Not many people know but we have an piece of open source software for controlling an Antenna Tracker. It's been built by Tridge (Arduplane lead developer) for use in the outback challenge.
Sadly we have no documentation and, as far as I know, nobody except Tridge has used it. Still given Tridge's track record on building great software I suspect it works well and if it doesn't, I'm sure we can fix it. So to not let this piece of code go to waste, I'd like some help from people who are interested to give it a try and help me figure out how it works.
Here's the little that I know:
- It runs on any of our supported board (APM1, APM2, PX4, Pixhawk, Flymaple and perhaps VRBrain)
- For APM1/APM2 users building the code is as easy as opening our hacked ArduinoIDE and selecting File > SketchBook > Tools > AntennaTracker and then building in the normal way. For PX4/Pixhawk, our autobuilder doesn't automatically build a binary but I can provide one if people are interested.
- It can control a Pan and Tilt gimbal like this or this found on servocity.com.
- It may or may not require a GPS
- It must somehow receive vehicle position updates from the ground station which has the telemetry radio that is connected to the vehicle. Maybe through a USB cable. Tridge probably uses the python ground station, MAVProxy, to passthrough the vehicle position data to the AT but perhaps we can get MichaelO to build out a similar feature in Mission Planner.
- I imagine this antenna tracker could also be used to keep a camera focused on the vehicle which might be good for easing the burden on creating videos of our vehicles.
So if you want to give it a try please do and stick any findings, questions or issues below. Alternatively Issues can go into the issues list.
I'll start sticking things into the wiki as they become clear.
Replies
Jakub, thanks for exhausting description, I really appreciate it and I hope it could be good guideline for everyone interested in antenna tracker setup.
Anyway I have one problem with pitch servo - it is digital HS 5975HB. It has range only -45° +45°. You wrote that in middle/neutral position that is 1500ms antenna should point horizontally - that means 0° from level. But in that case I cann't achieve vertical position 90° :-(. Is there a way how to set it up that in center position (1500ms) antenna will point 45° up ? Because actually I need range only 0°-90° where 0° (cca 1100ms pulse width) means antenna is leveled and 90° (cca 1900ms pulse width) antenna points upright.
This servo is indeed programmable and the range could be increased to 180° but as it is obsolete product I cann't find any specifications for it.
It would of course be easier if you could reprogramm the servo.
You can try setting TRIM value to PWM that gives you 0 degrees, MAX to 90 degrees and MIN to 0 degrees. I'm not sure this works but you can try
I tested my AT yesterday and the pitch was perfect but the yaw was off by 30 degrees. My AT using a hawk (like Randy's setup) and the v0.7 firmware. Is the yaw determined by GPS coordinates or compass or both? Since I see no parameter for adjusting the yaw offset, would a re-calibration of the compass affect the yaw offset? Thanks.
Hi, Grey I remember you had pitch problem after you upgrade from v0.5 to v0.7, Now I have same problem as yours tilt 45 degree no move, now you solve your pitch problem can you let me know how to solve this pitch problem?
45 degrees in pitch sounds like my custom firmware. This problem is visible only in some cases and I don't have a solution yet (the same firmware works fine in my tracker). Did you download firmware via MP or from my posts somewhere on this forum?
I download v0.71 via MP
Dick, I don't remember ever having a pitch issue. My original yaw issue was due to the servo reverse function being incorrect. I discovered it by pointing my AT 180 degrees away from the MRC. Now that you mention it, I probably still have v0.5 firmware in my AT. I remember seeing the changes Randy committed and thinking that that didn't affect any of my issues. I will upload the latest from MP and retest this weekend. I forgot to add the AT to my latest video on Triple Autonomous Flight using APM below. The AT was tracking the POI drone as one of two video downlinks.
Triple Autonomous Flight 2 from Gregory Covey on Vimeo.
This second test of our triple autonomous flight was at the CHIEFS field in Canandaigua, NY where the AMA District II Event will be held on August 15th & 16th. I modified the grid pattern to last 6 minutes and we had our video down links working which use 3-axis brushless gimbals and STorM32 controllers. The entire three flights were automated from take-off to landing.
There was a 15mph wind from the West but the hexacopters had no issue. If the drone was pushed a bit, the APM: Copter v3.2.1 firmware would correct itself and continue the grid. After the 6-minute demo flight, all three MRCs returned to their home position and landed.
Very nice video though. One of the best demos of APM I have seen.
Greg,
very impressive video. The only "unprofessional" stage of your flights is using RC transmitter for takeoff. This can be easily done without touching the transmitter - the procedure is simple:
1. Turn on transmitter, set stabilize mode and move throttle just a tiny bit above minimum (1 or 2 marks)
2. Via MP click "ARM" and when it gets armed change mode to AUTO.
You always have an option of manual override (just cycle your RC Transmitter from stabilize to any different mode and back). You can also leave the transmitter in AUTO at the beginning, then from MP switch to stabilize, arm, switch back to auto. In case of emergency you would just need to switch back to stabilize to take over. You cannot arm in AUTO. The copter will not begin takeoff if the throttle is at minimum, thus the needed adjustment.
Other than that very nice demonstration.
This is strange. Can you describe the behavior?
From what I understand YAW axis is working fine and tracks the vehicle correctly while PITCH stays at 45 degrees (looking up)?
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