Beacon (IR?) for simple navigation outdoors
TL/DR: Circuit recommendations for simple robot navigation outdoors seeked, perhaps IR.
I've been tasked with developing a "working" prototype of a robot navigating on a driveway outdoors. If approved, I'd get paid for the effort, parts, and for the documentation. "Working" = it's more about showing what's possible with fairly low-tech solutions, pitfalls, costs etc., than something that has to be scaled up.
In this first version it would be ok to only have the robot going back and forth, more or less in a straight line, in next project I might want to expand it with more advanced sensors and navigation (e.g. GPS-RTK), but that's out of scope right now.
In addition to travel back and forth, the robot will be equipped with another separate device that I can disclose first after the project is completed. The other device has its own circuit and power source. Some simple serial communication might be needed between the P1 and the separate device.
I've been studying (and discussing with ChatGPT) different options, putting reflective markers on ploughing poles, using long distance RFID-tags, Bluetooth solutions etc. As the first version should be quite simple, I thought about using a IR-beacon (or a few) at the start of the driveway, and equip the robot with two IR-receivers. So the robot would just "home" in on the beacon, similarly as many robot vacuums do.
Line-following would probably be even easier than IR, but no permanent painting can be done on the driveway, also snow/ice/uneven asphalt will play a factor.
The driveway is ~30 meter x 3 meter wide, so distance might become a problem with IR. I'd though be satisfied with getting 5-10 meter range. Let's assume the robot is only working during dark hours without any light interferences. The weather is a factor, but for this POC I'd ensure no harm will be done to the robot or to the electronics, I'll also 3D-print enclosures for the electronics.
The robot I'd use is a Wild Thumper I already own, it's equipped with a Propeller Project Board and working pretty well.
Any thoughts on this?
If IR is the "easiest", any circuit recommendations for the beacon and for the receivers?
Comments
I work for a laser tag company. Our "taggers" use IR, so the parts are common on both ends. That said, we do run the IR LED through a lens and at very high power (about 1A when the output is on). The LED tolerates this because the modulation frequency is 56kHz, and the bit timing is pretty short (longest is 2.4ms using SIRCS protocol). We play outdoors in the daytime without a lot of problems. We once did a night test and got about 1500 feet.
Thx Jon! I thought laser tags use laser, but guess IR is safer than laser. Good to know long distance is possible with proper design.
I remembered I bought the set including the book "IR Remote for Boe-Bot", so will refresh my memory around IR using a BOE or an PAB. For this POC the beacon could even be a Sony Remote controller if the range is > 5 meters.
Hi,
you don't say much about the precision needed and other restrictions, so it's hard to answer.
For low cost odometry is interesting, a compass and ultrasonic beacons are possible perhaps too. Synchronised Ultrasonic beacons would give distance from time of flight like GPS satellites. One would have to find a way to deal with wind.
Precision differential GPS is hard to beat though....
Christof
Valid comment!
It does not need to be that precise for this first version, it would be ok if the robot veers 0.5 meters or so to each side of the imagined center line as long as it corrects itself. Lenght wise it would need to stop before hitting a wall, so need to put a sensor for that purpose.
Using a compass would indeed help as long as it does not need to be completely flat, have varying experience from compass sensors. The robot has DC-motors and no odometry is built in, an home-made solution would be to paint a white strip on the black wheel, and using a proper sensor count the revolutions. This assuming no wheel slipping.
Using a Lidar Lite-3 (range up to 40 meters) I have could also work for odometry, that is, measuring how the distance changes to whatever is in front of it when the robot starts.
D-GPS is something I'm planning for the potential follow-up project. As I've understood the technology, one needs to get correction data continuosly from a base station via RF/Wi-Fi/cable for the precision to be better than traditional GPS.
Thanks for your suggestions, gave more options to consider. Initially I'll try IR inside with an Activitybot to understand the technology and pros and cons.
Some years ago, I had a little robot with P1, which had a ultrasonic ping sensor and a compass. It could explore a room and build a map of the room with obstacles scanned by the ping sensor. For odometry I only calibrated speed. It worked more or less. I always run into problems with the very limited amount of ram of P1. So I would go at least with P2 for this project to avoid these problems. Nowadays we own a vac robot, which also builds up a map with it's 360° lidar.
Perhaps you have seen my experiments with camera and blinking beacon? In principle this is a nice idea, because it is quite simple, cameras are very cheap precision sensor arrays and if you have more than one beacon in one picture, you can calculate distance. Unfortunately with low light my camera went into a very slow mode for long exposure times. https://forums.parallax.com/discussion/175897/thoughts-about-robot-navigation-using-blinking-beacons-and-camera-s#latest When working with pictures, P2 comes into it's limitations though.
Perhaps you could also swap the entire setup, give the robot a colour, which is nowhere else in that place. Have one camera (or more) on a pole. Searching for a colour blob in a picture is very simple and fast. Just convert the picture into hue values. Then build for each X and Y direction the average position of all pixels of that hue value.
Thanks for your ideas and comments!
Actually similar kind of crude mapping I started with a long time ago with a BoeBot and ping sensors. Very quickly I recognized that 256 bytes of RAM is limited for this purpose. Then attached a Memory Stick Datalogger to have "unlimited" storage, but then got distracted by the Propeller ActivityBot. If you happen to find the mapping program and want to share it, I could at least try it inside where it's probably more reliable than outside.
Yes, I remember I saw your experiment, very innovative! If Tensorflow Lite would work on the P2, it might be fairly easy to use image or sonar data classification for recognizing different landmarks, I've actually tested a simple neural network on a P1 for classifying images, but run quickly out of memory. With the 40 meters range of Lidar Lite-3, it would in theory be possible to use it outside in our yard. I however guess some kind of fuzzy logic or neural networks might be needed as there are not any flat surfaces apart from our house.
So, would the camera then communicate the calculated X and Y positions to the robot via some RF?
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Yes, that's the idea. Of course only possible, if the area and application allow it. Even WLAN might be a possibility in some cases.