# Tag Info

### Is the translational vector (positon) in transformation matrices in cm or another unit (MATLAB)?

They are in whatever units the kinematic analysis uses. It could be feet, inches, meters, millimeters, or whatever. Your question is a bit like asking “what unit is the Pythagorean theorem written ...
Accepted

### Calculate transform from different poses

I am just going to explain from the basics. So feel free to skip through the first part and scroll to the bottom if you want the answer. Basics: The 3 parameters of your pose are $x,y,\theta$. These ...

### World and Map Frame for a real robot

As you've figured, static transforms are valid for fixed offsets such as sensor positions. They are the minimal solution the more complete recommended solution is to setup a robot model. There's ...

### Obtaining Heading vector from IMU

Probably the easiest way to do this would be to convert from Quaternion to Roll-Pitch-Yaw rotations, and then your heading is the Yaw angle. I'll note that the Yaw angle is not fixed/correct unless ...
Accepted

### Conveyor Belt Calibration for a Robot - Rotation Matrix

A general approach would be to construct a so called axis-angle representation and convert that to a rotation matrix representation. On order to do so, one could start with a normal vector of the ...
Accepted

### orientation transformation

Your 6d vector can also be considered a frame. Lets call it the frame of the object. Convert your 6d vector to something easier to work with like Homogeneous Transforms. Another alternative is ...

### How to use Quaternion from IMU to get the transformation to inertial reference frame?

You should use ROS' inbuilt transforms. Assuming that your IMU data is being read as a ROS message, and you know all the frame id's, this example template explains the basics of using tf's.
Accepted

### Question about getting global coordinates of lidar point cloud from relative in Webots

Basic Example of solution on Python: ...

### homogeneous transformation matrix only given sensor extrinsic values

You can do this easily just by using homogeneous transformation. Attach a local frame to each sensor , and make sure your sensor measurements can be represented in this frame. For example, I would ...
Accepted

### URDF for a real robot

For a real robot, do I need a URDF as well? It is not necessary to create a URDF for a real robot, but it's highly recommended. Many of the tools are designed to leverage it. For example the ...
Accepted

### ROS force vector transformation

If you have robot state publisher that publishes transformations between links/joints. You can use tf package to fetch those transformations. If you want to ...
1 vote

### Standard Notation/Name for Velocity Transformations

This matrix has different names based on what version of screw theory, spatial notation, etc. in which you're using it. In general, when working with these various formulations, the 6-element velocity ...
1 vote

### Move gantry system to detected position in image plane

You could do a manual calibration: Measure a far left x_target aruco in camera pixels (x_pixel_left), Put the pointer on that ...
1 vote
Accepted

### Python's all tf frames function in ROS2 only returns some frames

The tf information is published from one of more nodes across the system. Because you are creating a fresh buffer with a new buffer you need to let it listen long enough that it will have heard from ...
1 vote
Accepted

### Are the DH parameters in this text wrong?

If the only problem you see in the DH parameters presented is with the $\theta$ values, it is common practice to drop any offset associated with this value. In other words, $\theta = 0$ is not ...
1 vote

### Denso 6DOF Industrial Robot Flip vs NonFlip

To flip the wrist on a 6 axis robot, rotate joint 4 by 180 degrees. Rotate joint 6 by 180 degrees in the opposite direction. Move joint 5 to mirror of it previous position, that is if joint 5 was at +...
1 vote

### How to get transform between two fixed frames using a camera

The most simple and easy way is using a common third frame. Attach a camera to the end effector of each robot and place a calibration board on the ground. Do a hand to eye calibration using the ...
1 vote

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

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