Need help on final antenna tracker tweeks.
I've built it (YAY ME!).
The Parts:
I used this as a guide and I followed right down to the decimal on the setup EXCEPT instead of 360deg from center to left and 360deg from center to right I put in only 180deg of travel in each direction. That means that the pwm numbers are a little smaller in range than what is posted on the link for the set up but other than that its darn near identical.
I used the eagle eye antenna tracker body (long story, had one designed, did not work out).
Mine uses the same servo for the pan, namely this one, and for the 90 deg tilt I used this one.
I used this servo controller.
If I control the tracker via the Maestro servo controller card's universal program I can get the range of motion exact with the tilt, the pan is a little off on one direction by about 20deg or so. I can't get it perfect no matter what I try.
The Description:
So here is what I need help with, I'm sure someone has tackled this problem, it's got blatantly obvious signs. And one more thing, I have read EVERY page on instructions for both the Mission Planner and all instructions for this build, but this is still kicking my ass. It seems as if I am the only one that does this in the entire Dallas/Fort Worth area so asking you guys for help is my only recourse and I thank you all ahead of time for any help given!
Settings:
This is what is plugged into APM Mission Planner for the Antenna tracker settings:
Interface: Maestro, COM3, 115200
Pan: Angle 180, trim at 0
Tilt: Angle 90, trim at 0
Both PWM entries at 1000
Both have REV checked.
In the Flight Planner section I have Absolute Alt unchecked. Alt(abs) is fed from google maps and reads 242 meters. The FAA maps say my altitude is 763 feet above sea level, so these numbers are very close and I consider them correct.
Meters and meters/second is the Dist Units and Speed Units set in the Configuration tab, Planner section.
For the Maestro software settings:
When I fire this system up I point the antennas due north manually. I click on the home position link in the Flight Planner section and it locks there. When I connect to the plane (telemetry) It then starts to track. I then pick up the plane and move around in a circle about 60 feet away or so to see if it tracks.
This is the behavior:
Sometimes it tracks fine, but only through a certain range of motion. After this range (about 50deg or so) it then goes wonky, it spins 180 degrees. I know it is supposed to, but it has NOT completed the range of motion before it spins to keep the antennas pointed at the plane.
If I adjust the trim to about 50-60 this spin also occurs but after that spin it seems to track proportionally to my trim input, until I get back to about 50-60 degrees and it again does the spin. Keep in mind the Maestro software range of motion is SMOOTH, but not the AP Mission Planner behavior.
This spin throws off all tracking.
I get the feeling that the altitude tilt is not correct either. In the lower right corner you can manually input an altitude. If I increase it incrementally the behavior should be that the tilt goes up incrementally too (I'm talking like 10m in altitude change at a time) but it does not behave like that. The tilt too wants to reach a certain degree and then it goes to the opposite end of the range spectrum.
Summary:
1) What is that extra 20deg of motion from center to left?
2) Why wont this sucker track correctly?
3) Is altitude always in meters if I set it so in the Configuration tab? As in EVERYWHERE in the Mission Planner, or are there some parts that always remain in meters, seconds, kilometer units? Is all altitude measured in absolute?
Replies to This Discussion
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Permalink Reply by Burt Green on -
I have a setup very close to yours, I've been working on.
I use the same Tracker base, same control pcb, and am using the Mission Planner.
One thing that I do have that’s different is the track servo. I was just using a normal one. (the gear setup with the tracker will let it rotate 360 degrees)
I did have to change it to a high torque servo to get it to work all the time. I found that it would work, but after a while it would start doing what you describe. I would think it was the mission planner, but started watching the Maestro Servo Controller and see that the mission planner was moving the servo, but it didn’t move.
I also set it up for 180 degree movement, I setup and fly to the west and south of where I fly so a setup of 180 degrees is good.
I also reduced the pwm number in the Mission Planner Configuration tab and played with that number till it tracked well.
One question, I see two ant's on the tracker, one for video, what the other one for?
Later
Burt
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Permalink Reply by Chad Frazer on -
So, by playing with PWM number in the mission planner you were able to get it to behave 100%?
I was worried that the gear ratio would indeed throw off the tracking as (I guess) the Mission Planner ASSUMES a 1:1 servo to antenna tracker body ratio.
One antenna is for 1280Mhz video and the other is for 900Mhz telemetry (the 3DR radio is in the black box). They are both 8dbi boost (gain). This adds weight and therefore makes tracking less smooth, but I think if I can get it to "track" then it will be ok as it would rarely need to move quickly.
I'll mess with the PWM till I can get it to work, past that, I'm still stumped.
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Permalink Reply by Burt Green on
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You do know you can test it out with saved telemetry logs?
Mine seemed to track ok till I had some flight time on it, thats when I found out the servo was having problems.. Watch the servo controller program and see that the tracker moves the way the mission planner tells it.
I adjusted the PWM to a lower value in the mission planner, I think the way the planner is programmed, it takes the number that is entered and sends a value to make the tracker move. When my plane was at the far right of the tracker I found the tracker itself was stil about 10 to 15 degrees off, so I started to reduce the PWM and it seemed to work.
I do wish Micheal would place a direction value on the main screen of the planner, like he has with the gps hdop and sats. Be nice to see just where the tracker thinks it's pointed like 270*.
Burt
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Permalink Reply by Chad Frazer on
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720. Yeah, that's the magic number. After a long time fooling around with it, when I entered 720deg for the angle for the pan and I kept the PWM numbers to what they were actually set at in the Maestro software that programs the servo controller it seemed to track well.
Now for the sad part. When the servo tries to spin the tracker too fast, the servo slips and the tracking is off permanently! So I remodeled the tracker and lightened it up and balanced it far better than the first attempt. It still slips. The servo for the tilt works like a champ as far as handling the strain of the two patch antennas but the pan I just can't get to behave.In order to pick out a better servo I need to understand some things, perhaps you guys might help?
1) The torque rating for this servo is 7.6 kg·cm which it can rotate the tracker just fine, unless its a small increment, then it gives that typical servo RRRRRRR sound. I imagine that the plane would just have to go far enough past the cords given to make it want to move the tracker "far enough" to get it past this stall? I don't think I want that as a characteristic correct?
2) I realize I don't need 360 in each direction, so if I was to do this again, I'd go with the 180deg or 1/2T version which should be just fine yes?
3) If I got a servo with metal gears but the same torque, would this solve the micro motion stalling i'm getting? Am I wanting too much out of this?
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Permalink Reply by Chad Frazer on
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Another quick question, would a digital servo solve this slip problem? As in, even though it would slip internally in the servo, that digital signal would still make it want to keep going until it hit the right PWM value?
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Permalink Reply by Chad Frazer on
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Think I'll go with this one: http://www.springrc.cn/english/product.asp?id=143 it's about 18 bucks, has a butt load of torque and I think it will make waffles in the morning.
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Permalink Reply by AlexP on
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I'm seeing the same behavior. This tracker is not well documented and that is our problem. I could not clearly find that setting a 'tracker home location' in MP was required (makes perfectly sense though!).
I'm using the readymaderc frame, with the recommended high torque servo's. Maestro controller. It also spins 180degrees when adjusting the trim. Tilt is close to being OK, but not perfect.
Still playing with all the parameters, it is only since 30 minutes that I have the tracker respond when playing a recorded flight, not until I found out that setting tracker home location was required.
If anyone has the parameters for the Maestro, readymaderc frame and HS-645MG servos...that would be great!!!!
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