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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• Software design/development status• Project completion timeline• Questions / discussion
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.
Project-Specific Success Criteria
1. An ability to remotely monitor remaining battery life (fuel gauge).
2. An ability to hover in a stable position (based on autonomous stability / control algorithm).
3. An ability to fly in any direction (compass orientation) at a variable speed and a stable altitude (based on autonomous stability / control algorithm).
4. An ability to take off/land (ascend / descend) while remaining level (based on autonomous stability / control).
5. An ability to remotely control flight functions (e.g., ascend, descend, hover, compass orientation, forward speed).
Block Diagram
Component Selection RationaleIMU Sensors
3-Axis Gyroscope
ITG3200 (I2C interface)
Dedicated 16-Bit Onboard ATD
3-Axis Tilt-Compensated Magnetometer
HMC6343 (I2C interface)
2 degree resolution
3-Axis Accelerometer
LIS3LV02DQ (I2C interface)
Dedicated 16-Bit onboard ATD
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
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
Component Selection Rationale Brushless Motors
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
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
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
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
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
Component Selection Rationale Airframe
Constraints:• Rigid structure• Lightweight / durable material
Selection:• Mikrokopter MK50 Frame• Extruded Aluminum beams• Carbon fiber base plate• 120 grams
Packaging Design
Above: Top view of Airframe.
50cm motor-to-motor (diagonal)
Packaging Design
Above: Airframe with cover.
Carbon Fiber Cover
Tubular Aluminum
Packaging Design
Above: Airframe with cover removed.
Packaging Design
Above: 3 PCB Stack positioned at center of airframe.
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
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.
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.
Schematic/Theory of Operation 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.
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).
Schematic/Theory of Operation 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 OperationPID Stability: Roll
H3 H2 H1 GcV
c
cWx LR
Loop #1Loop #2
Loop #3
:c
:c
Wx
:LR
:cV Left-to-right translational velocity Roll Rate
Roll angle Left-to-right sensor data
Schematic/Theory of OperationPID Stability: Pitch
H3 H2 H1 Gc
U
c
cWy FB
Loop #1Loop #2
Loop #3
:c
Wy
:FB
:c
U forward translational velocity
Pitch angle
Pitch rate
Front-to-back sensor data:c
Schematic/Theory of OperationPID Stability: Altitude
H2 H1 Gch
cW Tsum
Loop #1Loop #2
:Tsum:ch Altitude
Vertical Velocity
Total thrust
:c
W
Schematic/Theory of OperationPID Stability: YAW
H2 H1 Gc
cWz FBLR.
Loop #1Loop #2
:.FBLR:c
Heading
Yaw rate:c
Wz
Ratio of thrusts
Feedback Loop – “Firing Order”
LR
Wx
Wx
C
C
CV
FB
Wy
Wy
C
C
CU
Tsum
Wc
Wc
Ch
FBLR.
Wz
Wz
C
SET #1
SET #2
SET #3
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.
PCB Layout
Above: PCB bottom level.
PCB Layout
Above: PCB middle level
PCB Layout
Above: PCB top level.
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.
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
Project Completion TimelineWeek # Milestone Items Due
8 I2C complete workingDROID Accel. working
Formal Design Review
9 PCB submissionPID preliminary testDROID Gyro working
Final PCB Final SchematicProof-of-Parts
10 SPRING BREAK
11 PCB assemble & testPID implementationDROID Wi-Fi working
Software Design Narrative
12 Packaging PID debuggingDROID Wi-Fi debugPSSC #2 test
Parent Liability Analysis
Week # Milestone Items Due
13 Wi-Fi testingSensor testingDROID communicationPID debuggingPSSC #3 test
Reliability and Safety Analysis
14 Wi-Fi debuggingSensor debuggingDROID com debugPID debuggingPSSC #4 testPSSC #5 test
Ethical and Environmental Impact Analysis
15 Test and Clean-UpPSSC #1 test
User Manual
16 Vehicle demonstration PSSC Demo
Project Completion Timeline
Questions / DiscussionQuestions / Discussion