PX4二次开发快速入门

前言

交流学习可加文章底部作者微信

本教程的适用对象：
1、零基础或者有较少基础（尚未入门）
2、希望在短时间里（一到两个月）学会对PX4进行二次开发的开源爱好者或工程师

硬件：
pixhawk飞控
超维M系列无人机

软件：
PX4 1.13.3
QGC4.2.4

课程源码：https://gitee.com/Mbot_admin/px4-1.13.3-cwkj

一、概述

二、二次开发基础（自定义工作队列，自定义uorb）

在modules文件夹下添加work_item文件夹

添加下面四个文件

CMakeLists.txt

px4_add_module(MODULE modules__work_itemMAIN work_item_testCOMPILE_FLAGS#-DDEBUG_BUILD   # uncomment for PX4_DEBUG output#-O0             # uncomment when debuggingSRCSWorkItemTest.cppWorkItemTest.hppDEPENDSpx4_work_queue)

Kconfig

menuconfig MODULES_WORK_ITEMbool "work_item"default n---help---Enable support for work_item

WorkItemTest.cpp

#include "WorkItemTest.hpp"WorkItemTest::WorkItemTest() :ModuleParams(nullptr),ScheduledWorkItem(MODULE_NAME, px4::wq_configurations::test1)
{
}WorkItemTest::~WorkItemTest()
{perf_free(_loop_perf);perf_free(_loop_interval_perf);
}bool WorkItemTest::init()
{
ScheduleOnInterval(100000_us);return true;
}void WorkItemTest::Run()
{if (should_exit()) {ScheduleClear();exit_and_cleanup();return;}perf_begin(_loop_perf);perf_count(_loop_interval_perf);// Check if parameters have changedif (_parameter_update_sub.updated()) {// clear updateparameter_update_s param_update;_parameter_update_sub.copy(&param_update);updateParams(); // update module parameters (in DEFINE_PARAMETERS)}PX4_INFO("test workitem");perf_end(_loop_perf);
}int WorkItemTest::task_spawn(int argc, char *argv[])
{WorkItemTest *instance = new WorkItemTest();if (instance) {_object.store(instance);_task_id = task_id_is_work_queue;if (instance->init()) {return PX4_OK;}} else {PX4_ERR("alloc failed");}delete instance;_object.store(nullptr);_task_id = -1;return PX4_ERROR;
}int WorkItemTest::print_status()
{perf_print_counter(_loop_perf);perf_print_counter(_loop_interval_perf);return 0;
}int WorkItemTest::custom_command(int argc, char *argv[])
{return print_usage("unknown command");
}int WorkItemTest::print_usage(const char *reason)
{if (reason) {PX4_WARN("%s\n", reason);}PRINT_MODULE_DESCRIPTION(R"DESCR_STR(
### Description
Example of a simple module running out of a work queue.)DESCR_STR");PRINT_MODULE_USAGE_NAME("work_item_example", "template");PRINT_MODULE_USAGE_COMMAND("start");PRINT_MODULE_USAGE_DEFAULT_COMMANDS();return 0;
}extern "C" __EXPORT int work_item_test_main(int argc, char *argv[])
{return WorkItemTest::main(argc, argv);
}

