Humidity and temperature detection
The device needs to be able to detect the humidity and temperature of the surrounding area. The part of the design requires high sensitivity and veracity.
Approach: We will be using a DTH22 which is a temperature and humidity sensor. This sensor can operate with a 3.3-6v DC power supply. The sensor can operate within -40~80 °C. The sensor can only send data every 2 seconds, but this should not become an issue in the final design. The sensor costs $15. This sensor is both precise and cheap.
Data receiving and system control
In order to make all the desired functions work, the control system is required to receive data stably and effectively. Meanwhile, the size of the whole control system shall be small enough to be integrated into the umbrella structure.
Approach: The Raspberry Pi Zero would be an ideal control board to handle the multiple functions of the umbrella. The DTH22 is directly compatible with the Pi zero, it only requires some libraries to be installed.
There is a rigid demand that the device shall be integrated with a cooling system. The design of the cooling system needs to meet the required temperature range that the customer specified.
Approach: The material of the umbrella cover will have reasonable defensibility of heat and ultraviolet rays. Two or more mini humidifiers will be integrated into the umbrella to spray a mist to reduce the surrounding temperature. There are two potential pumps to use. The Anself can pump 240 L/H and the Vipe can do 120 L/H. The Anself is the bigger and more powerful pump, but reviews state that it is notorious for burning out if it is run dry. The Vibe is reviewed much more highly but it’s a weaker pump. We will be choosing the Vipe because it costs less and reviews state that it is more reliable.
The whole umbrella will be highly integrated. The factors of weight, size, and durability need to be considered.
The whole umbrella will be highly integrated. The factors of weight, size and durability need to be considered.
Approach: The umbrella will use bubble style, which has about 51” canopy size and manual opening. The advantage of the bubble umbrella is that it can cover the upper body more effectively than the regular one. What’s more, the bubble umbrella would be the best shape during the windy conditions. The shape is considered a reasonable solution to make the inner area of the umbrella stable. The bubble shape ensures the mist spray naturally down. We will use 3D printing to build some of the structures as well as housing for the electrical components. The filament of the 3D printer has extrusion temperature from 356F to 210F. The PCB design may be also applied because we will have to design a waterproof housing for it.
The user-specified that a solar panel is implemented into the design.
Approach: The solar panel that will be used is the uxcell 5Pcs 5V 60mA Poly Mini Solar Cell. It delivers enough power to charge the battery as well as power the circuit. When there is enough voltage coming from the solar panel, it will be used to power the umbrella. If not, the Samsung 20S 18650 2000mAh 30A Battery will be used to power the umbrella. The excess voltage from the solar panel will be used to charge the battery. There will be a diode circuit which compares voltage coming from the battery and the solar panels. Whichever is delivering more voltage will be the one used at that moment to power the umbrella.
The user-specified a humidifier in order to aide them with breathing properly outside.
Approach: The humidifier type that will be incorporated is an ultrasonic humidifier, in particular, the 20mm transducer fogger ceramics discs humidifier. There will be four separate humidifiers placed on the umbrella ribs, on opposite sides of each other. Since the humidifiers are spread out there will be ample surface area coverage to aid the users breathing. They will be controlled from the Raspberry Pi and will be adjusted based on the humidifier sensor reading. A single humidifier operates on 5V 300mA, which will be obtained from solar power supply or the backup battery.
The user required the humidifier umbrella to lower the temperature. We choose to use an integrated fan to accelerate evaporation and thus cool the air temperature.
Approach: An integrated fan with a foldable propeller will be placed at the upper part of the umbrella. The propeller will be folded when the motor is off, and the umbrella is folded. This type of propeller shall be made using a 3D printer. For the motor of the fan, we choose a 1.5V to 3V DC motor. This motor runs at a continuous current of 0.09 A, consuming power as low as 0.135 W. Also, its size is small enough to fit in the umbrella rod, with a length of 17mm, a width of 9mm, and a thickness of 7mm.