in rosaria the pos.getTh() the data from encoder or gyro;

[DavidHan008]

ROSAriacpp
ArPose pos;
robot = new ArRobot();
pos = robot->getPose();
tf::poseTFToMsg(tf::Transform(tf::createQuaternionFromYaw(pos.getTh()*M_PI/180), tf::Vector3(pos.getX()/1000,
pos.getY()/1000, 0)), position.pose.pose); //Aria returns pose in mm.

pos.getTh() the data from encoder or gyro;

[reed-adept]

ArRobot::getTh() returns the theta component of the pose estimate calculated by the robot. If a Pioneer 3 (DX/AT, as well as Amigo, PeopleBot, Powerbot) robot has a gyro, and the gyro mode is 2 (HasGyro 2 in robot controller firmware parameters), then it may have used the gyro as well as wheel odometry (encoders) to determine theta. If the robot does not have a gyro, or HasGyro=0, or HasGyro=1, then it will not include the gyro. (The orientation part of the pose topic in RosAria is from this theta, just converted to a quaternion with radians as seen in the code above.)

If anyone is interested in adding a separate topic to RosAria for gyro data (for the case where HasGyro=1), then discuss on the sig-ros-pioneer mailing list, or let me know, and I can give some info on how to do that, or just post an Enhancement request here

For other types of robots (Seekur, PioneerLX), the robot controller will generally use the gyro data in its calculation, but the data is also available separately as well. So that could be made available if that's useful (unfortunately due to this design I don't know if the odometry-only theta would be available but I could check.)