# Tag Info

### If I must fly my drone in bad weather, how can I maintain control of it in strong winds?

In controls this is known as disturbance rejection. In order to sustain your motion in the presence of high winds you need the controller to be as responsive as possible, and an accelerometer would ...
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### Instantaneous velocity calculation from accelerometer?

The only way to get a velocity from an accelerometer is to numerically integrate the output of the accelerometer. That is, $$v = v_0 + a*dT \\$$ where $dT$ is the elapsed time between ...
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### How to estimate yaw angle from tri-axis accelerometer and gyroscope

Assuming your vehicle is roughly horizontal to the ground, you won't be able get a good estimate of yaw from the accelerometer. Consider the nominal case: when your accelerometer is pointing straight ...
• 2,679
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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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### How to interpret and use values of an accelerometer

You should really read the datasheet that acs linked in a comment to your question. The device you're using has a set of 16-bit analog to digital converters (ADCs) that convert the actual outputs of ...
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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 ...
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### Stabilising an inverted pendulum

There are lots of ways to solve this problem, which falls into the category of Control Engineering. There are two standard approaches: Classical Control: The control command has to be proportional ...
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### How to estimate yaw angle from tri-axis accelerometer and gyroscope

Gyroscopes will only give you the rate of change of the yaw angle, not the absolute yaw angle. Unless you plan to set the yaw angle initially and have it drift further and further into garbage ...
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### What does "6 degrees of freedom" mean?

Most "meters" of all varieties include up to three degrees of freedom simply to observe all three dimensions of reality we find ourselves in. That said, every object in our three space has three ...
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### Accelerometer deterministic errors

Cross-axis sensitivity: A reading on one axis creates a false reading on another axis. This could be because the signal traces are close together and capacitive coupling induces a voltage on the ...
• 14.7k
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### Complimentary filter issues

There are quite a few things wrong here. I'll split them into two sections: technical errors, and coding warnings. Technical Errors: You are not calculating your angles from accelerometer readings ...
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I encountered the same puzzle. I had a clue at the beginning that the gravity information is contained within accelerometer measurements due to aerodynamic drag. Then I found a paper The True Role of ...
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### Which sensor type most accurately measures position?

I would use linear or rotary encoders - the difference in terminology, encoder vs. potentiometer, is in the fact that any linear potentiometer could be used as a linear encoder, but not all linear ...
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### 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 ...
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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 ...
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### Accelerometer calibration - how to get cross-axis sensitivities

I realize this question is 2 years old, but I have direct recent experience with this. The way I did this is with 6 rotated cube positions with 1000 points at each position, so a total of 6000 ...
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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, ...
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### How to calculate Euler Angles from gyroscope output?

Using the Gyroscope First thing to note is that the gyroscope is reporting angular rates with respect to the sensor. So if the sensor is rotating with some rate, the data it's outputting will be in ...

### How to calculate Euler Angles from gyroscope output?

First you need to integrate the output from the gyro to get the actual X, Y and Z angles. angleX = gyroAngleX + gyroInputX angleY = gyroAngleY + gyroInputY ...

### How to calculate Euler Angles from gyroscope output?

Look into a complementary filter. It isn't the correct way to go out this but it will give you usable data for attitudes around level. It's also worth mentioning that you will not be able to track yaw....
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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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### Stabilising an inverted pendulum

The theory that describes what you are looking for is call Control Theory. Search for the Nonlinear Systems textbook by Hassan Khalil for an excellent overview of the material--the inverted pendulum ...
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### Localising a robot placed at an unknown position in a known environment

The problem is that you can't apply path planning until you know where the robot is in the global coordinate frame. There are many localization techniques, and each has its pros/cons; I have used ...
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### Can I use a 3D gimbal system as a simplistic quadcopter IMU(3 axis accelerometer)?

A gimbal system will not replace an accelerometer. I assume by gimbal system you mean something like a Gyroscope, i.e. a device that has a fixed orientation allowing you to measure your orientation ...

Accelerometers measure kinematic acceleration with the addition of gravity. So for an accel to measure 0, the vehicle would need to be accelerating downward at $g$. To get inertial acceleration out of ...
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### Compensation for IMU mounting misalignment

You need the transformation from the car to the IMU. You can get this by recording the IMU published attitude with the car in known orientations. You should be able to construct the IMU to car ...
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### Data collected from ROS

As Ben noticed, you may want to elaborate on your question, but in general data collection in ROS is performed using tools from the rosbag package. As you'll find when you read the documentation, ...
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