double min_cost = std::numeric_limits< double  >::max();

double min_cost = std::numeric_limits< double  >::min();

template< class T > class numeric_limits;

一、IMU误差源

      IMU需要标定的参数主要是:确定性误差和随机误差，确定性误差主要包括：bias、scale、misalignment，随机误差主要包括：noise、random walk。

二、imu_utils 开源工具

       imu_utils开源ROS工具用于分析IMU的随机误差。

       github: https://github.com/gaowenliang/imu_utils

二、kalibr_allan

        kalibr_allan开源工具用于分析IMU的随机误差。

        github:  https://github.com/rpng/kalibr_allan

三、imu_tk

      imu_tk开源工具是用于标定IMU的确定性误差。

      github: https://github.com/Kyle-ak/imu_tk/tree/master/src

四、allan_variance_ros

        allan_variance_ros开源ROS工具用于分析IMU的随机误差。

        github: https://github.com/ori-drs/allan_variance_ros

https://github.com/mad-lab-fau/imucal/tree/master/docs

https://imucal.readthedocs.io/en/latest/

一、字符串分割

static     std::vector<std::string> getWords(const std::string  &s, const std::string  &delim)
{
    std::vector<std::string> res;
    //std::string delim = ",";
    std::string token = "";
    for (int i = 0; i < s.size(); i++) {
        bool flag = true;
        for (int j = 0; j < delim.size(); j++) {
            if (s[i + j] != delim[j]) flag = false;
        }
        if (flag) {
            if (token.size() > 0) {
                res.push_back(token);
                token = "";
                i += delim.size() - 1;
            }
        } else {
            token += s[i];
        }
    }
    res.push_back(token);
    return res;
}

二、读取CSV格式文件

static  void    Load_Full_IMU_Data(const std::string  &csv, std::vector<Eigen::Vector3d>  &gyro, \
                                   std::vector<Eigen::Vector3d>  &acce, std::vector<Eigen::Vector3d>  &magn)
{
    FILE  *fp = fopen(csv.c_str(), "r");
    if(nullptr == fp)
        return;
    char  buf[2048] = "";
    while(fgets(buf, sizeof(buf), fp)){
        std::vector<std::string> all_str = getWords(std::string(buf), ",");
        if(all_str.size()>=9){
            Eigen::Vector3d   acc;
            Eigen::Vector3d   gyr;
            Eigen::Vector3d   mag;
            double  t = strtod(all_str[0].c_str(), nullptr);

            double  gyrox = strtod(all_str[1].c_str(), nullptr);
            double  gyroy = strtod(all_str[2].c_str(), nullptr);
            double  gyroz = strtod(all_str[3].c_str(), nullptr);
            gyr[0] = gyrox;
            gyr[1] = gyroy;
            gyr[2] = gyroz;
            gyro.push_back(gyr);

            double  accex = strtod(all_str[4].c_str(), nullptr);
            double  accey = strtod(all_str[5].c_str(), nullptr);
            double  accez = strtod(all_str[6].c_str(), nullptr);
            acc[0] = accex;
            acc[1] = accey;
            acc[2] = accez;
            acce.push_back(acc);

            double  magnx = strtod(all_str[7].c_str(), nullptr);
            double  magny = strtod(all_str[8].c_str(), nullptr);
            double  magnz = strtod(all_str[9].c_str(), nullptr);
            mag[0] = magnx;
            mag[1] = magny;
            mag[2] = magnz;
            magn.push_back(mag);
        }
        memset(buf, 0x00, sizeof(buf));
    }
    fclose(fp);
    return;
}