本小结将介绍传感器的校准方法，包括IMU和磁力计。传感器校准是状态估计与控制中至关重要的一步，它有利于降低状态估计与控制误差。

基本使用

RflyPilot内置了传感器校准功能，校准操作主要通过控制台命令实现，校准结果将以文本文件的形式存储在RflyPilot飞控中。
在这之前，需要设置rflypilot.txt中的valid_mode = 3，以启用实验模式。校准参数将被以文本形式存储在calibration.txt，在首次使用时，该文件需要手动创建，文件内容可以设置为如下

accel_scale_0 = 0.000000
accel_scale_1 = 0.000000
accel_scale_2 = 0.000000
accel_offset_0 = 0.000000
accel_offset_1 = 0.000000
accel_offset_2 = 0.000000
gyro_scale_0 = 1.000000
gyro_scale_1 = 1.000000
gyro_scale_2 = 1.000000
gyro_offset_0 = 0.000000
gyro_offset_1 = 0.000000
gyro_offset_2 = 0.000000
mag_scale_0 = 0.000000
mag_scale_1 = 0.000000
mag_scale_2 = 0.000000
mag_offset_0 = 0.000000
mag_offset_1 = 0.000000
mag_offset_2 = 0.000000

陀螺仪校准

在控制台中输入calib gyro，等待一段时间，即可完成校准。

vehicle > calib gyro
gyro calibration mode
Calibration thread created with process pid : 1036
Calibration starting
vehicle > thread calibration running
start gyro calibration process......
Please do not move the aircraft
 gyro calibration parameter is:
 gyro_x_offset =        0.013428
 gyro_y_offset =        0.006644
 gyro_z_offset =        -0.002992
calibration finished !

在输入calib save即可保存校准数据。

vehicle > calib gyro
gyro calibration mode
Calibration thread created with process pid : 1036
Calibration starting
vehicle > thread calibration running
start gyro calibration process......
Please do not move the aircraft
 gyro calibration parameter is:
 gyro_x_offset =        0.013428
 gyro_y_offset =        0.006644
 gyro_z_offset =        -0.002992
calibration finished !

vehicle > calib load
LOAD calibration mode
Calibration thread created with process pid : 1220
Calibration starting
vehicle > thread calibration running
key has 18
accel_scale_0 is 0.000000
accel_scale_1 is 0.000000
accel_scale_2 is 0.000000
accel_offset_0 is 0.000000
accel_offset_1 is 0.000000
accel_offset_2 is 0.000000
gyro_scale_0 is 1.000000
gyro_scale_1 is 1.000000
gyro_scale_2 is 1.000000
gyro_offset_0 is 0.013428
gyro_offset_1 is 0.006644
gyro_offset_2 is -0.002992
mag_scale_0 is 0.000000
mag_scale_1 is 0.000000
mag_scale_2 is 0.000000
mag_offset_0 is 0.000000
mag_offset_1 is 0.000000
mag_offset_2 is 0.000000
calibration finished !

校准结果将被存储在与rflypilot可执行文件同级的calibration.txt中。

加速度计校准

RflyPilot的坐标系定义如下

加速度计的校准采用了常用的六面校准法。输入指令calib accel，便开始了校准。
RflyPilot首先会提示，Please place the (+x) axis of the aircraft upward,使用者将+x轴朝上静置即可，待姿态稳定后，RflyPilot将提示Please do not move the aircraft，此时需要静置飞控，RflyPilot正在采集加速度计数据。待数据采集完成后，将会提示Please place the (+z) axis of the aircraft upward，后续操作以此类推，这里不再赘述。

vehicle > calib accel
accel calibration mode
Calibration thread created with process pid : 1406
Calibration starting
vehicle > thread calibration running
start accel calibration process......
Please place the (+x) axis of the aircraft upward
PX_UP is detected!
accel data: accel x = 9.7417, y = -0.7865, z = -0.2954
Please do not move the aircraft
step1 is completed!
A = 1381.0000

Please place the (+z) axis of the aircraft upward
PZ_UP is detected!
accel data: accel x = -0.6721, y = -0.4783, z = 9.6469
Please do not move the aircraft
step2 is completed!
A = 2763.0000

