Skyview Autopilot on approaches

[rogersmart]

I am in the testing phase of my new RV-8A.  I am now testing and calibrating the servos and feel I have the sensitivity setting where it needs to be according to the installation manual.  I am also testing AP performance on approaches in visual conditions.  I have a 10” screen, SV 32 servos, Garmin GNS 430 connected with ARINC-429.  
On GPS approaches the autopilot steers flawlessly through the waypoints to the runway and on missed.  

Using the localizer the autopilot stays on or close to course then wonders off when I get about a mile from the threshold.  In 3 approaches it has drifted off to the right each time and did not recover.  Can you explain what might be happening on the localizer approach and how I can correct it?

Using a VOR, the autopilot stays on or close to course but when getting close to the VOR station, makes too much course correction and changes the heading by 30 degrees or more.  During this time it changes to Track.  By the time I pass over the station the autopilot is way off course.
I can see how the VOR approach could be confusing to the autopilot when close to the station.  How is the autopilot suppose to behave when close to the station and the signal is erratic?  What should happen after station passage?

When using both the localizer and VOR, the HSI indication was correct to my position.

 

[dynonsupport]

To start, what are all of your roll axis settings?

 

[rogersmart]

Here they are:

roll_servo_torque=100
roll_servo_sensitivity=9
bank_limit=30
turn_rate_limit=2.0
bank_mode=BANK_MODE_TURN_RATE

thanks.

 

[dynonsupport]

A few thoughts:

The AP follow the needs, period. So as you get close to the station, it's possible to get large deflections with a minimal off-course excursion. Since the AP doesn't inherently know how far you are from the station, this can be hard to correct. That applied to both VOR and LOC.

As for VORs - as you get close to the station, the VOR may flag. In that case, the AP jumps down to HDG/TRK mode automatically.

One thing to try is the alternate roll control mode. Turn the turn rate limit down to 0, and it will use an alternate bank algorithm. Then, it may use up to the max bank to control the aircraft, so you may want to play with that a bit (turn it down some if anything)