Questions tagged [transforms]

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

I'm reading an article about teleoperation systems and it talks about three spaces that include joint space, configuration space and task space frames. I do not know what these are, can you explain?
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sensor breaks tf tree in ROS

I am currently trying to add sensor(lidar) into my robot. I made base for a sensor, link to which sensor is attached through gazebo reference. The problem is that adding a tag for some reason creates ...
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Sending Universal Robots UR5e to specific place Using Camera

I have a UR5e installed with a simple camera on its end effector. The robot is at a known position (Cartesian pose/angles and joint angles) Using the camera I took a picture of a QR code and got the ...
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How to republish odometry in different frame?

I have navigation Odometry, but its some how not in the robot body frame. The odometry is being published in world frame, so its not correct. So i need to transform in the robot body frame as that how ...
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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?

Im using thisrobot_lokalization robot_localization package for the linear velocity. As only sensor input in my case is IMU. I configure the parameters and set the frames as follow ...
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Static transform difference between command line and launch file

I'm having a problem setting up the static transform between my base_link and my camera. If I use rosrun tf static_transform_publisher in a different command line the camera is alligned with my axes ...
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Identifying joints from transformation matrix (DH matrix)

Given a transformation matrix formed using the Denavit Hartenberg method, is there a way to identify joint paramters: for example the order of joints? I've come across a solution to an exam question ...
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doubt regarding the base_local_planner::transformGlobalPlan() function

I am trying to understand the base_local_planner::transformGlobalPlan() function. As per my understanding, the function takes in the global_plan (generated by the <...
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Significance of fixed_frame parameter in lookupTransform function

I was going through the implementation of the lookupTransform function defined inside the base_local_planner::getGoalPose() function. What is the significance of ...
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Transform Velocity data from sensor frame to world frame

I am new to Robotics and transformation topics. I need help in understanding and solving the below problem. I have data (surrounding obstacle position, orientation and velocity) which are in sensor ...
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How to make two frames relative to each other

I have a Velodyne and camera that both have transformations specified relative to the origin of the robot. The original transformations were specified as yaw, roll, pitch, x, y, z. I wrote a script to ...
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Finding orientation of object in 3D space

Given the above constellation, I have to find the orientation of object B in the coordinate system of Object C. The objects A and B are fixed to a certain place and the object C can move in freely in ...
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Determining Base Configuration Tsb from End-Effector Configuration Tse for youbot

Hello there, hope you are doing great. Right now I am trying to control youbot to pick and cube and place it to a certain position, on simulation. However, I believe that the reference trajectory is ...
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Getting the new heading after a Transformation

Lets say I have 2d poses as such (angles in degrees): world_to_robot = {0, 4, 45} robot_to_object = {4, -4, -45} From a graph it would be easy to see that: world_to_object = {4, 8, theta}, what goes ...
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Compute path in absolute frame from sequence of measurements

I have a sequence of measurements $\{(x_i, y_i, \theta_i)\}_{i = 1 \:...\: N}$. Each of these represents the new pose of the robot seen from the previous pose, i.e. a measurement $(x', y', \theta')$ ...
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Motion model and homogeneous transformation issue on a drone

I am trying to develop a EKF-SLAM algorithm for a drone, and I want to estimate its position in the inertial/world reference frame. I have as control variables the linear and angular velocities in the ...
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Understanding Twists as 3D Velocities

I am just learning about twists to represent 3D velocities (e.g. of a robot's end-effector), and I have two questions: 1) Wikipedia defines a twist as "an angular velocity around an axis and a linear ...
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How to calculate rotation angle from 3D points

I have 4 3d points(x, y, z). Using these points how can I calculate rotation angle? Consequently, I want to have a 4x4 transformation matrix including rotation and translation information. 4 points ...
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Reference frame, vector

How do I specify the directions of a unit vector $X_n$ and $Y_n$ of a frame $\{n\}$ at an angle $θ$ relative to a frame $\{a\}$ in the form $$ X_n=cosθX_a + sinθY_a $$ $$ Y_n=-sinθX_a+cosθY_a $$ ? Can ...
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Absolute 2D pose from previous pose and measurement

I have a pose $\boldsymbol{x}_0 = (x, y, \theta)$ in an absolute frame, right-handed and centered in (0, 0, 0). I obtain a measurement $\boldsymbol{m} = (\Delta x, \Delta y, \Delta \theta)$ in the ...
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