Modelling
In the following, we suppose that the shaker is not coupled to an exterior structure.
The motor is composed of an electrical circuit that creates a magnetic field
in which is placed a coil of length
, which has a DC resistance
and an electrical inductance
.
The electro-mechanical transduction is characterised by a force factor
.
The mechanical part can be represented by a mass
, corresponding to the mass of the mobile part (rigid piston + coil + suspensions + various parts), a mechanical compliance
corresponding to the elastic suspension, and a mechanical resistance
which expresses all the mechanical losses of the system (friction in the magnet air gap, losses in the suspension, etc.).
The electrical system (signal generator + amplifier) can be represented by an equivalent Thevenin generator whose unloaded voltage is
and output impedance
.
