|Alguien dijo ...|
|La Física es como el sexo: seguro que da alguna compensación práctica, pero no es por eso por lo que la hacemos.|
Físico estadounidense, premio Nobel de Física en 1965
|PIC18 Microcontrollers for Record-Breaking 48-Hour Flight|
CHANDLER, Ariz. - Microchip Technology Inc., announced that AC Propulsion utilized the high-density
memory, high pin count PIC18 microcontrollers to control its SoLong Solar Electric-Powered Unmanned Aerial Vehicle
(UAV) during its record-breaking 48-hour flight earlier this month. The SoLong’s creator and chief pilot, a
self-proclaimed analog guy, selected Microchip because of its development tools.
“I consider myself a newcomer to
microcontrollers –- I was strictly an analog guy until four years ago,” said Alan Cocconi, founder, chairman and
chief engineer of AC Propulsion Inc. “With Microchip’s MPLAB® Integrated Development Environment (IDE), I only had
to learn one set of development tools to use a wide variety of products, which gave me more time to concentrate on
completing the SoLong.”
The SoLong UAV’s systems that are controlled by the 12 onboard PIC18
A PIC18LF452 operating at 20 MHz clock
speed decodes 13 Pulse-With Modulator (PWM) control inputs from the uplink receiver, serial data from the Ublox GPS
module, and takes in analog sensor data from 23 channels. The assembly-language code calculates four PID loops for
stability augmentation, as well as managing the GPS navigation and waypoints. The same PIC18LF452 microcontroller
also generates the telemetry data stream and eight channels of command pulses for the flight controls.
A PIC18F452 operating at 24 MHz clock speed is used in conjunction with a Flash
memory lookup table to generate nine sine-modulated 38 kHz PWM outputs for the 800W sensorless Brushless DC (BLDC)
Peak Power Tracker
A PIC18F452 operating at 40 MHz clock speed
controls the 4 phase 38 kHz PWM of the 300W DC-DC converter, with a dynamic peak power tracking algorithm to match
the solar array output to the Lithium-Ion (Li-Ion) battery.
Each of the
six servo motors use a PIC18LF1320 operating at 20 MHz clock speed to calculate a 600 Hz PID loop, and output 78 kHz
PWM to run the small DC motor. The PIC18LF1320 stores in-flight load and wear data to help ensure system reliability
for the long flights.
Two PIC18F1220s using the internal
clock, operating at 250 kHz, monitor the individual cell voltages with 20 mV resolution and protect the Li-Ion
battery pack. A serial data-stream is available for diagnostics.
Tracking Downlink Antenna and
A PIC18C452 operating at 20 MHz clock speed communicates with the telemetry decoding
PC (which runs Labview) using the serial port, and controls two servos that aim the antenna at the airplane using
the GPS data. Analog wind speed and direction data is acquired and sent to the PC through the same port for
Lunes, 27 Junio, 2005 - 04:47