LibrePilot is a

Free software Free software or libre software is computer software distributed under terms that allow users to run the software for any purpose as well as to study, change, and distribute it and any adapted versions. Free software is a matter of liberty, no ...

unmanned aerial vehicle An unmanned aerial vehicle (UAV), commonly known as a drone, is an aircraft without any human pilot, crew, or passengers on board. UAVs are a component of an unmanned aircraft system (UAS), which includes adding a ground-based controller ...

project for model aircraft aimed at supporting both multi-rotor craft as well as fixed-wing aircraft. Initially founded by David Ankers, Angus Peart and Vassilis Varveropoulos in late 2009, under the name OpenPilot, it was conceived as both a learning tool and to address areas the developers perceived were lacking in other small UAV platforms. In July 2015 OpenPilot, was

fork In cutlery or kitchenware, a fork (from la, furca 'pitchfork') is a utensil, now usually made of metal, whose long handle terminates in a head that branches into several narrow and often slightly curved tines with which one can spear foods ei ...

ed to create LibrePilot. The OpenPilot open source autopilot software could be combined with hardware such as an

inertial navigation system An inertial navigation system (INS) is a navigation device that uses motion sensors (accelerometers), rotation sensors ( gyroscopes) and a computer to continuously calculate by dead reckoning the position, the orientation, and the velocity (dire ...

board, a main control board, a GPS receiver, and a 2.4 GHz serial communications link with the ground station. The OpenPilot software is released under the

GPL The GNU General Public License (GNU GPL or simply GPL) is a series of widely used free software licenses that guarantee end users the four freedoms to run, study, share, and modify the software. The license was the first copyleft for general u ...

version 3 license.

Components

The OpenPilot project consisted of two component parts, these are the on-board firmware and the

ground control station UAV ground control station (GCS) is a land- or sea-based control centre that provides the facilities for human control of ''Unmanned Aerial Vehicles'' (UAVs or "drones"). It may also refer to a system for controlling rockets within or above the ...

(GCS). The firmware part of the project is written in C whilst the ground control station is written in

C++ C++ (pronounced "C plus plus") is a high-level general-purpose programming language created by Danish computer scientist Bjarne Stroustrup as an extension of the C programming language, or "C with Classes". The language has expanded significan ...

utilizing Qt.

Hardware

The current on-board hardware is based on the

STM32 STM32 is a family of 32-bit microcontroller integrated circuits by STMicroelectronics. The STM32 chips are grouped into related series that are based around the same 32-bit ARM architecture, ARM processor core, such as the ARM Cortex-M#Cortex ...

microcontroller A microcontroller (MCU for ''microcontroller unit'', often also MC, UC, or μC) is a small computer on a single VLSI integrated circuit (IC) chip. A microcontroller contains one or more CPUs (processor cores) along with memory and programmable i ...

. There are two physical boards that are part of the hardware, the first is the main OpenPilot board which contains the core

, SD socket,

barometer A barometer is a scientific instrument that is used to measure air pressure in a certain environment. Pressure tendency can forecast short term changes in the weather. Many measurements of air pressure are used within surface weather analysis ...

plus

servo Servo may refer to: Mechanisms * Servomechanism, or servo, a device used to provide control of a desired operation through the use of feedback ** AI servo, an autofocus mode ** Electrohydraulic servo valve, an electrically operated valve that ...

connectors and second, the

AHRS An attitude and heading reference system (AHRS) consists of sensors on three axes that provide attitude information for aircraft, including roll, pitch, and yaw. These are sometimes referred to as MARG (Magnetic, Angular Rate, and Gravity) sens ...

board which contains the sensor hardware. In other words, the hardware consists of two boards: the microcontroller board (the core) and the sensors board (the

AHRS

The OpenPilot

was a 9DOF unit and contains

MEMS Microelectromechanical systems (MEMS), also written as micro-electro-mechanical systems (or microelectronic and microelectromechanical systems) and the related micromechatronics and microsystems constitute the technology of microscopic devices, ...

gyroscope A gyroscope (from Ancient Greek γῦρος ''gŷros'', "round" and σκοπέω ''skopéō'', "to look") is a device used for measuring or maintaining orientation and angular velocity. It is a spinning wheel or disc in which the axis of rota ...

accelerometer An accelerometer is a tool that measures proper acceleration. Proper acceleration is the acceleration (the rate of change of velocity) of a body in its own instantaneous rest frame; this is different from coordinate acceleration, which is accele ...

s and a 3 direction

magnetometer A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, o ...

. Combined with the sensors, the OpenPilot

contains its own Cortex M3 microcontroller which runs a Kálmán filter. Filtered orientation data and inertial measurements are presented back to the main OpenPilot board using an SPI interface. The OpenPilot AHRS contained the following components: * STM32 F1 Onboard (STM32F103C8) * 3× ADXRS610 Rate Gyros * 1× HMC5843 Magnetometer * 1× LIS344ALH 3-Axis Accelerometer

References

{{Reflist Avionics computers Transport software Free software Open-source hardware

Components

Hardware

AHRS

See also

References