The Smart Plastic House ************************ .. image:: Images/TheSmartPlasticHouse.jpg :align: center Significance ============ The people who live permanently in the Bekaa area of Lebanon depend mainly on agriculture to earn a living. They plant several types of field crops in spring and summer. However, most of the vegetables need to be planted in plastic houses as the winter season and part of spring are extremely cold. Plastic houses provide a protected environment from adverse weather conditions. They are controlled environments for plant growth and need to be always monitored in terms of soil moisture, temperature, and humidity depending on the type of plantation. Automating such an environment will provide a suitable growth environment and reduce the use of labor. It will improve the yield, reduce diseases and infestations by insects, and improve the financial return. In addition, installing surveillance cameras will help protect them from robbery, abuse, and theft. The Smart Plastic House is designed to provide a fully automated and surveilled environment that fulfills the need of the farmer(s). Description ============ The Smart Plastic House is a fully automated project which includes: motors that open and close the plastic on the top of the structure in order to provide proper ventilation when temperature and humidity go beyond favorable plant growth conditions (based on temperature and humidity sensors), an irrigation system which provides the required amount of water when the soil water level drops (based on the moisture sensors), and security surveillance cameras that are connected to the internet and send pictures whenever motion is detected to a pre-set email account. .. image:: Images/TheSmartPlasticHouse1.jpg :width: 45% .. image:: Images/TheSmartPlasticHouse2.jpg :width: 45% Learning Objectives =================== The Smart Plastic House is an integrated system through which students will learn and apply the following: - Coding, electronics, robotics science, and physical science through a hands-on application that can be directly related to real life situations. - Force and Motion - Power and energy - Fluid mechanics - Heat transfer - The implementation of the engineering design process - Application of theoretical concepts to real life situations Materials Needed ================ - Raspberry pi with micro SD card and Raspbian - Jumper wires - Breadboard - Soil Moisture Sensor - MCP3008 - Ultrasonic Sensor - PiCamera - 2xL293D - 3xDC Motors - 9V Battery Setup and Functionality ======================= The automated plastic house is designed to open and close automatically based on internal temperature and/or humidity that is set for a specific crop using motors that are programmed for that purpose. The irrigation system runs automatically based on the soil water content and provides irrigation water based on the exact plant water requirement. A surveillance camera is installed in a position that oversees the area and is activated when there is motion where it takes shots at regular intervals and sends them to a specific email address that is set on the system. Circuitry and Electronics: ========================== .. image:: Circuits/TheSmartPlasticHouse.png :align: center Programming =========== .. literalinclude:: Code/TheSmartPlasticHouse.py Science Concepts and Skills ============================ To select a proper motor, we need to look at different science concepts: - The Force needed - The power of the motor - Angular and linear momentum - The number of rotations for minutes - The Diameter of the motor wheel - The speed of opening of the plastic Force and Motion ^^^^^^^^^^^^^^^^^ Force and motion are two concepts that are applied in this project since the plastic needs to open and close to maintain a controlled environment in terms of temperature and humidity. The force required to open the plastic is provided by the electric motor as the system is fully automated. A force is a push or pull. A force makes things move forward or backwards, in other words, a force makes things change their motion. Forces are affected by external factors such as friction, gravity, and opposite forces acting on the same object According to Newton’s Second Law of Motion, when a force is applied on an object of a certain mass, it will cause it to accelerate. :: This is expressed in the formula: F = m*a F is force in Newton m is mass in kg a is acceleration in m/s^2 In this project, the force that is required to pull the plastic should be greater than the weight of the plastic. If the pull is vertical, then acceleration is that of gravity which is 9.8 m/s^2 Again, the plastic will be pulled by a motor which should be able to apply enough force to pull the plastic vertically or horizontally. `Tutorial Video 1`_. .. _Tutorial Video 1: https://www.khanacademy.org/science/physics/forces-newtons-laws Motors can be selected based on two main properties, the voltage and the power. The voltage is determined based on the AC output in each country, whether 110V or 220V. Other DC voltages may be used such as 6, 12, or 24V, especially when building a prototype where the use of high voltage is a safety hazard. Electrical Power ^^^^^^^^^^^^^^^^ *Finding the amount of power needed:* It is the rate, per unit time, at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt. One watt is equivalent to one joule per second. The motor power can be selected (or calculated) based on the need. In