Our team has been experimenting with the idea of a scissor lift to hang the robot at the end of the game. We were wondering if other teams had far, far better ideas to handle this, since we have been having a lot of trouble implementing it without structuring the robot around the system. Something simpler would be great. :]
I’ve got a few ideas.
Linear lift system. A number of teams in 2004 used a telescoping pole to put their hook on the bar. 1 motor, 1 tape measure, and a set of nested poles, if you do it right. 330 in that year used a more traditional forklift-type lift to get up.
Arm. You can do a smaller one to grab the vertical poles, or a longer or multi-joint arm to get up to the top. You’re going to need a lot of torque on that joint to do that, though.
Look for pictures of robots from 2004 in CD-Media. There are a number of ideas there.
There was a commonly used simple solution to a similar problem in 2004’s FRC game “First Frenzy”. Many teams used a hook that was lifted to the bar via a lightweight pole, with the hook separating from the pole and remaining connected by a cable to a winch on the robot body.
The point to keep in mind - your method of lifting can be different from your method of hooking onto the bar. Taking these one at a time:
Most teams will use a winch (or something similar) to lift themselves up:
http://www.mercomarine.com/images/winch.jpg
It’s really nice for two reasons: First, it usually has a built in gear reduction that you’re going to want to use. Second, you usually can’t backdrive them, meaning your robot won’t come back down when they power off the robots at the end of the match (at least, not until you release it). Hook a CIM up to a winch (with the appropriate gear reduction), and you’re good to go.
To get the hook for your winch to the top, there are a number of ways. A scissors lift would work, but you’ve probably already seen some of the limitations of such a device. Alternatively, consider the distances involved. Your robot can start out 60 inches tall, and the bar is only 84 inches high. Closing that 24 inches can be done a number of different ways:
- A telescoping rod has already been suggested - google “power antenna” to get an idea of how that works.
- A fork lift design has also already been suggested. To see one of those in action, check out videos of 2177 from 2008 (http://www.thebluealliance.net/tbatv/team/2177/2008).
- You could also do a standard articulated arm with a single point of rotation. Something that swings through 180 degrees to double the height of your robot.
There are certainly plenty of other ideas out there… many of which you’ll see at competition!