Advanced Multi-rotor Drone

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Example
Sponsors	Peter Baran
Team Name	Two birds and one drone(TBOD)
Duration	Fall 2018 - Spring 2019
Faculty Adviser	Dr. Feng Li
Client	Peter Baran
Team Members	Caleb Smith Makynzie Zimmer Preston Stephens Matthew Shryock Pengqiang Ge

Design Goal

The main project objective is to understand the ground-up multi-rotor drone design. It will include the electro-mechanical design and construction of the airframe, the design and construction of electrical/electronic circuitry to implement the control system that allows the drone to fly, and the design and construction of tools to aid in the process. The control system design will be implemented in an FPGA. A large portion of this project is developing tools to pass on to future teams. This includes various customized tools and methodologies for the development process.

Project learning

FPGAS: Field Programmable Gate Arrays are devices that are based on around a matrix of configurable logic blocks (CLBs) which have programmable connections. We can use this property to monitor and respond to all of our sensors simultaneously, allowing extremely fast response time.

ESCs:In terms of individual components to go on the boards, we needed MOSFETs to drive the motors, current switching ICs to drive the MOSFETS, comparators to measure back EMF, and an assortment of resistors, capacitors, and diodes. A brushless DC motor to turns as the result of switching the flow of current through its three coils. At any given time, one coil is connected to the supply voltage, another coil is connected to ground, and the other coil is connected to high impedance. Depending on which coil is in which state, the motor will align to a certain position. By switching the states of the coils, the motor can be operating in a similar way to a stepper motor. The motor will have an optimal speed depending on the supply voltage so state transitions need to occur at specific times. Additionally, a PWM signal can be used to modulate the source voltage and the resulting optimal motor speed. Brushless DC motors are designed so that when the coil connected to high impedance passes a magnet on the stator, it is time to switch to the next state. This time can be determined by sensing the back EMF on that coil and comparing it to a virtual neutral.

Motor characterization

While researching potential motors and propellers for our drone, it became evident that larger propellers are more efficient than smaller propellers in producing thrust. We also learned that propellor material and design is also important. The strength, as well as the angle of attack of a given propellor, determine its efficiency and its weight to thrust ratio. This led to our choice to use Carbon Fiber blades for our rotors.

According to the data from the real-time plotting, each motor with this specific propeller produces a reasonable amount of lift which is Approximately 380g.

Mechanical Design

There are the early mechanical modelings of our final deliverables.

Part	Description
	Early in this project the conclusion was reached, that drone development required more than just the production of a drone. To successfully design and manufacture a drone, we first needed to develop tools and systems with which we could develop and characterize power, control, and avionics systems. To accomplish this task, two drone test stands were developed.
	There are two processes that I highly recommend for the conceptualization of a lifting body for future drone frames. An indispensable tool for balloon shape and profile design is SolidWorks. A wide range of design option allows for simple geometry advancing up to complex models. Converting the volume into Litres (if not already). Since 1L of Helium produces 1 g of lift it’s possible to figure out how much lift your balloon should produce.

Final deliveriables

There are final Mechanical and Electrical Engineering deliverables.

