Hi,
You can typically invert the discrete transfer function simply by swapping the numerator and denominator. However, if the denominator order is less than the numerator order the inverted system becomes non-causal, meaning it would respond to inputs before they are applied. Non-causal systems are not physically realizable. This usually indicates that the system or the model might need to be reconsidered.
You can still try an approximation of the inversion by adding delays or modifying the system to ensure causality. This might involve introducing additional poles to the denominator to increase its order as compared to the numerator.
