Recent content by FGD

It is the same project but different problem.

Hi everyone, I’m using the Adafruit ICM-20649 IMU attached to a frisbee, and I'm trying to capture the orientation data during the throw. In the attached data, you can see a throw with a 30-degree roll angle. The beginning of the throw is calculated correctly, but the yellow-highlighted area...

Is this correct? "arccosine(opposite/hypotenuse) using opposite = dot product(x, roll) and hypotenuse = dot product(y, pitch)? Below is exacly what I am trying to accomplish. Initial Orientation and Tracking During the Throw: Determining Initial Orientation: At the start of the throw, while...

This is the IMU. https://www.adafruit.com/product/4464. Nothing fancy.

I have an IMU that includes an accelerometer and a gyroscope. The IMU is moving through 3D space while rotating around it's z axis(yaw). Here's what I know so far: Velocity Vector: I have a 3D velocity vector (x, y, z) that was integrated from a resting position using the accelerometer data...

Wait, you can't retire! I need so much help! In all seriousness, I just want to say thanks for all your time helping others. You and the many others helping are truly awesome people! Enjoy your retirement!

Ok, thank you very much. I think this has been put to bed. The concensus is that you can not measure linear velocity from a rotating accelerometer. Velocity needs to be integrated from a known state. (like rest). I also thank all the ones who gave their insights. I learned a lot in this thread...

Yes, this is plotting the X, Y axis. All of the plots in this post are mostly from the same data so as to keep things consistant. As Z wobbles, so does the rotation around the X, Y axis. I am testing the conclusion that the sin wave in the accelerometer X, Y data is due to the wobble. In post...

Ok, so I've been working with the data and the wobble does not seem to contribute a lot to the accelerometer values. I used a fairly large value for the z offset from the center of rotation. (A value of 13mm). I take the gyro value (in rad/s) and calculate centripetal acceleration using this...

That makes sense. I am going to try and model this but need to make sense of the data. It looks like from the model in the video that the foot of the bear (logo) is pointing down on the right side and then pointing up on the right side so there must be a rotation around the axis. (Like the video...

Yeah, it is a fairly cheap acclerometer. The z gyro saturates past 4000dps. The x and y gyros actually give a fairly similar sin wave to the accelerometer data. Here is an image of the accelerometer and gyro data plotted together. So, after seeing this would you conclude the sin wave is from...

Yeah, I will have to take into account lift, orientation, etc. But then it should be better than what kalman filters can do alone atm. Just need to make sure it is actually deceleration causing the sin wave.

That is what I was wondering earlier. If it measures deceleration then I believe you can determine instantaneous velocity. (Haven't seen info on this though, so maybe I'm missing something.) I love all the different ways of looking at this problem so far. Very interesting.

Way to make things more complicated. lol It's a relief the earth won't flip on it's axis though. (Had me worried for a sec) :)

This is the accelerometer I am using. https://www.adafruit.com/product/4464. The accelerometer is fixed 3 axis attached to the plate. It has a separate gyroscope that has no effect on the accelerometer from what I see. So the sin wave has to be from another source correct? Also the simulation I...