日志记录源码

// Code to Write and Read packets from AP_Logger log memory
// Code to interact with the user to dump or erase logs

struct PACKED log_Control_Tuning {
    LOG_PACKET_HEADER;
    uint64_t time_us;
    float  throttle_in;
    float  angle_boost;
    float    throttle_out;
    float    throttle_hover;
    float    desired_alt;
    float    inav_alt;
    float    baro_alt;
    int16_t  desired_rangefinder_alt;
    int16_t  rangefinder_alt;
    float    terr_alt;
    int16_t  target_climb_rate;
    int16_t  climb_rate;
};

// Write a control tuning packet
void Sub::Log_Write_Control_Tuning()
{
    // get terrain altitude
    float terr_alt = 0.0f;
#if AP_TERRAIN_AVAILABLE
    if (terrain.enabled()) {
        terrain.height_above_terrain(terr_alt, true);
    } else {
        terr_alt = rangefinder_state.rangefinder_terrain_offset_cm * 0.01f;
    }
#else
    terr_alt = rangefinder_state.rangefinder_terrain_offset_cm * 0.01f;
#endif

    struct log_Control_Tuning pkt = {
        LOG_PACKET_HEADER_INIT(LOG_CONTROL_TUNING_MSG),
        time_us             : AP_HAL::micros64(),
        throttle_in         : attitude_control.get_throttle_in(),
        angle_boost         : attitude_control.angle_boost(),
        throttle_out        : motors.get_throttle(),
        throttle_hover      : motors.get_throttle_hover(),
        desired_alt         : pos_control.get_pos_target_z_cm() / 100.0f,
        inav_alt            : inertial_nav.get_position_z_up_cm() * 0.01f,
        baro_alt            : barometer.get_altitude(),
        desired_rangefinder_alt   : (int16_t)mode_surftrak.get_rangefinder_target_cm(),
        rangefinder_alt           : rangefinder_state.alt_cm,
        terr_alt            : terr_alt,
        target_climb_rate   : (int16_t)pos_control.get_vel_target_z_cms(),
        climb_rate          : climb_rate
    };
    logger.WriteBlock(&pkt, sizeof(pkt));
}

1. 油门控制输入（throttle_in）和输出 （throttle_out）；

2. 期望深度desired_alt通过 pos_control 对象提供的get_pos_target_z_cm() 接口获取，并除以100，单位转换为m。结合
   定深模式源码分析 中深度控制逻辑中，调用了 pos_control对象提供的set_pos_target_z_cm 和 set_pos_target_z_from_climb_rate_cm接口，而日志获取的期望深度就是获取深度控制中设置的值；

3. 气压计高度 BarAlt 直接从压力深度传感器获取；

4. 对于装载测距仪机器，desired_rangefinder_alt和rangefinder_alt 为测距仪期望高度和采集的实际高度；

5. 期望爬升率target_climb_rate 通过get_vel_target_z_cms()获取，又油门控制输入指定。

导出日志分析

// @LoggerMessage: CTUN
// @Description: Control Tuning information
// @Field: TimeUS: Time since system startup
// @Field: ThI: throttle input
// @Field: ABst: angle boost
// @Field: ThO: throttle output
// @Field: ThH: calculated hover throttle
// @Field: DAlt: desired altitude
// @Field: Alt: achieved altitude
// @Field: BAlt: barometric altitude
// @Field: DSAlt: desired rangefinder altitude
// @Field: SAlt: achieved rangefinder altitude
// @Field: TAlt: terrain altitude
// @Field: DCRt: desired climb rate
// @Field: CRt: climb rate


// type and unit information can be found in
// libraries/AP_Logger/Logstructure.h; search for "log_Units" for
// units and "Format characters" for field type information
const struct LogStructure Sub::log_structure[] = {
    LOG_COMMON_STRUCTURES,
    { LOG_CONTROL_TUNING_MSG, sizeof(log_Control_Tuning),
      "CTUN", "Qfffffffccfhh", "TimeUS,ThI,ABst,ThO,ThH,DAlt,Alt,BAlt,DSAlt,SAlt,TAlt,DCRt,CRt", "s----mmmmmmnn", "F----00BBBBBB" },
    ...
}