Hello, I'm having a hard time getting output 8 on my APM 2.5 to control any of the three Savox servos on an AV200 gimbal. The servos freakout, jumping to random places, jittering, etc.
APM 2.5.1
Mission Planner v.1.2.26
ArduCopter v2.8.1 Hexa
Spektrum DX7s to (AR8000 receiver for flight control and AR6115e for gimbal control)
PhotoHigher AV200 gimbal with the following servos:
Savox SH1290MG (roll/dutch)
http://www.savoxusa.com/Savox_SH1290MG_Digital_Servo_p/savsh1290mg.htm
Savox SC1258TG (pitch/tilt)
http://www.savoxusa.com/Savox_SC1258TG_Digital_Servo_p/savsc1258tg.htm
Savox SC0252MG (yaw/pan)
http://www.savoxusa.com/Savox_SC0252MG_Digital_Servo_p/savsc0252mg.htm
in6 = out A11 (pitch)
in7 = out A10 (pan)
in8 = out8 (roll)
The gimbal servos work great out of outputs 10 and 11, which I understand are 50 Hz data rate. None of the servos function while connected to output CH 8 which, I understand, outputs 490 Hz.
Info on some forums reveals that these Savox digital servos work at 330 Hz and 250 Hz. I had to search quite a bit to unearth that spec, it doesn't seem to be listed in the manufacturer's technical specs. Is there a way to calculate this based on other available specifications? Or do all "digital" servos work within a certain data rate range?
I have a feeling that the data rate on outputs 7 and 8 is too high for these servos.
Is the data rate selectable for output pins A0 thru A11?
Or, alternatively, can the servos be calibrated to function at a certain data rate?
Also, is output 9 ever going to put into play? And, lastly, is there a document that explains all the parameters in the Advanced Parameter List in detail?
Any help would be appreciated. This is the last thing I need to get working on this setup before I go out and test it. Thanks in advance!
Replies
Hi Julio,
Have you solved the problems with the servos,
I am getting lots of jumping and jittering when I connect the AV200s servos both in A10-A11 and Ch8 ,Ch7 is there any solution to this?
Thanks
You could hook the pan up directly to the radio depending on how you want to use the pan function. Then that would allow the roll and pitch to be on the APM channels that work better for the digital servos (10 and 11). Not a great solution but it would smooth things out for the roll axis. Or maybe use a different channel besides 8 (don't have Mission Planner in front of me to see if this is possible). If there's a way to make channel 8 work better I'd like to know as well, currently using a two axis gimbal but would like to upgrade to a three axis at some point down the road.
I tried setting the "RC Speed" parameter in the Advanced Parameters List to "125" (from where it was at "490") but the servo didn't respond well to that either.
Some interesting information on this topic:
http://www.spartan-rc.com/resources/faq/faq.php?topic=1
http://www.spartan-rc.com/resources/faq/faq.php?topic=12&catego...
I guess that answers the digital servo side of the question. Now I guess I just need to find out how to change the frame rate of output A08 on the APM 2.5.