Truck to Follow Anklet

My 10-year old daughter and I are aiming to blend two passions - electronics and detrashing! We have a vision of creating a truck that follows us as we pick up neighborhood trash and carries our 5 gallon bucket for the trash. To get it to follow us, we’re thinking we’d have two sensors on the front of the truck looking for a transmitter on an anklet that one of us would be wearing. Our first question is, what sensor system would be best for such as setup? The anklet would have batteries on it, and assuming it emits some signal, the two sensors could each determine how powerful/far away the transmitter is and drive each front wheel of the truck accordingly (if the left/right sensor saw the transmitter was far, it’d speed up, and if it was close it would stop). This would in theory give direction control and keep it driving after us. We’ve got a lot more to figure out from there in this project, but this seemed like the important first step in prototyping. Thanks for any suggestions on what sensor/transmitter system to use (or any other advice for a project like this).

I’d recommend checking out some motorized cooler and/or follow-along golf caddy projects online and going from there

Thanks for the tip Russell!