Control Talk Blog

Nonlinearities Recommendations Tips

We conclude our review of nonlinearities with an overview of applications and a detailed list of simple solutions to minimize the adverse effects of this everyday problem in nearly all control loops. It is impressive how setting lambda equal to 3x the largest deadtime value helps to solve most nonlinearity problems. Lambda...

Effect of Nonlinearities Perspective Tips

Here we use the broader definition of linearity to mean constant dynamics. A linear control loop has a constant total loop dead time, constant primary and secondary time constants, and a constant open loop gain. This perspective reviews the sources of dynamics and causes of nonlinearity.

Plant Speedup Stability Tips

The speedup of a plant’s response can cause loops to go from a smooth to an oscillatory response. In actual plants, the faster rate of change of a process variable important for product quality such a temperature or composition occurs for various changes in operating conditions.

The Primary Source of Disagreement in Process Control Tips

The primary reason why there are so many and so different schools of thought about control algorithms and tuning can be traced back to one parameter in the process response. What PID tuning and what PID structure is pronounced as best and even whether PID control should be used is...

Disturbance Dynamics Recomendations Tips

If there were no unmeasured disturbances, feedback control would not be necessary. Process engineers and operators could home in on the best PID output and just leave it at this value. In fact many process engineers are much more comfortable with setting a stream flow per a process flow diagram...

Effect of Disturbance Dynamics Perspective Tips

Much of the differences in approaches to controller algorithms and tuning can be traced back to assumptions made about the type and importance of disturbances. Each method has merits based on the disturbance frequency, location, and time lag.

How A Young Small Company can Maximize Performance Tips

A young small company is able to take university graduates and immediately make them productive in industrial applications. The open, positive, and enabling culture fostered by management has recently elevated and accelerated employee knowledge by providing a means to gain key fundamentals and essential concepts.

Measurement Dynamics Recommendations Tips

The effects of measurement dynamics are similar to the effects of controller dynamics except there are often many more sources of lags and delays and the consequences are generally more severe. Delays are the result of transportation delays and discontinuous updates from periodic sampling and cycle times in digital signals,...

Effect of Measurement Dynamics Perspective Tips

The measurement provides the window into the process. Smart transmitters have made the view clearer. Installation and operating condition effects are compensated for allowing the transmitter to have an installed accuracy close to the sensor capability.

What Does a Car Collision Teach us about Process Control Tips

The use of the term "process dead time" can mislead us in terms of recognizing the many sources of dead time. Also we don't often take into effect the profound effect of the speed and the entry point of a disturbance into the process.