Saturday, 14 June 2014

Pitch Mixing (Video)

posted 23 Sep 2011 01:55 by David Taylor

I recorded a quick video this morning showing me testing TriRot’s Pitch Mixing routines. I zip-tied a pivot beam to the chassis to limit movements to the Pitch axis only and also commented out the mixing code for Roll and Yaw.

In the video you can also see TriRot going through its full pre-flight self-check. Flashing the LED’s 5 times after the motors spin up for the first time means all is good and we are ready to go. I temporarily set channel 5 on my remote to be a kill switch. When this switch is toggled it either sends command to the motors and servo, or not. This is very handy for this part of the testing, where I’m not quite sure what TriRot will do as soon as it lifts off.
Below is a graph based on the data I captured during this test:
·         The top blue line is both the left and right motor speeds.
·         The Green line is the throttle
·         The orange line shows the rear motor speed.
·         The red line shows the input from the Received. It shows that I did not control TriRot from the Transmitter and that it is self-stabilising. (Notice that it is biased a bit forward in this graph and not on zero, because the pivot is a bit too far back so there is more weight in the front.)
·         The blue line in the bottom shows the Yaw input from the IMU.
I have done exactly the same testing to sort out the Roll axis. Tonight (possibly) I will be testing the Yaw axis. I think this is going to be a bit more complicated because I need to be able to override the IMU Yaw over time; otherwise TriRot will always try to turn back into the direction it started up in. But, when I’m not applying any Yaw input it should hold in that direction.
Watch this space.

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