Autonomous Helicopter James LydenEE 496Harris Okazaki

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.

Hardware Modules Onboard Controls  Master Microcontroller  Slave Microcontroller Sensors  Accelerometer  Gyroscope Communications  Bluetooth Transceivers onboard and on PC PID Correction System  PC

Block Diagram User: input flight plan 3 Axis Accel Gyro Servos PC w/BT: calculates control signals Master μ C BT transc eiver Slave μ C OFFBOAR D ONBOARD

Software Flow PC Software Flow Initialize: Open Serial Port Test Serial Port Get Data: Listen for Packet Parse Packet Store Data: Update Pos/Vel/Acc Update Error Values PID Calculations: Read Error Values Compute Corrections Flight Planning: Check Flight Mode Add Desired Offsets Format Output: Combine Offsets+PID Put Data Into Buffer Send Data: Write Buffer to Serial Port

Software Flow Master μ C Software Flow Initialize: Open Serial Ports Initialize Sensors Initialize PWMs Get Sensor Data: Send Commands Read/Save Responses Format Sensor Data: Use 8 MSbs Cast To Chars Send Sensor Data: fprintf Each Byte Wrap Word With Tags Get Correction Data: Wait For UART Ready Read 4-Byte Word Set Control Signals: Parse First 2 Bytes Set PWM Duty Cycles

Software Flow Slave μ C Software Flow Initialize: Open Serial Port Initialize PWMs Get Correction Data: Wait For UART Ready Read 4-Byte Word Set Control Signals: Parse First 2 Bytes Set PWM Duty Cycles

Focus: Accelerometer Interface (components) ‏ Digital Interface Microcontroller: I²C Master Accelerometer: I²C Slave ADC performed by accelerometer All data transfer performed via register read/write Wiring SCL: clock, synchronizes data rate SDA: Bidirectional data line; only one device can transmit at a time, negotiated by I²C protocol

Focus: Accelerometer Interface (tests) ‏ Communications test: Read the WHO_AM_I register, verify it reports known value Write config data to CTRL_REG1, read to verify it worked Scale test (once per axis): Tilt sensor so target axis is subject to gravity, read the value of each axis, verify target axis is roughly 1g while other axes are roughly zero. Speed test: Read values from all 3 axes at a rate of 2.56KHz (delay 390 µs between reads), ensure data changes as we tilt sensor

Focus: Accelerometer Interface Master MicrocontrollerAccelerometer Initialize I ² C Send: I ² C Start Send: Write EnableADC Register Send: Read [X,Y,Z] Axis Register Receive: [X,Y,Z] Axis Value Store: [X,Y,Z] Axis Value Listen on Bus Start ADC Conversions Fetch Register Contents Send: Register Contents Wait for Conversion to Finish (Updates at 2.56KHz)‏

Focus: Accelerometer Interface (design decisions) ‏ Using digital vs. analog interface Analog interface would have required using microcontroller's ADC, which would also be occupied by gyroscope Analog interface used 3.3V logic, limiting the full range when coupled to the 5V microcontroller ADC Less ADC code interspersed through the microcontroller code Using I²C vs. SPI SPI uses 4 wires, where I²C only requires 2 Using one 3-axis device vs. multiple single-axis devices Size and weight constraints, as well as wiring complexity

Remaining Work Testing Gyroscope digital interface Master microcontroller loop speed We need to know if the loop runs faster than ADC Refinement PID scale tuning Optimize code in master microcontroller main loop If we have time, increase baud rate for serial communications Implementation Accelerometer interface (partially done) ‏ User interface

Gantt Chart