Building a Delta Robot: 3D model version 2

Let’s review: So far…

…I’ve defined success

…I’ve used Math ™ to calculate the size of the humerus (red), ulna (yellow), wrist (light blue) and base (dark blue).

…I’ve changed the joints (white) so that they more closely mimic the math (see image).  In the previous version the lengths of the ulnas was much harder to keep track of.  Curious note: I’m told that Solidworks reported a lot of “rebuild errors” with the previous type of joint and those are now fixed.  Yay?

…I’ve written an open source computer simulation of the math, and included Arduino code to run a delta robot with three hobby servos.

…I’ve tried to print the previous joints and found the hole for each bearing was too small.

I have yet to…

…3D print both halves of a joint and assemble a working model.  This is my current challenge.

…3D print the wrist.  Nothing is stopping me, so this will be my next challenge.

…3D print the brackets to hold the steppers (green).  I want to find a way to add a limit switch so that I can calibrate the robot the instant it turns on.  Even better would be a rotary encoder so I could track the arm movement in real time.  I suspect such additions will change the shape of the brackets.

…make the base plate.

…test all the wiring.  Make sure that the steppers move as instructed and that the encoders/switches work.

…make the humerus bars and assemble the machine.

…test axies: moving to zero, then 1 cm on each axis (to make sure +x,+y, and +z are not flipped in my software)

…test range of motion: moving from 0,0,0 to the eight corners of a box at each corner of the envelope.

…test repeatability: moving from 0,0,0 to some fixed point with a digital touch probe.  Repeat 500 times and find the max of the error.

…test drawing straight lines in the air: video the tool moving in front of a checkered background.

… test drawing arcs in the air: video the tool moving in front of a checkered background.

… test speeds: ? ? ? At this point my knowledge completely runs out.

More news Tuesday night when I try to reprint these joints.

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