Help with Jetway Rig (How to rig wheel pillar)


I have a jetway model that I’m trying to rig in such a way that I can easily pose it in static positions. So far I’ve been able to get by with using bones, vertex groups, and constraints. However, I’ve hit a wall with the wheel pillar (see images). There are two parts to the wheel pillar. The upper part is rigid with respect to the bridge (bridge 3) and the lower part extends out of the upper part down to the wheels.

As you’ll notice from the images below, when I change the slope of the jetway, the wheels (and staircase) sink below ground level. I think the obvious questions here is when I adjust the slope, how do I restrict the wheels from sinking below ground level while at the same time keeping the lower pillar inline with the upper pillar? I’ve tried a couple different variations on this rig that restrict the wheels to stay above ground level, however, the lower pillar does not stay inside the upper pillar. With this simpler rig I’m able to semi-easily re-position the wheel pillar (and staircase) after every change in the slope.

I look forward to your replies and greatly appreciate the help!



A limit location costraint?

Thanks for the reply.

I had tried this before to keep the wheels from sinking into the ground, but it doesn’t solve the problem of the lower pillar not staying in line with the upper pillar. Instead, the wheel runs horizontal to ground as the slope is increased. Some movement in this manner is necessary, but it needs to be restrained such that the lower pillar moves up into the upper pillar as the slope is increased.

Here is a clearer view of the pillar, which might give a better sense of the desired mechanics when the jetway is sloped:

Note as well that the angle of the pillar does not change with respect to the bridge, but does change with respect to the ground when the jetway is sloped.