Question on Graulidar Project! :)

lloyd

New member
Hi
I came here via Alexander Grau's blog, in the hope of tracking him down so I can chat to him about his super cool graulidar project! I built a variant on it and used his code, and would like to get some pointers on solving a cloning problem I am having with data points! Basically the arduino code is assigning the same distance measurement to a series of angles when they are actually different, producing multiple small curves rather than lines.

I am an intermediate C programmer and understand more or less what is happening in the code, but cannot for the life of me figure out why I am getting these doppelgangers in my data and whether its code or hardware related. I am using an arduino nano, running Alex's code. The hardware base is quite different, and most of the electronics is the other side of the slip ring, but it still uses a 12 degree graduated encoder as in the original design. If Alex is here or is someone could point me in his direction, that would be a great christmas present!

This is a shot of my lidar build, am aiming to reduce this significantly in size as it currently houses the arduino, protoboard and motor driver which could be made smaller.
20181219_175211_2018-12-19.jpg


Here is a shot of the data visualisation in RVIZ, showing the duplicates as "curving" around the lidar centre.
lidar_2018-12-19.jpg


And this is a snip of the data in rostopic echo where the duplication is a lot clearer.

Code:
header: 
  seq: 5
  stamp: 
    secs: 1545243131
    nsecs: 381030082
  frame_id: "odom"
angle_min: 0.0
angle_max: 5.28318548203
angle_increment: 0.0174532923847
time_increment: 0.000771604944021
scan_time: 0.0
range_min: 0.0
range_max: 40.0
ranges: 2.9100000858306885, 2.9100000858306885, 2.890000104904175, 2.890000104904175, 2.0399999618530273, 2.0399999618530273, 2.0299999713897705, 2.0299999713897705, 2.559999942779541, 2.559999942779541, 2.5199999809265137, 2.5199999809265137, 2.5199999809265137, 2.5199999809265137, 2.5399999618530273, 2.5399999618530273, 2.549999952316284, 2.549999952316284, 2.569999933242798, 2.569999933242798, 2.430000066757202, 2.430000066757202, 2.190000057220459, 2.190000057220459, 2.200000047683716, 2.200000047683716, 2.200000047683716, 2.259999990463257, 1.3600000143051147, 1.3600000143051147, 1.3600000143051147, 1.340000033378601, 1.309999942779541, 1.309999942779541, 1.350000023841858, 1.350000023841858, 1.3300000429153442, 1.3300000429153442, 1.340000033378601, 1.340000033378601, 1.309999942779541, 1.309999942779541, 1.3300000429153442, 1.3300000429153442, 1.350000023841858, 1.350000023841858, 1.3600000143051147, 1.3600000143051147, 0.0, 1.340000033378601, 1.340000033378601, 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Once again thank you for the project and the code, which helped more than you can imagine. Looking forward to talking with you!
 
Oben