the value of /odom/twist/twist/linear and angular is not in the unit of m/s and rad/s

[TouchDeeper]

Hello,

I found that the value of /odom/twist/twist/linear and /odom/twist/twist/linear/angular is not in the unit of m/s and rad/s.

If I want to convert it to the unit of m/s and rad/s, what coefficient should I multiply? Thank you a lot.

[dolikemedo]

HI!
according to this:
http://library.isr.ist.utl.pt/docs/roswiki/navigation(2f)Tutorials(2f)RobotSetup(2f)Odom.html
Isnt it m/s?

also:
28 //compute odometry in a typical way given the velocities of the robot
29 double dt = (current_time - last_time).toSec();
30 double delta_x = (vx * cos(th) - vy * sin(th)) * dt;
31 double delta_y = (vx * sin(th) + vy * cos(th)) * dt;
32 double delta_th = vth * dt;

so if vx (x component of velocity) is m/s, dt is second, then delta_x (x component of distance traveled) is meter.
It says vth is rad/s so, delta_th is radian

or do i interpret this incorrectly?

[zhh2005757]

Hello TouchDeeper !
I found something wrong about timestamp transformation from the original code "ROSThread.cpp". The timestamp of the code is nanoseconds, and there is no any transformation to seconds. So you only need to divide it by 1000000000 at line 314, like follows

Then, the odom output will be the m/s and rad/s