Hi Everyone,
I’m new on this forum and just starting with the ArduPilot world, so please forgive me if I’m posting in the wrong place.
I need an advice with my first drone build, which has kind of unusual requirement.
My application requires autonomous UAV to track an object in different light conditions, therefore tracking via camera is not an option. The only flexibility I have is that the tracked object can be equipped with the transmitter, so the tracking could be achieved via RSSI. Unfortunately, I don’t know the drone market long enough to know what options/sensors are available out there. The RF transmitters could do the job and ultrasonic as well. However, I could not find any lightweight sensors (transmitter/receiver) that could talk directly to the autopilot in order to track/follow the object. Any advice/recommendation in this area would be highly appreciated.
Thank You
If the object to track can be equipped with some electronics, forget about RSSI and ultrasonic. The simplest thing will be to equip that object with a GPS and a SIK telemetry radio. Then with that you could implement follow me mode.
Read this to see how the follows me mode works: https://ardupilot.org/copter/docs/ac2_followme.html
Thanks for quick reply. Unfortunately, the GPS based solution takes too much space. The transmitter needs to be a low-power device and fit in the enclosure about 4cm x 4cm x 2cm. I was looking at 802.15.4 devices, which seem to be a good fit with enough power, but I’m not sure how to implement the receiver on the UAV. Perhaps I have posted too little information. The tracking would be performed at very low speed and the UAV would hover above the target at no more than 5-8m. I was looking at Antenna Tracker solution, which is kind of similar approach, but instead antennas (at least two) would have to be mounted on the drone. I still don’t know which 2.4Ghz receiver would have to be fitted on UAV, or if I could re-use existing UAV 2.4GHz radio to read RSSI from specific transmitter’s mac address.
Thanks
Easiest way to do it is with a GPS, tracking an rf signal is not trivial.
https://www.amazon.com/Matek-Module-SAM-M8Q-GLONASS-Galileo/dp/B07Q2SGQQT
Direction Finding is an art, you need the right signal pattern and frequency and know how to deal with reflection and other characteristic of rf.
One interesting and potentially successful system is used for avalanche rescue
Can also confirm, Tracking RF is hard. 
But not impossible…
I’m not sure why you say GPS is not an option? Would also be my first suggestion. The existing modules seem to fit your size requirements?
I don’t think you will be able to track a position via RSSI very accurately. Electromagnetic waves propagate in very unintuitive ways… especially unless you use light, for which we have pretty good built in sensors (eyes… ).
So if bad light conditions are the only prevention to use an optical system, you might want to try to track an LED maybe?
If you really have to track in the 2.4Ghz range maybe talk to https://metirionic.com/, they have build a tracker in that range and when we last talked were looking for drone applications for their system.
Fitting the GPS based solution won’t fit into 4x4x2(cm) enclosure… at least for now 
This one takes up 1/8 of your volume, I really don’t see the issue
Lol @chopperpl , I think you should do some research 
…
I just googled GPS LORA and I quickly found this … maybe longer bu a lot slimmer
P.S. A big thank you to our community members for quick answer and comments 
The gps linked above are 20x20x10 so they do fit.
I above all, and regardless of the size required to install the gps, I believe that the option of tracking using RF is extremely complex, not impossible obviously, but very complex. Many factors must be taken into account, such as frequency, antennas, radiation patterns, etc, etc. As @moobsen said another option would be to use an optical system, since tracking using light will be easier. But I still think that you should not try to rule out the GPS option.
Thanks for all replies and suggestions. Unfortunately, the enclosure needs to fit the whole package and that includes the battery. I’m also stuck with given dimensions, so I can’t go beyond that.
Cheers,
Well… good luck with your project and dont be afraid to ask for help, as you can see we are a very ressourcefull community
The antenna tracker uses for location of craft fed down to gcs via telem link, then the pan and tilt is calculated from the gcs position and the craft position.
It’s not rf tracking at all. Am i right?
Isn’t there an optical flow option that can position a copter above an IR led or something to allow accurate landing? Maybe that idea could be used to track a slow moving object
Maybe in 60ghz band or some uwb i believe?xiaomi is doing something similar,but it is still very early technology,it is more like lidar than tracking
You are right, Antenna tracker is not based on RF signal seeking , it is pointing to a GPS position.
As for Precision Landing, I think you refer to IRLOCK
https://ardupilot.org/copter/docs/precision-landing-with-irlock.html
Yes Thank you, IRLock used for auto precision landing but maybe the OP could adapt that to be used in loiter over the led, his range of 5-8m is within spec.
Regards
Scott
Did you have any lich with the RF tracking? I would like to fit something similar to one of my quads to seek 2.4ghz Tx.
I was planning on putting directional antennas on the drone and connecting them to a power receiver. My plan was to compare signal strengths in order to select the strongest signal strength and fly towards that signal.
Luckily, the project is in an area where there are not many transmitters so it should always just have one transmitter to find.
If it works, I then need to make it as small as possible.