Deadbeat algorithms

DAHLIN<44) suggested that, in order to avoid the large overshoots and oscillatory behaviour which are characteristic of the deadbeat algorithm, the specification of the system closed-loop response to a step change in set point should be the same as that for a first-order system with dead time. The first-order time constant can then be employed as a design parameter which can be adjusted to give the desired closed-loop response. Hence ... 

The deadbeat algorithm is physically realizable if the time delay in... 

With Dahlin s algorithm we can avoid the excessive control action produced by the deadbeat algorithms, thus reducing significantly the undesired large overshoots or highly oscillatory closed-loop response. 

Suppose that the sampling period is T = 1 second. Then the process dead time is ta = 2 T and the corresponding deadbeat algorithm is given by... 

For a discussion of the deadbeat algorithms the reader can consult Ref. 10, while Dahlin s method can be found in the original paper ... 

VII.41 Consider the cascade control system of Figure PVII.2. Design two deadbeat algorithms for the primary and secondary controllers. 

There is a variety of specifications that can be imposed on the system closed-loop response for a given change in set point. These lead to a number of alternative discrete-time control algorithms—the best known of which are the Deadbeat and Dahlin s algorithms. 

Fig. 7.96. Comparison of response of the controlled variable using deadbeat and Dahlin s response specification algorithm...

Unfortunately, the deadbeat and Dahlin s algorithms usually contain poles that cause severe ringing of the controller output. This may be the... 

The digital control algorithms discussed in Sections 30.2 and 30.3 were designed for set point changes (servo problem). Therefore, the question arises as to how well they perform for load (disturbance) changes. It is a fortuitous coincidence that algorithms such as the deadbeat or Dahlin s perform well for both set point and load changes. 

Discuss the construction of the deadbeat and Dahlin s algorithms. Which one imposes more stringent specifications on the closed-loop response What are the consequences of such stringent requirements ... 

Design the deadbeat control algorithms for a first-order process with dead time equpl to 3T. Can we have a physically realizable controller if we require that the response exhibit zero error at all sampling instants after the first ... 

What do we mean when we say that a control algorithm is physically unrealizable What are the necessary conditions for designing physically realizable deadbeat and Dahiin algorithms ... 

Figure 30.5 Closed-loop responses to unit step change in set point using deadbeat and Dahlin algorithms.

How can you eliminate the ringing from a deadbeat or Dahlin algorithm ... 

---