LIDAR project

Projects General Guidance
1

I've been working on a LIDAR measurement project using arduino and passing it via bluetooth.

Great success so far (hardware works great) but now I've got to start improving the coding.

Right now I have 1 LIDAR sensor passing data via A4/A5 (SCL/SDA) successfully. This is constant output data with values of 0 - 8900.
Problem is, I'd like to add another LIDAR sensor and average the two values out. I might even to add more; the issue is accuracy; I've reached the software limits of the accuracy of the chip (which averages out hundreds of readings to output one reading). But if I could add more LIDARs, then I could average each one and theoretically continue to improve the accuracy.
I'm a noob here so bear with me please.
Can I add multiple sensors using other pins? Should I run into any issues with digital data instead of analog input/output when using other pins? I read the output via Serial at 9600 baud (actually, should go up to 115200 with no problem).

Thanks for your help.

2

Do You say that all the LIDARs will aim at the same object? Buy 2 and use the best one!
Averaging over "a few" good ones and "several less good ones" looks as a waist of money, gaining nothing.

If You can select different addresses for the LIDARs just connect them to the same A4/A5 pins. Maybe a pullup is needed when increasing the number of them.

3

Not a question of using the 'best' ones. It is a question of time - if I average the readings too many times, the results become too slow. If I use multiple chips I can keep the results times at a higher rate.

4

Making several readings using one sensor and use averaging is common practise given certain rules are fulfilled but reading several different sensors...., I wonder what support there is for that.
Note that using the same I2C bus only one sensor can be read at the time. The bus might be set up for the highest functioning rate but time will still be a factor.

At what rate does the LIDAR manage to make new readings?

5

Problem is, I'd like to add another LIDAR sensor and average the two values out.

That adds several complications and is very unlikely to yield better results than simply averaging two readings from one sensor.

If I use multiple chips I can keep the results times at a higher rate.

No. It takes as long, or longer, to get one reading each from two independent sensors, than two readings from one sensor.

Can I add multiple sensors using other pins?

Not if you use the hardware I2C. You can have several sensors on the same I2C bus, but they all must have different addresses, and must be accessed independently. The computer does only one thing at a time.

6

Railroader:
<< At what rate does the LIDAR manage to make new readings?
I think the default is 5 milliseconds (this is a time of flight laser reading so it is fast.)
The problem is that the accuracy is achieved not through engineering or optics but through statistics - so their standard accuracy is achieved by averaging 50 or 100 readings readings. I have tested averaging for as long as 200 readings, but that means you're getting only one reading a second.
This is why I am considering more than one LIDAR - to get more accuracy you end up with unacceptably long times to gather a reading.

7

Read reply #4...

8

Hi,

Problem is, I'd like to add another LIDAR sensor and average the two values out.

If you have two LIDAR units and you wish to average the two readings, the two LIDAR will have to be synchronised together to ensure that they are measuring the distance from the SAME point.
Have you checked if you can have two LIDARs scanning the same scene at the same time and give independent readings?

What LIDAR units are you using and what is their resolution and accuracy?
Can you please post a link to specs/data of your LIDAR unit.

What is your project?

Thanks.. Tom... :slight_smile: