Questions tagged [transforms]

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Defining static transform publisher in launch file

I'm trying to include to my main launch file settings to start my depth camera with pointcloud. It's launching the pointcloud OK, but I need to set a transform between the base link and my ...
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1answer
10 views

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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1answer
16 views

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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1answer
24 views

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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1answer
60 views

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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29 views

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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1answer
15 views

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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0answers
12 views

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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2answers
60 views

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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1answer
38 views

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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2answers
69 views

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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1answer
258 views

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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1answer
50 views

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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1answer
49 views

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 ...