South West Makers

A couple of meetings ago I bought in some LIDAR units I purchased off eBay from the XV11 Vacuum bots, these units are a low cost full 360Deg range scanner using laser with a reported range of 3-5 Meters, update rate is 5Hz

I now have one hooked up to an Arduino ProMicro which will be my dedicated LIDAR controller for my up coming bot. The ProMicro is a cheap Chinese clone( $6 ) of the spark fun model (http://www.sparkfun.com/products/12640 )of the same name, works well once you work out how the drivers go. These are different from the standard Arduino as they're based on the ATmega32U4 chip which has USB on chip which = custom USB HID's not just the stock serial that Arduino normally comes with. Also has an additional Serial port on board.

I can't seem to attach a photo of the setup as forum attachment limit is not letting me grr btw what is our limit for attachments, from what I can gather seems to be about 150K I think this would be better if its raised a bit.

Speed of motor is PID controlled, however I'm still having issues with this and should be driving at 300RPM, possibly tuning and will be looking at this next, however is still proving data, but will not be accurate.


Full 360Deg Scan @1Deg Resolution Readings are Angle (Degrees), Distance (mm) and Reading Quality as reported back from the unit. I have no idea how this is used, from the looks of it the hight the number the better, in the screen shot below you can see some readings at 0, this because my hands are too close while I was taking screen shot on there keyboard.


Angle Range Data Showing Just 0 Deg, same goes here, my hand was right up close so is invalid reading. unit minimum range is a about 5-10cm out



Next steps, get PID working properly and design a housing for it.

...Stay tuned More to follow

Just a note that manually controlling the motor down to 300RPM from initial measurements seem reasonably accurate. I do some more tests once I get it mounted properly

And here is its view of the corner of my room where my computer using a python test script I found.

Nice readings from the wall, and to top Left and bottom right you can see where the curtains are

Motor PID Speed control is working, look like I was on a bum steer with the values reporting back on the terminal screen are incorrect. The raw data values as seen on the screen below are correct and fluctuates between 300 and 290rpm, so some tuning is in order

Motor Speed now fixed. was stupid mistake.....I had the motor going in the wrong direction Doh!. Now is pretty spot on at 300RPM and readings are actually better, which makes sense as need to be scanning in the right order, I'm surprised it works in both directions, I'm guessing the data will have more errors.

Sitting on my desk looking through my 3D printer to the corner of the wall

Ok have been getting a handle on the data quality field thats one of the fields transmitted by the unit

From the screen shots you can get an idea how it works. The higher the value the more power is received i.e. the stronger the Laser bounce

The Quality is represented by the yellow dots, while the Green dots are the measured distance, Red Ones I'm assuming are errors/bad readings

As a side note, you can see the window on the right side of the screen where I have the curtains partially open and where the window is setback, but as the blind is down its giving a strong reflection, while the glass itself would probably not be seen.

In this screen you see the wall I'm closest to so power returned is greater compared to the other wall where I'm further away.



And as I get closer, very strong.



And along the wall a bit near the curtains, laser gets absorbed/not reflecting as well and is all over the place



So this Data Quality field is more like a SNR.

Now everything seems to be doing as it should it's time to design a housing for it and print it up and get it connected to my RPi

Nice one Stephen. I love the visual representation of the data. I guess the rest of the room is out side of the 2-5m range of the unit? What is the current draw of the Lidar unit?

-Paul

parkview wrote:Nice one Stephen. I love the visual representation of the data. I guess the rest of the room is out side of the 2-5m range of the unit? What is the current draw of the Lidar unit?

-Paul

I'm up close to one of the walls and others are out of range.

Haven't measured the current draw as yet

I've now designed a stand for it while I play around on the desk

Just waiting for it to print



With the LIDAR unit mounted.

Version 2

V3 With Lid with wiring exits, not shown is the DX H-Bridge Board that sits on the raised standoff in the middle that the motor of the LIDAR connects to.

The circuit board shown is a Spark fun Pro Micro, well a cheap chinese copy anyway and does the job, at $6 you can't go wrong

I've put all the files up on Thingiverse (http://www.thingiverse.com/thing:796866)

After a couple of iterations and some modifications that adds a status LED.

All printed up and waiting for hardware.

Did you design the LIDAR unit as well, or did you find that online? Silver colour - I love it. Who needs a lathe when you can just 3D print a look-a-like.

parkview wrote:Did you design the LIDAR unit as well, or did you find that online? Silver colour - I love it. Who needs a lathe when you can just 3D print a look-a-like.

The 3D Model of the Lidar I found online, Yes I love 3D prints

parkview wrote:Nice one Stephen. I love the visual representation of the data. I guess the rest of the room is out side of the 2-5m range of the unit? What is the current draw of the Lidar unit?

-Paul

Current Draw is about 200mA