A dynamic collision model for improved over-range protection of cantilever-mass micromechanical accelerometers

A dynamic collision model is proposed and built to analyze over-range protection of cantilever beam-mass structured micro-accelerometers. The model encloses angular momentum of the seismic mass, squeeze-film air damping, inertial force and supporting force (acting at the cantilever-root) during the collision between the seismic mass and the over-range stopping bumpers. Based on angular momentum balance equation we obtain the relationship among the supporting force F, the collision time duration t and the rotation center c where the bumpers are located. In the best case of F=0 which means no supporting force acts on the cantilever, we find the optimal bumper location of c. The accelerometers have been fabricated with the over-range protection design according to the dynamic collision model. Experimental test shows that 5g measure-range accelerometers can endure 9000g acceleration and there is no sign of performance degradation, which well verified the dynamic collision model.