Very confused about motors and gears

Beginner here.

I’m making a powered leg.from research I’ve got that I need a separate motor for each movement (hip and knee)
BUT I want to use 1 motor for both movements.

(Gets even more complicated when you introduce the other leg)

How would I go about controlling 2 pieces separately with 1 motor, by using gears? If this is the case, can you control gears on an arduino? If you can, then how is this done?
There’s also using pulleys but even there I’m a little confused as I’ll still need 2 pulleys from 1 shaft

BUT I want to use 1 motor for both movements.

Not possible, if two independent movements are supposed to happen at the same time.

Why set yourself such a poorly thought out challenge? Start small, get one joint to work, and go from there. If this is an entirely DIY project, you will encounter very difficult problems in the very first step. Guaranteed.

Or, buy one of the many available hobby-style robot arms and learn how they work.

Right thanks for clearing that up. It’s been boring a hole in my head for weeks.

The reason I’ve set myself this challenge is because I’m in a wheelchair and 10 years later, it’s gotten to a point where I’m sick of it. I can’t sit by doing nothin and watch my body balance get worse every few months.

I’m currently 3D printing a very small scale version, attaching 2 small motors (nema 17) to the hip and knee and testing that. Once I get the small version working okay, I’m hoping to try pulleys, experiment, move further and up from there.

I’m new to Arduino/engineering but I do have a Game Development/programming background.

jremington:
.
Or, buy one of the many available hobby-style robot arms and learn how they work.

Oh, I have. It was the PiArm. What I got from that it that each movement has its own individual motor, and I’m trying not to do this.

When I Google powered exoskeletons, there doesn't seem to be multiple motors and the hip/knew/ankle all seem to be connected by pulleys of some sort. Extremely confusing at how they’ve done this since that equals to 3 motors per leg.

shazhazel:
When I Google powered exoskeletons, there doesn't seem to be multiple motors and the hip/knew/ankle all seem to be connected by pulleys of some sort. Extremely confusing at how they’ve done this since that equals to 3 motors per leg.

You are absolutely correct! Three movements mean at least three motors. The motor movement is connected to cables or rods or something so the movement is there, but the motors are where their weight and torque is best supported. That makes for much lighter arms, etc.
One motor can cause the appendage to move two directions, but more.
Paul

PS, Just like the tendons in your arm/leg. One end connected to your muscle ad the far end connected to a bone after the joint. Seems to work!

The rule is one motor per "degree of freedom", which you can think of as a bidirectional motion.

Walking generally requires at least two degrees of freedom per leg (up and down, forward and backward). A flexible joint in the middle of the leg adds a third.

Hi
Have a look at Robot arms on google made with 3D printing. There is a very good one which is open source

You will see how the motors and gearing works for three degrees of freedom.. Not exactly a leg but good learning for articulated movement