Final Design

Overview

All components of the final design can be categorized in three categories:

1) Mount Structure

2) Electronics

3) Data Acquisition

Mount Structure

Components

Platform

The platform attaches the four legs of the mount to the mast that holds the anemometer. It also carries the electronics box. Because of the angular constraints, no extra support is needed to keep the legs of the mount attached once it is assembled. The slot for the mast has two layers, a press fit and an inner sleeve. There are also holes for a set screw on either side, which hold the mast in place. The electronics housing mounts to the bottom of the platform.

Clamps

The clamps were made to securely attach to the arms of the drone while being easy to attach and detach. They have a +0.1 mm tolerance compared to the drone arms and mount legs, which was found to be a secure but easy to assemble fit. The final design was 3D printed out of ASA.

Anemometer Adapter

This part is attached to the top of the mast and holds the anemometer. Similarly to the mount plate, it has two layers on the slot that attaches it to the mast and is held on via a set screw. The holes on the four petals align with the mounting points on the anemometer, attaching it with M2 screws.

Carbon Fiber Tubes

The carbon fiber tubes function as the legs and mast of the mount. Their strength and remarkable lightness make them the ideal choice for the project, since a heavier payload would drain the drone's battery faster.

Assembly

Cross Section of Anemometer Mount

The anemometer mount connects the anemometer to the carbon fiber mast. The blue is cross section of the ASA 3D-printed anemometer mount, and the pink parts are the screws that prevent the carbon fiber tube and mount from pulling apart axially. In addition to holding the outer diameter of the tube via press fit, the anemometer mount supports the inner diameter of the mast to prevent excess screw tightening.

Cross Section of Platform to Mast

The platform connects the four mount legs to the mast and also functions as a mounting place for the electronics housing. The green is the cross section of the ASA 3D-printed platform, and the pink parts are the screws that prevent the carbon fiber tube and platform from pulling apart axially. In addition to holding the outer diameter of the tube via press fit, the platform supports the inner diameter of the mast to prevent excess screw tightening.

Cross Section of the Platform and Clamps to the Legs

The platform and clamps are connected to the legs with a press fit. The green is the platform and the red is the clamp.

Cross Section of the Platform to the Electronics Housing

The platform connects to the electronics housing with screws that thread into heat-set inserts built into electronics housing. The green is the platform, the pink are the screws, and the orange is the housing.

Electronics

Overview

The electronics system collects data with an anemometer and I2C sensors, collects it with a Raspberry Pi 4, and transmits it through a LoRa module.

Electronics Housing

This component holds the Raspberry Pi, USB adapter, and power bank. The holes on the bottom align with those on the RPi, and attach via M2.5 screws. The USB adapter and the power bank are attached with a Velcro strip on the side, allowing for easy removal and maintenance. The box also has slot on the lip that the lid fits into.

The lid encloses the electronics box and holds the I2C sensors from a previous student design team. The holes on the top align with the sensors and hold them in place with M2.5 screws. It slides securely into the slot on the electronics box.

Anemometer

The anemometer is an Li-550f 3D anemometer. It can record wind speed and direction, temperature, pressure, humidity, pitch, roll, and heading. It outputs data at a rate of 1-40 Hz. It outputs data via RS-232 protocol from 4 wires attached at its base.

USB Adapter

The USB interface adapter for TriSonica sensors is to convert the RS232 protocol from the anemometer into USB so that the Raspberry Pi can log the data.

Raspberry Pi Model 4B

This is the primary data processor for the design. It runs a python program on startup that collects data from the anemometer and I2C sensors, prints the data to terminal and writes it to serial to be sent to the LoRa

LoRa Modules

The design uses two LoRa modules to transmit data. One is connected to the Raspberry Pi via USB and is configured as a sender node and the other is connected to the computer's serial port and is configured as a receiver. They are programmed via Arduino IDE.

I2C Sensor Suite

These sensors were inherited from the 2021-2022 Spring Mae 156B Team 15 and they record altitude, humidity, pressure and temperature. They communicate via I2C, and are connectde to the Raspberry Pi via an I2C hat.

Power Bank

This is a 6000mAh Power Bank that powers the Raspberry Pi and LoRa Modules.

Data Transmission

Data Logging and SSH

The data logging is done with a python script that runs on startup. This script reads data from the anemometer and I2C sensors and prints it to the terminal, allowing it to be viewed through SSH protocol. It also sends the data to serial port tty/USB1 on the Raspberry Pi, which is where the sender LoRa module is connected, allowing the data to be sent to the receiving nodule connected to a computer. The script also opens a live dashboard of sensor data that can be viewed through SSH.

LoRa

The data is transmitted through LoRa communication from the sender nodule on the Raspberry Pi to the receiver nodule on the computer. The data is then read with a LabView program, which parses it

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