I am building a chain bar and I am not sure what mechanism I should use. For example should I use a four bar, chain bar, or just lift it off the ground?
There are loads of different variations I think the best option would be to look at some videos and choose the Mobile Goal Carrier that suits your robot:
these are the 4 main types of mogo: chain bar, 2 variations of the 4-bar positioning and a rack and pinion.
Hope this helps,