px4 seminar 02
TRANSCRIPT
PX4 Autopilot• Independent, open-source, open-hardware autopilot
system oriented toward autonomous aircraft
• BSD License
• Started in 2009
• Be being developed and used at Computer Vision and Geometry Lab of ETH Zurich and supported by the Autonomous Systems Lab and the Automatic Control Laboratory
Main Software Modules• PX4 Flight Stack
• Flight control modules (Controller, Attitude estimator, MAVLink and etc)
• PX4 Middleware
• Drivers, uORB
• PX4 ESC Firmware
• PX4 Bootloader
• Operating System
• NuttX OS
On-board Applications• System Applications
• mavlink – Sends and receives MAVLink messages via serial port
• sdlog2 – Logs system/flight data to the SD card
• tests – Test applications to test the system (during bringup and troubleshooting)
• top – Lists current processes and their CPU load
• uORB – Micro Object Request Broker - distributing information between other applications
• Drivers
• mkblctrl – Mikrokopter BLCTRL Driver
• esc_calib – ESC calibration tool
• fmu – Configures FMU GPIO pins
• gpio_led – GPIO LED driver
• gps – GPS receiver driver
• pwm – Command to set PWM update rates
• sensors – Sensor utility
• px4io – PX4IO driver
• uavcan – UAVCAN driver
On-board Applications (cont’d)
• Flight Control Applications
• Flight Safety and Navigation
• commander – main flight safety state machine
• navigator – Mission, failsafe and RTL navigator
• Attitude and Position Estimators
• attitude_estimator_ekf – EKF-based attitude estimator
• ekf_att_pos_estimator – EKF-based attitude and position estimator (Paul Riseborough)
• position_estimator_inav – Inertial navigation position estimator
• Multirotor Attitude and Position Controllers
• mc_att_control – Multirotor attitude controller
• mc_pos_control – Multirotor position controller
• Fixedwing Attitude and Position Controllers
• fw_att_control – Fixed wing attitude controller
• fw_pos_control_l1 – Fixed wing position controller
• VTOL Attitude Controller
• vtol_att_control – VTOL attitude controller
System Startup• The boot process of PX4
• /etc/init.d/rcS (https://github.com/PX4/Firmware/blob/master/ROMFS/px4fmu_common/init.d/rcS)
• /etc/rc.txt on the SD card (for advanced users)
• If /etc/rc.txt does not exist, set to autostart mode
• /etc/config.txt is executed if it exists
• Configuration to set the environment variables (https://pixhawk.org/dev/system_startup#configuration_variables)
• /etc/extras.txt is executed if it exists
• Start custom apps after the autostart process
• All scripts belonging to the autostart process (https://github.com/PX4/Firmware/tree/master/ROMFS/px4fmu_common/init.d)
/etc/config.txt Example for Custom Model
# Generic Quadcopter + set VEHICLE_TYPE mc set MIXER FMU_quad_+ # PX4IO PWM output will be used by default set PWM_OUT 1234 # Change parameters for the first 4 outputs set PWM_RATE 400 # Set PWM rate to 400 Hz for better performance set PWM_DISARMED 900 # Motors should stop at this PWM value set PWM_MIN 1100 # Motors should spin at low, idle speed at this PWM value set PWM_MAX 1900 # Motors should spin at max speed at this PWM value
NuttShell• An embedded equivalent to bash and similar Unix
shells
• It is used to start all on-board applications and manage a executed process
• It interacts with the user over a serial port (FMU system’s UARTS or USB)
• http://nuttx.org/doku.php?id=documentation:nuttshell
Makefile• Default available targets
• archives - Build the NuttX RTOS archives that are used by the firmware build.
• all - Build all firmware configs: aerocore_default px4fmu-v1_default px4fmu-v2_default px4fmu-v2_multiplatform px4fmu-v2_test px4io-v1_default px4io-v2_default. A limited set of configs can be built with CONFIGS=<list-of-configs>
• aerocore_default - Build just the aerocore_default firmware configuration.
• px4fmu-v1_default - Build just the px4fmu-v1_default firmware configuration.
• px4fmu-v2_default - Build just the px4fmu-v2_default firmware configuration.
• px4fmu-v2_multiplatform - Build just the px4fmu-v2_multiplatform firmware configuration.
• px4fmu-v2_test - Build just the px4fmu-v2_test firmware configuration.
• px4io-v1_default - Build just the px4io-v1_default firmware configuration.
• px4io-v2_default - Build just the px4io-v2_default firmware configuration.
• clean - Remove all firmware build pieces.
• distclean - Remove all compilation products, including NuttX RTOS archives.
• upload - When exactly one config is being built, add this target to upload the firmware to the board when the build is complete. Not supported for all configurations.
• testbuild - Perform a complete clean build of the entire tree.
Additional Rule for Makefile
• /makefiles/*.mk
• Details on /makefiles/README.txt (https://github.com/PX4/Firmware/blob/master/makefiles/README.txt)
Reference• http://en.wikipedia.org/wiki/PX4_autopilot
• https://pixhawk.org/start
• https://pixhawk.org/firmware/source_code
• https://github.com/PX4
• https://pixhawk.org/dev/system_startup
• https://pixhawk.org/firmware/apps/start
• https://pixhawk.org/firmware/apps/nsh