Quadrocopter-IMU

The Quadrocopter Project

Main Page |   Control Board  |   Sensor board  |   Frame  |   Software  |   Research  |  Old Info

= Our IMU =



The LPCXpresso IMU is an add-on board for the LPCXpresso 1769. The board provides a full set of sensor inputs to implement the inertial guidance system of a quadracopter. The sensors included on the board include the following features:
 * Accelerometer - three axis acceleration
 * Gyro –three axis rotation
 * Magnetometer – three axis dead reckoning compass
 * Pressure – 30cm accuracy altitude measurements
 * Voltage – 12 bit resolution voltage sensors for the main motor battery and for the logic battery

The control function is implemented using an NXP LPC1769, 32 bit Cortex M3 processor running at 100MHz and provides 512K of Flash and 64K of SRAM. Using the LPCXpresso board as an initial processor platform allows for rapid code development using the low cost ($30) off the shelf hardware. An IMU sensor board will be built to add-on to base processor board. Once the features and functions of the quadracopter control system are completed the hardware will be redesigned into a single board solution targeted specifically at the quadracopter design.

The LPCXpresso platform provides in circuit debugging for code up-to 128K. It is also possible to load code directly into the processor using the USB boot-loader which makes the chip appear as a Flash memory disk when plugged into a host PC. This allows larger code images to be loaded to the microcontroller. The add-on board will provide a USB connector and soft connect circuit to allow the user direct access to the target processor on the LPCXpresso board. This allows you to separate the debugger of the LPCXpresso board from the target processor resulting in a compact processor/IMU assembly measuring just 2” square.

In addition to the sensor functions the IMU add-on board also provides USB access, along with 4 radio PWM channels and 4 PWM servo outputs. The servo outputs are tied to the hardware counters of the LPC1769. Each radio input is connected to a pin change interrupt to allow for efficient detection of the PWM period. Finally there is a TTL UART connection that will allow a GPS sensor to be added to the design.

‎schematic

For some background information on getting started with this processor family check out this link.

Current status
The board is built and working. Now to work on the software.

Gyro test, sept. 20, 2011 (Youtube)

Sensors

 * Accelerometer - MMA7455LT, 3 axis, $2, datasheet


 * Gyro - L3G4200D 3 axis, $14, datasheet


 * Magnetometer - Honeywell HMC5883L-TR, 3 axis, $3.91, datasheet


 * Barometric Altitude and Temperature Sensor - Bosch BMP085, 25cm resolution, $8.90, datasheet
 * Note: a difference of 1 Pascal corresponds to a change in altitude of 8cm