var prevX = 0 var prevY = 0 var prevY = 0 var alpha = 0.1 var prev_x = 0 var prev_y = 0 var prev_t = 0 var integral = 0 var is_first = true var first_value = 0 // source: https://en.wikipedia.org/wiki/Conversion_between_quaternions_and_Euler_angles function quaternionToYaw(x, y, z, w) { // yaw (z-axis rotation) t1 = 2.0 * (w * z + x * y); t2 = 1.0 - 2.0 * (y * y + z * z); yaw = Math.atan2(t1, t2); return yaw }