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ECE 477 Design Review Team 9  Spring 2011

ECE 477 Design Review Team 9  Spring 2011. Left-to-right: Oliver Staton, Vinayak Gokhale, Vineet Ahuja, Nick Gentry. Outline. Project overview Project-specific success criteria Block diagram Component selection rationale Packaging design Schematic and theory of operation PCB layout

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ECE 477 Design Review Team 9  Spring 2011

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  1. ECE 477 Design Review Team 9  Spring 2011 Left-to-right: Oliver Staton, Vinayak Gokhale, Vineet Ahuja, Nick Gentry

  2. Outline • Project overview • Project-specific success criteria • Block diagram • Component selection rationale • Packaging design • Schematic and theory of operation • PCB layout • Software design/development status • Project completion timeline • Questions / discussion

  3. Project Overview The proposed project is a four rotor helicopter platform that will run a stability algorithm. Furthermore, the helicopter will have object avoidance capabilities and basic waypoint navigation. Sensor data will be sent out wirelessly.

  4. Project-Specific Success Criteria • An ability to remotely monitor remaining battery life (fuel gauge). • An ability to hover in a stable position (based on autonomous stability / control algorithm). • An ability to fly in any direction (compass orientation) at a variable speed and a stable altitude (based on autonomous stability / control algorithm). • An ability to take off/land (ascend / descend) while remaining level (based on autonomous stability / control). • An ability to remotely control flight functions (e.g., ascend, descend, hover, compass orientation, forward speed).

  5. Block Diagram

  6. Component Selection RationaleIMU Sensors 3-Axis Gyroscope ITG3200 (I2C interface) Dedicated 16-Bit Onboard ATD 3-Axis Accelerometer LIS3LV02DQ (I2C interface) Dedicated 16-Bit onboard ATD 3-Axis Tilt-Compensated Magnetometer HMC6343 (I2C interface) 2 degree resolution

  7. Component Selection RationaleObject Avoidance and Translational Motion Ultrasonic Sensor Maxbotix LV EZ4 (Analog) 10mv/inch, up to ~21 feet Optical Flow Sensor (provides X-Y location) ADNS2620 (SPI) 3000fps, 400cpi resolution, accurate up to 12 ips Retrofitted with alternate lens for 3ft focal length

  8. Component Selection Rationale Brushless Motors Constraints: • Greater than 2:1 thrust to vehicle weight ratio • Current should not exceed 10A per motor @ 14.8V Selection: • MK2832/35 Brushless 14-Pole • Lithium Cell Count: 4 • Maximum load current: 10A • No load speed: 760RPM/V • Maximum Thrust (10x4.5 prop): 820g per motor

  9. Component Selection Rationale Electronic Speed Control Constraints: • Must be able to source > 10A @ 14.8V Selection: • Turnigy Basic 18A ver3.1 • Lithium Cell Count: 2-4 • Maximum load current: 22A • Continuous Current: 18A

  10. Component Selection Rationale Battery • Constraints: • Must be able to supply > 50A @ 14.8V • Runtime > 10 minutes • Selection: • Turnigy Nano-Tech • 14.8V / 4500mAh • 25C Discharge Rate

  11. Component Selection Rationale Wi-Fi Module • Constraints: • Baud rate > 400kbps to achieve proper transmission of video and control data • Selection: • Roving Networks RN-131G • 802.11 b/g • WPA/WPA2 • 4uA sleep • 40mA Rx • 210mA Tx

  12. Component Selection RationalePrimary Microcontroller • Constraints: • Purpose: Run Stability Algorithm • Peripherals • I2C x2 • SPI x1 • UART x2 • Six channels of 12-Bit ATD • Four channels of PWM • Selection: • Texas Instruments MSP430F5438 16-Bit 25MHz • 256KB Flash • 16KB Ram

  13. Component Selection Rationale Secondary Microcontroller • Constraints: • Purpose: Process video + WiFi interface • Peripherals • I2C x2 • UART x2 • Selection: • Texas Instruments MSP430F2618 16-Bit 16MHz • 116KB Flash • 8KB Ram

