硬件架构图

可以看到左下角的“GNSS定位模块”其实是有IMU和GPS Antenna 组成的。

执行分析

代码

class GpsMonitor : public RecurrentRunner {
 public:
  GpsMonitor();
  void RunOnce(const double current_time) override;
};

void GpsMonitor::RunOnce(const double current_time) {
  auto manager = MonitorManager::Instance();
  Component* component = apollo::common::util::FindOrNull(
      *manager->GetStatus()->mutable_components(), FLAGS_gps_component_name);
  if (component == nullptr) {
    // GPS is not monitored in current mode, skip.
    return;
  }
  ComponentStatus* component_status = component->mutable_other_status();
  component_status->clear_status();

  static auto gnss_best_pose_reader =
      manager->CreateReader<GnssBestPose>(FLAGS_gnss_best_pose_topic);
  gnss_best_pose_reader->Observe();
  const auto gnss_best_pose_status = gnss_best_pose_reader->GetLatestObserved();
  if (gnss_best_pose_status == nullptr) {
    SummaryMonitor::EscalateStatus(ComponentStatus::ERROR,
                                   "No GnssBestPose message", component_status);
    return;
  }
  switch (gnss_best_pose_status->sol_type()) {
    case SolutionType::NARROW_INT:
      SummaryMonitor::EscalateStatus(ComponentStatus::OK, "", component_status);
      break;
    case SolutionType::SINGLE:
      SummaryMonitor::EscalateStatus(
          ComponentStatus::WARN, "SolutionType is SINGLE", component_status);
      break;
    default:
      SummaryMonitor::EscalateStatus(ComponentStatus::ERROR,
                                     "SolutionType is wrong", component_status);
      break;
  }
}

分析

gps monitor 核心内容就70 line code

基本思路如下：

1. 从配置文件中查找GPS是否是被配置的监控组件
2. 如果是的话，订阅GnssBestPose topic，并收取数据
3. 获取最新的数据，如果最新的数据为null，发出ERROR级别的故障
4. 如果获取的数据类型为NARROW_INT，表示正常
5. 如果获取的数据类型为SINGLE，表示WARN
   1. 这里根据apollo 的定位算法设计与硬件架构，不难猜SINGLE 代表IMU 惯性单元或GPS有一个没有正常输出数据
   2. 如果获取的数据类型为其他情况，表示ERROR

GnssBestPose 和 SolutionType 的定义都来自 GNSS 驱动。

modules/drivers/gnss/proto/gnss_best_pose.proto

enum SolutionType {
  NONE = 0;
  FIXEDPOS = 1;
  FIXEDHEIGHT = 2;
  FLOATCONV = 4;
  WIDELANE = 5;
  NARROWLANE = 6;
  DOPPLER_VELOCITY = 8;
  SINGLE = 16;
  PSRDIFF = 17;
  WAAS = 18;
  PROPOGATED = 19;
  OMNISTAR = 20;
  L1_FLOAT = 32;
  IONOFREE_FLOAT = 33;
  NARROW_FLOAT = 34;
  L1_INT = 48;
  WIDE_INT = 49;
  NARROW_INT = 50;
  RTK_DIRECT_INS =
      51;  // RTK filter is directly initialized from the INS filter.
  INS_SBAS = 52;
  INS_PSRSP = 53;
  INS_PSRDIFF = 54;
  INS_RTKFLOAT = 55;
  INS_RTKFIXED = 56;
  INS_OMNISTAR = 57;
  INS_OMNISTAR_HP = 58;
  INS_OMNISTAR_XP = 59;
  OMNISTAR_HP = 64;
  OMNISTAR_XP = 65;
  PPP_CONVERGING = 68;
  PPP = 69;
  INS_PPP_CONVERGING = 73;
  INS_PPP = 74;
}