I don’t think you have it quite right. There are four cylinders (one for each hook), but only the hooks on the same “end” of the windmill are plumbed together (on either side of the robot). For instance, you might have noticed the bit of green electrical tape on one end of the windmill arms. When we climb, one solenoid releases the “green” hooks (which are connected in parallel) and another solenoid releases the “not-green” hooks. All of the plumbing runs through the center of the axle tube (and out slots in the middle of the axle), so it may look like there are more interconnections than there are.
The climber arms had to meet some tricky packaging requirements:
- The turret should shoot in any direction, with no “dead spots” caused by the climber or superstructure
- The climber should climb no matter what position the turret was in.
- Our CG should be as low as possible, and the robot should fit under the Low Bar
- The hooks had to accommodate a +/- 0.5" allowable difference in rung spacing
That meant that the turret had fit into as small a diameter envelope as possible (~20" diameter), and the arms had to be as thin as possible and be pushed right to the edge of the frame perimeter. The whole climber arm and gearbox also pops up on a neat little custom linear slide. It took a few iterations, but I’m pretty happy that we were able to come up with something that met these requirements and also performs really well.