Questions tagged [rotation]

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How to measure an optical encoder resolution and gear ratio?

I've bought a DC geared motor with an optical encoder. The vendor didn't provide specification. I can read MITSUMI M25N-2R-14 2241 and 25GA-370-12V-330RPM on the motor. There are some pages on the ...
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1answer
41 views

Multiple Rotations via Matrix Multiplication

so I am having an issue understanding why you right multiply for current frame rotation vs left multiply for fixed frame. Let us say you want to: Rotate about x, then Rotate about current y, then ...
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56 views

How to avoid gimbal with Quaternions

I'am working with an LSM6DSO32, so I'am starting with Kalman filter, everything works but with Euler angle I got gimbal lock I think... But if my pitch angle approach to 90° my roll angle jump and I ...
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1answer
59 views

Can the tangent space vector of SO3 be interpreted as Euler angles?

I want to compare the rotation of two cameras with respect to a common frame. Let's call these R_World_Cam0 and R_World_Cam1. ...
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24 views

How to compute linear speed on scooter without gps and wheel odometry

My project is to be able to compute my linear speed on my scooter only with my IMU. I have a IMU build with my arduino which is in my backpack. I want first to compensate the acceleration measurement ...
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55 views

What type of electric motor and speed-controlled circuit do I use to bounce a hanging, 5 pound weight? (it's for a Halloween decoration)

I'm trying to make a roughly 5 pound, hanging halloween decoration bounce on a string from about 1-3 times per second, preferably at variable speeds if I can. I've looked up a simple DC motor circuit ...
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1answer
60 views

Inertial frame's angular velocity expression

I'm following a robotics course on coursera which talks about aerial robotics and more specifically quadrotors. I'm trying to understand the logic behind the relationship between the angular velocity ...
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1answer
102 views

Calculating rotation matrix efficiently

I'm trying to efficiently calculate the vertical offset of each corner of a rectangular base. I have an accelerometer mounted in the middle of the base, ADXL345. The steps I have taken, and seems to ...
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1answer
93 views

How to handle robot movement close to coordinates x=0 with atan2

I am working on controlling a robot to various points on an x,y grid. The robot starts at random locations and I can control it's velocity and angular velocity. Currently, I am using the technique of ...
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2answers
94 views

How can I draw a line using rotation of two circles?

I’m building a drawbot with a self imposed constraint that it’s method of motion is just two rotating disks. One holding the paper and one holding the pen. However, the math to calculate the right ...
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1answer
30 views

How do I calculate components of an angular rate on end effector frame?

I’ve helped develop the forward kinematic chain for a two-axis gimbal. The Denavit-Hartenberg parameter table for the kinematic chain is given below. $\theta$ $\alpha$ $r$ $d$ $90^{\circ}$ $90^{\...
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179 views

IMU Change of reference frame

Im trying to rotate one accelerometer vector from body frame to ned frame, but i cant found what im doing wrong. For now, im using an online dataset that provides me roll, pitch and heading ...
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77 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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62 views

Rotate while strafing with mecanum wheels

I have a robot with a drivetrain that is comprised of 4 mecanum wheels. These wheels are able to move vertically and horizontally, as well as rotate. The robot is square (18in x 18in) with the front 2 ...
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2answers
48 views

What type of rigid body rotation can best be learned by neural networks?

I am training a reinforcement learning network in simulation for a robot which at the current stage learns Euler Angles to rotate the end-effector based on the actual state. The performance is overall ...
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19 views

What could cause quaternion error to go up drastically when a gyroscope is rotated on more than one axis at a time?

Alright, I'm working on a small Arduino script that determines orientation using a a gyroscope and a quaternion. My hardware: LSM9DS1 IMU (Gyroscope, Accelerometer, Magnetometer) Teensy 4.0 My basic ...
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1answer
41 views

Does every rotation vector has an one-to-one corresponding rotation matrix?