Please place the (-x) axis of the aircraft upward
NX_UP is detected!
accel data: accel x = -9.7803, y = -0.4612, z = -0.1445
Please do not move the aircraft
step3 is completed!
A = 4144.0000

Please place the (-z) axis of the aircraft upward
NZ_UP is detected!
accel data: accel x = 0.1338, y = 0.0895, z = -9.9620
Please do not move the aircraft
step4 is completed!
A = 5526.0000

Please place the (-y) axis of the aircraft upward
NY_UP is detected!
accel data: accel x = -0.2413, y = -9.8469, z = -0.2811
Please do not move the aircraft
step5 is completed!
A = 6908.0000

Please place the (+y) axis of the aircraft upward
PY_UP is detected!
accel data: accel x = 0.3244, y = 9.7597, z = 0.8039
Please do not move the aircraft
step6 is completed!
A = 8290.0000

1.000355 0.998360 0.997071 
0.022998 0.011350 0.116596
calibration finished !

磁力计校准

磁力计校准使用的方法是椭球拟合。输入命令calib mag, RflyPilot首先会提示，Please place the (-z) axis of the aircraft upward,使用者将-z轴朝上静置即可，待姿态稳定后，出现提示
Please rotate the aircraft around -z axis，此时绕-z轴缓慢单向旋转RflyPilot即可（旋转方向任意），RflyPilot需要使用者在7秒钟内绕一圈，7秒钟后，校准程序将自动进入下一阶段，Please place the (+x) axis of the aircraft upward, 此时按照步骤操作即可。

Calibration thread created with process pid : 786
Calibration starting
vehicle > thread calibration running
start mag calibration process......Please place the (-z) axis of the aircraft upward
NZ_UP is detected!
accel data: accel x = -0.2963, y = 0.3090, z = -10.0077
mag data: mag x = -0.099583, y = 0.007083, z = 0.261417
Please rotate the aircraft around -z axis
step1 is completed!
A = 695.0000
 Please place the (+x) axis of the aircraft upward
PX_UP is detected!
accel data: accel x = 9.7193, y = 0.5693, z = -0.6472
mag data: mag x = -0.553500, y = -0.092667, z = -0.231417
Please rotate the aircraft around +x axis
step2 is completed!
A = 1391.0000
 Please place the (-x) axis of the aircraft upward
NX_UP is detected!
accel data: accel x = -9.8372, y = 0.5258, z = -0.2316
mag data: mag x = 0.443917, y = 0.078917, z = -0.021417
Please rotate the aircraft around -x axis
step3 is completed!
A = 2087.0000
 Please place the (-y) axis of the aircraft upward
NY_UP is detected!
accel data: accel x = -0.3618, y = -9.7050, z = -0.9713
mag data: mag x = 0.136000, y = 0.345000, z = -0.076250
Please rotate the aircraft around -y axis
step4 is completed!A = 2783.0000
 Please place the (+y) axis of the aircraft upward
PY_UP is detected!
accel data: accel x = 1.3548, y = 9.6512, z = 0.4473
mag data: mag x = 0.017250, y = -0.516000, z = 0.026833
Please rotate the aircraft around +y axis
step5 is completed!
A = 3479.0000
 Please place the (+z) axis of the aircraft upward
PZ_UP is detected!
accel data: accel x = -0.3423, y = 0.1443, z = 9.5431
mag data: mag x = -0.063333, y = -0.248750, z = -0.517500
Please rotate the aircraft around +z axis
step6 is completed!
A = 4175.0000
 1.912619 2.172892 2.158774 
0.092122 0.183707 0.208248
calibration finished !

磁力计计校准完成后，利用calib save保存即可，数据将写入到calibration.txt中。

IMU与磁力计安装角校准

由于飞行器结构的限制，当用户需要对飞控进行倾斜安装时，需要对飞控进行设置，相应设置方法请查看传感器安装角设置。

其他

1. 如要查看当前传感器校准参数，可以输入命令calib load，即可列出当前校准参数。
2. RflyPilot默认保存了校准时读取的传感器数据，这些数据在校准完成之后将存储在当前目录，分别名为accel_data.txt, gyro_data.txt, mag_data.txt，这些数据可用于在MATLAB中进行处理。
3. 首次使用RflyPilot时，calibration.txt文件并不存在，需要使用者自行创建。