3 Hidden PX4 SITL tricks for everyday development · 2019-06-26 · 3 Hidden PX4 SITL tricks for everyday development Julian Oes - 2019-06-20

3 Hidden PX4 SITL tricks for everyday development

Julian Oes - 2019-06-20


What is Software In The Loop (SITL) simulation?

Simulator PX4

Sensor values

Actuator outputs

Local computer

3 Hidden PX4 SITL tricks for everyday development 4

https://makeameme.org/meme/the-simulation-environment


1 Lockstep


Common problems with SITL● CPU load too high

● Interruptions can cause crashes


How does lockstep work?Sensor valuesand timestamp

Actuator outputs

Simulator PX4

https://dev.px4.io/v1.9.0/en/simulation/#lockstep-simulation

https://dev.px4.io/v1.9.0/en/simulation/#lockstep-simulation


How does lockstep initialize?

Sensor valuesand timestamp

Simulator PX4

Actuator outputs


Why should I use lockstep?

● Bonus: Run simulations faster or slower than realtime 💡

https://beorganizing.com/2017/12/22/dear-old-computer-ive-moved/

● Pause to inspect or debug ✅● Runs better on slower computers ✅

https://giphy.com/explore/hamster-wheel


How to pause?

Press P


How to speed up or slow down?

https://dev.px4.io/v1.9.0/en/simulation/#simulation_speed

https://dev.px4.io/v1.9.0/en/simulation/#simulation_speed


Demo


2 Shell scripting


NuttShell on NuttX

nsh>

https://docs.px4.io/en/flight_controller/pixhawk.html


NuttShell


Startup


Startup


./px4 sh rcS ekf2 start px4-ekf2 startaliasevaluatecall

IPC call

ekf2 threadspawn

What about SITL?

https://dev.px4.io/v1.9.0/en/concept/system_startup.html#posix-linuxmacos

How to use it



Use your system shell with SITL


...



Demo





3 Debugging with GDB, valgrind, callgrind


Debugging using GDB (or LLDB) in console


Debugging using GDB (or LLDB) in VSCode

https://dev.px4.io/master/en/setup/vscode.html (work in progress)

https://dev.px4.io/master/en/setup/vscode.html


Demo



Memory error detection using valgrind● Find reads from uninitialized memory● Find memory leaks● Etc.

https://dev.px4.io/v1.9.0/en/setup/building_px4.html#make_targetshttp://www.valgrind.org/

https://dev.px4.io/v1.9.0/en/setup/building_px4.html#make_targets

http://www.valgrind.org/


Memory error detection using valgrind


Profiling using callgrind● Function call graph● Function call counts● Time spent in functions● And much more

https://dev.px4.io/v1.9.0/en/setup/building_px4.html#make_targetshttp://valgrind.org/docs/manual/cl-manual.html

https://dev.px4.io/v1.9.0/en/setup/building_px4.html#make_targets

http://valgrind.org/docs/manual/cl-manual.html


Profiling using callgrind


KCacheGrind visualization of callgrind data

https://kcachegrind.github.io/html/Home.html

https://kcachegrind.github.io/html/Home.html


EKF2



http://www.quickmeme.com/meme/3qjtpp

Documents

3 Hidden PX4 SITL tricks for everyday development · 2019-06-26 · 3 Hidden PX4 SITL tricks for everyday development Julian Oes - 2019-06-20