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Automated Chicken Door
Motivation
Automating the opening and closing of the chickens door reduces the mental payload and gives more freedom. It also makes the chickens more safe as humans might forget to close the door in the evening.
This is the very definition of progress: making life easier.
Comparable systems
- http://www.chickencoopdoor.com/Products/products.html, ~200$, sash based
- https://www.chickendoors.com/, ~200$, hinge based
- And many others which can be found with your favorite search engine
Possible designs
Controllers
Solution | Price | Plus | Minus |
---|---|---|---|
12V timer | ~10€ | Easy to set up, reliable | Setup has to be changed over the year ; 12V powering needed ; Power consumption ? |
Arduino mini + electronics | ~8€ | If battery/solar powered, the board has to be modified to reduce the power consumption ; Electronic circuit has to be built and programmed | |
Analog electronics | ~5€ | Low power | Electronic circuit has to be built |
Actuator
Solution | Price | Plus | Minus |
---|---|---|---|
Electric car antenna | ~20€ | Easy to integrate | |
Winch actuating a sash | ~10€ | Can be built with broken electronics | Has to be built |
Servo-actuated self-locking door | ~10€ | Complex to build |
Powering
Solution | Price | Plus | Minus |
---|---|---|---|
Solar panels | ~5€ | Energy self-sufficient ; Coop easy to displace | Requires low power electronics |
Power adapter | ~5€ | Stability | Requires a power line |
Rechargeable Battery | ~15€ | Coop easy to displace | Inconvenient ; Requires low power electronics |
Selected design
As we try to reuse the tings we have and to buy as less as possible, the solution depends a lot on the material already available.
Function | Selected solution | Why |
---|---|---|
Controller | Analog electronics | low power, low cost |
Actuator | Winch actuating a sash | no cost because reused materials |
Power | Solar panels | we can reuse solar lightings for garden, can be moved, energy self-sufficient |
The total cost will only be around 5€ for the electronics. The drawback to this is the time demanding construction work.
Mechanical Analysis
Electrical Analysis
Energy Analysis
If the system is powered by a battery or a solar panel, an energy analysis can be done to be sure of the feasibility, or to be able to improve the design.
Energy used by the motor
Parameters we need to know:
Current measured through motor while door is lifted | I_motor = 100mA |
Voltage powering the motor | V_motor = 6V |
Time measured to open | T_open_door = 10s |
First we calculate the power drawn from the motor:
P_motor = V_motor * I_motor = 6V * 100mA = 600mW = 0.6W |
Then we can calculate the energy used by the motor to open the door:
E_open_door = P_motor * T_open_door = 0.6W * 10s = 6W.s |
This energy can be converted in W.h:
E_open_door = 6W.s = 6/3600 W.h = 1.6mW.h |
As the door needs to be closed as well, we just double this value to get an approximation of the total energy used by the motor per day.
E_motor_per_day = 2 * E_open_door = 3.2mW.h |
Energy used by the electronics
The electronic component consuming most of the energy is the Op-Amp. A calculation could show that the power consumed by the other components is negligible. Indeed, we try to use resistors having high values.
Below is a graph from its datasheet showing the power supply current. We can see that it is about 1.2mA at 6V.
Power consumed by the Op-Amp:
P_oa = V_oa * I_oa = 6V * 1.2mA = 7.4mW |
Energy used by the Op-Amp per day:
E_oa_per_day = P_oa * 24h = 7.4mW * 24h = 0.177W.h |
We can see that it is much more than the energy used by the motor. While the motor consumes 100 times more power than the Op-Amp, it is used only 20s a day, while the Op-Amp is always on.
Energy available per day
The solar garden lighting give approximately 4h of light every night. From this information, we can estimate the energy available per day.
The LED is powered with 1.2V and consumes 30mA. We can measure this with a multimeter.
P_led = V_led * I_led = 1.2V * 30mA = 36mW |
E_led_per_day = P_led * 4h = 36mW. 4h = 144mW.h |
The batteries of the garden lighting have a voltage of 1.2V (can be read on the package). As we want to power our system with about 6V, we have to use 5 garden lightings, and to connect their batteries in series.
E_available_per_day = 5 * E_led_per_day = 144mW.h * 5 = 720mW.h |
Conclusion
Summary:
E_motor_per_day | 3.2mW.h |
E_oa_per_day | 177mW.h |
E_used_per_day | 180mW.h |
E_available_per_day | 720mW.h |
We are happy to see that more energy is available than used. The security margin tells us that after one normal sunny day, the system can work without additional energy for 3 more days.
Security_margin = E_available_per_day / E_used_per_day = 720mW.h / 180mW.h = 4 |
For improved performance, we need to use a low power Op-Amp (such as TLC3702CP)