Hey guys n' gals!
I'm wondering if anybody can provide advice for something I must totally be doing wrong which has been driving me crackers for probably close to a year now. I've been trying to learn electronics so hopefully this is just something with a really easy fix.
Problem first, in case anybody wants to help but not read a life story...
Short version of problem
I'm building a robot, 6 legs, 3 servos per leg (these LD-220MG servos).
These servos have to lift the robot... but I think some are taking the brunt of the lift, and subsequently burning out. Yay as another £20 goes up in magic smoke. I've tried to calibrate so they all start at the same position and move at the same rate, but nope... burnout. Usually a few at a time
So... is there something I can do to limit the servo, or to stop it from frying itself?
Life story / TMI version...
I'm building/printing a SpiderBot, with the aim to open source publish it when complete (link to files I've made so far). The design intent is "make it badass".
I didn't start with this one... I first did one similar to OpenCat, then moved on to Vorpal. Both of these were nice, and I figure it's time to move onto something a bit more... powerful.
But the robot weighs in at about 5kg. I'd thought that spreading that over 6 legs would be fine... but nope... burnout every time it stands.
Today I've made a test rig to try and test what kind of weight i can lift with a single leg and keep under the 2.4-3A stall current as per the servo spec.
I've currently got a set of 25W 8 Ohm resistors on order to try again... according to my calculations with 7.4v at 8 Ohms, this should limit the available power to the servos to 0.925A.
I've also got some current sensors to rig up to an arduino and read the current from... thought being that if one leg pulls too much power, then the resistor will prevent it going further, and the sensor should report back to a Pi controller to stop moving / retract a bit.
End bit...
Sooooo... am I going about this in completely the wrong way? About a year has passed trying to make this thing stand up without going into meltdown.