For one of my class final projects, we were tasked to design and build a robotic manipulator with at least 3 degrees of freedom (DOF). Other than that, the only requirement was that it could move.
My group decided to build a 6 DOF arm. Five of the joints are powered by 180 degree servos and the base joint uses a NEMA 17 stepper. I designed the following,
Joint 1 (base): The rotational joint for the entire arm. It uses a ring of bearings to emulate a larger thrust bearing. It’s belt driven by a stepper motor.
Joint 2: The largest of the bending joints; mounted directly to joint 1. It’s driven by a servo that’s geared down to increase torque.
Joint 3: Very similar to joint 2. The servo for this joint is placed as close to joint 1 as possible to reduce the torque required to lift it. This meant that a series of two belts were needed to drive it.
Joint 5: This is the last of the bending joints. It’s placed between the rotational joints 4 and 6. It’s similar to joint 1 but smaller.
