NOTE: This the Next-Generation Work-In-Progress Branch of PenguPilot. For a stable release, check the master branch!

What is PenguPilot?

PenguPilot is a GNU/Linux based Multi-Rotor UAV Autopilot.

Unlike other platforms, PenguPilot does not require a dedicated low-level microcontroller for real-time

• sensor data acquisition,
• data fusion / filtering, and
• motor control.

The whole flight infrastructure is based on Linux (PREEMPT/PREEMPT_RT) user-space tasks.

Some highlights of the PenguPilot software are:

• component based software architecture allows to run code on demand (power savings in standby)
• memory protection among critical and non-critical components
• message-passing among components via ZeroMQ/MessagePack/Protobuf
• process/priority management and dependency tracking
• online parameter configuration usable for in-flight parameter updates
• SSH based user interfaces for parameters, calibration, ...
• blackbox functionality to log sensor values at each control step to sdcard
• sensor data replay capabilitiy for offline PC-based optimization, filter tuning, ...
• quick integration of new hardware through Linux HAL
• platform-neutral code without low-level interrupt and timer programming

What's different compared to other Approaches?

The three main factors that make PenguPilot based systems different, compared to microcontroller-based autopilots, are the

• Linux operating system, the
• powerful underlying computer-on-module (COM), and
• PenguPilot's component-based software architecture.

These factors generate a lot of possibilities and benefits for UAV software development, summarized as follows:

• Powerful Hardware and OS:

  • no microcontroller-like flash/RAM memory restrictions
  • high memory bandwidth allows to log every sensor value per control step
  • memory protection for improved task safety
  • USB host support (Cameras, WiFi and UMTS sticks, FTDI's, ...)
  • symmetric multi-processing (e.g. ODROID U3)

• Advanced Programming Possibilities:

  • high-level programming languages and libraries (Bash, Python/numpy)
  • rich networking and routing functionality
  • file system abstractions instead of raw memory access
  • debugging via GDB and code profiling without extra effort
  • myriads of open source device drivers and software libraries

• Advanced Field Software Development:

  • software development on the UAV via SSH from virtually any device
  • native source code compilation (no cross-compiler required)
  • on-device software version control via Git

Filesystem Contents

Flight Infrastructure:

• autopilot: automatic flight code with/without remote control based safery
• i2c_sensors: ready gyro, acc, mag, baro, and ultrasonic sensors
• gyro_cal: gyroscope calibration
• acc_cal: accelerometer calibration
• mag_adc_cal: magnetometer calibration
• cmc: current magnetometer calibration
• rs_ctrl: rotation speed control for stabilizing the UAV
• rp_ctrl: rotation position control
• vs_ctrl: vertical speed control using barometer
• vp_ctrl: vertical position control using barometer/ultrasonic/elevation map
• hs_ctrl: horizontal speed control
• hp_ctrl: horizontal position control
• battmon: battery monitor; warns the user when the battery is low
• gpsp: gps publisher, similar to gpsd but much simpler; uses NMEALib
• remote: remote control channels publisher
• rc_cal: remote control channel calibration service
• geomag: subscribes to gps position and date/time; publishes magnetic declination in degrees
• elevmap: subscribes to gps position; publishes SRTM3 elevation data
• ads1x15: Raspberry PI I2C ADC voltage/current publisher
• arduino: ODROID U3 Arduino R/C, ADC voltage/current publisher; reads from ttySAC0
• twl4030_madc: Gumstix Overo ADC voltage/current publisher

Support Infrastructure:

• gpstime: GPS time zone / date / time setting service
• config: configuration files
• scl: signaling and communication link (IPC framework), see config/system.yaml
• opcd: online parameter configuration daemon, see config/params.yaml
• svctrl: service management and control utility, see config/services.yaml
• logger: logging services and utility programs
• shared: shared libraries shared among all PenguPilot components

Additional Features:

• aircomm: encrypted aerial communication daemon, using NRF24L01+
• display: shows battery, mem, cpu, satellite status via I2C SSD1307 128x64 display from Adafruit
• wifi_sensor: publishes wireless network data acquired via iwlist
• wifi_loc: combines gps measurements and wifi scan results and publishes it

Build System and Environment:

• site_scons: related to build system
• SConstruct: scons build file
• scripts: various scripts, e.g. bashrc

Software Dependencies:

• Gentoo: app-admin/sudo app-misc/screen dev-lang/python dev-lang/swig dev-libs/glib dev-libs/libyaml dev-libs/msgpack dev-libs/protobuf dev-libs/protobuf-c dev-python/imaging dev-python/msgpack dev-python/numpy dev-python/psutil dev-python/python-daemon dev-python/pyyaml dev-python/pyzmq dev-util/scons sys-power/cpufrequtils dev-python/pyproj sci-libs/gdal
• Ubuntu: realpath scons swig python-msgpack protobuf-compiler python-protobuf libmsgpack-dev libprotobuf-dev python-yaml protobuf-c-compiler libprotobuf-c0-dev libzmq-dev python-zmq libyaml-dev libglib2.0-dev python-daemon python-dev

Service Dependencies

The service dependencies of PenguPilot are depicted in the figure below:

Services indicated in yellow are platform-specific, as specified in file config/services.yaml.

Example UAV System

Here's an example of a Gumstix Overo Air based PenguCopter with GPS receiver and I2C OLED display:

PenguCopter Video

Flying Penguins from BBC :)