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
Randy,
I'm using $30 JR DS821 Digital High Torque Servos on 6v in my EZTracker frame. It provides 88oz/in torque at 6v. It works well but the pan servo does get hot. For $10 more, the Hitec HS-5645MG Digital High Torque servo provides 168oz/in (or double the DS821) on 6v so I was thinking of buying one for the pan servo if the DS821 ever stops working.
Randy, I purchased and setup a PT785-S with a 7:1 pitch servo and a 3.8:1 pan servo (to get 360 rotation). It's not a ready out of the box setup, but it's coming along nicely with the software updates you and others have made. Still looking to tune it to a point where it tracks smoothly, but I've also not spent much time on tweaking it.
20141102_123138.jpg
20141110_181245.jpg
I tested the AT with the Op Resend unchecked in the telemetry link and it eliminated the disconnects previously seen on my videos. The change was suggested on this thread by Dick Ou. It was an easy fix and the AT worked quite well!
I decided to post images of my current telemetry setup from AT to MRC as well a my current PID settings and encourage others to post their setups. I don't see this information on the Wiki and feel that my Yaw and Pitch Gain PIDs are not optimal. I simply set PIDs, based on previous posts, to allow the tracker to point in the proper direction with minimal hunting and overshoot. I have no idea if this is optimal. Perhaps I missed it but it would be nice to see PIDs from other setups (including Randy's) using standard servos on the Eagle Eyes Antenna Tracker frame.
Hi Greg,
I am looking to pass my vehicles information on to the Antenna tracker (Pixhawk used as a controller board for yaw and pitch) What settings shouls i use??? or am i missing something very basic here. Would highly appreciate ur help!!!
Also i am using RFD900 for my telemetry which would be directly connected to my GCS laptop..
What about support for serial servos like this one --> http://www.robotshop.com/en/dynamixel-ax-12a-smart-servo-serial.html
It is much cheaper than comparable RC servos and it seems to support continuous rotation.
I have never used this kind of servos and I believe you need an external controller for these. Basically CR servo mode is meant for servos (or motors) that stay still at ~1500us (PWM center value) and start rotating when the value goes above or below this value with the speed proportional to the amount of us in PWM signal. Technically with large RATE_I and RATE_IMAX of PID this mode would also drive standard servos.
Here is a nice description and youtube movie of what CR servo does and how it works.
Fortunately for my girlfriend and less fortunately for me and Antenna Tracker community I am going on a vacation and I won't be taking my laptop with me (I can still receive condolences and comforting emails on my phone :) ) and I won't make any changes till the end of next week. I will be testing my tracker extensively when I get back (I have some additional changes that need to be tested) and I should produce a usable version in 2 weeks. For now the CR servo mode that was pushed as 0.7.1 will work only when we have a valid location from the vehicle - otherwise the servos won't receive frequent updates and will most likely rotate erratically. I didn't explain it well enough and proper changes (some additional if's) were not pulled into master.
One should be able to connect these servos to the serial port of the Pixhawk. As they can be daisy chained they'll only use one UART.
My first suggestion would be setting AHRS_ORIENTATION to 0, mounting the board accordingly (default mode) and try it then after ACC and compass calibration. There is some banking in mine but it is not nearly as much as yours. I would say that your board is damaged but since you tested it with multiple boards it is not the case. Maybe you changed something in AHRS configuration? Is your board mounted close to center of rotation (close to axis) or far away causing it to sense centrifugal forces? Maybe your MAG is not mounted strictly to APM/Pixhawk and their orientations to each other change during rotation?
-
73
-
74
-
75
-
76
-
77
of 104 Next