10-20-2005, 09:56 PM
<img src='http://img470.imageshack.us/img470/5254/helixpad4lz.jpg' border='0' alt='user posted image'>
Cheap Robotic Microhelicopter HOWTO
1. Introduction
RC model helicopter prices have reached a point where all sorts of challenging (i.e. crash-prone) robotics projects become affordable. This document explains how to build a 300 g, 3D-capable helicopter with embedded Linux and Bluetooth datalink for less than 500 EUR.
As a proof of concept, we provide software which allows the helicopter to be remotely controlled over Bluetooth with a PC joystick. Future work will focus on the integration of sensors (IMU, altitude, magnetic compas, GPS, camera) and flight control software (either third-party or dedicated).
2. Off-the-shelf Components
2.1. Helicopter platform
A number of inexpensive microhelicopters are now available to RC model hobbyists: Ikarus Piccolo, MS Hornet, Carboon, Dragonfly, Hummingbird, Tiny, Aerohawk. These are essentially scaled-down versions of regular model helicopters, made possible by advances in battery technology. Some models have a rotor head with fixed collective pitch (FP), while others have both cyclic and collective pitch (CP). Most have a dedicated tail motor rather than a variable-pitch tail rotor.
A recent radical innovation is the "ProxFlyer" self-stabilizing deformable rotor design. Unfortunately, current commercial implementations are too small to be used as robotic platforms. Besides, stability is obtained by sacrificing maneuverability.
For this project we use a commercial ARF microelicopter kit containing:
A pre-assembled helicopter with collective-pitch rotor, two brushed motors and three miniature servos
An electronics package with BEC, 6-channel RC receiver, yaw gyro, and motor drivers
A 41 MHz 6-channel RC transmitter with hardwired CCPM mixing
A 11.1 V, 850 mAh lithium-polymer battery
A battery charger.
The aircraft weighs 270 g and can lift at least 50 g of payload.
The electronics package is a "black box" which connects all components together. This is in contrast with larger model helicopters, where the connections between the receiver, gyro, BEC and motor drivers are exposed and documented. Integrating all these components reduces size, weight and cost, but makes modifications harder.
Fortunately, in some commercial microhelicopters, the "black box" can be tinkered with fairly easily. It actually consists of two boards connected back-to-back with a 2x3-pin connector (see Figure 1):
A generic RC receiver board with seven 3-pin PWM servo outputs.
A power/gyro board with BEC, gyro, failsafe, and motor controllers.
Figure 1. Contents of the integrated controller in a typical commercial microhelicopter kit.
Table 1 lists the PWM outputs, two of which are routed internally between the two boards.
Table 1. RC receiver PWM outputs.
<img src='http://img483.imageshack.us/img483/5391/boxdiagram1bq.gif' border='0' alt='user posted image'>
http://perso.wanadoo.fr/pascal.brisset/chr.../chromicro.html
Cheap Robotic Microhelicopter HOWTO
1. Introduction
RC model helicopter prices have reached a point where all sorts of challenging (i.e. crash-prone) robotics projects become affordable. This document explains how to build a 300 g, 3D-capable helicopter with embedded Linux and Bluetooth datalink for less than 500 EUR.
As a proof of concept, we provide software which allows the helicopter to be remotely controlled over Bluetooth with a PC joystick. Future work will focus on the integration of sensors (IMU, altitude, magnetic compas, GPS, camera) and flight control software (either third-party or dedicated).
2. Off-the-shelf Components
2.1. Helicopter platform
A number of inexpensive microhelicopters are now available to RC model hobbyists: Ikarus Piccolo, MS Hornet, Carboon, Dragonfly, Hummingbird, Tiny, Aerohawk. These are essentially scaled-down versions of regular model helicopters, made possible by advances in battery technology. Some models have a rotor head with fixed collective pitch (FP), while others have both cyclic and collective pitch (CP). Most have a dedicated tail motor rather than a variable-pitch tail rotor.
A recent radical innovation is the "ProxFlyer" self-stabilizing deformable rotor design. Unfortunately, current commercial implementations are too small to be used as robotic platforms. Besides, stability is obtained by sacrificing maneuverability.
For this project we use a commercial ARF microelicopter kit containing:
A pre-assembled helicopter with collective-pitch rotor, two brushed motors and three miniature servos
An electronics package with BEC, 6-channel RC receiver, yaw gyro, and motor drivers
A 41 MHz 6-channel RC transmitter with hardwired CCPM mixing
A 11.1 V, 850 mAh lithium-polymer battery
A battery charger.
The aircraft weighs 270 g and can lift at least 50 g of payload.
The electronics package is a "black box" which connects all components together. This is in contrast with larger model helicopters, where the connections between the receiver, gyro, BEC and motor drivers are exposed and documented. Integrating all these components reduces size, weight and cost, but makes modifications harder.
Fortunately, in some commercial microhelicopters, the "black box" can be tinkered with fairly easily. It actually consists of two boards connected back-to-back with a 2x3-pin connector (see Figure 1):
A generic RC receiver board with seven 3-pin PWM servo outputs.
A power/gyro board with BEC, gyro, failsafe, and motor controllers.
Figure 1. Contents of the integrated controller in a typical commercial microhelicopter kit.
Table 1 lists the PWM outputs, two of which are routed internally between the two boards.
Table 1. RC receiver PWM outputs.
<img src='http://img483.imageshack.us/img483/5391/boxdiagram1bq.gif' border='0' alt='user posted image'>
http://perso.wanadoo.fr/pascal.brisset/chr.../chromicro.html