ROS Answers: Open Source Q&A Forum - RSS feedhttps://answers.ros.org/questions/Open source question and answer forum written in Python and DjangoenROS Answers is licensed under Creative Commons Attribution 3.0Mon, 16 Apr 2018 12:44:03 -0500what are the units in joint_limits.yaml?https://answers.ros.org/question/243105/what-are-the-units-in-joint_limitsyaml/ Hello!
In joint_limits.yaml, there are two kinds of limits which are max_velocity and max_acceleration.
I wonder what are the units of those limits?
max_velocity : m/s or rpm ?
max_acceleration : m/s2 or rpm/s?
I will be grateful if any of you could help!
Thank you!
Gu Tianqi!
gutianqiMon, 05 Sep 2016 04:53:20 -0500https://answers.ros.org/question/243105/Units of nav_msgs/Odometryhttps://answers.ros.org/question/288813/units-of-nav_msgsodometry/ Dear all,
I would appreciate if you can tell me what are the units used for nav_msgs/Odometry :
- twist : linear and angular twists
is it in meter and radians per seconds ? or meters and radians per timestamp ?
Regards.
lounisMon, 16 Apr 2018 12:44:03 -0500https://answers.ros.org/question/288813/Units of hardware_interface::VelocityJointInterfacehttps://answers.ros.org/question/252500/units-of-hardware_interfacevelocityjointinterface/ Hi,
what are the VelocityJointInterface's command's units? I am using two such interfaces on my robot class but I can't make sense of the data I get.
For example, I am using a DiffDriveController. My wheels have a radius of 4.5cm and I set the forward speed to 1m/s (x component of the cmd_vel linear velocity set to 1). With these parameters the command-values are set to 55, which does not make sense if I assume the unit to be rad/s, m/s, frequency or rpm.antipatternFri, 20 Jan 2017 07:57:11 -0600https://answers.ros.org/question/252500/Information on message sensor_msgs/Imuhttps://answers.ros.org/question/53993/information-on-message-sensor_msgsimu/Hi guyz,
I am new with ROS, and I am trying to use the output of the hector_mapping and my IMU data and fuse them into the robot_pose_ekf filter.
I wanted to have more information on the message units and frame of the data.
1)The angular_velocity is in rad/s or in deg/s ?
2)The linear acceleration are in g or in m/s^2 ?
3)What is the meaning of the covariance matrix? Shouldn't it be called the variance matrix? By definition :
> The variance is a measure of how far a
> set of numbers is spread out.
>
>
> The covariance is a measure of how
> much two random variables change
> together.
Since the measure of, for exemple, the acceleration, only depends on the accelerometers in the IMU, there is no point of using the covariance between the accelerometers, the gyrometers and the magnetometers since they are not related ...
Also, what are the units of the different covariance matrix?
I have also a suggestion: It could also be great documentation if each message description explained those information and not only the data types.
Cheers!
ETS-DronolabFri, 01 Feb 2013 06:06:15 -0600https://answers.ros.org/question/53993/Units for cmd_velhttps://answers.ros.org/question/55977/units-for-cmd_vel/I'm implementing my own base_controller to listen on /cmd_vel for motion commands. I'm aware of the REP103 units convention document, but I haven't found anything on what the units in a geometry_msgs/Twist are. I am assuming it's m/s and rad/s?bjoerngieslerFri, 22 Feb 2013 00:25:19 -0600https://answers.ros.org/question/55977/Relation between cmd_vel and odometry twist data.?https://answers.ros.org/question/44624/relation-between-cmd_vel-and-odometry-twist-data/Hi,
I have some short questions please if anyone can answer these questions.
Q1: What will be the unit of angle when we use
angle = tf::getYaw(odom.pose.pose.orientation);
Q2: What should be the unit of linear and angular velocity when setting cmd_vel of diffrential drive robots?
i.e. cmdvel_.linear.x = vt; (m/s)
cmdvel_.angular.z = w; (rad/s) is it ok?
Q3: What is the unit of (Odometry.twist.twist.angular.z)?
Q4: If I want to find the previous velocity vector from Odometry data. Am I doing right? I want to find velocity vector in Odom frame?
linearV = (odom.twist.twist.linear.x);
angularV = (odom_globalVal.twist.twist.angular.z);
Vx = linearV * cos(angularV) // wrong::its not an angle its angular velocity
Vy = linearV * sin(angularV) // wrong::
Thanks a lot.abdullahWed, 26 Sep 2012 10:34:36 -0500https://answers.ros.org/question/44624/What are the units and coordinate conventions in ROS?https://answers.ros.org/question/9065/what-are-the-units-and-coordinate-conventions-in-ros/Has ROS agreed on a units standard? mwiseTue, 15 Feb 2011 07:04:04 -0600https://answers.ros.org/question/9065/