Given a rotation vector, can we always get the same corresponding rotation matrix computed by the Rodrigue's rotation formula?
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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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40 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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1answer
173 views

Conveyor Belt Calibration for a Robot - Rotation Matrix

Short Question: As demonstrated in the image below, how can I calculate the rotation matrix that relates the base coordinate and the rectangle coordinate, given 3 known points P1, P2, P3 on the ...
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1answer
40 views

what are shoulder ball and socket joints called? (i am trying to design and build a hydraulic assistance mech suit)

I'm having problems finding the right sort of joint for my shoulder connection. It is a flat surface on the side of the mech body and I need to create a joint with maximum movement rotating: up, down ...
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2answers
80 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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2answers
330 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
82 views

Rotate coordinate frame using 2-axis inclinometer angles

How to rotate coordinate frame (transform point or vector coordinates) using angles from 2-axis inclination sensor if both X and Y angles are non-zero?
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1answer
37 views

Doubt about axis\angle representation

I am trying to understand the axis/angle representation. So far, I have understood that the main idea is that every rotation can be represented as a rotation around an arbitrary axis of an angle $\...
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1answer
72 views

Reset coordinate system of robot while maintaining relationship to the previous

I am currently estimating a robot's pose (3d position and rotation matrix) with an IMU and I want to reset the localizer in the middle of the run while keeping the relationship to the pose it had when ...
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1answer
130 views

What is my last rotation matrix for the last three angles when i have found the first three when doing inverse kinematics to a 6dof robot?

I am doing inverse kinematics for a 6dof robot. I have used the geometrical method to describe the angles from one to three. I have trouble doing the next part. I know I that I have found the ...
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1answer
35 views

Finding quaternion Q, where Y = q * X * q.inv()

Problem Quaternions $X$, $Y$, which represents 3-dimensional points are given. Quaternion $q$ is what is to be solved. I want to know unknown rotation between $X$ and $Y$. In other words, I want to ...
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51 views

What's the result of multiplying a rotation matrix having only ψ components by another which has (−φ,θ,−ψ) components?

Given the following rotation matrix: $ R(φ, θ, ψ) = \left( \begin{smallmatrix} cos(θ)*cos(ψ) & -sin(φ)*sin(θ)*cos(ψ)-cos(φ)*sin(ψ) & -cos(φ)*sin(θ)*cos(ψ)+sin(φ)*sin(ψ) \\ ...
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1answer
140 views

Solving for rotation matrix: Aligning vector a with vector b and then rotating around vector b

Currently working on a quadcopter simulation. I have a desired thrust vector, t =sin(30)cos(45)a1+sin(30)sin(45)a2+cos(30)a3 and desired yaw angle, ...
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2answers
176 views

How to compute the orientation error between two 3D coordinate frames?

For my master thesis in robotics I have to compute the orientation error between two coordinate frames, called E and H. Their orientation is expressed through rotation matrices (3x3) with respect to a ...
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1answer
114 views

Rotating a lever with a small servo

I'm trying to rotate a lever link to gently "offload" a load using a servo. Here's a drawing: Here, the red is a lever, yellow pivot and black is the load. To offload, the lever needs to be turned 90 ...
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31 views

MPU6050 Gyro rotaion always around Y axis

I am using an MPU6050 IMU. I did a small experiment having Z-axis pointing upwards. 1. Rotate 90deg around Z-axis (yaw) and back to the original position 2. Rotate 90deg around X-axis (roll) and back ...
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34 views

Moment of Inertia of a planar rotation link with a 6-DOF base

I'm interested in analytic calculation of a moment of inertia of a robot's arm in the following situation. Let us assume the following: Stationary reference frame $ \{b\} = \{X_B, Y_B, Z_B\}$ and ...
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2answers
360 views

How to calculate heading more accurately using dead wheels?

