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ROS Navigation stack. Code for finding where the robot is and how it can get somewhere else.
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amcl odom_alpha parameters have wrong description in wiki.ros.org #542

Open luke321 opened 7 years ago

luke321 commented 7 years ago

It took me quite some time till I figured out that something is wrong with the documentation on wiki.ros.org, I hope this gets fixed to spare others some time.

The Description texts actual describe this values: alpha4 alpha2 alpha3 alpha1 alpha5

alpha1 and alpha4 are switched

CURRENT Description in wiki.ros.org:

~odom_alpha1 (double, default: 0.2) Specifies the expected noise in odometry's rotation estimate from the rotational component of the robot's motion. ~odom_alpha2 (double, default: 0.2) Specifies the expected noise in odometry's rotation estimate from translational component of the robot's motion. ~odom_alpha3 (double, default: 0.2) Specifies the expected noise in odometry's translation estimate from the translational component of the robot's motion. ~odom_alpha4 (double, default: 0.2) Specifies the expected noise in odometry's translation estimate from the rotational component of the robot's motion. ~odom_alpha5 (double, default: 0.2) Translation-related noise parameter (only used if model is "omni").

actual code in amcl_odom.cpp:

double trans_hat_stddev = sqrt( alpha3 * (delta_trans*delta_trans) + alpha1 * (delta_rot*delta_rot) ); double rot_hat_stddev = sqrt( alpha4 * (delta_rot*delta_rot) + alpha2 * (delta_trans*delta_trans) ); double strafe_hat_stddev = sqrt( alpha1 * (delta_rot*delta_rot) + alpha5 * (delta_trans*delta_trans) );

This would be the CORRECT Description:

~odom_alpha1 (double, default: 0.2) Specifies the expected noise in odometry's translation estimate from the rotational component of the robot's motion. ~odom_alpha2 (double, default: 0.2) Specifies the expected noise in odometry's rotation estimate from translational component of the robot's motion. ~odom_alpha3 (double, default: 0.2) Specifies the expected noise in odometry's translation estimate from the translational component of the robot's motion. ~odom_alpha4 (double, default: 0.2) Specifies the expected noise in odometry's rotation estimate from the rotational component of the robot's motion. ~odom_alpha5 (double, default: 0.2) Translation-related noise parameter (only used if model is "omni").

DLu commented 7 years ago

Were you not able to make the change on the wiki?

spmaniato commented 7 years ago

@luke321 @DLu It's a bit more nuanced than that: #499

In a nutshell, alpha1 and alpha4 are in the omni model's source code (compared to diff and the wiki page) IMHO the change should be done at the source code level (in L distro), not the wiki.