Why "rate random walk" exists on gyroscpe ?

[kawabonga]

hi
I read an article about stochastic error modeling, and I didn't understand this extract about error sources :

Angular random walk. This is an angular error process which is due to white noise in angular rate.
Rate random walk. This is a rate error due to white noise in angular acceleration.

how can the "rate random walk" be present, while the gyroscope directly angular rate ?
the article's title is : "Stochastic Modeling of MEMS Inertial Sensors " by Petko Petkov and Tsonyo Slavov

 

[mfb]

Some external influences can exert a torque on the system. It could also be related to your measurement which will have some noise.