Introduction to Drone basics, classes and uses

esentation Title: Intro to Drones
Author: Karthik Rajendran

Description:
This comprehensive presentation introduces the foundational concepts of drones, also known as Unmanned Aerial Vehicles (UAVs), and their classification across land, water, and air domains. It explores the complete architecture of Unmanned Aerial Systems (UAS), delving into the various types of UAVs categorized by weight, range, purpose, propulsion, and configuration.

The presentation further explains the essential components that make up a drone, including motors, ESCs, propellers, batteries, flight controllers, and sensors. It covers advanced topics such as the dynamics of multicopters, hybrid VTOLs, and tail-sitter UAVs, alongside insights into BLDC motor operation, ESC protocols, and PID tuning.

With a detailed overview of component selection and a section on thrust bench testing, this presentation serves as a valuable learning tool for enthusiasts, students, and professionals entering the field of drone technology and aerodynamics.

1. Basics of Drones Karthik Rajendran

2. What is a Drone D – Dynamic R – Remotely O – Operated N – Navigation E – Equipment Anything that satisfies the above terms, they will be considered as drone

3. Classification of Drones Drones can be classified based on the surface area they operate. Drones operated on the Land – Rovers, RC Cars Drones operated in Water – RC Boats, Submarines Drones operated in Air – UAS (Unmanned Aerial System)

4. UAS(Unmanned Aerial Systems) A UAS (Unmanned Aircraft System) is a complete system consisting of an Unmanned Aerial Vehicles (UAV) and all associated components required for its operation. This includes The Aircraft itself, Ground Control Stations, Communication links, Launch and Recovery equipment Other supporting hardware or software.

5. Types of UAVs Classification of UAVs can be based on various factors such as Weight Range Altitude Purpose Propulsion Systems Configuration

6. Based on Weight, Range and Altitude Based on Weight Nano UAVs: Weigh less than 250 grams . Micro UAVs: Weigh between 250 grams to 2 kg Small UAVs: Weigh between 2 kg to 25 kg Medium UAVs: Weigh between 25 kg and 150 kg. Large UAVs: Weigh more than 150 kilograms Based on Range Altitude and Endurance: LADP – Low Altitude and Deep Penetration MALE – Medium Altitude and Long Endurance HALE – High Altitude and Long Endurance

7. Based on Purpose Reconnaissance and Surveillance UAVs: Used for monitoring and intelligence gathering. Combat UAVs: Armed drones for offensive military operations (e.g., UCAVs - Unmanned Combat Aerial Vehicles). Logistics and Delivery UAVs: For transporting goods or supplies. Research and Development UAVs: Used for testing and innovation. Civilian UAVs: For photography, mapping, agriculture, etc.

8. Based on Propulsion Type

9. Based On Configurations

10. BiCopter and TriCopter:

11. QuadCopter

12. HexaCopter

13. OctoCopter

14. Parts of UAVs A UAV consists of several essential parts that work together to enable stable flight and control. Here are the key component: Frame Motors Propellers Electronic Speed Controllers (ESCs) Flight Controller Power Distribution Board (PDB) Servos(FW & Hybrid Vtols) Airspeed Sensors(FW & Hybrid Vtols) Battery GPS Module Sensors(Ultrasonic & Flow Sensor, Lidar, Infrared) Transmitter and Receiver Camera and Gimbal (optional) Landing Gear Antennas BECs

15. Parts of UAV

16. Dynamics of a Multicopter Motor Rotation: Two motors rotate clockwise (CW), and two rotate counterclockwise (CCW) to ensure torque balance and maintain stable flight By having two motors rotate clockwise and two counterclockwise, the torques cancel each other out, ensuring the quadcopter remains stable. Summary of Control Actions Motion Motors Speed Ascend Increase all motors equally. Descend Decrease all motors equally. Roll Increase speed on one side, decrease on the opposite side (e.g., left motors vs. right motors). Pitch Increase speed on one pair (front/rear), decrease on the other (rear/front). Yaw Increase speed on one diagonal pair, decrease on the other diagonal pair to create rotational torque.

17. Dynamics of a Hybrid VTOL Ascend/ Descend: The takeoff and landing will be done with all the four motors rotating. Transition(Q2F, F2Q): During Q2F transition, The rear motors and the FW motor will rotate much faster and during landing the The front motors will rotate faster and the FW motor gradually stops. In Flight(Roll, Pitch, Yaw): All the Control surafces will take care of this.

