Autonomous Helicopter

James Lyden Harris Okazaki EE 496

Project Overview

The goal of this project is to create a helicopter capable of flying itself. The helicopter should be able to take off, fly to a predetermined location, and land without user input (during flight). The

target will be specified pre-flight by a user, through a computer interface.

Systems Overview

Computer with Bluetooth

Interpret sensor data/calculate and maintain course

Transceiver: Class 1 Bluetooth Radio

Send formatted sensor readings to the PC

Receive control signals from the PC

PIC Microcontrollers with UART, SPI/I2C

Collect/Format sensor readings prior to transmission

Convert/split control signals prior to sending to servos

Gyroscope Sensor

Read rotation around rotor axis

3-Axis Accelerometer Sensor

Read acceleration in X, Y, and Z directions

Sensor Orientation

Subsystem Design

User: input flight plan

3 AxisAccel Gyro

Servos

PC w/BT:calculates

control signals

Master μCBT

transceiver

Slave μC

OFFBOARD

ONBOARD

Processing

PC (POSIX OS)

PID calculations

position/velocity/acceleration data storage

Master Microcontroller

Sensor interface

Servo control

PC relay

Slave Microcontroller

Servo control

PC Software Flow

Initialize:Open Serial PortTest Serial Port

Get Data:Listen for PacketParse Packet

Store Data:Update Pos/Vel/AccUpdate Error Values

PID Calculations:Read Error ValuesCompute Corrections

Flight Planning:Check Flight ModeAdd Desired Offsets

Format Output:Combine Offsets+PIDPut Data Into Buffer

Send Data:Write Buffer to Serial Port

Master μC Software Flow

Initialize:Open Serial PortsInitialize SensorsInitialize PWMs

Get Sensor Data:Send CommandsRead/Save Responses

Format Sensor Data:Use 8 MSbsCast To Chars

Send Sensor Data:fprintf Each ByteWrap Word With Tags

Get Correction Data:Wait For UART ReadyRead 4-Byte Word

Set Control Signals:Parse First 2 BytesSet PWM Duty Cycles

Slave μC Software Flow

Initialize:Open Serial PortInitialize PWMs

Get Correction Data:Wait For UART ReadyRead 4-Byte Word

Set Control Signals:Parse First 2 BytesSet PWM Duty Cycles

TimelineTimeline

\ Week February March April May Todos \ 02/03/08 02/10/08 02/17/08 02/24/08 03/02/08 03/09/08 03/16/08 03/23/08 03/30/08 04/06/08 04/13/08 04/20/08 04/27/08 05/04/08 05/11/08 05/18/08

Hardware:3.3V Power Supply5V Power Supply μC <-> Gyro Interface μC <-> Accel. Interface μC <-> Bluetooth InterfacePCB LayoutPCB AssemblyDebugging

PC Software:Data AggregationPID Algorithm/TuningBT Serial InterfaceUser InterfaceDebugging

Documentation:Draft of Final PaperFinal Paper

Constraints to Consider

Weight

The sensors, transceiver, and power supply must be as light as possible, since they will be onboard.

Power consumption

Trade-off between flight time and weight of batteries

Trade-off between wireless range and power use

Trade-off between navigational accuracy and microprocessor speed (sensor data transmission)

Sensor/Control delays

Trade-off between sensor sensitivity, size, and speed

Activation speed of servos is our limiting factor in adjusting course