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How to fix problem searchDir angle change too large

asked 2015-10-04 22:42:55 -0500

Chaiyakit gravatar image

I found this problem, which I used hector_slam with RPLidar ran on Ubuntu desktop 14.04 lts don't know anyone ever had. It show that message. "SearchDir angle change too large" makes the map that was created is distorted. By what the leap of the position or direction is distorted. As shown in the figure, ( https://drive.google.com/file/d/0B6qK... ) and ( https://drive.google.com/file/d/0B6qK... ) which maps should be shown. ( https://drive.google.com/file/d/0B6qK... ) and ( https://drive.google.com/file/d/0B6qK... ) Can anybody help? Or this problem caused by setting parameters, I set my right, parameters are as follows

START CODE

<launch>

<node pkg="hector_mapping" type="hector_mapping" name="hector_mapping" output="screen">

<!-- Frame names -->
<param name="pub_map_odom_transform" value="true"/>
<param name="map_frame" value="map" />
<param name="base_frame" value="base_link" />
<param name="odom_frame" value="base_link" />

<!-- Tf use -->
<param name="use_tf_scan_transformation" value="true"/>
<param name="use_tf_pose_start_estimate" value="false"/>

<!-- Map size / start point -->
<param name="map_resolution" value="0.025"/>
<param name="map_size" value="2048"/>
<param name="map_start_x" value="0.5"/>
<param name="map_start_y" value="0.5" />
<param name="laser_z_min_value" value = "-1.0" />
<param name="laser_z_max_value" value = "1.0" />
<param name="map_multi_res_levels" value="2" />

<param name="map_pub_period" value="2" />
<param name="laser_min_dist" value="0.4" />
<param name="laser_max_dist" value="5.5" />
<param name="output_timing" value="false" />
<param name="pub_map_scanmatch_transform" value="true" />
<!--<param name="tf_map_scanmatch_transform_frame_name" value="scanmatcher_frame" />-->

<!-- Map update parameters -->
<param name="update_factor_free" value="0.4"/>
<param name="update_factor_occupied" value="0.7" />    
<param name="map_update_distance_thresh" value="0.2"/>
<param name="map_update_angle_thresh" value="0.06" />

<!-- Advertising config --> 
<param name="advertise_map_service" value="true"/>
<param name="scan_subscriber_queue_size" value="5"/>
<param name="scan_topic" value="scan"/>

</node>

<node pkg="tf" type="static_transform_publisher" name="base_to_laser_broadcaster" args="0 0 0 0 0 0 /base_link /laser 100"/>

</launch>

END CODE

Thank you for your answer soon. I just learned to use,Sorry about my grammar.

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1 Answer

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answered 2015-10-07 04:03:52 -0500

This error indicates that the scanmatcher failed to find a plausible solution. Given that many people reported good results with the RPLidar I suspect the parameters you chose cause the lower performance. I haven't tried the RPLidar myself, but on a quick glance I'd set the map resolution to 0.05 (as opposed to 0.025) and try again.

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Thank you, I will test again.

Chaiyakit gravatar imageChaiyakit ( 2015-10-07 04:21:06 -0500 )edit

@Chaiyakit: did Stefan's recommendation fix your issue? I too am seeing this error every so often, usually caused by moving or turning too quickly. Thanks!

dchang0 gravatar imagedchang0 ( 2016-02-09 02:03:32 -0500 )edit

@dchang0,Hi,Are your problem fixed?

little_bob gravatar imagelittle_bob ( 2017-05-31 02:30:17 -0500 )edit

Yes, sort of. The fix was to upgrade from an RPLidar unit to a Hokuyo UTM-30LX lidar unit. With this superior unit, it could handle the much higher scan rate with far fewer map errors. (It was still possible to break the map when other people moved on the map.)

dchang0 gravatar imagedchang0 ( 2017-05-31 02:34:30 -0500 )edit

谢谢。Thank you!

little_bob gravatar imagelittle_bob ( 2017-05-31 05:11:07 -0500 )edit

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Asked: 2015-10-04 22:42:55 -0500

Seen: 2,768 times

Last updated: Oct 07 '15