1. Navigator模块简介

### Description
Module that is responsible for autonomous flight modes. This includes missions (read from dataman),
takeoff and RTL.
It is also responsible for geofence violation checking.### Implementation
The different internal modes are implemented as separate classes that inherit from a common base class `NavigatorMode`.
The member `_navigation_mode` contains the current active mode.Navigator publishes position setpoint triplets (`position_setpoint_triplet_s`), which are then used by the position
controller.navigator <command> [arguments...]Commands:startfencefile     load a geofence file from SD card, stored at etc/geofence.txtfake_traffic  publishes 4 fake transponder_report_s uORB messagesstopstatus        print status info

注：print_usage函数是具体对应实现。

class Navigator : public ModuleBase<Navigator>, public ModuleParams

注：Navigator模块采用了ModuleBase, 但没有使用WorkQueue设计，因此在实现上需要实现instantiate方法。

2. 模块入口函数

2.1 主入口navigator_main

同样继承了ModuleBase，由ModuleBase的main来完成模块入口。

navigator_main└──> return Navigator::main(argc, argv)

2.2 自定义子命令custom_command

模块除支持start/stop/status命令，自定义命令支持以下子命令：

fencefile: load a geofence file from SD card, stored at etc/geofence.txt
fake_traffic: publishes 4 fake transponder_report_s uORB messages

Navigator::custom_command├──> <!is_running()>│   ├──> print_usage("not running")│   └──> return 1├──> <!strcmp(argv[0], "fencefile")>│   ├──> get_instance()->load_fence_from_file(GEOFENCE_FILENAME)│   └──> return 0├──> <!strcmp(argv[0], "fake_traffic")>│   ├──> get_instance()->fake_traffic("LX007", 500, 1.0f, -1.0f, 100.0f, 90.0f, 0.001f, transponder_report_s::ADSB_EMITTER_TYPE_LIGHT)│   ├──> get_instance()->fake_traffic("LX55", 1000, 0, 0, 100.0f, 90.0f, 0.001f, transponder_report_s::ADSB_EMITTER_TYPE_SMALL)│   ├──> get_instance()->fake_traffic("LX20", 15000, 1.0f, -1.0f, 280.0f, 90.0f, 0.001f, transponder_report_s::ADSB_EMITTER_TYPE_LARGE)│   ├──> get_instance()->fake_traffic("UAV", 10, 1.0f, -2.0f, 10.0f, 10.0f, 0.01f, transponder_report_s::ADSB_EMITTER_TYPE_UAV)│   └──> return 0└──> return print_usage("unknown command")

3. Navigator模块重要函数

3.1 task_spawn

这里直接使用px4_task_spawn_cmd创建任务。

Navigator::task_spawn├──> _task_id = px4_task_spawn_cmd("navigator",SCHED_DEFAULT,SCHED_PRIORITY_NAVIGATION,PX4_STACK_ADJUSTED(1952),(px4_main_t)&run_trampoline,(char *const *)argv)├──> <_task_id < 0>│   ├──> _task_id = -1│   └──> return -errno└──> return 0

注：鉴于ModuleBase::run_trampoline会直接调用instantiate初始化任务，Navigator模块就必须对Navigator::instantiate方法进行重载实现。

3.2 instantiate

初始化Navigator类实例。

Navigator::instantiate├──> Navigator *instance = new Navigator()├──> <instance == nullptr>│   └──> PX4_ERR("alloc failed")└──> return instance

3.3 init

注：鉴于该模块采用任务，而之前大量的模块使用了WorkQueue的设计方法，在task_spawn里会调用init这个方法，为了对比，保留这个方法。

3.4 Run

根据输入参数及业务逻辑计算输出量，并发布消息。

Navigator::Run├──> [Try to load the geofence: /fs/microsd/etc/geofence.txt]├──> params_update├──> [wakeup source(s) setup]│   ├──> fds[0].fd = _local_pos_sub;│   ├──> fds[0].events = POLLIN;│   ├──> fds[1].fd = _vehicle_status_sub;│   ├──> fds[1].events = POLLIN;│   ├──> fds[2].fd = _mission_sub;│   ├──> fds[2].events = POLLIN;│   └──> orb_set_interval(_local_pos_sub, 50);  // rate-limit position subscription to 20 Hz / 50 ms└──> <!should_exit()>├──> int pret = px4_poll(&fds[0], (sizeof(fds) / sizeof(fds[0])), 1000);  // wait for up to 1000ms for data├──> <pret < 0>  // this is undesirable but not much we can do - might want to flag unhappy status│   ├──> PX4_ERR("poll error %d, %d", pret, errno);│   ├──> px4_usleep(10000);│   └──> continue;├──> [update vehicle_local_position]├──> [update vehicle_status]├──> [update mission]├──> [update vehicle_gps_position]├──> [update vehicle_global_position]├──> [update parameter_update]├──> [update vehicle_land_detected]├──> [update position_controller_status]├──> [update home_position]├──> <_vehicle_command_sub.updated()>│   └──> [execute commands]  【发布vehicle_roi/vehicle_command/vehicle_command_ack】├──> check_traffic()├──> geofence_breach_check(have_geofence_position_data)  【发布geofence_result消息】├──> [judge navigation new mode]  // Do not execute any state machine while we are disarmed├──> [reset triplet, when we have a new navigation mode]├──> [iterate through navigation modes and set active/inactive for each]├──> <_navigation_mode == nullptr && !_pos_sp_triplet_published_invalid_once> // if nothing is running, set position setpoint triplet invalid once│   ├──> _pos_sp_triplet_published_invalid_once = true;│   └──> reset_triplets();├──> <_pos_sp_triplet_updated>│   └──> publish_position_setpoint_triplet();  【发布position_setpoint_triplet消息】└──> <_mission_result_updated>└──> publish_mission_result();  【发布mission_result消息】

