If you are flying a UAV DevBoard in a plane without ailerons, you should be interested in a recent revision to MatrixPilot that will tighten the turns in waypoint mode, without overshoot. The above picture is the track of a portion of a test flight in an EasyStar. The control mode was switched from stabilized mode to waypoint mode with the EasyStar flying away from the first waypoint. So the controls performed a tight (less than 15 meter radius) "snap-turn", with very little overshoot.
Up until now, the only way to prevent turning overshoot with MatrixPilot was to use a large value for the yaw damping parameter. Although that certainly prevented overshoot, it made the turns very wide. The latest revision prevents overshoot, while still enabling tight turns.
The revision is rather simple: an optional negative feedback term equal to a gain times the roll has been added to the rudder control. The effect is to reduce the steering time constant. It is equivalent to controlling the roll rather than the yaw rate. It is something that has been on my list to do for a long time, I finally got around to it. Rana and Sid have been using this feature unofficially for some time, they encouraged me to add it. Also, there have been posts from time to time from other authors recommending roll-based steering. MatrixPilot has always used roll-based steering with ailerons, but until now, for mostly historical reasons, it used yaw-based steering with rudder.
The new parameter is ROLLKP_RUDDER in the options.h file of MatrixPilot. It is now available in MatrixPilot2.5 in the branches directory, or in the "developers" version in the project main trunk, or as a version 2.5.1 zip file. If you want to try it out, to start with set ROLLKP_RUDDER to the same value as YAWKP_RUDDER. For an EasyStar, set them both to 0.15, and set YAWKD_RUDDER to 0. For now, leave "dead-reckoning" and "cross-tracking" turned off, I am working on improving the performance of both of those. Right now they are not performing up to their potential.
The following is a portion of the track during a test with an EasyStar in which ROLLKP_RUDDER was deliberately set to 0, with YAWKP_RUDDER = 0.15, and a modest value of YAWKD_RUDDER (I forgot what it was.) to show what happens without rudder-roll stabilization. Note the large amount of slowly decaying overshoot after the snap turns.
So, if you are using MatrixPilot in a plane without ailerons, I highly recommend trying this new feature, it should improve waypoint performance.