What effect does the low msg update rate do to the SLAM map ?
hi
i'm building the map with Hector SLAM and my customized lidar. The structure of customized lidar is just like RPLidar, it's always rotating.
▼ I got a good scanning result when i placed the lidar in a single point.
(there's a big window, so the down side of the map looks like that, it's correct)
▼ but the map sometimes failed.
I have no idea why the system is so weak that once if i moved or rotated the heading of lidar too fast with hands, the map failed easily. After checking some of the Q&A here, and i found this, here's some questions about the problem happened on my system :
Is it caused by the low msg update rate too ? Or is it caused by some other problems ?
If it's not caused by the low msg update rate, what effect does the low msg update rate do to the SLAM map ?
what's the minimum angle resolution or the basic needs for Hector SLAM that can make the scan matching work successfully ?
it is that the angle should always be 0~ 2pi in a single msg ? is 0~ pi enough for Hector SLAM to make a map ?
- thanks ! :)
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here's some info of my system
- LaserScan.msg publishing frequency : about 3.1 hz
- Sampling rate : 2000 (sample / sec) in total
- rqt :
- LaserScan.msg sample :
header: seq: 31 stamp: secs: 1459761437 nsecs: 218499461 frame_id: laser_frame angle_min: 0.0 angle_max: 6.25863647461 angle_increment: 0.00892857182771 time_increment: 0.000553450663574 scan_time: 0.371918857098 range_min: 0.10000000149 range_max: 40.00 ranges: [ ... ] ( about 590~670 data in this vector ) intensities: []
Asked by alice222777 on 2016-04-07 13:41:08 UTC
Comments
One of the core assumptions of hector_slam is that the world does not move much between laser scans. With a 30Hz scanner like the UTM30-LX, this works fairly well. For lower rates you'll need to move the scanner more slowly.
Asked by ahendrix on 2016-04-07 13:53:39 UTC
oh 30 Hz ? thank you :) i'll make some test to see what will happen if the msg publishing frequency is higher.
Asked by alice222777 on 2016-04-08 05:46:52 UTC
The publish rate on the UTM30-LX is a direct result of their rotation rate; they publish one message per spin. Unless you change the rotation rate of your scanner, changing the publish rate probably won't have the desired affect.
Asked by ahendrix on 2016-04-08 17:51:19 UTC
ah, okay, i'll make the device rotate faster :) thanks for telling me so much things
Asked by alice222777 on 2016-04-09 10:00:23 UTC