PIDMA - PID controller with Moment Autotuner

The source files illustrating the use of a PID controller with Moment Autotuner in the REXYGEN Control System are located in this folder.

The block PIDMA extends the control function of the standard PID controller by the built in autotuning feature. Before start of the autotuner the operator have to reach the steady state of the process at a suitable working point (in manual or automatic mode) and specify the required type of the controller ittype (PI or PID) and other tuning parameters (iainf, DGC, tdg, tn, amp, dy and ispeed). The identification experiment is started by the input TUNE (input TBRK finishes the experiment). In this mode (TBSY = on), first of all the noise and possible drift gradient (DGC = on) are estimated during the user specified time (tdg+tn) and then the rectangle pulse is applied to the input of the process and the first three process moments are identified from the pulse response. The amplitude of the pulse is set by the parameter amp. The pulse is finished when the process variable pv deviates from the steady value more than the dy threshold defines. The threshold is an absolute difference, therefore it is always a positive value. The duration of the tuning experiment depends on the dynamic behavior of the process. The remaining time to the end of the tuning is provided by the output trem.

The controlled system is simulated by the pid_autotuning_process task. Replace it with I/O flags for real-world applications.

The signals are recorded in the TRND_PIDMA block which allows displaying of the trends (graphs) in the Watch mode of REXYGEN Studio or in the REXYGEN Diagnostics diagnostic tool.

Timing of the project

The algorithm runs each 100 milliseconds (0.1 s). See the EXEC function block,
tick x ntick0 = 0.05 x 2 = 0.1

Prerequisites

• REXYGEN Runtime Core must be installed and running on the target device.
• License for advanced blocks library must be installed.

Running the example

• The *exec.mdl file is the project main file.
• Open it with REXYGEN Studio, compile and download it to the target device.
• Switch to Watch mode and observe the algorithm.
• Select the PIDMA block and enable online monitoring (Target->Watch Selection).
• Check that the CNB_MAN is off, try the automatic control with CNR_sp function block and watch the responses of the system with trends in REXYGEN Diagnostics.
• After reaching the steady state of the process, tick the BSTATE parameter of the MP_TUNE to switch on the autotuning experiment.
• When the experiment is done, PIDMA:ite parameter is 0 and pk, pti, ptd,... parameters are set to optimal values.
• Try again the automatic control with CNR_sp.

User interface (HMI)

The example is accompanied by a HTML5-based user interface built on the WebBuDi framework (Web Buttons and Displays). There is also a WebWatch HMI generated directly from REXYGEN Studio.

Documentation

• Press F1 for help on the selected function block in the REXYGEN Studio.
• PIDMA function block documentation
• REXYGEN HMI User Guide
• Function blocks of REXYGEN
• REXYGEN Studio User Guide
• Complete documentation of REXYGEN

Additional information

• Visit the REXYGEN webpage for more information about the example projects and developing advanced automation and control solutions using REXYGEN.