Conclusions

Nowadays the implmentation of contorl systems is mostly done in computers. So, there is a clear need to understand the methologies involved in digital control. The key difference with continuous control is the presence of sampled-data signals. This implies the use of new methodologies to model the system: now the basic mathematical tool is the Z-transform. The models for a discrete system are the discrete transfer function and the discrete state-space representation.

In digital control system, one characteristic is the presence of sample and hold elements. They will appear in the conversion from analog to digital and from digital to analog (AD/DA converters).

Concerning methodologies there are to main possibilities when designing a controller:

• Design the controller in the continuous space and then obtain the discrete equivalent model.
• Design the controller directly using discrete methods. 

s de ellas son expecíficas para un tipo de entrada determinado y la otra es un función que permite simular sistemas ante cualquier tipo de entrada. Estas funciones son:

1. Para simulación de la respuesta impulso: impulse.
2. Para simulación de la respuesta escalón: step.
3. Para simular un sistema ante una entrada cualquiera definida por el usuario: lsim.