The controllers in Hysopt take inputs, coming from constants, sensors or the output from other controllers/operators and use either the PI algorithm or a self-defined algorithm to make computations.

The PI-algorithm

the Proportional-Integral (PI) controller computes and transmits a controller output signal every timestep to the component (e.g., valve). The computed output from the PI algorithm is influenced by the controller tuning parameters and the controller error. For more info about the PI algorithm itself, please visit https://controlguru.com/integral-action-and-pi-control/.

The controller is defined through multiple parameters:

• Proportional band: The value of the proportional band determines how fast the system responds, whereas the value of the integral gain determines how fast the steady-state error is eliminated. When the value of these gains is larger, the control performance is better. However, large gains may lead to an oscillatory response and result in an unstable system.
• Repeat time: Provides a separate weight to the integral term of the PI algorithm, so the influence of integral action can be independently adjusted. It is in the denominator so smaller values provide a larger weight to (i.e. increase the influence of) the integral term. It had units of time so it is always positive. Warning; the proportional band and repeat time interact with each other and their influence must be balanced by the designer.
• Control delay: Inserts a delay time on the valve actuation, which may prove useful to remove quick oscillation, but also may lead to larger overshoot.

Available controllers

• Positive/negative PI controllers
• Positive/negative modulating room controllers
• Positive/negative on/off room controllers
• Thermostatic room controller
• Programmable controller