|16||Automated Pet Cage
- Christina Hejny (chejny2)
- Avram Fouad (afouad2)
- Saurav Kumar (sauravk2)
I have a pet rat and as every good rat owner knows, rats (and many other pet rodents) need plenty of daily enrichment time outside the cage. During days when I have a lot of schoolwork, I am often too busy to walk back to my apartment, let him out, then walk back to where I was working. The crux of the problem is that I have to manually open the cage door. Having an automatic door would mean that the rat could get let out of his cage every day, even when I'm stuck in ECEB all day working.
# **Solution Overview:**
An automatic cage door opener/closer! The idea is a device that you hook onto the outside of a cage door as well as a feeder inside the cage. At specific times during the day, the cage door will open or close letting the pets out. Most cage doors unhook from the top and hinge forward from the bottom. The device would use a small servo motor to rotate the door along its hinge a specific amount to fully open or close it. The servo motor would be controlled by a control unit that uses a clock to determine when to open the door. It will have an interface that allows the user to enter the “open” time. Once the “open” time is reached, the cage will open for at least 2 hours, after which it will begin the closing process. The device should not lock the rodent outside the cage. There will be a pressure sensor that senses when the rodent has entered the cage and the door will not close before then. To give an incentive for the pet to re-enter the cage, the device will beep when it is time to re-enter the cage (2 hours after the door initially opened). After the beep, the pet can trigger the pressure sensor and a feeder will dispense food (think skinner box). The pet can be easily trained to understand the beep means to re-enter the cage and get a treat. Once the pressure sensor is triggered by the pet, the cage door will start closing and then food will be dispensed. There will also be a button that opens and closes the cage door that the owner can trigger. This will primarily be used for emergency purposes in case the owner needs to open or close the cage outside of the programmed time slot.
# **Solution Sub-Systems:**
**SUBSYSTEM 1:** The first subsystem of this project is the user interface which allows the owner to set the time for the cage to open. The user will enter the precise time to open the door using pushbuttons. The selected time input will then be displayed on a Hex Display and be sent to the microcontroller. There will also be emergency buttons for the user to open or close the cage (outside of the set daily time).
**SUBSYSTEM 2:** The next sub-system of this project is a servo motor mounted on top of the cage to open and close the door. The servo motor will be controlled by the microcontroller and will open the door once the “open” time initially entered by the user is reached or if the “open” emergency button is pressed by the user. The servo motor will then close the door only if at least 2 hours have passed and if the pressure sensor is activated by the rat. This means the rat has returned to the cage and is ready to devour its treat. The servo motor can also close the door if the emergency “close” button is pressed by the user.
**SUBSYSTEM 3:** The third sub-system of this project is an electronic feeder placed inside the cage to give the pet motivation to return to the cage. A speaker will generate a beep noise 2 hours after the door was opened in order to alert the pet that it is time to re-enter the cage. This will act as a positive reinforcement training for the pet. A timer chip will be used to determine when 2 hours have passed. The rodent will then trigger a thin film pressure sensor (20g trigger force) near the feeder to get the food. Once the pressure sensor is triggered, the device knows that the pet is safely inside the cage. The device will then close the cage door and then dispense food. If the rat comes back inside the cage before 2 hours have passed, the treat will not be dispensed and the door will remain open. To summarize, the rodent will hear the beep after the door has been open for 2 hours, enter the cage, and then trigger the pressure sensor which will cause the door to close. The feeder will release the food after the door closes so that the rodent doesn’t quickly take the treat and leave the cage before the door closes.
**SUBSYSTEM 4:** The fourth subsystem is the power system. The device will be powered by a rechargeable 3.6 V lithium battery with a capacity of 7.8 Ah. We may use linear regulators in order to step down the voltage if necessary for chips that require smaller supply voltages. In case any supply chips require higher supply voltages we can use a boost converter to increase the 3.6 V to a required value.
**SUBSYSTEM 5:** The fifth subsystem is a clock and timers. We will use an IC chip with a real time clock to keep track of the time. The clock will be set with the interface when the device is powered on. One timer will be used to track the minimum duration (2 hours) the cage stays open. Another timer will be used to create the delay between closing the door and activating the feeder.
**SUBSYSTEM 6:** The sixth subsystem is the microcontroller. It will interface with the clock, servo motor, pressure sensor, feeder, and speaker to execute the functions of the device. The microcontroller will take the time desired for the cage to open and compare this with the real-time value provided by the clock. If these values are equal or if the “open” emergency button is pressed, the microcontroller will send a pulse to the servo motor which will then open the cage. Once the 2 hours have passed, the microcontroller will trigger the beep played by the speaker. Once the pet activates the pressure sensor (only after the 2 hours), the microcontroller will send a pulse to the servo motor to close the cage. After the cage has been closed, it will send a pulse to dispense the food. If the cage is open and the “close” emergency button is pressed, the microcontroller will send a pulse to the motor to close the cage but will not dispense food.
# Criteria for Success:
1) The automated pet cage must be able to successfully open the door at the time selected by the user. The door should not open automatically at any time outside the time specified by the user.
2) It should not close the door unless the door has been open for at least 2 hours and the rat has returned inside the cage or if the close” emergency button is manually pressed by the user
3) The cage must close the door and dispense a treat once the 2 hours have passed and the rat has triggered the pressure sensor.
4) The rat should not be able to pick up the treat and then leave the cage before the door closes.
5) There should be buttons that can override the current status of the door in case of emergencies.
6) The dispenser should not activate and the door should remain open if the pet comes back to the cage earlier than it's supposed to.
7) If the pet comes back to the cage later than it's supposed to, it should find the door open and the door should close only when the pressure sensor is activated by the rat. The food dispenser should then be activated.