IR-LOCK Sensor with 2 Beacons?

nabatta

Novice Member
Hello!

I am looking to use IR sensors to get an accurate location for a hovering quadcopter. I have been looking into the IR-lock sensor and it seems like a viable option. However, in order to increase the level of precision, I was hoping to use 2 beacons rather than one.

Does anyone have experience with this or know if the sensor can differentiate between 2 separate sensors? Thank you!
 

noiseboy72

Distinguished Member
Not come across this, but it appears to just be a PIXY camera with a filter and some LEDs that flash in a pattern. I doubt therefore that a 2nd beacon would make it more accurate.

Have a look at using an OpenMV camera - similar form factor to PIXY, but more powerful and use some Apriltags. You can create a giant one - about A0 size and then a smaller one embedded in the middle of it. That will give reasonable capture range and then a precise landing to within 6" or so. I've played with this - if your drone has PX4 it's fairly easy to integrate, and also using the camera for optical flow. I added an ultrasonic height detector to help with soft landings, as it gives much better results than the standard barometer.
 

nabatta

Novice Member
I will look into that! The main goal is to get the quadcopter to identify its location without a GPS with a high degree of precision. The beacons will be placed on a vehicle on the ground that could move so it is important for the camera to be able to detect two distinct IR sources on the vehicle. Trying to figure out the best method to do that.
 

noiseboy72

Distinguished Member
The cameras have a fairly narrow field of view, so you have to be pretty much over the target for either system to work well.

Ideally you would use a 2 step process, possibly a GPS location or Follow Me to get close to the vehicle and then a more precise system at closer range.

IR has a range of no more than about 6-10M outdoors and this will reduce in bright sunlight. Apriltags are limited to a similar range but are dependant upon the size of tag. A larger tag will work from further away and the design of them is that you can embed 1 tag within another to increase accuracy.

Where GPS is unavailable - indoors for example, there's some pretty good ultrasonic systems with an accuracy of a few cm. These will position the drone and vehicle and allow the coordinates of the vehicle to be sent to the drone so that it can home in on it.
 

nabatta

Novice Member
Ideally, I would be operating in the dark as well which is why the IR beacons were my initial idea. The quadcopter would hover over the vehicle and move/rotate if it moved.
 

noiseboy72

Distinguished Member
I think for that to work you would need to broadcast the vehicles location and get the drone to fly to those coordinates - in a Follow Me type setup.

The update rate of the camera is likely to be the limiting factor, as any significant change in speed or direction and it's likely the drone will fly out of range of the sensors.

In answer to your original question about multiple beacons, I would imagine you could do this by modifying the code the camera is running. Maybe set offsets based upon where the beacon is positioned on the car so that the camera can work out headings.

Another suggestion might be to make the beacon intelligent, so it has an IMU and can send out it's velocity and direction of travel? If you are using something like a PX4 FC, this could be processed along with the position of the beacon within the view of the camera. You might need some off board processing like Raspberry pi to feed the information back into the FC as they don't have particularly high speed processing and very little spare memory.

You are going to need to re-write the camera software, but in Pixy or OpenMV this is reasonably straight forward.
 

nabatta

Novice Member
Thank you for the help! Do you have any experience with POZYX equipment? It looks like that might be an option too.
 

noiseboy72

Distinguished Member
I've looked at it but not in detail. £1k is too rich for me!

This sort of technology should work for you however.
 

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