  14. Component Selection Rationale Airframe • Constraints: • Rigid structure • Lightweight / durable material • Selection: • Mikrokopter MK50 Frame • Extruded Aluminum beams • Carbon fiber base plate • 120 grams

  15. Packaging Design 50cm motor-to-motor (diagonal) Above: Top view of Airframe.

  16. Packaging Design Tubular Aluminum Carbon Fiber Cover Above: Airframe with cover.

  17. Packaging Design Above: Airframe with cover removed.

  18. Packaging Design Above: 3 PCB Stack positioned at center of airframe.

  19. Schematic/Theory of Operation Lithium Polymer Battery • 14.8 V • 4500 mAh • LM7805(5V) & UA78M33(3.3V) • Microcontrollers • MSP430F5438: IMU, PWM, Ultrasonics, PID controller • MSP430F2618: WIFI module, Optical Flow Sensor, Battery Monitor • WIFI Module (RN121) • 3.3V • Uart TTL logic interface • Placed on board the MSP430F2618, it will transfer control data sent from base station to MSP430F5438 via UArt

  20. Schematic/Theory of Operation • Ultrasonic Sensors • 6 Ultrasonic Sensors connected to top board • Operates at 3.3V • Measures distance from obstacle & outputs analog voltage at 6.4 mV/in sampled via ADC channels in micro.

  21. Schematic/Theory of Operation Electronic Speed Controller (Turnigy Basic 18A) • 10 A at 14.8V • Connected to headers on the bottom board. • Takes PWM input and interprets duty cycle into 3 phase power output to Brushless DC motors.

  22. Gyroscope (ITG-3200) 3.3V I2C, 400KHz fast mode Gives radians/s along X, Y and Z axes which will be fed into PID controller to stabilize vehicle. Schematic/Theory of Operation • 3 axis Accelerometer (LISL3LV02DQ) • 3.3 V • I2C device connected to MSP430F438 • Will provide real time calibration of Gyroscope. • Magnetometer (HMC6343) • 3.3V I2C slave device connected to MSP430F5438 • This compass corrects the gyroscope reading for heading read error (yaw drift).

  23. Battery Monitor 4 Voltage divider circuits which divide the battery voltage down to a level that can be monitored on the ADC channels Schematic/Theory of Operation

  24. Schematic/Theory of OperationPID Stability: Roll H3 H2 H1 G Loop #1 Loop #2 Loop #3 Left-to-right translational velocity Roll Rate Left-to-right sensor data Roll angle

  25. Schematic/Theory of OperationPID Stability: Pitch H3 H2 H1 G Loop #1 Loop #2 Loop #3 forward translational velocity Pitch rate Front-to-back sensor data Pitch angle

  26. Schematic/Theory of OperationPID Stability: Altitude H2 H1 G Loop #1 Loop #2 Altitude Total thrust Vertical Velocity

  27. Schematic/Theory of OperationPID Stability: YAW H2 H1 G Loop #1 Loop #2 Heading Ratio of thrusts Yaw rate

  28. Feedback Loop – “Firing Order” SET #1 SET #2 SET #3

  29. PCB Layout • Small board area but multiple (three) boards. • Precise placement of components. • Avoid congestion on any one board. • Keep center of gravity low. • Keep boards level.

  30. PCB Layout Above: PCB bottom level.

  31. PCB Layout Above: PCB middle level

  32. PCB Layout Above: PCB top level.

  33. Software Design/Development Status • MSP430F5438 : I2C, PWM, Uart, ADC • Tested ADC sampling of ultrasonic sensors • Uart, PWM generic libraries available • Established communication with magnetometer via I2C • Currently working on Gyroscope and Accelerometer • MSP430F2618: Uart, SPI, ADC • Tested Generic Uart Code.

  34. Software Design/Development Status • Constructed test stand • Allows roll, pitch, and yaw measurements • Characterized brushless motors • Torque and thrust curves given unit step and ramp inputs • Established values for motor Tau Example of motor characterization given unit step input

  35. Project Completion Timeline

  36. Project Completion Timeline

  37. Questions / Discussion

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