[bogally99]

We had also considered a system like this, the problem with shooting darts up is that they are unreliable. Instead we are considering a telescoping arm that can just drag a hook up there. The arm doesn't have to be strong since it never takes more than the hook's force. Then in order to stay perpendicular to the wall we are going to mount the cable to the back of the frame as well as the motor.

We haven't been able to test this yet as it is the last thing we would put on our robot given the time. I would recommend that you don't focus on the lifting until you have everything else perfect. The lifting is one of the most difficult challenges and has a very small benefit. I mean you get 10 extra points for adding an entire new subsystem.

Either way good luck with this, it will be challenging.