Hello,
I would like to build a small gate that would lift to allow my robot mower to go through my fence to access the front yard. I have an escape artist dog so the sensor has to be reliable and not allow everything to go through.
So far I've considered a Pixy2 object detection camera but those are expensive and I would need 2 of them; the robot needs to be detected from both side of the fence to allow back and forth passage to the charging station.
I also thought of a rfid sensor but I believe the range would be to small; I would like for the gate to open as the robot gets in acceptable range (3 or 4 feet).
Is there some kind of device I could put on the robot-mower that would ping the distance from the receiver and switch state when at a specific distance?
If you guys have any better ideas to solve this isssue, I would appreciate the feedback.
Most RFID scanners sold for use with Arduino have a very limited range to keep power requirements low. But a better scanner would have more range. I have used industrial, hand-held scanners which could detect and recognise hundreds of ID tags within a 10 metre range in a few seconds!
So maybe look for RFID scanners suitable for use with Arduino but with a better range.
You could probably use some cheap BLE-tag on mower and use Esp32 as a sensor. Then detect RSSI to estimate distance.
Or if robot uses ultrasonic sensors, you could try to detect those.
Or glue strong magnet on robot and detect that (I assume the robot arrives to the "gate" using always same path).
How will You stop Your engineering talented dog from following the robot when the gate opens?
Mount one camera at enough hight and let a controller send You a picture when movement is detected and You operate the gate when the robot is there, alone.
This seems like sounds advice for an engineering talented dog proof electric fence, I'll consider it. Creative solution although a bit to permanent for my situation.
Thanks for the advice, I like the idea of using the ultrasonic sensor however the robot position itself using a camera and a reference station, so no ultrasonic sadly!
I will google what is a BLE-tag and see if it fits my criteria.
I didn't know the possibility of a longer range on RFID, I bought a cheaper card/sensor kit off amazon and believed those were the general idea/specs with those sensors; thanks for letting me know!
Not at all, approach has been used for decades and all animals seem to develop respect to it. After few trials, you can probably remove the fence and respect reminds.
Hardware wise BLE or some other sensor detection is more simple though.
Use a UHF RFID reader, this will read multiple tags in the field at the same time. The only problem is that they are very expensive. You used to be able to get then from SparkFun but they are no longer in stock. This I believe is an alternative. Long range project
Use an active tag. This will work with what ever sort of RFID you use, but it means that the tag will have to contain a small battery cell in it that will need to be replaced occasionally.
Never underestimate a dog !!
You need a dog lock ( cf air lock)
Have two gates . Open first, drive mower in, close first .
If no dog open second and drive mower out .
If dog , then re open first and check for dog .
The small area between gates will make it easier to detect the dog .
Problem with long range stuff is covering Greg whole area and the dog could run past when it sees the door opening.
I guess you could just have a spring loaded gate , unlatched when mower is present , ( detect the steel in it ?) mower the slides through with gate dragging the gate across its top and then slams Shut behind it .
Much simplier .
Whatever you do the dog will learn to get around it, jamming its fav toy in the gate for example . How will the mower know where the gate is and to wait for it to open ?
Indeed, but I would automate it a bit more. A camera and an AI image recognition system running on a Raspberry Pi, is that an option? You can buy a cheap desktop cam with USB output and connect it to the Raspberry Pi. The 'AI' (don't expect too much of it) can be trained with these online websites like: Teachable Machine . It should be quite convenient to use it with Raspberry Pi and Python.
Thanks for the reply, I also am coming down to the same conclusion; maybe the final product will never be safe enough for me to deem usable vs the simplicity of taking the robot to let it mow the front lawn and grab it back when it is done.
