Improved inertial measurement device and aircraft carrying such a device

The device has an electric motor (6) comprising units for controlling inertial rotation speed of a moving element, so that sine and cosine functions of an angle of the moving element with respect to reference inertia are zero on average on integer number of revolutions. The inertial rotation speed is greater than a reference value of imposing bias frequency shifting of measurement units, where the shifting is greater than bandwidth of bias instability of the measurement units. Independent claims are also included for the following: (1) a method for measuring inertia of a vehicle or aircraft (2) a method for controlling and regulating enslaving inertial rotation speed of an electric motor of an inertia measuring device.