IMU中使用的卡尔曼滤波器，融合过程会合并哪些信号？

Question

from what I read, Kalman filter basically tries to "reconcile" the predictions for one variable based on history of this variable, with actual observation of this variable. in the case of finding the position of an IMU , I would imagine that we need the speed read out, so that we can predict x_(k+1) = v * dt + x_(k) , and we would also need the direct read out for z_(k+1).

but in fact on a IMU we don't have this z read out. so what exactly does kalman filtering on IMU do ?

thanks Yang

Answer 1

ok, after reading more on related resources, i figured out:

the "baseline" report is that vertical vector for earth gravity, measured by the 3-axis accelerometer, which really measures force, either force induced by gravity or force induced by acceleration; noise(including the "noise" introduced by actual horizontal acceleration) is repaired by using gyro's rotation rate readout , in a Kalman filter.

heading is obtained from earth magnetic field , through compass (only on the horizontal plane, compass doesn't tell you the tilt away from earth z-axis). again Kalman filter uses the gyro rotation rate to repair the compass read out.

once you have the earth vertical axis and north axis, you have your full orientation