Part	Description
	This "Teeter-totter" test stand allows us to test our equipment in a safe controlled environment. It limits movement to two degrees of freedom, sliding up and down, and rotation along one axis. This modular design allows for testing of various different components including batteries, motors, ESCs, control systems and etc. By developing a teeter-totter stand we were able to produce a single degree of freedom between a pair of motors. This allowed for a handful of vital tests and calibrations. Most important of these, was the ability to test and calibrate the first Arduino based control system and eventually the FPGA based control system. This allowed for rapid feedback on design prototyping and development.
	By utilizing a helium filled balloon, the weight of the drone’s airframe could be offset. The resulting lightened drone frame would then require less power from the motors. I.E. less power draw on the batteries lending to a longer available flight time.The first step to create a balloon is to have a design thoroughly thought out and sketched, with rough dimensions, on engineering paper. Since the shape being created is going from 2D to 3D keep in mind how it will change when blown up, as the vertical element can cause unexpected malformations. For example, to create the conical cylinder, triangle are used. When two layers shaped like the blue conical cylinder below are placed over each other, sealed, and inflated they will take on a cigar shape.
	The custom-made, electronic speed-control circuit board provides a direct interface between our FPGAs and our motors and provides filtered feedback to allow our program to be light and respond quickly and reliably.Signal tap could be integrated into the FPGA development process to better understand the signals inside of the design and a more robust interface between the AVR core and the Verilog block would allow for quicker prototyping.
	The 360-degree test stand allows for movement in the traditional aeronautic principal axis: roll, pitch and yaw, as well as vertical movement.Our testing drone model whose frame is DJI F450 has been assembled with several electrical components including data transfer, data display, data record and wireless control. Firstly, four stacked boards which include LCD, SD and IMU(BNO055) shield, Xbee Shield and Arduino Uno have multiple functions that are point-point data transfer between master and slave through Xbee wirelessly, recording IMU data including yaw, roll and pitch, magnetic field intensity and 3-axis acceleration onto SD card and displaying real-time IMU data on the LCD screen.
	The visualization software displays real-time data from the sensor and stimulates the position change of the drone in the three-dimensional space.a 360-degree test was developed. This test stand allowed for movement in the three principles aeronautic axis: Roll, Pitch, and Yaw. It also allowed for vertical, or Z axis movement. While it will eventually be used for the same control system calibration processes as the Teeter-Totter, the purpose for this stand ended up being used for Radio Control and Remote sensing. A system was developed where real-time drone orientation could wirelessly be transferred from the sensors on the drone to a computer program. The telemetry gathered through this system is essential to calibrating and autonomous flight control system.
	The customized transmitter converts analog signals to PWM signals that the receiver receives drive those four motors in the drone wirelessly.This simple RF transmitter that contains two RF modules NRF24L01 and Xbee can be used to control four brushless motors and transfer IMU data wirelessly. The principle is that we convert analog signals of potentiometers to sampled digital signals that are wirelessly transferred to the control board on the drone and then those sampled digital signals are regulated to be PWM signals by those electronic speed controllers. Therefore, the speed of four brushless motors can be controlled wirelessly. In fact, the gestures of drone movements are based on the combination of four motors.

Team Members

Picture	Bio	Discipline
	Caleb Smith: I'm a senior in Mechanical Engineering from Boise, ID.	ME
	Makynzie Zimmer : I’m a senior in mechanical engineering here at UI and am from Boise, ID.	ME
	Preston Stephens: I am a senior from Coeur d'Alene, Idaho focusing on digital design.	CompE
	Matthew Shryock: I'm a senior in Electrical Engineering, and I'm from Coeur d'Alene, Idaho.	EE
	Pengqiang Ge: I am a senior from China.	EE

Design Validation

Requirement	Test	Test subject	Target Date	Result	recommendation
Prototype Motors need to be able to produce enough lift for flight and control	Measure the thrust produced by the motors with a motor test rig	prototype Motors and Rotors	10/17/2018	Motors produced a reasonable amount of lift. Approximately 380g.	N/A
Finished Product may not exceed 6 feet in any direction	Measure finished product	Fully functional final product	4/26/2019	Yes	N/A
The helium balloon will displace at least 1/3 of the total drone weight.	Lift of the balloon and drone weight will both be measured using the wheatstone bridge in the drone lab	Fully functional prototype	4/26/2019	Yes	N/A
Must account for variability in BC consistency and texture	Manually, visually inspect BC for clumping and inconsistencies in texture; should be no particles larger than 0.25 inches	Functional prototype	3/21/2019	Yes	N/A
Be able to control its flying direction by using programming and controller	Set product in an uncontrolled environment outside	Fully functionnal final product	4/26/2019	Yes	N/A
Produce a balloon for prototype that has approx 280 g of lift	Measure the lift of the balloon using the wheatstone bridge assembly in the drone labes	Fully functioning prototype balloon	4/26/2019	Yes	N/A
Produce an Arduino based flight controller	Confirm that the controller produces stable flight and responds to user commands	Fully functioning prototype product balloon	4/26/2019	Yes	N/A
Produce a FPGA based flight controller	Confirm that the controller produces stable flight and responds to user commands and verify use	Fully functioning final product	4/26/2019	Yes	N/A
Be able to perform the grid path and return to home point	Field testing	Fully functioning final product	N/A	N/A	N/A

Flow chart for control system

File:FPGA Flow Chart.pdf

File:MicroController Flow Chart.pdf

Additional Documentation

Meeting Minutes

9/20 Meeting Minutes
9/28 Meeting Minutes
10/04 Meeting Minutes
11/01 Meeting Minutes
11/08 Meeting Minutes
12/13 Meeting Minutes
3/1 Meeting Minutes
3/22 Meeting Minutes
3/23 Meeting Minutes
4/5 Meeting Minutes
4/12 Meeting Minutes
4/19 Meeting Minutes
4/20 Meeting Minutes
4/22 Meeting Minutes

Design EXPO Materials

4/26 Presentation Outline
4/26 Technical Presentation