WorkItemTest.hpp

#pragma once#include <px4_platform_common/defines.h>
#include <px4_platform_common/module.h>
#include <px4_platform_common/module_params.h>
#include <px4_platform_common/posix.h>
#include <px4_platform_common/px4_work_queue/ScheduledWorkItem.hpp>#include <drivers/drv_hrt.h>
#include <lib/perf/perf_counter.h>#include <uORB/Publication.hpp>
#include <uORB/Subscription.hpp>
#include <uORB/SubscriptionCallback.hpp>
#include <uORB/topics/orb_test.h>
#include <uORB/topics/parameter_update.h>
#include <uORB/topics/sensor_accel.h>
#include <uORB/topics/vehicle_status.h>using namespace time_literals;class WorkItemTest : public ModuleBase<WorkItemTest>, public ModuleParams, public px4::ScheduledWorkItem
{
public:WorkItemTest();~WorkItemTest() override;/** @see ModuleBase */static int task_spawn(int argc, char *argv[]);/** @see ModuleBase */static int custom_command(int argc, char *argv[]);/** @see ModuleBase */static int print_usage(const char *reason = nullptr);bool init();int print_status() override;private:void Run() override;// PublicationsuORB::Publication<orb_test_s> _orb_test_pub{ORB_ID(orb_test)};// SubscriptionsuORB::SubscriptionCallbackWorkItem _sensor_accel_sub{this, ORB_ID(sensor_accel)};        // subscription that schedules WorkItemExample when updateduORB::SubscriptionInterval         _parameter_update_sub{ORB_ID(parameter_update), 1_s}; // subscription limited to 1 Hz updatesuORB::Subscription                 _vehicle_status_sub{ORB_ID(vehicle_status)};          // regular subscription for additional data// Performance (perf) countersperf_counter_t	_loop_perf{perf_alloc(PC_ELAPSED, MODULE_NAME": cycle")};perf_counter_t	_loop_interval_perf{perf_alloc(PC_INTERVAL, MODULE_NAME": interval")};// ParametersDEFINE_PARAMETERS((ParamInt<px4::params::SYS_AUTOSTART>) _param_sys_autostart,   /**< example parameter */(ParamInt<px4::params::SYS_AUTOCONFIG>) _param_sys_autoconfig  /**< another parameter */)bool _armed{false};
};

修改仿真的编译脚本

添加如下：

CONFIG_MODULES_WORK_ITEM=y

然后执行

make px4_sitl_default gazbo

启动仿真后执行：

work_item_test start

正常的话会打印下面的信息

三、自定义串口驱动（添加一个毫米波雷达并定高）

PX4二次开发快速入门（三）：自定义串口驱动

四、自定义I2C驱动（驱动一个oled显示屏）

五、自定义参数

在第一节的基础上进一步修改
添加params.c

params.c内容如下：

PARAM_DEFINE_FLOAT(PARAM_TEST1, 0.2f);
PARAM_DEFINE_INT32(PARAM_TEST2, 0);

CMakeLists.txt

px4_add_module(MODULE modules__work_itemMAIN work_item_testCOMPILE_FLAGS#-DDEBUG_BUILD   # uncomment for PX4_DEBUG output#-O0             # uncomment when debuggingSRCSWorkItemTest.cppWorkItemTest.hppDEPENDSpx4_work_queue)

Kconfig

menuconfig MODULES_WORK_ITEMbool "work_item"default n---help---Enable support for work_item

WorkItemTest.cpp

#include "WorkItemTest.hpp"WorkItemTest::WorkItemTest() :ModuleParams(nullptr),ScheduledWorkItem(MODULE_NAME, px4::wq_configurations::test1)
{
}WorkItemTest::~WorkItemTest()
{perf_free(_loop_perf);perf_free(_loop_interval_perf);
}bool WorkItemTest::init()
{
ScheduleOnInterval(100000_us);return true;
}void WorkItemTest::Run()
{if (should_exit()) {ScheduleClear();exit_and_cleanup();return;}perf_begin(_loop_perf);perf_count(_loop_interval_perf);// Check if parameters have changedif (_parameter_update_sub.updated()) {// clear updateparameter_update_s param_update;_parameter_update_sub.copy(&param_update);updateParams(); // update module parameters (in DEFINE_PARAMETERS)}double param_test1=_param_test1.get();int param_test2=_param_test2.get();PX4_INFO("param_test1=%lf param_test2=%d\n",param_test1,param_test2);PX4_INFO("test workitem");perf_end(_loop_perf);
}int WorkItemTest::task_spawn(int argc, char *argv[])
{WorkItemTest *instance = new WorkItemTest();if (instance) {_object.store(instance);_task_id = task_id_is_work_queue;if (instance->init()) {return PX4_OK;}} else {PX4_ERR("alloc failed");}delete instance;_object.store(nullptr);_task_id = -1;return PX4_ERROR;
}int WorkItemTest::print_status()
{perf_print_counter(_loop_perf);perf_print_counter(_loop_interval_perf);return 0;
}int WorkItemTest::custom_command(int argc, char *argv[])
{return print_usage("unknown command");
}int WorkItemTest::print_usage(const char *reason)
{if (reason) {PX4_WARN("%s\n", reason);}PRINT_MODULE_DESCRIPTION(R"DESCR_STR(
### Description
Example of a simple module running out of a work queue.)DESCR_STR");PRINT_MODULE_USAGE_NAME("work_item_example", "template");PRINT_MODULE_USAGE_COMMAND("start");PRINT_MODULE_USAGE_DEFAULT_COMMANDS();return 0;
}extern "C" __EXPORT int work_item_test_main(int argc, char *argv[])
{return WorkItemTest::main(argc, argv);
}

