A few days ago
me: "let's make a cube, click on the tool, and attach the right pin number."
me: "No more error messages, time to animate!"
me: *rotates the cube*
me: "Look it moves?!"
Servo: *bzz* bzz*
Servo: *Crack* * brrrzzhhhbrrzzzz?!?!*
me: "Ohno!"
me: *grabs USB cable and pulls it out of the PC*
So let's talk about what happened:
I was very happy to see the first servo move by rotating a 3D model in Maya. The Arduino script allows us to connect up to 4 different servos. Since the prototype I'm currently working with has 2 servos, the logical next step is to test the second servo.
Generally, a servo's range of motion is 180 degrees. The first connected servo demonstrated this; The servo followed the 3D model's rotation when the value was between 0 and 180 but stopped moving as soon as the value exceeded this range.
Connecting a second servo wasn't difficult. A second cube was made and assigned to the right pin number. As soon as I started to rotate the cube I heard a "crack" and a loud noise continued to come from the servo. I looked over and saw that the servo's horn was pushing against the 3D printed frame. The servo's horn tried to move to the rotation given by the 3D model, but since there was something in the way, it couldn't, but it didn't stop trying.
The initial "crack" was when I first started to move the 3D cube away from the value "0". This made the servo hit the 3D printed frame, so hard that it broke the glue seal between the servo and the 3D printed frame.
Luckily I reacted fast by removing the servo out of its position and disconnecting it from power. The servo could have stripped its teeth making it no longer usable.
So... How NOT to break your animatronic?
Can we prevent this from happening the next time?
constrain!!!
Constraining the movement of the 3D model in Maya so it matches the real-world constraints of the servo is the way to go. To see if the model has the right constraints we can hold the servo outside of the animatronic and test it before securing it in place.
A virtual copy of the animatronic inside Autodesk Maya can also help to correctly constrain the servo.
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