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# Brian Fanous

### MathWorks

21 total contributions since 2018

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Question regarding quaternion conventions; particularly with respect to point vs frame rotations
The quaternion class does follow the Hamilton convention – the scalar part is first. Point rotations are active rotations and c...

11 days ago | 0

Is there a mistake on The Help document?
See the diagram above the equations you’ve cited. The linear acceleration is decayed from one iteration to the next by the dec...

1 month ago | 0

Which are the state and measurement functions employed in insfilterAsync?
The documentation describes the state vector and the state transition function. The insfilterAsync uses a continuous time motion...

2 months ago | 0

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How to simulate IMU data and obtain variation of drift errors in the path?
For imuSensor, the input acceleration is the linear or translational acceleration in the global frame. The output acceleration i...

2 months ago | 0

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ahrsfilter tune sensor fusion
The ahrsfilter should give relatively good results without much tuning, but adjusting the parameters always helps. If you are st...

3 months ago | 0

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Problem with calculating relative orientation using quaternions
As I understand it you have two quaternions and and a third rotation that you are looking for which denotes the difference in ...

4 months ago | 0

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Problem with calculating relative orientation using quaternions
AM, Can you explain your setup a little more? What are you trying to achieve and why are you multiplying the two quaternions? ...

4 months ago | 0

Why don't the Sensor Fusion Toolbox IMU filters consistently provide the same results?
Hi Jaime The fusion filters are generally objects which retain state from one call to the next. In your example code, the first...

4 months ago | 0

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why the yaw angle from the IMU+AHRS block have cnstant error with the true yaw angle?
There are tools in Aerospace Toolbox and Aerospace Blockset to calculate the magnetic declination at any location. You can use t...

4 months ago | 0

why the yaw angle from the IMU+AHRS block have cnstant error with the true yaw angle?
It's tough to say what is going on without more information. Is this recorded or synthetic data and where/how was this recording...

4 months ago | 0

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Setup constant gravity vector for imusensor object of Sensor Fusion and Tracking Toolbox
Hi Jan The syntax you are using on the final line assumes the IMU always has its (body) coordinate system aligned with the g...

6 months ago | 1

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waypointTrajectory orientation is not matching
Hi Ravindra In the first example you are not specifying the Orienation so the waypointTrajectory infers that the vehicle is poi...

7 months ago | 0

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Position estimation using inertial sensor (dead reckoning)
Hi Swapril What your are trying to do is called “dead reckoning” and is not generally recommended with just an accelerometer a...

9 months ago | 0

whats difference beetween angvel and rotvec?
angvel gives you the angular velocity – essentially, change in orientation over time. rotvec is simply an alternate expression ...

10 months ago | 0

IMU and GPS Fusion for Inertial Navigation
Roman You can use either the insfilterMARG or the insfilterAsync without the Magnetometer. You will get drift in your orientati...

1 year ago | 0

Why ,the quaternion values from sensor fusion toolbox are switched ?
Hensham There are a few issues that might be going on. First, if you are using the NED convention of the imufilter, then you ha...

1 year ago | 0

IMU and GNSS fusion
Hi Silvia Sorry for the late reply on this. The various insfilters are based on a few sources. At least some of the MARGGPSFuse...

2 years ago | 0

AHRS sensor fusion IMU input values
Hi Ben Using magcal should definitely help. Collecting a good distribution of magnetometer samples is very important for suc...

2 years ago | 0

AHRS sensor fusion IMU input values
Hi Ben The ARHS filter has several parameters that will affect its response. The first 4 you have listed are related to the ...

2 years ago | 0

Is it possible to get position data of an IMU 9D: Accelerometer / Gyroskop /Magnetometer without GPS ?
You can use the orientation data from the ahrsfilter to compute the gravity vector and derive a linear acceleration, however the...

2 years ago | 1

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