如何从磁力计的 X Y Z 值计算方位角？

Posted 2023-04-14

【中文标题】如何从磁力计的 X Y Z 值计算方位角？

【英文标题】：How to calculate azimuth from X Y Z values from magnetometer?

【发布时间】：2019-11-28 22:06:24

【问题描述】：

我想用 Arduino 和 QMC5883 做指南针。现在，磁力计只输出 X Y Z 值，我必须自己计算其余的值。到目前为止，我已经使用了这个：

float azimuth = atan2(x, y) * 180.0/PI;

但它非常有问题，并且容易向任何方向倾斜。有没有更好的算法——例如——电话制造商使用？如果需要，我可以使用加速度计寻求帮助。

【参考方案1】：

BBC micro:bit 的device abstraction layer (DAL) 包含此代码，用于根据加速度计数据得出的角度进行倾斜调整。来自https://github.com/lancaster-university/microbit-dal/blob/master/source/drivers/MicroBitCompass.cpp

/**
 * Calculates a tilt compensated bearing of the device, using the accelerometer.
 */
int MicroBitCompass::tiltCompensatedBearing()

    // Precompute the tilt compensation parameters to improve readability.
    float phi = accelerometer->getRollRadians();
    float theta = accelerometer->getPitchRadians();

    // Convert to floating point to reduce rounding errors
    Sample3D cs = this->getSample(NORTH_EAST_DOWN);
    float x = (float) cs.x;
    float y = (float) cs.y;
    float z = (float) cs.z;

    // Precompute cos and sin of pitch and roll angles to make the calculation a little more efficient.
    float sinPhi = sin(phi);
    float cosPhi = cos(phi);
    float sinTheta = sin(theta);
    float cosTheta = cos(theta);

    // Calculate the tilt compensated bearing, and convert to degrees.
    float bearing = (360*atan2(x*cosTheta + y*sinTheta*sinPhi + z*sinTheta*cosPhi, z*sinPhi - y*cosPhi)) / (2*PI);

    // Handle the 90 degree offset caused by the NORTH_EAST_DOWN based calculation.
    bearing = 90 - bearing;

    // Ensure the calculated bearing is in the 0..359 degree range.
    if (bearing < 0)
        bearing += 360.0f;

    return (int) (bearing);