Large modal coupling error seriously influences zero-offset stability of gyroscope.The formation mechanism of modal coupling error of a micromachining vibration gyroscope is studied

and the effect rule of structural machining error on modal coupling error is simulated.Simulation result shows that machining error on the support beam is the major factor contributing to the dissymmetry of structural stiffness that results in modal coupling error

and the modal coupling error can be to decreased or even eliminated by removing corresponding material in the symmetrical location.Structural balance experiment is implemented on the microgyroscope by UV laser micromachining technology

when there is no angular velocity inputs after laser trimming

the peak-peak voltage of the modal coupling error signal of microgyroscope is reduced from 2.88V to 0.24V

trimming effect is obvious.