4. 总结

具体逻辑业务后续再做深入，从模块代码角度:

输入

uORB::SubscriptionData<position_controller_status_s>   _position_controller_status_sub{ORB_ID(position_controller_status)};uORB::SubscriptionInterval _parameter_update_sub{ORB_ID(parameter_update), 1_s};uORB::Subscription _global_pos_sub{ORB_ID(vehicle_global_position)};    /**< global position subscription */
uORB::Subscription _gps_pos_sub{ORB_ID(vehicle_gps_position)};      /**< gps position subscription */
uORB::Subscription _home_pos_sub{ORB_ID(home_position)};        /**< home position subscription */
uORB::Subscription _land_detected_sub{ORB_ID(vehicle_land_detected)};   /**< vehicle land detected subscription */
uORB::Subscription _pos_ctrl_landing_status_sub{ORB_ID(position_controller_landing_status)};    /**< position controller landing status subscription */
uORB::Subscription _traffic_sub{ORB_ID(transponder_report)};        /**< traffic subscription */
uORB::Subscription _vehicle_command_sub{ORB_ID(vehicle_command)};   /**< vehicle commands (onboard and offboard) */

输出

uORB::Publication<geofence_result_s>       _geofence_result_pub{ORB_ID(geofence_result)};
uORB::Publication<mission_result_s>       _mission_result_pub{ORB_ID(mission_result)};
uORB::Publication<position_setpoint_triplet_s>    _pos_sp_triplet_pub{ORB_ID(position_setpoint_triplet)};
uORB::Publication<vehicle_command_ack_s>  _vehicle_cmd_ack_pub{ORB_ID(vehicle_command_ack)};
uORB::Publication<vehicle_command_s>      _vehicle_cmd_pub{ORB_ID(vehicle_command)};
uORB::Publication<vehicle_roi_s>      _vehicle_roi_pub{ORB_ID(vehicle_roi)};

5. 参考资料

【1】PX4开源软件框架简明简介
【2】PX4模块设计之十一：Built-In框架
【3】PX4模块设计之十二：High Resolution Timer设计
【4】PX4模块设计之十三：WorkQueue设计
【5】PX4模块设计之十七：ModuleBase模块
【6】PX4模块设计之三十：Hysteresis类
【7】PX4 modules_main

PX4模块设计之三十八：Navigator模块相关推荐

BetaFlight模块设计之三十：Cli模块分析
BetaFlight模块设计之三十:Cli模块分析 Cli模块 Cli接口 Cli框架 Cli命令结构主要函数分析 cliProcess函数 processCharacterInteractive函 ...
PX4模块设计之三十五：MulticopterAttitudeControl模块
PX4模块设计之三十五:MulticopterAttitudeControl模块 1. MulticopterAttitudeControl模块简介 2. 模块入口函数 2.1 主入口mc_att_c ...
PX4模块设计之三十四：ControlAllocator模块
PX4模块设计之三十四:ControlAllocator模块 1. ControlAllocator模块简介 2. 模块入口函数 2.1 主入口control_allocator_main 2.2 自 ...
PX4模块设计之三十一：ManualControl模块
PX4模块设计之三十一:ManualControl模块 1. ManualControl模块简介 2. 模块入口函数 2.1 主入口manual_control_main 2.2 自定义子命令cust ...
PX4模块设计之三十三：Sensors模块
PX4模块设计之三十三:Sensors模块 1. Sensors模块简介 2. 模块入口函数 2.1 主入口sensors_main 2.2 自定义子命令custom_command 2.3 模块状态 ...
BetaFlight模块设计之三十五：RSSI信号强度链路稳定性分析
BetaFlight模块设计之三十五:RSSI信号强度&链路稳定性分析 1. RSSI信号强度 1.1 RSSI Value 1.2 RSSI dBm Value 2. 链路稳定性 3. RS ...
BetaFlight模块设计之三十二：MSP协议模块分析
BetaFlight模块设计之三十二:MSP协议模块分析 1. MSP协议模块 1.1 MSP描述 1.2 MSP版本优缺点 1.3 MSP代码资源 2. MSP报文解析 2.1 MSP收包状态机 2 ...
BetaFlight模块设计之三十四：OSD模块分析
BetaFlight模块设计之三十四:OSD模块分析 1. OSD模块 1.1 osd状态机子模块 1.2 osd_warnings检查子模块 1.3 osd_elements子模块 2. OSD设备 ...
BetaFlight模块设计之三十三：Pid模块分析
BetaFlight模块设计之三十三:Pid模块分析 Pid模块 1. Pid_audio子模块 2. Pid_init子模块 3. Pid算法子模块 3.1 TPA模式 3.2 飞行模式 3.3 L ...

PX4模块设计之三十八：Navigator模块