Archive for the Home Made Lidar Category

DOH!

Posted in Home Made Lidar on April 11, 2018 by asteriondaedalus

So, I am having to hurry up as the commercial lidar are now coming down to where they should be in terms of price/performance.

 

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One step closer

Posted in Home Made Lidar on April 9, 2018 by asteriondaedalus

Here is the gimbal board blinking.

What it took was a bit of work to sort a driver for a USBtinyISP programmer.

Then some fidgeting to get the programmer header to stay in place.

You can actually crash the programmer it turns out by shorting pins – if the header is not seated properly or it moves.

Otherwise, if everything is in place it takes literally a second to burn the bootloader onto the board.

I set the board up as an Uno in the IDE, opened up blink example and uploaded.

Next is to strip out the code from drive one of the 3 motor ports to get a motor rotating for the LIDAR.

Back to the home-made LIDAR

Posted in Home Made Lidar on March 27, 2018 by asteriondaedalus

So, got my travel approved for the conference I am going to.  I am still waiting on the review comments back before I generate the final paper.

In the meantime I thought I would dust off the bits I bought for the home-made LIDAR and start fidgeting.

bottom

As I am cheating for the prototype, I will need to do something about setting up the Atmega328P based board.

To setup up the board I need burn on the Arduino bootloader, since the system has its own (or so it would seem).

To do that I need use the ISP and …

DOH!

The pesky board has pads, with no through holes, on the bottom.

Hmmm.  Nasty fiddly work.

But wait!  I did get a gadget for bombing the small quad flight controllers I scrounged.  Et voila!

programmer

The gadget fits over the atmel chip and has pins enough to power and program the chip in situ.

Not a common gadget, came across it … don’t remember where.

pgmhead

Only downside it fits a 10 not 6 pin ISP USB programmer.

DOH!

I have a BAITE evUSBASP 10 pin!

All coming together.

Blowed if I can find info on the pin-outs of the header LOL.  Long lost the paperwork.

However, I do note Atmega328P programming uses pins 1, 7, 8, 17, 18 and 19 on the DIP chip.  So that’s RESET, VCC, GND, MOSI, MISO and SCK.

On the 32pin quad pack it looks like 29, 4, 21, 15, 16 and 17.

So …

quad

Phew!

The three pins grouped in one corner sit over the corner opposite the chip key.

So now we can re-burn the sucker with the Arduino bootloader.

It would seem that the smudge of bolognese sauce in the photo coincidently marks the keyed corner too LOL.  Do they sell indalable bolognese sauce?  I might substitute with a marker.

Nuances factor, is the chip on the gimbal board 3.3V of 5V.  I have an older programmer that is 5V so I am screwed if the dang board is 3.3V.  That’ll be the next hurdle.

Gag! Need a 12volt BEC as well

Posted in Home Made Lidar on January 18, 2018 by asteriondaedalus

So, for the final prototype I will likely need a 12volt BEC to drive the gimbal board – though I won’t need that for the bench.  What I am missing is an adjustable bench supply.  Still something that should have on my bench.  So, off to Jaycar on weekend.

Otherwise, here are the basic innards of the home made lidar.  The bore on the gimbal is not wide enough for the slip ring body, but that is not a problem – it will be accommodated by the way I mount the slip ring.

20180118_180855

As for the Benewake TFmini Micro Lidar, I think I might play with a 3D print for the final prototype.  My geek sister has a 3D printer and I am most of the way through an online Blender course (specifically so I can fall into 3D printing design).  Otherwise, a short piece of aluminum angle should do.

20180118_183933

Just for posterity the physical specs for the gimbal motor are:

Spec:
Poles: 12N14P
Resistance: 10.0 omh
Weight: 41.42g
Wire: 0.19mm
Turn: 100T
Bottom holes center to center: 16mm and 19mm
Top holes center to center: 16mm (vendor website says 12mm in on place and 16mm in another).

1389280705

Physical specs for the lidar are:

lidar

HALP!

Posted in Home Made Lidar, The after market on January 3, 2018 by asteriondaedalus

So, mislaid the cable from my Benewake TFmini Micro Lidar.   What on earth is this socket type please?  Anyone?

POSTSCRIPT

I pinged 3XDR, from where I got the gadget, for a hint as to the connector type. He is kindly sending me one!  Otherwise, it’s a JST-GH 4-pin.  Used in pixhawk.

POST-POSTSCRIPT

All good.  New cable on hand. I have the gimbal board too, and a 4 core slip ring, so just waiting on the gimbal motor (with the large bore).  To give a keyed position I have a line sensor so I will add a reflective line to the gimbal motor spindel.

Cheap lidar

Posted in Home Made Lidar, Sensing on December 9, 2017 by asteriondaedalus

So my Benewake TF Mini LiDAR turned up.

TFmini

Now for the fun.

It has to rotate in a circle to create a scan.

I had an idea to mount either of a Seeeduino Film or an ESP8266, with battery, on a spindle to wirelessly send readings – all while it is spinning.

Then BOOM!

You can get “hollow” spindle gimbal motors with slip rings!  So, again a

So, you can attach the TF Mini to the spinning part of the gimbal motor and drive the motor and take readings.

All good but for one thing.  Currently the idea is a open-loop solution.  It will need to be keyed to at least one position (at least) so that the “beams” are relative to a direction.

Hmmm!

So, being lazy I found a really cheap MEGA328P driven gimbal board, but I only want it for the gimbal driver and the ease of software hacking.

HMBGC

The beauty is is a clone of the Martinez toy, so it has code to manage the phases of the motor inputs.   Should be interesting as it looks like you only need a few functions to set it up to run a motor continuously, but who knows – I still have to read into the theory.