Testing new controllers PX4 autopilot

Ranjeet · April 13, 2021, 8:26pm

Hello @bresch ,
I am working to implement different controllers other than PID and want to test on PX4 autopilot in SITL.

Can you please guide me where do i need to make changes in the firmware stack to test a new controller?
thanks

benasena · April 16, 2021, 12:50am

Hi @Ranjeet. This might be a good place to start looking:

github.com

PX4/PX4-Autopilot/blob/master/src/modules/mc_rate_control/RateControl/RateControl.cpp

/****************************************************************************
 *
 *   Copyright (c) 2019 PX4 Development Team. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name PX4 nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

This file has been truncated. show original

Ranjeet · April 16, 2021, 5:56am

Hi @benasena @bresch , I have gone through the current PID controller that works at 4 levels (attitude rate, attitude, velocity and position). And, I can see that mc_att_control, mc_pos_control and mc_rate_control are modules that deal with controller implemented.

Like, Suppose I just want to implement a position controller (say sliding mode controller), then many parameters (PID gains) will not be required and few parameters has to be added.
I was thinking of testing different controllers in PX4_sitl. I am aware that i need to write a module for another controller but what communications are going on among other modules and the present controller, if there is some picture, then that would be great.

Zhengtian_Ma · April 19, 2021, 6:20am

You can probably take a look at this uorb graph to get an idea of message passing between the modules. Do note that some of the topic names maybe changed for the most-updated version.
https://dev.px4.io/v1.10_noredirect/en/middleware/uorb_graph.html

Jaroan · September 11, 2021, 5:28pm

Hello @Ranjeet
According to the Multicopter Control Architecture the Position and Velocity Controller Diagram are a mix of P (for position) and PID(for velocity).

I was trying to add a PI/PD/PID controller module instead of the P controller for Position?
I note the following codes (mc_pos_control module) have the controllers.
I wanted to know if there are other places to be modified for the different types of controllers based on your work. Thank you in anticipation!