# Tag Info

### What is the meaning of joint space and configuration space and task space?

All "spaces" are used to define the current state of the robot, but with differences. The state of the robot is a point (also known as a configuration or pose) in a space. Please note that ...

### Get a rotation to align a vector, n with another vector, a and be able to rotate around a

Assuming you are working in 3-dimensions, this is exactly what the cross-product does. To find the vector of rotation that rotates $\mathbf{n} \in \mathbb{R}^{3}$ into $\mathbf{a} \in \mathbb{R}^{3}$, ...

### Significance of fixed_frame parameter in lookupTransform function

From what I understand, the fixed frame is one where objects are assumed to be stationary with time. Maybe an example will make this clear: Assume a robot with a lidar sensor moving in your world. It ...

### How to republish odometry in different frame?

It sounds like you need a static frame transform node. I suggest you look up how to launch a static frame transform in a launch file. Static frame transforms allow you to connect 2 separate frames ...

### ros2: transform pointcloud2 data from one frame to another in python

I don't know if it is too late but to anyone wondering how to do this, in this PR just they solved that for ros2 (https://github.com/ros2/geometry2/pull/507) So you need to upgrade your ros version to ...

### How do I convert a set of coordinate and rotation values

What you are looking for here is homogeneous transformation matrices. The purpose of these matrices is to seamlessly integrate rotation and translations into one matrix that acts as a change of ...

### Absolute 2D pose from previous pose and measurement

For your first question, it's just a a change in coordinate frames, you have the absolute coordinate frame and a coordinate frame "local" which is centered in x0 and the pose is in the local ...

### Compute tranformation matrix for odom to base_link depending on tracking camera attached relative to base_link

One way is with a utility node I made called 'old_tf_to_new_tf' which is configured with four frames: lookup_parent lookup_child,...
1 vote
Accepted

### How to approach a target pose via the XY surface normal?

Recall that one of the reasons we like quaternions is, like Matrices, we can multiply them to get one quaternion that represents both of their effects together. So, yes, if we know the orientation of ...
1 vote
Accepted

### How can I convert Quaternions rotation values into Angular Velocity?

It is possible to calculate x,y,z angular velocities from the time derivative of Quaternion. This blog has a detailed explanation for doing so: https://mariogc.com/post/angular-velocity-quaternions/ ...
1 vote

### From euler angles to rotation matrix and vice versa

Assuming that Rotation is scipy.spatial.transform.Rotation, the seq string specifying the ...
1 vote

### From Euler angles to Rotation matrix Staubli

Consider using elemental rotation matrices as defined on this wikipedia.org page: ... then substituting the angle into the trigonometric functions in the matrix and finally cross multiplying the X, Y ...
1 vote

### transform Pose - undefined reference to std::chrono::time_point, tf2::doTransform

To use type transforms you need to include the appropriate packages + link against them. When you call doTransform against a ...
1 vote

### sensor breaks tf tree in ROS

This does not appear to be breaking your tree, but creating an additional detached tree. The tree will only connect if they share a common ancestor. As pointed out by @Chuck you appear to have two ...
1 vote

### ROS - RViz reports "No transform from [kinect] to [world]" when URDF appears correct

Solved; it was an issue with the container networking configuration. I am testing with RViz outside of the container and only port 11311 was forwarded. ...
1 vote
Accepted

### TF is broken when using robot_localization package with only IMU sensor, how to assure that the measured velocity is the one from the robot?

Based on your configuration, you are trying to create map -> odom -> /thrbot/base_link. But you do not have a map frame. Looking at your oroginal TF, you ...
1 vote
Accepted

### Identifying joints from transformation matrix (DH matrix)

Okay, so let me preface this with the statement that I think this is a lame question. First, because I can't imagine a scenario where you're going to be given just the transform matrix and have to ...
1 vote

### doubt regarding the base_local_planner::transformGlobalPlan() function

Shouldn't this cause the first while loop to break immediately because the first point in the global_plan would be the one that ...
1 vote

### Significance of fixed_frame parameter in lookupTransform function

An example use case: "For example if one wants to know what was the position of the right arm two seconds ago relative to the position the left arm has now" Here we have two different time ...
1 vote

### Transform Velocity data from sensor frame to world frame

You can use the rotation matrix. linear_v= R*sensor_linear_v + p X sensor_angular_v p is the translation vector and the X is the cross operator angular_v=R*sensor_angular_v
1 vote

### How to make two frames relative to each other

So it seems like what you want to perform is camera-lidar extrinsic calibration. Seems like you have the translations figured out but not the rotation? You can use one of the already available ...
1 vote
Accepted

### Determining Base Configuration Tsb from End-Effector Configuration Tse for youbot

Do I understand correctly, that the problem is with the matrix equation you have posted and how to calculate $T_{sb}$ from that equation? You can solve the matrix equation by multiplying from the ...
1 vote
Accepted

1 vote

### Understanding Twists as 3D Velocities

1) There are many ways to express velocities. All of them are mathematical constructs to describe the same motion. They can have some minor advantages/disadvantages depending on the applications. The ...
1 vote

### Reference frame, vector

Here's a graphical answer. Given some vector $r$ in Frame 1: You can rotate to a new frame, F2: All you do is project to the new axes. Counting along the x-axis in $F_2$, you can see that you go ...

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