Patent ID: 8538039

Claim:
A system for compensating for unwanted behavior of a transducer having a magnet system with an air gap, and a voice coil movably arranged in the air gap and supplied with an electrical input voltage, the system comprising: a transducer modeling unit for calculating the mechanical, electrical, acoustical, and/or thermal behavior of the transducer by solving a differential equation system in the discrete time domain for an upcoming discrete time sample, where the differential equation system in the discrete time domain describes the motion of the voice coil is dependent on the input voltage and certain parameters dependant on the transducer; and a signal processing unit that receives control signals from the transducer modeling unit and compensates for a difference between a behavior calculated by the modeling unit and a predetermined behavior, where the differential equation system for electrical voltage Ue(t) over time t, the electrical current Ie(t) over time t, and the x(t) is the displacement of the voice coil over time t is: Ue ⁡ ( t ) = Re · I ⁡ ( t ) + I ⁡ ( t ) · ⅆ Le ⁡ ( x ) / ⅆ t + Le ⁡ ( x ) · ⅆ I ⁡ ( t ) / ⅆ t + ∑ i = 0 8 ⁢ Bl i · x ⁡ ( t ) i · ⅆ x ⁡ ( t ) / ⅆ t ⁢ ∑ i = 0 8 ⁢ Bl i · x ⁡ ( t ) i · I ⁡ ( t ) = m · ⅆ 2 ⁢ x ⁡ ( t ) / ⅆ t 2 + Rm · ⅆ x ⁡ ( t ) / ⅆ t + ∑ i = 0 8 ⁢ K i · x ⁡ ( t ) i · x ⁡ ( t ) - 1 / 2 · I ⁡ ( t ) 2 · ⅆ Le ⁡ ( x ) / ⅆ x where the continuous time t is substituted by discrete time n so that t=n; dx/dt=(x(n)−x(n−1))/Δt=xp(n); and d 2 x/dt 2 =(x(n+1)−2*x(n−1))/Δt2; and where the certain parameters comprise Re, Le, Bl, m, Rm, and K.