White (Quadricopter III)
My third-generation quadrotor robotic helicopter, intended as an open redesign of previous projects. Most components are in early stages of development, except the IMU, which has matured from Quadricopters I & II.
White’s footprint, propulsion, and power system will not deviate from most other hobbyist quadrotors; instead, it will feature vastly improved sensory and onboard computing capabilities. Adding to previous iterations will be GPS, 3-axis magnetometer, and a Surveyor Corp. SRV-1 Blackfin camera.
The SRV-1′s 500MHz ADI Blackfin BF537 (1000 MIPS) will serve as higher-level control for White over the IMU and flight control loops. The Blackfin and the SRV-1′s high-speed Lantronix 802.11g Wi-Fi radio link and 1.3MP camera open up many new possibilities for the platform.
The IMU itself, into which most of the work in the past have gone, is now powered by a Microchip dsPIC33FJ256GP710, which is a 80MHz (40 MIPS) 16-bit RISC/DSP processor with an PIC-like ISA. It interfaces with and applies filters to the accelerometer and gyro, and will also do the same with the GPS and magnetometer. The specific model was chosen because it is the most powerful device in the dsPIC33 line, which has a lovely RISC ISA and much useful hardware for DSP and external control.
The dsPIC prefilters accelerometer and gyro input with its Q15 DSP engine, maintains the flight state with a 32-bit floating point Kalman filter (possibly an Extended/Unscented Kalman filter in the future) runs the control law (likely to remain a PID controller), and interfaces with the brushless motor controllers.
An ambitious future goal is to integrate brushless motor controllers onto the dsPIC board, and to use the ADC and DSP capabilities for brushless control. This will eliminate the bandwidth and latency problems of using common PWM hobby brushless controllers, while also offering some form of RPM/positional feedback, which will allow closed-loop rotor speed control.
Sponsored by Analog Devices, Inc.
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