Senior Project

[BrianEET]

I'm working on my senior project in college and could use some advice on my idea. I'm building an automated pet door. It would work by having some type of sensor on the pet door that would give out a signal which would be received on the dogs collar and sent back to the sensor on the door to open it. Once the signal is received it would trigger a motor to open the pet door so the pet can go outside. My question is what type of sensor system would be best. I'm wondering if a ultrasonic sound wave which is transmitted from a ultrasonic transmitter/receiver on the door of say 40kHz to the dogs collar, which would also have an ultrasonic receiver/transmitter would work. Any advice would be much appreciated.

 

[Solidus]

Have you considered using a laser or diode source and a phototransistor or other photodetector, like a garage door? With that, you wouldn't need a collar (from the dog's perspective, it's completely passive), there would be no ambiguity about if the door triggers or not, and with some work on debouncing it could be made fairly seamless.

 

[Laplace]

What is the chance of training the dog to change the battery in its collar transmitter? As an alternative approach have you seen the battery-powered toothbrushes that recharge without electrical contact when placed in their holder? Imagine a low-level AC magnetic field emanating from the dog's bed, and a coil in the dog's collar generating enough voltage to keep the battery charged from that AC magnetic field.

 

[Arouse1973]

Look up RFID. This is how the current market ones work with the microchip in the animals neck.

 

[(*steve*)]

Look up RFID. This is how the current market ones work with the microchip in the animals neck.

I've looked at RFID for exactly this purpose.

Things you need to be aware of:

1) small RFID antennas generally have a short range (it may be 5 to 10 cm).
2) animals will crowd around a door, so you need to beware about opening the door for one and allowing two inside (this is probably less of a concern if the animals are not known to each other). This might be an issue if you have cats and dogs and you want to allow the cats in but not the dogs (for example)
3) the range of the system depends heavily on the orientation of the device with respect to the antenna in certain designs.
4) You don't want the door to shut after the animal's head passes through it, but before the rest of the body has.

I think all of these can be overcome to some extent.