About this lab

Move a two-link arm and a payload and see the gravity torque each joint must hold, against the servo’s stall torque.

Ideas covered: torque, lever arm, centre of mass, holding torque.

Common questions

Why does an arm need the most torque when fully extended?

Torque is weight times the horizontal distance to the joint. Fully extended and horizontal, that distance is largest, so the joint carries the most torque.