Manual tunning tips explain!

ArduPlane Plane 3.9
1

After autotune ,the plane can flight almost steady .In order to increase accuracy of the plane ,I try to use manual tunning .Who can explain the meaning of the following three paragraphs in the manual.

  • WARNING : If PTCH2SRV_IMAX is set too high, then there is a danger that in FBW-A, if the model has been levelled so that zero pitch is too nose-up to glide at a safe speed, that the integrator will continue to keep increasing the elevator to maintain the demanded pitch angle until the model stalls. PTCH2SRV_IMAX should be set to a value that is big enough to allow from trim changes, but small enough so that it cannot stall the plane.

  • The rate of pitch (and therefore the reduce the number of g’s) used to correct pitch angle errors can be limited setting the pitch rate limit PTCH2SRV_RMAX_DN and PTCH2SRV_RMAX_UP parameters to non-zero values. Setting these values to 560 divided by the airspeed (in metres/second) gives a limit equivalent to approximately ± 1g.

  • The time constant parameter PTCH2SRV_TCONST can also be used to adjust how rapidly the pitch angle reaches the demanded value. The effect of this parameter will be seen mostly in the response to small step changes in demanded pitch. For larger pitch demands, the pitch rate limits PTCH2SRV_RMAX_DN and PTCH2SRV_RMAX_UP tend to mask its effect. Making this parameter smaller will cause the aircraft to reach its demanded pitch angle in less time, but only if the aircraft is capable. A very slow responding airframe may require a slightly larger setting for this parameter.

  • Plot the pitch_speed in the tuning window. This shows the rate of pitch in radians/second. A value of 1 radian/second is approximately equal to 60 degrees/second (57 to be more precise), so if for example you had PTCH2SRV_RMAX_DN /UP set to 30, the maximum pitch_speed when responding to a large pitch angle demand (eg full pitch one way to full pitch the other way) should be just above 0.5. A value of greater than 0.6 would indicate that PTCH2SRV_P is too high and should be reduced, whereas a value of less than 0.5 would indicate that RLL2SRV_P should be increased.

Do I need to change these parameter or just let it as default value ?

2

Honestly manual tuning is rarely needed if you run an auto tune. The defaults are great!