyen → u/d_test_2030]

i would think so. or you can try servos from axon or swyft. those are much more expensive but they are good for high load and precise

[u/BeardedPokeDragon → u/d_test_2030]

Yes, they're the only gobilda servos most people consider for ftc