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FORUM.XUFO.NETMikrokopter
From UfoWiki
Mikrokopter is a do-it-yourself construction Quadcopter project from Holger Buss and Ingo Busker.
It is based on the main board Flight-Ctrl and 4 brushless controllers BL-Ctrl.
Contents |
[edit] Flight-Ctrl
Heart of the Flight-Ctrl is an AVR microcontroller Atmel ATMEGA 644 @20Mhz. The SMD style board contains 3 piezo gyros, an acceleration sensor and an optional barometric sensor for altitude control. Communication with the four brushless controllers occurs via I2C bus for a fast (0,5ms) engine speed adjustment. Flight-Ctrl needs an RC-receiver which can deliver the modulated PPM-multi-signal. The microcontroller decodes the PPM-sum-signal for all channels by itself.
[edit] BL-Ctrl
Each BL-Ctrl controller uses an AVR Atmel Mega 8 microcontroller to set the three-phase current for one brushless engine. It is designed to deliver about 5 amps continuous current with a short time maximum of about 11 amps. The microcontroller measures the actual engine speed and adjusts its when necessary. Also the consumed current is measured and the power is reduced softly if the maximum current flows for more than 10 seconds. Bl-Ctrl can receive engine speed data via I2C Bus, serial interface or PPM Signal from a RC receiver.
[edit] Mikrokopters
A good configuration is a 32cm diameter frame with 4 Robbe Roxxy 2815 engines and the original 8" X-Ufo propellers. Power-Schnurzz (lightweight (18-23g) self-wound brushless motors with high quality magnets) could also be used.
Larger quadrocopters use a 40cm diameter frame with 10" EPP 1045 propellers. Many different engines have been used here: Roxxy 2824-34, Roxxy 2827-34, Roxxy 2827-26, AXI 2212-26. For stronger engines like AXI 2217-xx BL-Ctrl must be modified (stronger or parallel FETs) to deliver more current.
[edit] Current extensions
Holger and Ingo implemented an extension with GPS navigation to hold position or return to starting coordinates. Source code for this extension is not available for download.
Pitschu ported his software to run on a Flight-Ctrl, where GPS and compass support should be available to the public.
