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# Tag Info

## Hot answers tagged gyroscope

6 votes
Accepted

### 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 ...
• 1,278
4 votes
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### Is there a commercially available inertial gyro with electronic control?

The device you describe is known as a Control Moment Gyroscope (CMG). These devices are mostly used for attitude control in spacecraft, but are also commercially available.
• 562
4 votes
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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 ...
• 15.9k
3 votes
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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 ...
3 votes

### 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 ...
• 926
3 votes

### 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 ...
3 votes
Accepted

### 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 ...
• 926
3 votes

### 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 ...
• 1,853
3 votes

### angular velocity output of IMU

1) An inertial frame is one in which a free particle travels in a straight line at constant speed, or is at rest. Practically speaking, you usually check if a frame is inertial or not by ...
• 341
3 votes

### 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, ...
• 1,363
2 votes

### Use data from gyroscope to calculate orientation

Short answer: A gyroscope by itself cannot determine its global reference frame. You either need to start the device in a known initial global orientation and measure how much the orientation changes, ...
• 121
2 votes

### Localising a robot placed at an unknown position in a known environment

There are many tactics for localization in a known environment. the most popular ones are the Filtering methods which include Kalman filtering and Particle filtering. Nowadays the second one is the ...
• 400
2 votes

### Should I use gyro or encoders for robot moving in straight line?

The problem here is that you are trying to drive in a straight line without any external reference. Wheels slip (making encoders give error), gyro's drive (so there's error there to), magnetometers ...
• 151
2 votes

### Handling GYROSCOPE BIAS DRIFT

You say, Then why can't we track [the angles] for first ten seconds and then keep subtracting the present angles from initially calculated angles for every ten seconds during movement? You can't ...
• 15.9k
2 votes

### Angles from gyroscope readings using quaternions

I'll link you to some math but try to give a conceptual explanation, too. Consider a case where you want to start with the IMU upright and pointed forward and want to end with the IMU upside-down (...
• 15.9k
2 votes
Accepted

### Pitch angle is either +90° or -90°

The problem is that the quaternions given in id: 4 distance: 1048 q0: 646 q1: -232 q2: -119 q3: 717 are not normalized. In fact, $$\|\textbf{q}\| = \sqrt{q_0^2+q_1^2+q_2^2+q_3^2} = 999.6950$$ I ...
• 385
2 votes

### How is gyroscope bias exposed and tracked?

I think you're confused. The method you're talking about would only really work if you know the magnitude and orientation of the accelerations you're trying to measure. If that's the case, then why ...
• 15.9k
2 votes

### Convert local coordinates of a moving IMU to global coordinates

It isn't really a problem but a solution rather. The difficult part is pose estimation, comparison just needs to have a transformation between the estimated poses. There have been research works on ...
• 671
2 votes

### What is required to get the roll, pitch and yaw of an aerial vehicle?

The only sustainable long-term acceleration (for anything terrestrial) is gravity. The Madgwick algorithm uses gravity and a magnetometer to correct gyro drift. Watch the video, then head to the ...
• 15.9k
2 votes

### How to create a Complementary Filter for a linearly accelerating body to obtain estimate of orientation in quaternion?

The point of a complementary filter is combine the low-pass parts of some measurements (e.g. accelerometer) with the high-pass parts of other measurements (e.g. gyro). If the accelerometer perfectly ...
• 2,814
2 votes

### IMU gravity sensing

That is partly possible if you fuse linear acceleration and angular velocity. Estimate the gravity direction from IMU when the robot is stationary. Now you know the gravity direction. Once your ...
• 1,577
2 votes
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### angle rates wrt another frame

It sounds like part of the problem here is what frame the RPY derivative, $\dot{\mathbf{x}}_{RPY}$, is in. Considering the fact that the RPY values, lets call them $\psi, \theta, \phi$ respectively, ...
• 904
2 votes
Accepted

### Opposite direction of rotation calculated by Gyro and Accelerometer

Welcome to Robotics, KMC! One thing I noticed is that your equation gives $\phi=\arctan2(-a_y,-a_z)$, but you're calculating it as $\phi=\arcsin(-a_y/\cos(\theta))$. If your sensor is oriented as ...
• 15.9k
2 votes

### accelerometer and gyroscope fusion using extended kalman filter

You should be using quaternions for fusion for good behaviour. Addition and multiplication for quaternions will be swapped out by rotation composition operations for quaternions and your orientation ...
• 128
1 vote

### Does multiple IMU increase accuracy

For a quadcopter, I would argue that the benefit of multiple imu's does not justify the effort. The bias issue you mentioned might be reduced but unless you can guarantee zero bias you still have to ...
• 2,814
1 vote

### Does multiple IMU increase accuracy

Already from a probability point of view one can argue that the standard deviation of the mean drift goes down when stacking multiple IMU's together. However, things might also turn out nastier when ...
• 562
1 vote

### Does multiple IMU increase accuracy

Multiple IMU systems are used to make more accurate measurements. However, the main purpose of these systems is to take multiple measurements and make use of the differences between these measurements ...
• 1,124
1 vote

### Lego Mindstorms EV3 gyro sensor offset fix

Not sure about matlab/simulink, but siply substracting the offset is not possible? I would solve it in code, just ... dx=readDx(); dx=dx-offsetdx; ...
• 453
1 vote

### Do I need gyro sensor to make sure my automower turn 180deg if I already used 9DOF IMU?

A 6 DOF IMU refers to 3-axis accelerometers and 3-axis gyroscopes. A 9 DOF IMU refers to a 6 DOF IMU plus a 3-axis magnetometer. Since you already have 3-axis gyroscopes in your 9 DOF IMU, adding ...
• 4,545
1 vote
Accepted

### Why does one IMU axis influence another?

The problem is estimating angles in regions of instability. Let us look at equations used for estimation of pitch and roll angles. For aerospace rotation sequence e.g. $xyz$: \$\tan(roll)=\frac{G_{y}...
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