Dave Mincin's Posts (2)

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My IMU stabilized bike has yet to (intentionally) leave the ground, so it doesn't get very far away from me.  I'm not sure if this would be useful to those of you with drones - definitely not planes, but maybe quad rotors could benefit?

From the beginning, I've been sending data from the bike to my laptop and logging that data so I have some idea of what's going on.  It's been useful for bench testing as I can lean the bike and see the graphics on the screen change or I can watch the noise on the accels when the motor runs and see that I need to adjust the filtering, etc...

The problem is when I go to run the bike and see something funny happen, I can't go back through the data and pinpoint the exact instance that the glitch occurred.  I don't know when the bike is in a turn if it really knows the current lean angle or is the lateral acceleration throwing off the DCM at the time.  I can try and watch the laptop screen and the bike at the same time, but that hasn't worked very well.  (Though this does seem like a good use for those Epson Moverio glasses. hmm..)

Well, this is the solution I've come up with for now.  The bike sends data to the laptop using a pair of Xbee transceivers (I can also send data back to the bike - currently just using this to update the PID constants).  The laptop logs this data to a file but also sends it to another application that is capturing video from a Dazzle USB frame grabber.  Using a DirectShow overlay filter the video capture application adds a time stamp and a limited subset of the data to the video frame.  Using this I can now go back and review the video footage along with all of the data that was captured during that frame.

Now I just need to wait for the weather to improve so I can get back outside.  I also need to look into a head mounted camera so I don't have to bug a friend to help out.

No doubt this has all already been done before, just thought I'd share...

Dave

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IMU in 1/4 Scale R/C Motorcycle

I noticed that Chris posted a while back about the use of an Arduino in an R/C car.  I've haven't posted anything here about my project as it's not autonomous, doesn't fly, and isn't really a drone.

It does, however, borrow code from the ArduIMU for the sensor fusion so perhaps someone may find it interesting.  "Normal" r/c motorcycles (yes, they do exist and are far more popular in Europe) use a loose spring linkage between the steering servo and the forks.  This allows the geometry of the bike to do the balancing and the servo can just nudge the bike to lean to one side (using counter steering.)  

My solution uses a more rigid servo connection driven by the output of a PID control.  The operator's steering input, the IMU's roll angle output, and the forward velocity of the bike are used to compute the steering angle to hopefully maintain balance while providing steering control.  Works well on road - real objective is for off road though.  

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