WorkItemTest.hpp

#pragma once#include <px4_platform_common/defines.h>
#include <px4_platform_common/module.h>
#include <px4_platform_common/module_params.h>
#include <px4_platform_common/posix.h>
#include <px4_platform_common/px4_work_queue/ScheduledWorkItem.hpp>#include <drivers/drv_hrt.h>
#include <lib/perf/perf_counter.h>#include <uORB/Publication.hpp>
#include <uORB/Subscription.hpp>
#include <uORB/SubscriptionCallback.hpp>
#include <uORB/topics/orb_test.h>
#include <uORB/topics/parameter_update.h>
#include <uORB/topics/sensor_accel.h>
#include <uORB/topics/vehicle_status.h>using namespace time_literals;class WorkItemTest : public ModuleBase<WorkItemTest>, public ModuleParams, public px4::ScheduledWorkItem
{
public:WorkItemTest();~WorkItemTest() override;/** @see ModuleBase */static int task_spawn(int argc, char *argv[]);/** @see ModuleBase */static int custom_command(int argc, char *argv[]);/** @see ModuleBase */static int print_usage(const char *reason = nullptr);bool init();int print_status() override;private:void Run() override;// PublicationsuORB::Publication<orb_test_s> _orb_test_pub{ORB_ID(orb_test)};// SubscriptionsuORB::SubscriptionCallbackWorkItem _sensor_accel_sub{this, ORB_ID(sensor_accel)};        // subscription that schedules WorkItemExample when updateduORB::SubscriptionInterval         _parameter_update_sub{ORB_ID(parameter_update), 1_s}; // subscription limited to 1 Hz updatesuORB::Subscription                 _vehicle_status_sub{ORB_ID(vehicle_status)};          // regular subscription for additional data// Performance (perf) countersperf_counter_t	_loop_perf{perf_alloc(PC_ELAPSED, MODULE_NAME": cycle")};perf_counter_t	_loop_interval_perf{perf_alloc(PC_INTERVAL, MODULE_NAME": interval")};// ParametersDEFINE_PARAMETERS((ParamInt<px4::params::SYS_AUTOSTART>) _param_sys_autostart,   /**< example parameter */(ParamInt<px4::params::SYS_AUTOCONFIG>) _param_sys_autoconfig,  /**< another parameter */(ParamFloat<px4::params::PARAM_TEST1>) _param_test1,   /**< example parameter */(ParamInt<px4::params::PARAM_TEST2>) _param_test2  /**< another parameter */)bool _armed{false};
};

修改仿真的编译脚本

添加如下：

CONFIG_MODULES_WORK_ITEM=y

然后先执行（不执行这一步后面会报错）

make distclean

再执行

make parameters_metadata

最后执行

make px4_sitl_default gazbo

启动仿真后执行（注意要启动work_item_test ，不然地面站搜不到参数）：

work_item_test start

如果在启动work_item_test 之前已经打开了地面站，还需要再刷新一下参数

就可以搜到添加的参数

六、自定义日志

七、自定义机型

八、自定义mavlink消息和QGC通信

九、自定义mavlink消息和MAVROS通信

十、OFFBAORD控制接口（状态控制 pwm输出）

十一、基于模型开发（替换控制律/基于模型的编队）