I have a pair of legs for a balancing robot. The feet are wheels with motors. I’m about to design and build the hips, and I want the robot to be able to swing the legs forward and backward independently, as well as be able to move the legs apart and together. I am hoping for types of movement like a roller skater might have where the feet can even cross behind each other to maintain balance during fast roller skating.
So my plan is currently to design and 3D print (in ABS) either a simple reduction gearbox for the hip so the NEMA 17 stepper motor I’m using will have enough torque to swing the legs forward and backward or perhaps try using planetary gears for building torque if there are benefits. The legs weight maybe 10 lbs each. The whole robot will be about 4 or 5 feet (like 1.5m) tall and roughly human shaped. I have also considered casting the gears from epoxy, but would need a very strong reason for doing so since it is much more time consuming. I have machinable wax, epoxy, and a vacuum chamber for that kind of work, if needed.
To make the legs move apart and together, I’m thinking of a couple gears in the middle with partial gears to the pivot point. Turing a motor makes the angles change between the legs.
Pictured is roughly what I’m imagining. If you have any suggestions, I’d really like to hear it. Thanks.
From left to right, here’s what I’m picturing – motor with reducer (front view), side view of the hip with the leg connected, front view of the hips showing the gears that make them move relative to each other.