11
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Quadcopter PID Algorithm
The glaring issue I see at the moment is that you are forcing polarity on the I and D terms. In general, you are using a lot of sign checks, sign assignments, and conditional programming.
None of that ...
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9
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what is the algorithm to get position (Linear displacement and linear velocity ) using IMU (Like MPU6050)?
I thought for sure that there would have been a duplicate question somewhere on the site that answers this question, but I can't find one, so here's a quick description of the method.
Put your IMU ...
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8
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Why do 3-axis accelerometers seemingly have a left-handed coordinate system?
The answer is that 3-axis accelerometers don't have a left handed coordinate system just for the gravity. In static condition (i.e. if the accelerometer is not accelerating with respect to any ...
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Open source implementations for GPS+IMU sensor fusion?
Yes. The px4 software for the pixhawk autopilot has an extended kalman filter that uses an accelerometer, a gyroscope, gps, and mag.
A paper describing the a smaller ekf which only estimates attitude ...
- 1,833
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What information an IMU gives to a drone?
You already know the answer - because as you say it contains an accelerometer and a rate gyro.
An accelerometer measures linear acceleration, a rate gyro measures angular velocity. These are the only ...
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Stabilizing a Drone
Gyro is needed to stabilize angular acceleration. Knowing only your attitude, drone doesn't know how fast on which axis is rotating, knows only where is gravity ...
- 440
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Explanation of Quadcopter Dynamics, Components and Control
A couple things, the first is that the controller does not really care what the "real" values are. Everything is relative, if the controller sees that it is sinking it will increase the thrust until ...
- 1,909
6
votes
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Kalman Filter GPS + IMU
This is a complete re-working of the answer I had originally provided. If you're curious, you can check the edit history and see what was posted earlier.
In comments to this question, OP stated that ...
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6
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How to avoid gimbal with Quaternions
Quaternions are a more efficient way of storing the orientation matrix of a frame.
I use the vector-scalar convention for quaternions (3+1 = 4 quantities) and have defined the following utility ...
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5
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How to track robot position?
How to estimate a robot's position depends on how well you'd like to estimate it. If you just need a rough guess, try odometry, it works OK. For better results, you have to incorporate more sensors. ...
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4
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How to track robot position?
I am not allowed to comment, so I have to add a reply. By position, do you mean the location in space (so X, Y coordinates), or orientation (tilt, etc)?
If position, you can use the accelerometer ...
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Angular velocities and rotation matrices
If your object $O$ has a different orientation from your global frame $S$, and you know what that difference in orientation is, you can create a 4x4 transform matrix between the two:
$$
T = \left[ \...
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4
votes
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Balancing a plate with an IMU offset from the center
Basically it does not matter.
But you have to be carefull if the plate is rotating fast, because the rotation of the plate around its center point, with the IMU placed out of center, will cause the ...
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4
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Open source implementations for GPS+IMU sensor fusion?
ROS has a package called robot_localization that can be used to fuse IMU and GPS data. This package implements Extended and Unscented Kalman filter algorithms.
The package can be found here.
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Pose-Graph-SLAM: How to create edges if only IMU-odometry is given?
First off, it doesn't sound like you're actually doing SLAM. You didn't mention an exteroceptive sensor (e.g., laser, camera) that actually maps the environment. With just an IMU, you are doing ...
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Practicality of using magnetometer inside AUV
Mags are used in almost all UAVs. It will be useful and it will be a unique source of information.
Adding a some shielding between the mag and your computers and power lines will greatly reduced the ...
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4
votes
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Detection of linear acceleration vs rotational velocity/acceleration
The IMU itself cannot distinguish between "true" linear acceleration and "fictitious" (Coriolis) linear acceleration induced by rotation of the IMU coordinate frame with respect to ...
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What is the consquence of Gimbal lock?
I made a clip for you (https://imgur.com/a/KPeQ7Ia) using Unity, which internally represents rotations as quaternions, but uses Euler angles for display and positioning.
You can see that, at zero ...
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4
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Why do we need to know the translation between Camera and IMU?
You answered yourself.
Your underlying model of point moving through space usually assumes the center of gravity to match the camera frame.
If your inertial sensor have a translational offset from ...
- 211
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votes
Simple Sensor Fusion for pose estimation
So you have acceleration readings from your IMU (linear and angular), and you get velocity readings (linear only) from wheel encoders.
Get velocity from linear and angular accelerations with
$$
v = ...
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3
votes
Displacement with accelerometer
This will depend on what you mean by "displacement" and for how long you want to do this. Can you supply more details on what your trying to accomplish and why?
As Bending Unit 22 mentioned, you ...
- 106
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Simulate IMU (2D gyro and accelerometer) data
This is really simple. First of all, you need to understand how the sensor works. In other words, you need understand whether the measurements is coming from linear or nonlinear model. Second, what is ...
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votes
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How do I get MPU 6050 gyroscope data using "MPU6050_6Axis_MotionApps20.h" library
I went through the header files of the 12cdev lib and I figured it out.
you have to first add the line VectorInt16 gyro; to your motion variables, then you add the line
mpu.dmpGetGyro(&gyro, ...
- 397
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How to estimate yaw angle from tri-axis accelerometer and gyroscope
yaw can be measured by rate gyro and magnetometer not with accelerometer because accelerometer values depends on gravity component but on rotation in z axis only there is no change in gravity ...
- 31
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Minimising lateral drift in a PID (Arduino) controlled quadcopter using a 6DOF IMU
IMUs have accumulating error and can not be a reliable sensors by themselves if you want to measure velocity or even worse, position.
I believe your safest bet would be doing a sensor fusion between ...
- 306
3
votes
Minimising lateral drift in a PID (Arduino) controlled quadcopter using a 6DOF IMU
Unfortunately, with just an IMU there's virtually no way for your quad to know that it's drifting so it can't stop it.
For outdoor flight you can add a GPS to detect the drift. For indoor flight, ...
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imu position without GPS or camera
No, it is not possible to eliminate the cumulative position error caused by sensor noise and bias without using an additional sensor which can report any kind of position measurement.
Even the best ...
- 550
3
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Is there a way to measure 3 axis orientation without a magnetometer?
Calibration procedures for magnetometers exist, to compensate for soft iron (nearby ferromagnetic objects) and hard iron (nearby magnetic fields) offsets, which skew the measurements. However, these ...
- 550
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Multi-Rate Sensor Fusion using EKF
Part 1. Use one or the other. Often odometery is used instead of kinematics or dynamics for prediction, at least in my work.
Part 2.
This is handled by the construction of the measurement equation ...
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Using Accelerometer, Gyroscope and any sensor to track speed, position,
You are essentially making your own IMU. The way this works is essentially:
the accelerometer gives you linear acceleration
the rotational gyro gives you angular velocity
integrate the rotational ...
Ben♦
- 5,780
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