ROS Resources: Documentation | Support | Discussion Forum | Index | Service Status | ros @ Robotics Stack Exchange

Attention: Answers.ros.org is deprecated as of August the 11th, 2023. Please visit robotics.stackexchange.com to ask a new question. This site will remain online in read-only mode during the transition and into the foreseeable future. Selected questions and answers have been migrated, and redirects have been put in place to direct users to the corresponding questions on Robotics Stack Exchange. Additional details are available here.

0

How do I get the angle in radians (0 to 2pi) from a quaternion?

asked 2012-08-14 07:55:17 -0500

Clefairy
9 ●6 ●7 ●12

I'm trying to get the angle of a position model in Stage in radians from the Odometry message published to the "odom" topic.

This is how I've done it:

theta = 2 * asin(msg.pose.pose.orientation.z);

This sort of works in getting the angle in radians, but whenever the angle is below the x axis it gives me a negative angle.

Is there anyway of getting the angle in radians going from 0 to 2pi, starting from the positive x axis going anti-clockwise?

Thanks.

edit retag flag offensive close merge delete

2 Answers

Sort by » oldest newest most voted

2

answered 2012-08-14 08:13:43 -0500

flag of Germany

31395 ●134 ●284 ●498

Look in the angles package. There is a header with functions that normalize the radian. I think there is also one for [0, 2 Pi).

For getting yaw of a quaternion, there should be a function in tf that does this for you.

edit flag offensive delete link

Comments

3

You are looking for the tf::getYaw function: http://ros.org/doc/fuerte/api/tf/html/c++/namespacetf.html#a33e93f413622e296d0a2a93b252bbb4b

Eric Perko ( 2012-08-14 08:30:11 -0500 )edit

0

answered 2018-11-22 12:21:51 -0500

A formula that give an angle from 0 to 2pi is:

f(x,y)=pi()-pi()/2(1+sign(x)) (1-sign(y^2))-pi()/4(2+sign(x))sign(y)

      -sign(x*y)*atan((abs(x)-abs(y))/(abs(x)+abs(y)))

There is x=x2-x1 and y=y2-y1,and the formula is working

for any value of x and y.For x=y=0 the result is undefined.

edit flag offensive delete link

Question Tools

Stats

Asked: 2012-08-14 07:55:17 -0500

Seen: 3,085 times

Last updated: Aug 14 '12

Related questions

ROS Answers is licensed under Creative Commons Attribution 3.0 Content on this site is licensed under a Creative Commons Attribution Share Alike 3.0 license.

Powered by Askbot version 0.10.2