18. Dynamics of a Tail-Sitter Ascend/ Descend: The aircraft starts in a vertical position, with its tail on the ground. Control surfaces or vectoring mechanisms adjust yaw, pitch, and roll during takeoff Transition(Forward): The aircraft begins tilting forward using a combination of aerodynamic control surfaces (e.g., elevons, ailerons) and motor thrust vectoring. This phase involves careful balance to avoid instability as lift transitions from propeller thrust to aerodynamic surfaces. Transition(Reverse): The aircraft slows down by reducing forward thrust and using control surfaces to pitch up gradually. The aircraft transitions back to a vertical orientation for hovering. In Flight(Roll, Pitch, Yaw): All the Control surfaces will take care of this.

19. Selection of Components Selecting the Motor Key Factors: Thrust-to-Weight Ratio: Motors should produce a total thrust of at least 2x the quadcopter’s weight (including frame, battery, and payload). KV Rating: Low KV motors (<1000 KV): Suitable for large propellers and heavy-lift quadcopters (more torque, lower RPM). High KV motors (>1000 KV): Suitable for smaller propellers and lightweight racing drones (higher RPM, less torque). Motor Current Draw: Ensure the motor’s current draw matches the ESC and battery capacity. Voltage: Select motors compatible with the battery voltage (e.g., 3S = 11.1V or 4S = 14.8V).

20. Working of a BLDC Motor With a BLDC motor, it is the permanent magnet that rotates; rotation is achieved by changing the direction of the magnetic fields generated by the surrounding stationary coils. To control the rotation, you adjust the magnitude and direction of the current into these coils, which can be done with a Hall Sensor attached With a Brushed motor, there is a brush which is connected with the commutator, which whenever comes in contact with the commutator, it energises the electric coil and makes it as magnetic coil and it repels from the permanent magents.

21. BLDC Motor – Poles and Magnets Increasing either the stator width or height increases the stator volume, the size of the permanent magnets, as well as the electromagnetic stator coils. As a result, the motor’s overall torque is increased, enabling it to spin a heavier prop faster and produce more thrust (at the expense of drawing more current). However, the downside of a larger stator is that it’s heavier and less responsive. The number of poles has a direct impact on motor performance. If there are fewer poles, you can incorporate more iron content into the stator, resulting in greater power output. However, a higher number of poles leads to a more evenly spread magnetic field. This, in turn, provides a smoother-running motor with finer control over the rotation of the bell. In Nutshell, More Poles : Smoother Performance Fewer Poles : Increased Powered

22. Selection of Components Selecting the Propeller Key Factors: Size: Larger propellers (e.g., 10 inches) generate more thrust and are suitable for heavy quad copters Smaller propellers (e.g., 5 inches) are better for racing and agility. Pitch: Higher pitch propellers (e.g., 4.5 inches) are faster but less efficient. Lower pitch propellers provide better stability and efficiency. Match the propeller size with the motor’s recommended specifications to avoid overloading the motor.

23. Selection of Components Selecting the ESC (Electronic Speed Controller) Key Factors: Current Rating: Choose an ESC with a current rating 20-30% higher than the motor’s maximum current draw (e.g., if the motor draws 20A, use a 25-30A ESC). Voltage Rating: Ensure the ESC supports the battery’s voltage (e.g., 3S, 4S, etc.). Firmware: Use ESCs with compatible firmware (e.g., BLHeli or SimonK) for smoother and responsive motor control. Type: Opt for high-performance ESCs for racing drones and standard ESCs for general use.

24. ESC Anatomy The essential components on an ESC are Microcontroller unit (MCU) Gate driver MOSFET Low dropout voltage regulator (LDO) Current sensor Filtering capacitors Gate Driver Gate drivers are used to amplify low-voltage signals from a microcontroller to high-voltage signals for power switches. This allows the switches to turn on and off quickly, which reduces power loss and increases efficiency. MOSFET MOSFETs are like switches; they switch the power on and off thousands of times per second, which is how the motors are driven. Bigger MOSFETs usually mean the ESC can handle higher voltage and current, making the ESC more robust and capable of withstanding abuse

25. ESC Protocol An ESC protocol is crucial for communication between the flight controller (FC) and the electronic speed controller (ESC), which governs the motor’s rotation speed. Traditionally, this communication has relied on PWM signals, ranging from 1000ms to 2000ms (0% to 100% throttle). Other protocols used are as follows: OneShot125  - Oneshot uses a shorter signal width, allowing the FC to communicate with the ESC/motor more rapidly, theoretically enhancing your multirotor’s performance. While traditional PWM signals range from 1ms to 2ms, Oneshot reduces this to just 125us-250us. OneShot42 - Oneshot42 is 3 times faster that Oneshot125 MultiShot - Multishot is 10 times faster than Oneshot Dshot - Dshot is a digital protocol, when others are analog protocols, depending upon the length of the electric pulse, Dshot uses zeros and ones which are much resistance to electrical noise. DShot offers three speed options, indicating the data sent per second: DShot600: 600,000 bits/sec DShot300: 300,000 bits/sec DShot150: 150,000 bits/sec

