I was reviewing the energy-based control loops for fixed wing, and I had a few questions about the intended implementation. I notice that the example Mentor airframe for energy control is actually set up with no feedback loops for vertical climb control - in fact, there is only the P feedback for altitude, and then the throttle feedforward from the climb setpoint and the pitch feedforward from the climb setpoint, as all other gains are basically set to zero/undefined. Looking at the control loops, there are a number of similarities to the existing basic and airspeed control loops. There are also the considerable additions/improvements for the energy based control. Depending on which gains are defined a number of different behaviours can be obtained.
Currently, we are flying a Mentor with the same gains enabled as the conf/airframes/examples/MentorEnergy.xml file, with a few tweaks based on a different power/weight of our aircraft. This works, but the climb control isn't very good (since there is no feedback). The altitude control is quite acceptable for constant altitude and setpoint changes, but for, say, a constant glide slope, things are definitely sub-par. There are also oscillations, or if gains are reduced, time constant and steady state error increase.
What was the intended gain configuration for energy control? Which set of gains should be enabled and used together (all of them?)? Has anyone actually flown with the energy control gains vs the more traditional gains?
With a few more details, I would be happy to improve the documentation over the next weeks.