this project, the power of the motor required to pull a certain weight can be calculated using the formula below: :: p = m*g*h/t p is power in watt m is the mass of the plastic to be lifted in kilograms g is acceleration in meters per second squared (m/s^2) h is the distance of object movement in meters t is time in seconds *Finding the power of a device:* Electrical power of a device can be calculated using various formulas depending on the available information of a device. Derived formulas may include: :: P = V * I P is electrical power in watt V is voltage input in volts I is intensity of current in ampere A derived formula is: :: P = I^2 *R; or P = V^2 / R R is resistance of a device in ohm Momentum ^^^^^^^^^ Momentum refers to a mass in motion. Since motion is represented by velocity, then momentum could be illustrated by the equation: :: p = m * v p is momentum in kg*m/s m is mass in kg v is velocity in m/s Momentum can be linear or angular. Linear momentum refers to that of straight motion, and angular to rotation. Linear momentum can be calculated using the equation above. `Tutorial Video 2`_. .. _Tutorial Video 2: https://www.khanacademy.org/science/physics/linear-momentum/momentum-tutorial/v/introduction-to-momentum For this project, since the motor has angular momentum and most motors found in the market are categorized based on their number of rotations per minute, the following formula can be used to find the linear speed of motion based on the following relationship: :: v = r × RPM × 0.10472 v is linear velocity in meters per second r is the radius of the circle in meters RPM is the angular velocity in RPM (rotations per minute) .. note:: Keep in mind that the bigger the circle of the motor axis, the faster the motion. In addition, the lower the RPM, the more the torque: `Tutorial Video 3`_. .. _Tutorial Video 3: https://www.khanacademy.org/science/physics/torque-angular-momentum/torque-tutorial/v/introduction-to-torque Fluid Mechanics ^^^^^^^^^^^^^^^ Two main concepts that are used in this project are Pressure and flow. Pressure is the force exerted on a certain area. It is measures in Newton per meter squared (N/m^2). The higher the pressure on a fluid, the higher the flow. In this project, the amount of flow needs to be decided based on the plant needs. Whether a high water tank or a water pump are used, the amount of water flow per time can be determined. `Tutorial Video 4`_. .. _Tutorial Video 4: https://phet.colorado.edu/en/simulation/fluid-pressure-and-flow For water pumps, they have various flow rates and a choice is made based on the need of flow in a unit of time. The rate of flow is calculated by: :: Q = V/t Q is the rate of flow of a fluid in cubic meters per second (m3/s) V is the volume of a fluid pumped in cubic meters (m3) t is time in second (s) Heat Transfer ^^^^^^^^^^^^^^^ **What is Heat?** All matter contains moving molecules and atoms at all times. The movement of these molecules or atoms produce heat which is a form of thermal energy. The only time that molecules and atoms are theoretically not moving in a certain object is at Absolute Zero, which is the temperature of zero Kelvin. However, this temperature has not been reached. Temperature is a measure of the average motion of particles in a certain object. The faster the movement of particles, the higher the energy and vice versa. In other words, it is a measure of the average energy in a system. Heat transfer can happen all the time where heat can move from one place/object to another through many ways. We need to keep in mind that heat transfer takes place from a system of high temperature to a system of low temperature and the opposite does not apply. Heat can be transferred in three main ways: | *Conduction* It is the heat transfer between objects/matter that are in direct contact. For example, if a piece of metal is placed on a hot plate, heat will be transferred from the plate to the metal as they are touching. The particles in the hot plate are moving fast and bump into particles of the other metal and cause them to move faster. The faster the movement of particles (molecules or atoms), the more the amount of heat energy. In this case Heat has been transferred from the hot plate to the piece of metal due to contact. This process is called conduction. *Convection* It is the transfer of heat energy in the form of currents. For that reason, it can only happen in liquids or gases. The part with more heat energy (hotter) in a liquid or a gas has less density than the one with less amount of heat energy (colder) as the particles will move apart due to their movement thus filling more volume. This will make the hotter part move up and the cold part moves down creating currents which will allow heat exchange. *Radiation* It is the heat transfer through electromagnetic waves. Such a form of heat transfer does not require matter like in conduction and convection. It can travel across space where no matter is found. Example is sunlight and energy from a light bulb `Tutorial Video 5`_. .. _Tutorial Video 5: https://www.khanacademy.org/science/physics/thermodynamics/specific-heat-and-heat-transfer/v/thermal-conduction-convection-and-radiation `Tutorial Video 6`_. .. _Tutorial Video 6: https://www.youtube.com/watch?v=Atnjo7dD_bA | | **Flex your brain!** If you were to Build a system to automate a green house, how would it be designed and conceptualized, who would it serve and to which purpose?