Inertial sensor and method of inertial sensing with tuneable mode coupling strength

Abstract

There is provided an inertial sensor comprising a frame, a resonator assembly fixed to the frame comprising a first and second resonator coupled to one another by a mechanical coupling and a drive means coupled to the resonator assembly for driving the first and second resonators to vibrate. The resonator assembly is configured such that energy is transferred between the first and second resonators through the mechanical coupling. An amount of energy transferred through the mechanical coupling is dependent on the value of an input measurand acting on one of the first and second resonators. The inertial sensor also comprises a pumping means coupled to the resonator assembly for applying a pumping signal to the resonator assembly, the pumping means controlled by electrical circuitry, and a sensor assembly configured to detect the amplitude of oscillation of the first resonator at a first resonant frequency and the amplitude of oscillation of the second resonator at a second resonant frequency. The electrical circuitry is configured to control the pumping means to apply a pumping signal that has a frequency substantially equal to a difference between the first resonant frequency and the second resonant frequency. When the input measurand has the first value, the signal from the pumping means adjusts an amplitude ratio of the amplitudes of oscillation of the first and second resonator detected by the sensor assembly so that the amplitude ratio is within a predetermined amplitude ratio range over an expected range of input measurand values. An output of the inertial sensor is based on the amplitude ratio.