UAVPresented By: • Alexander Mohamed Osman • Riyad Ahmed El-laithy • Ruyyan Ahmed El-laithy • Peter Raouf Zaki
Introduction• What are UVs ?• What are UAVs ?• Types of UAVs – Fixed wing UAV – Helicopter UAV – Quadroter UAV
Quadrotor Advantage Over Fixed- Wing Vehicle• Less design complexity.• Minimal space for take-off and landing. A VTOL vehicle.
Quadrotor Advantage Over Helicopter• Quadrotors do not require mechanical linkages.• The use of four rotors allows each individual rotor to have a smaller diameter than the equivalent helicopter rotor.
The Third Prototype• What is improved in this prototype ?- Starting the X design- Reduced air resistance.- More lift gained .- Lightweight . • 45 Grams. Picture of the 3rd Prototype
The Third Prototype• Problems with the new design: – Too fragile. – The reduced air resistance was still not enough.• What can be done ?
The Fourth and Final PrototypeTop: Isometric: Front: Side:
The Fourth and Final Prototype• Achievements: - Rigid and Lightweight. (43 Grams). - Great lift. - Highly reduced air resistance. Picture of Final Prototype
The Fourth and Final Prototype• Specifications: -Total Weight (with all components) = 990 Grams (0.99 Kg) - Acceleration at Full Power = 4.061m/s2 - Vertical Force at Full Power = 4.021N (Assuming Differential Torque = 0) - Lateral thrust beyond Hover Thrust = 0.4141g - Power – to – Weight Ratio = 1.5 : 1
Controller Design• Design Objectives – Stability – Obstacle Avoidance – Determining Position – Communication
Controller Design• To achieve these objectives we need – IMU (Inertial Measurement Unit) – 5 Ultrasonic Sensors – GPS Receiver – RF Transceiver
Controller Design• MicroController requirements – 4 PWM Outputs – 11 Analog to Digital Channels – High speed crystal• PIC18F4431 – 4 14-bit Power PWM modules – 9 10-bit 200Ksps ADC channels – 40 MHz Crystal Max
Controller Design• Problems with PICxxFxxxx – IMU and RF work at 3.3V Logic – GPS messages are TTL 0 – 2.85V – Ultrasonic readings range from 0 – 2.54• PIC16LF777 – 3 10-bit PWM modules – 14 10-bit ADC channels – 10 MHz Crystal max – Operating voltage range from 2V – 5.5V – 2 Connected together
Controller Design• Last Main Board – Photo-couplers – Interface boards – Sub-boards – 90° Interface connections – Even smaller design – ICSP (In Circuit Serial Programming) wires were added onto the circuit later on – LEDs for easier debugging without the need for expensive hardware such as ICDs (In Circuit Debuggers)
PCB Production Procedures• What do you need to make a PCB – Laser printer – Glossy paper – Acetone – Clothing iron – Acid – Steel sponge
PCB Production• Clean the surface of the board• Print the circuit• Start folding• Start ironing• Put it in hot water• Start chemical etching• Finalize with drilling
Analog-To-Digital Converter• ADCs: - Importance of Data Acquisition in our UAV. - Vref set on 3 Volts. - Ultrasonic sensors. - Gyrometer. - Accelerometer.
ADCs• ADC Reading = (Vin/Vref) X (2N); where Vin : is the Voltage input. Vref : is the reference voltage. N : is the resolution of the ADC Conversion.
Ultrasonic Sensors• Ultrasonic Sensors: - Maximum Range: 254 inches (6.45m) - Minimum Range: 6 inches (15cm) (Blind Spot) - New Readings every 49 Milliseconds. - Has Serial/Analog/Pulse Width Modulation output. - Every 0.01V represents 1 inch.
Ultrasonic Sensors• Calculating Distance inside ADC: - Distance = (Vin/Vref) X (2N);• For example: 50cm = 0.20 Volts shown on Ultrasonic Sensor. (0.20/3.30)*1024 = 62.061 To calculate backwards to know accuracy: (62/1024)*3.3 = 0.1998 Volts on input pin. Therefore, the Error = (1-(0.1998/0.20))*100 = 0.1%
PWM• Pulse Width Modulation: - Processing after Data Acquisition for scenarios. - Implementing the data acquired as output on Motors. - Frequency for Motor Output (750Hz).
PWM• How It works? Obtains Average of On/Off Intervals within period.• VAV = 1.65 Volts since half the time is ON and the other half is OFF.
Testing Sensors• A great way to test the sensors is using an LCD. – Tangible.• Used to test all sensor outputs after processing: - Ultrasonic. - Accelerometer. - Gyrometer. - GPS Receiver. - RF Transceiver units.
GPS Applications• GPS has become a widely used aid to navigation worldwide.• A useful tool for – Map making. – Land surveying. – Scientific uses.
NAVSTAR Constellation• There is a constellation of 30 earth orbiting satellites transmitting precise radio signals.• Orbits are set up so that at any given point and time on the earth’s surface there are at least six of these satellites in reach.
GPS Messages• Almanac contains orbital data• Ephemeris contains the satellites precise orbit.
Pseudorange• Estimated distance calculated by the receiver between the satellite and receiver.
Trilateration• Pseudoranges intersect at a point.• This point is the receiver location.
Output Message• Message of choice was RMC, it contained all we needed which was: – Latitude & Longitude – Course Heading – Velocity
USART• The GPS communicates with the PIC through USART.• Communicates at 4800 bps• Asynchronous
Validating Message• When the message is validated: – The latitude, longitude and heading are ready to be extracted to the Main PIC. – RF function is called to transmit data, to the simulator.
Inertial Measurement Unit• Gyro – Measures angular velocity on the x and y axes – Can also be used to calculate displacement angle – Sensitivity of 2mV/°/sec
Inertial Measurement Unit• Accelerometer – Measures acceleration on the x,y and z axes – Sensitivity of 300mV/g – Can also measure angles
Inertial Measurement Unit• IMU – Gyrometer & Accelerometer – Transform acceleration readings onto the 3 original axes. – Velocity & Displacement can be calculated from accelerometer readings on 3 main axes.
Data Acquisition• What is Data Acquisition?• Why?
Data Presentation• What is Data Presentation?• Why?
Problems• Serial Port• Signed Byte• Graph Origin• Converting Longitude and Latitude to Pixels
Solutions• Javax.comm -CommPortIdentifier -Streams -SerialEvent -Converting any data to String then to Bytes• Convert to short add 256 if negative• -( ( (Height - 90 ) / Range ) * Actual ) + Separation• ((width /|(difference between top left longitude and bottom right longitude)|)*|(acquired longitude-top left longitude)|)
FUTURE IMPLEMENTATIONS• Gyrometer & Accelerometer drift correction• Ultrasonic sensors attached to servos.• High powered brushless motors.• A long range high resolution camera.• Magnetometer• Chassis redesign
CONCLUSION• Local market restrictions inhibited time.• Bottom down programming was the best approach.• Data presentation helps in detecting errors faster and avoiding problems.• Placing UAV on a map helps discovering its location.• Tester helps in testing the response of the RF and the pic programs