Daniel Reetz, the founder of the DIY Book Scanner community, has recently started making videos of prototyping and shop tips. If you are tinkering with a book scanner (or any other project) in your home shop, these tips will come in handy. https://www.youtube.com/channel/UCn0gq8 ... g_8K1nfInQ

Full Auto Brainstorming

DIY Book Scanner Skunk Works. Share your crazy ideas and novel approaches. Home of the "3D structure of a book" thread.
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jck57
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Joined: 23 Nov 2009, 15:21

Re: Full Auto Brainstorming

Post by jck57 » 24 Nov 2013, 15:52

Another page lifter gadget. The new gimmick here is a hobby servo to adjust downforce on the rubber tipped lifter. The goal is to have a microcontroller move the servo in response to inputs from a page checker which senses page thickness or light through the page or something else. If the lifter fails to pick any pages, downforce is increased by rotating the servo against the torsion spring which in turn pushes against the lifter arm. If the lifter picks more than one page, downforce is decreased.

The slide would be extended and retracted by another servo.
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jck57
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Re: Full Auto Brainstorming

Post by jck57 » 25 Nov 2013, 11:21

A simpler way to do it: Get rid of everything but one torsion spring and the lifter arm. Use the servo to raise and lower the arm as well as apply variable down force.

Sequence of ops:
1. Cameras fire. Lifter servo is up. Slide servo retracted away from page.
2. Slide Servo extends so lifter tip is over corner of page.
3. Lifter Servo drops lifter arm. Lifter tip contacts page. Downforce controlled by torsion spring.
4. Slide Servo extends slide 2 inches, bending up page.
5. Lifter Servo raises above page stack. Bent page held for flipping.
6. Slide Servo fully retracts slide with Lifter Servo in UP position.

If more downforce is needed, Lifter Servo is rotated a few more degree against torsion spring. The microcontroller needs to be programmed to reset CCW rotation angle. CW angle is always the same. I don't know how to program an Arudino or Pololu Maestro to do this. It's changing a single set point during a cycle according to an external variable. Maybe every reset in downforce would need to run a completely different script?

Why do I think of the simple method only after hours of tedious work on the complicated one? :lol:
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jck57
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Re: Full Auto Brainstorming

Post by jck57 » 29 Nov 2013, 21:17

Any Arduino programmers out there? Help.

This may be the rough idea:

The photoresistor is calibrated for a single page of the particular book loaded into the machine. Page faults are detected by tripping the low or high limits set by the limit pots. A low fault means not enough light, which means low voltage, which means more than one page. The software translates this into a DECREMENT function that moves the angle of the servo 2 degrees clockwise to apply weaker spring pressure to the rubber tip of the lifter. A high fault means too much light, higher voltage, and a subsequent INCREMENT bump of 2 degrees counterclockwise rotation of the servo, putting greater pressure on the lifter.

The jog buttons do INCREMENT and DECREMENT bumps manually to roughly set up the scanner for a particular book. Any fault detection stops the scan process and reverses to the point right after the cameras fire before starting forward again with the new setting.
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jck57
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Re: Full Auto Brainstorming

Post by jck57 » 13 Dec 2013, 20:20

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jck57
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Re: Full Auto Brainstorming

Post by jck57 » 13 Dec 2013, 20:48

Oops. It's Pololu not Pololo.

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relay and servo detail
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