Let's Make Robots!



I have started building a quadruped robot using Lynxmotion SES parts. I have the Lynxmotion quadruped body kit and 4 SES 3DOF legs. I have bought servos and put everything together. However, I'm much more comfortable with the code than with the mechanics.

The question I have is about the mass of the robot in relation to the servos. Unpowered, should the robot be able to stand fully raised upon its legs without slowly lowering itself to the ground again? Currently, I can move the legs into a standing position, but the centre of the robot will then slowly lower itself back down (while no power is given to the servos).

The reason that I ask is that the only mass on the central chassis at the moment is an arduino mega board (not connected yet). I intend to add 1 2200mah 7.2V lipo battery, one 2800mah NIMH 6V battery for the servos, and an SSC32 servo controller.

The servos I am using are Hitec HS-422 on the hips and the 3rd joint. I am using HS-635HB for the middle joint so that they have more torque.

Once it has power going to the servos, should it stand easily? Am I being paranoid?

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well the amount of weight a servo can lift is way bigger then the force it takes
to turn it by hand.

to me it sounds like a byproduct of using high quality servos with well lubricated gearboxes.
there is nothing in there that would arbitrarily retain the position, this is done electronically
via the potentiometer inside reporting the position back to the servo's internal regulator.

and no you are not being paranoid, with walking robots these are critical considerations.

Right. So, basically, once the servos are powered up and set to their 'home' position, they would be applying way more force to stay in that position than what it takes to turn them when they are idle with no power?

Thanks, that is promising.