This moth rig is an experiment that I learned quite a lot from.
Automatic wings and keyframable wings rest on top of one another. The keyframeable controls, in fact, are children of the automatic controls. So you can turn the automatic wing flapping on, but also key frame on top of it.
Attributes control the speed, wing sweep, and speed of secondary motion.
Secondary motion / automatic follow through is the coolest part of this rig, and opens up a door for all sorts of future experimentation. The animator only animates the flapping of the wings at the base of the wing, the rest of the lovely curving shape is controlled by MEL. The curve of the wing is dependent on time, (the frame number in the time slider, in fact). Which means you can key the wing to flap and then slowly come to a rest, and the curve of the wing will follow through gracefully. A keyable attribute let’s the animator decide the number of frames of delay the follow-through happens over, with a zero frame delay meaning a completely stiff wing, and increasing frames a slower and slower waving motion.
This MEL expression is a combination of a time-delay expression and a follow-through expression I found in Kirian Richie’s Art of Rigging. It took a bit of creative thinking and brain-hurting to put them together, which was terribly fun.
What is so earth-shatteringly cool about this MEL expression is that it acts an awfully lot like a dynamic simulation, but, it updates it real time! You can drag your mouse over the time-slider without crashing anything!
*I do not know the source of the moth model.