Close

First Run

A project log for Open LIDAR

This project is to build a motorized gimbal mount to convert a laser distance module into a 3d LIDAR.

caver.adamcaver.adam 08/30/2018 at 03:562 Comments

Tried a first run today of the mostly assembled project. 

Two issues showed up. 

First, the yaw axis is very jerky. I need to find a better way to turn it on the axis. It's doing too much balancing on the small shaft. 

Second, about 1/3rd of the way through the scan the LM7805CV overheated. I need to see about adding a heat sink onto that. Otherwise I'll have to re-design the 5V side of the project (medium). Or lower the 18V side of the project to 12V (easy)

Discussions

caver.adam wrote 09/10/2018 at 21:43 point

Nice! You hit on two points! I have to order a buck converter...the lidar overheats frequently using the regulator.

Also, I think that moving through yaw could help a lot, but I would also like to shore up the fixture. I figured out that the top of my shaft is actually wobbling. The yaw shaft mount was damaged when I tried to put in the screw mounts...and it is not secured properly. I'm also considering putting in a thrust washer. But I think your idea will help a lot once the other problems are fixed.

Also, after this video my pitch motor crapped out. Not sure if I damaged the motor, if it is out of alignment, or if the shaft is slipping. But I will probably have to disassemble the motor to figure it out.

Finally, I'm currently getting caught up on my honey-do list. Once I get caught up (and get another paycheck), I'll order the new regulator. Thanks for the recommendation on which ones might be good!

  Are you sure? yes | no

kevinj wrote 09/10/2018 at 19:56 point

Hi Adam! It's cool to see this coming together! Since you've switched away from rotating all the way through the pitch axis every scan, do you think continuously rotating the yaw axis and stepping the pitch would help remedy some of the jerkiness?

I'd also absolutely recommend a small buck regulator for the 5V side, regardless of your input voltage, especially if it's enclosed. Those linear regulators just convert your voltage difference to heat, and dropping 18V to 5V means means you're dissipating 1 watt with about 75 mA going through it, and a TO-220 package LM7805 can only dissipate about 2W at room temperature anyway.

Pololu's selection is pretty good, and some are nearly the same size as a LM7805. If you jump the shutdown pin then they pretty much drop in, too!

5V / 500 mA: https://www.pololu.com/product/2843

5V / 1A: https://www.pololu.com/product/2831

  Are you sure? yes | no