Edit: Look at post #2 for answer: Cire's post
Note: Fleg = F/#legs on ground
(Caution: I might not know what I'm talking about )
Hi, I wanted to expand on this subject since I hit a wall myself designing with weight and cost restrictions.
I have already bought tons of micro servos, their torque rating is only 1~1.9 kg*cm (different sites different value...)
Now I'm in the process of buying a battery, and prefer a lead acid battery for its cheapness (yea I'm cheap) However the battery is 2lbs....(2x 1lb BURRITO!)
I have 4 legs on my robot, with just 4 servos in the vertical plane.
Torque @ optimal conditions: 1~1.9kg*cm
Center Mass: Battery(2lb) + Guns + Sensors = 2lb+
Leg lengths: approx. 18cm
According to my brain,
At 1 cm from servo shaft, 1-1.9kg is ok......more kg = stall
To figure out how much mass x the servo can handle at radius r from shaft, its just a ratio:
[from servo specs]1kg/1cm = x(kg)/r(cm)
however the battery is not mounted at the end of "r", its in the middle of the body......and the servos are on the 4 corners of that body....
so...According to my brain again,
As the legs/servos "try" to hold the body up,............ah...thats all I got....T.T
Whatever you guys can help me figure out Ill make a tutorial on Weight Calculations out of this thread for others to reference.