26. Selection of Components Selecting the Battery Voltage (S Rating): Common options are 3S (11.1V), 4S (14.8V), or higher. Higher voltage increases power output but requires compatible motors, ESCs, and propellers. Capacity (mAh): Higher capacity batteries offer longer flight times but add more weight. Strike a balance between capacity and total weight. C-Rating: Determines the discharge rate. A higher C-rating ensures the battery can handle the current demands of the motors and ESCs. Use the formula: Weight: Ensure the battery’s weight doesn’t exceed the quadcopter’s payload capacity.

27. Thrust Bench This thrust test aims to measure the thrust and other characteristics of the selected VTOL propulsion system . The test will assess the Motor-propeller - Battery combination's performance and provide valuable data for analysis and optimization. Purpose of Test: Evaluate the thrust characteristics of the VTOL Motor with various propellers. Determine the VTOL combination power output and propeller efficiency at various throttle settings. Validate performance specifications and ensure compliance with regulatory requirements. Provide data for comparison with manufacturer specifications and performance expectations

28. Data Gathered in Thrust Bench

29. Flight Controller A flight controller is one of the most important components in a drone. It’s responsible for stabilizing the aircraft, ensuring precise flight manoeuvres, and providing data to the pilot.   It’s a circuit board equipped with sensors that detect the drone’s movements and user commands. With this information, the FC adjusts the speed of the motors to move the drone in the desired direction. Main Components in FC: Microprocessor: Processes inputs from the sensors and the operator Internal memory: Stores flight parameters, also known as the Black Box Serial interfaces: Allows the flight controller to communicate with other devices Input/Output Interfaces: Allows the flight controller to communicate with the remote control receiver, motors, and other devices Sensors: Accelerometer, Gyroscope, Barometer, Compass(Magnetometer)

30. Flight Controller – IMU Sensors IMU Sensor: An inertial measurement unit (IMU) is an electronic device that measures and reports a body's specific force, angular rate, and sometimes the orientation of the body, using a combination of accelerometers, gyroscopes, magnetometers. Sensors: Accelerometer, Gyroscope, Barometer, Compass(Magnetometer) Accelerometer: It measure the rate of change in an object's velocity, or acceleration. This can include vibrations, bumps, or sharp changes in speed Gyroscope: a gyroscope can measure the angular rate and angular velocity; In Short, accelerometers sense changes in speed and direction. Gyroscopes sense rotational speed. Barometer: Used to monitor the pressure difference and help in judging the Altitude Compass(Magnetometer): Helps in measuring the strength and direction of magnetic fields and it is used for Heading Reference systems.

31. PID and PID Tuning PID, which stands for Proportional, Integral, Derivative, is an algorithm within a flight controller’s software that reads data from sensors and processes radio stick commands to calculate the required motor speed for achieving the desired rotational rate. A PID controller’s primary goal in an drone is to correct the “error” by adjusting motor speeds. The control loop continuously reads sensor data and calculates motor speeds to minimize the error. P (Proportional) relates to the present error. The larger the error, the harder it pushes – in math term, it’s proportional to the error. D (Derivative) predicts future error. It considers how quickly the set-point is approached and counteracts P to minimize overshoot when nearing the target – in math term, it’s the derivative of the error. I (Integral) accumulates past errors. It addresses external forces that occur over time, such as a drone drifting away from set-point due to wind or an off-centered weight, by adjusting motor speeds to counteract it – in math term it’s the integral of the error.

32. PID and PID Tuning P Gain - P gain determines the intensity with which the flight controller works to correct errors. Consider P gain as a responsiveness setting. A high P gain creates a snappy response, making it feel as though your rates have increased. Signs of improper P: Excessively high P gain can cause rapid oscillations. Conversely, when P gain is too low, the quad copter feels sloppy and slow to respond. D Gain , D helps dampen oscillations caused by high P values. Fine-tune D to minimize oscillations without making the system too sensitive Signs of improper D : Too low : Persistent oscillations after movement. Too high : Jerky movements or noise in the motors. I Gain, Increasing the I-gain corrects for any drift during high winds or steady-state errors. If I gain is not set, the copter will move along with the winds in wind direction. Signs of improper I: Too low : The quadcopter drifts over time or cannot hold altitude/position. Too high: Oscillations or slow response to inputs.

33. PID Tuning Video PID Tuning

34. Architecture of Quadcopter

35. Architecture of Quadcopter

36. THANK YOU