ece 477 design review team 9 spring 2011 left-to-right: oliver staton, vinayak gokhale, vineet...

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