what method can i use sense movement of a person to design an auto following cart for supermarkets.? i need to follow a specific person can i use the WiFi or BLUETOOTH signal strength of consumer's mobile phone for following.?
put on hold as too broad by Milliways, Dmitry Grigoryev, Darth Vader♦ 2 days ago
Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.
The signal strength follows the inverse square law so fundamentally you can use this to work out a distance between the transmitter and receiver, but you'll need to know some information about the initial signal strength at the transmitter and assume some things about the transmission media like that there's nothing attenuating the signal (such as other metal shopping carts) and no "reflective" surfaces causing echoes (such as metal shelves stacked with cans).
Assuming you manage to get a (very approximate) measure of distance between the transmitter and receiver, to get your cart to follow a signal you also need a bearing in order to know in which direction the cart needs to travel in order to get closer to the transmitter. The signal strength alone does not give you this information.
I suppose you could have two or more receivers, one on each corner of your cart for example, and use trilateration to work out the direction given the relative distances to the transmitter and knowing the distance between the receivers.