I am trying to figure out a more accurate way to calculate the change in the heading of a robot. I have two small omni wheels on either side of the robot facing forward and one on the right side ...
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1answer
2k views

Rotating NED to ENU

I have an IMU in NED of which I need to rotate to ENU to conform with ROS. I know its a roll of pi and a yaw of pi/2 but what ...
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1answer
71 views

Does Vehicle Yaw angle measures same at every point on it? If not, how to translate yaw rotation to COG of the vehicle from different point?

I am using an IMU to measure the yaw rotation angle of a car. I need to translate the rotation measured to COG of the vehicle. I can ignore roll and pitch as I am driving it on a flat surface. So, ...
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1answer
697 views

What are wheel ticks and wheel impulses?

I'm tracking the position of a vehicle along a certain trajectory using the Kalman filter and we have odometry data provided to us which gives the x-position of the vehicle, y-position of the vehicle ...
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131 views

How to get RPY(Roll, Pitch, Yaw) from directional cosines from a single vector?

I'm trying to find the pose of an 3D vector in terms of RPY. Let's say the two end points of the vector is P0(x0, y0, z0) and P1(x1, y1, z1). So the centered vector I get is V(Vx, Vy, Vz) = P1 - P0 = (...
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73 views

Rotation at SerialLink.teach Robotic Toolbox

Im using robotic toolbox to simulate my robot, but i always confused when i see the value of rpy. It always different if i compare with tr2rpy and tr2eul. What kind of rotation used in SerialLink....
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26 views

Observed position update after motion of the robot

The equation (14) in this paper, $$ P_{Cj}=RP_{Pj}+T+e_j $$ where $P_{Cj}$ and $P_{Pj}$ are the observed positions of feature $j$ prior to and after the current robot motion, $R$(otation) and $T$(...
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Undo pitching effect of camera when pose (y-axis) is near 90 degrees?

I am using KITTI odometry dataset whereby the camera's axis is pointing X (east), Y (down) and Z (north). It also contain the frame to frame poses of the camera (first pose is fixed as the map frame). ...
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1answer
20 views

How should I create a Pangolin (Armadillo) structure?

I am new to this forum. I want to create a mechanical structure as depicted in the image A pangolin bag. And further wouls like to automate the closing and opening of the bag. But I am facing issues ...
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1answer
406 views

Adjusting the PWM frequency and duty cycle to achieve the desired angular velocity in differential drive robots

I am practicing C++ and intro to robotics using a simple differential drive robot and a raspberry pi. Also following along the GA Tech course on control of mobile robotics. The implementation I am ...
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2answers
1k views

Finding correct RPY for approaching a known point on a plane

I have a robot with 6 DOF that I want to use to grab a hanging sheet at a specific point near its edge. The grip needs to be perpendicular to the edge and co-planar with the point of course. I have ...
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1answer
676 views

How can I attach an arm to a double-flat drive stepper motor?

This is my first robotics experience, outside of one class 10 years ago. I've been Googling this question for about an hour but I can't find an answer! I'm using a ROHS Step Motor 28BYJ-48 (with an ...
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3answers
283 views

Forward Kinematics with matrices

From the image, I would like to find out how joint 1, 2 and 3 can be computed by using forward kinematics? (Assuming a theta value was given) I understand that to get point 3 to origin (...
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1answer
3k views

Using pre multiply or post multipy for rotational matrix to get a new homogenous transformation matrix?

I am confused about how do I multiply the rotational matrix in this case. I know that both T1 and T2 needs to be multiplied by a rotational matrix but I don't know how to multiply the rotational ...
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5answers
5k views

Why Euler Angle is set to be in ZYZ order?

We have 3 DOF for rotation in 3D space. So to describe an arbitrary rotation, we need to describe its 3 DOF. Euler angle does this by dividing a rotation in 3 steps, first rotate along the Z axis of ...
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1answer
2k views

Get Yaw from quaternion

I found a formula online to extract yaw from a quaternion like so: ...