# Laser receiver detections and Arduino PWM control of solenoids

#### deere_chaser

Joined Nov 29, 2020
4

My idea for the receiver is as follows -

5 light/ laser detectors - Part# B01M8PFZRC from amazon - more "eyes" added to the 5 boards/sections for a wider range of strike area - may break down into more sections like 7 or 9 possibly.

[ ] Very high level - high duty cycle to get the tool to move very quickly (coarse adjustment)
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[ ] Kind of high level - medium/low duty cycle to slow the movement down (fine adjustment)
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[ ] Spot on level - Stops all output control to solenoids
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[ ] Kind of low level - medium/low duty cycle to slow the movement down (fine adjustment)
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[ ] Very low level - high duty cycle to get the tool to move very quickly (coarse adjustment)

The system, at least on paper, will insist upon itself to get to and maintain the laser strike on the "spot on" eye. The tool this will go on will be like a bulldozer or a road grader with hydraulic adjustment, where the blade will either fill in a low spot or move a high spot.

Factors/questions
Physical factors - hysteresis, reaction time, accuracy (not looking for crazy tight tolerances but don't want it super lazy). I can always slow down and I plan to have the work area halfway close to the target before starting the automatic control.
Electronics - physical capability, design of receiver, overall plan, maybe having a dial and code for aggressiveness and an input for a "stop" "run" "hold" switch to override the control or make it start working.

Lasers-

https://www.toolbarn.com/dewalt-dw0...jC2sXJD5Z2STFzm4in6eTzswi2w-jwiBoCEtIQAvD_BwE

#### jpanhalt

Joined Jan 18, 2008
11,088
Welcome to AAC and thank you for the links.

As for your proposal, I don't see the need for separate "circuits" to handle high, medium, small, and no offsets. That's what PWM is for doing. In other words, I would design for proportional control. I would also consider that you may/will need to add dither to your valve control to get small and/or smooth corrections.

#### deere_chaser

Joined Nov 29, 2020
4
Welcome to AAC and thank you for the links.

As for your proposal, I don't see the need for separate "circuits" to handle high, medium, small, and no offsets. That's what PWM is for doing. In other words, I would design for proportional control. I would also consider that you may/will need to add dither to your valve control to get small and/or smooth corrections.
Thank you! Hopefully we can get this figured out. The separate circuits in regards to the offsets are for laser signal transfer to the board only. The 2 PWM signal circuits will control raise/ low only. I had never heard of dither, I appreciate the suggestion. I think it will greatly help the functionality of the control.

#### Bernard

Joined Aug 7, 2008
5,788
Photo transistor KDT00030ATR looks interesting; peak response @ 630 nm, 50% @ 500-650 nm. Small surface mount, .8 X 1.2 mm. Newark 1- $0.201. 9000-$ 0.203;
Rochester 1 @ 0.1972, 25- $0.1932. My want list is too short to justify an order at this time. Thread Starter #### deere_chaser Joined Nov 29, 2020 4 Photo transistor KDT00030ATR looks interesting; peak response @ 630 nm, 50% @ 500-650 nm. Small surface mount, .8 X 1.2 mm. Newark 1-$ 0.201. 9000-$0.203; Rochester 1 @ 0.1972, 25-$ 0.1932.
My want list is too short to justify an order at this time.
I did some digging on the specs of the laser I have VS one used for this type of work. I have a Dewalt unit now, which is a “class 3” and the one typically used is “class 2”. I am having an issue with determining the nanometer rating for a class 2 or 3 lasers, for the correct sensor, not to mention finding a sensor to read the laser and not ambient light.

#### jpanhalt

Joined Jan 18, 2008
11,088
On further thought, you can affect smoothness by adding flow constrictors to your hydraulic lines. When I added a blade for pushing snow to my skid steer, that's what I did to get smooth and easily adjusted increments. Of course with less restriction, changes are faster. Unlike a human, your automated system cannot see ahead, but it can react quickly, so adding flow restriction might alleviate "operator"-induced oscillations.