O'Reilly logo

Applied Process Control by Michael Mulholland

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

7Advanced Control Algorithms

This chapter focuses largely on multi-input multi-output (MIMO) controllers. The same equations can be simplified where necessary for the SISO case.

7.1 Discrete z-Domain Minimal Prototype Controllers

This is a sampled data controller based on a model of the process. The design procedure seeks to achieve a stipulated sampled response to a stipulated disturbance to the system. This may not always be achievable, so an alternative desired response may have to be given. Figure 7.1 shows a typical installation in which the manipulated variable values are updated by comparison of feedback with setpoint only at fixed intervals T. The aim will be to achieve a particular form of measured output y in response to particular forms of setpoint variation ys and/or load disturbance variations d.

Figure depicting a typical installation to measured output y in response to particular forms of setpoint variation ys and/or load disturbance variations d. The manipulated variable values are updated by comparison of feedback with setpoint only at fixed intervals T.

Figure 7.1 Discrete feedback control of process GP with load disturbance.

Recalling from Section 3.9.3.1 that the analogue sections must be combined between sampling points, before transforming to ‘impulse-modulated’ (z) form, and being careful to preserve the transfer function multiplication order so that MIMO systems are included, the system shown in Figure 7.1 is seen to have a measured output determined by

(7.1) equation

that is

7.1.1 Setpoint Tracking Discrete ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required