Hi.
I was just wondering, but what do you think is the best/most efficient lift?
We want to create a 2 motor/pneumatic lift for worlds, and we already are using 10 motors.
Would this be possible without creating a transmission?
Thanks.
If you have 2 ports (or 1) available, you can try a 2 motor 4 bar lift. For those, look at Skyrise robots’ lifts. If you want to use pneumatics, there are several designs out there for it. In either case, you should have some form of sturdy anti-tip mechanism. That can be as simple as a few c-channels that extend forward from the drive, released by rubber bands when the lift initially deploys.
How exactly would the rubber bands hold the lift in place when the robot is fielding?
Are there any videos of this?
I’ve seen some 4 bar lifts, but the videos don’t go in depth.
Look at the Cyber brains pneumatic lift, extremely impressive.
True…but they use a complex ratcheting transmission that i dont have the time and space for.
The pneumatic pistons would hold the lift in place, and the rubber bands would power the lift when the pistons retract.
4 bar lifts are basically 2 parallel c-channels (or I-beams for extra strength) on each side, connected by gears (idler gear in the middle, so they rotate in the same direction). Attached is a diagram. If it’s round, it’s a gear. Otherwise, it’s a c-channel. The purple c-channel is the tower which attaches the lift to the robot. The blue, red, and brown gears are mounted to it such that they rotate freely. The blue c-channel is locked to the blue gear, I would recommend using screws through the screw holes in the high strength gears. The brown c-channel is locked in the same manner to the brown gear. The blue gear meshes with the red idler gear, which also meshes with the brown gear. If you are using motors, you can power the red gears. That’s one way to get the gear ratio you need for a 2 motor lift. The orange c-channel on the other side of the blue and brown c-channels is the part that goes to your lift platform. It always remains in the same orientation (vertical, slightly pitched, horizontal, etc.) among positions (down, half elevated, elevated, etc.). You can directly power it with pneumatics by placing an 84-tooth ratchet on the same axle as that idler gear and using single-acting pistons to reduce air consumption, and rubber bands can be used to assist the lift by mounting standoffs to the arms (blue and brown c-channels), and wrapping rubber bands around them. If you want to use rubber bands with a pneumatic release, that might be a bit more tricky (you’re converting linear force to torque). You could, I suppose, use a rack gear for that, but that’s not very compact.
Edit: I found a picture of our old 8-bar lift. This was an early version of the robot, but the concept is the same. We used 4 motors for it, and you can kind of infer how the motors were connected based on the positions of the motors and gears.
Our ratchet is actually very simple. Just a 1x1 touching the gear at an angle to allow it to move in only one direction. We pull this out of the way to fold the arm back up. The ratchet isn’t completely necessary either. Mostly for heavier robots.
Pm me if you want more information.
The hardest part of a good lift is often just getting a good center of gravity so that you don’t fall over.