Windshield Wiper Linkage

[ZooHead]

I put together a rough simulation of half of a windshield wiper mechanism.

My goal with a linkage like this is to set it up so
only one thing is animated and drives the rest.

As usual it takes less time to set up the rigging than making the
parts, so I start off with rough pieces and refine them later, maybe.

 

[ZooHead]

For the other half of the linkage, you need a totally separate rig facing in the other direction.
The top bone of each rig is in the same position, and the second one is
driven by a Parent Constraint Tag, with the first top bone as it's target.

 

[ZooHead]

For more fun you can do it without any Bones at all.

 

[ZooHead]

Did you see the Folder at the end of the Hierarchy in the last post?
That serves as the equivalent of the final Joint in the Bone rig.

This is where you put the IK Handle Tag, and when you add
the Target, it keeps that point from changing position.

PS: The Orient Constraint Tag I used is unnecessary.

 

[ZooHead]

Here's a further illustration of the pivot point alignment.

 

[ZooHead]

In this version I added a very important part that oddly
enough the automotive industry calls the transmission.

The linkage is mounted to the transmission, and
the transmission is then attached to the vehicle.

I split the transmission bar in two parts, left and right,
and used them in place of the folders I used previously.

Now the Orient Constraint Tag is needed so the transmission
parts don't rotate. It didn't matter if the folders used before
were rotating, because we couldn't see them in the renders anyway.

Since the Backdrop is not moving, I used it as the Target for the Orient Constraint Tags.

 

[ZooHead]

I wasn't sure if I could do a ratchet mechanism,
and I can't remember ever doing one before,
so I thought give it a try using the same
parts from the windshield wiper linkage.

 

[ZooHead]

To make the wheel turn I used a Parent Constraint Tag and I used the Short Arm as a Target.
Then I keyframed the x y z Constraint property to achieve the oscillation.

The first Frame is keyed with the x y z properties all checked.
The next keyframe stops the rotation by unchecking the z property.

 

[ZooHead]

The problem with the previous ratchet setup is that the ratchet
cam passes through the teeth of the gear/ratchet wheel.
That’s why it has only 4 teeth, so it would be less noticeable.

I had an idea of how I could get the cam to move up and over the teeth, so I had to try.

The idea is to use a Spline Tracking Tag with a Spline made
from the cam wheel itself, offset by the proper amount.
The problem is it’s a totally separate system, so almost all frames
must be keyed to match the motion of the Short Arm.

So much for only key framing one part.

 

[kenludd]

fantastic study in mechanics - bravo!

 

[ZooHead]

@kenludd Thank you, I still can't figure out how to turn the wheel
continuously, rather than returning it returning to it's original position.