Leszek Trybus

CPDev Engineering Environment for Modeling, Implementation, Testing, and Visualization of Control Software

The paper presents the CPDev engineering environment, which is a comprehensive set of integrated tools for programming PLCs, PACs, and DCSs, according to the IEC 61131-3 standard. The environment supports various parts of the project development, including modeling (using SysML diagrams), implementation (with IEC 61131-3 textual, graphical, and mixed languages), testing (by textual, table, and performance tests), simulation (in off-line mode), debugging (with tracing variable values and breakpoints), hardware resources configuration, execution (either on the virtual machine or FPGA-based hardware machine), as well as visualization. The CPDev project is designed in a way supporting portability. Therefore, prepared control programs can be run on any supported target platform, such as AVR, ARM, and x86. The environment has a few applications, both industrial and laboratory.

Tuning Rules of Conventional and Advanced Ship Autopilot Controllers

Ship autopilots are divided into conventional, capable of keeping desired course, and advanced which can track the path connecting waypoints on the route. The paper presents tuning rules for PID controller of conventional autopilot and for PI or state-space controller of advanced one. Single design parameters determining closed-loop dynamics are specified for each of them. The rules are implemented in software of autopilot prototype developed jointly with a Dutch company.

CPDev engineering environment for control programming

Programming a control example by CPDev tool using LD, FBD, and SFC graphical languages of IEC 61131-3 standard is presented. Another example demonstrates the use of data structures and arrays of function blocks in ST textual language. The two parts indicate that CPDev provides now essential functionalities specified in the standard. Remarks how the tool relates to established engineering environments such as CoDeSys, STEP 7, Control Builder F, and ISaGRAF are also given.

IEC structured text programming of a small Distributed Control System

A prototype environment called CPDev for programming small distributed control-and-measurement systems in Structured Text (ST) language of IEC 61131-3 standard is presented. The environment consists of a compiler, simulator and configurer of hardware resources, including communications. Programming a mini-DCS (Distributed Control System) from LUMEL Zielona Gora is the first application of CPDev.

Exploiting a Graphical Programming Paradigm to Facilitate Rigorous Verification of Embedded Software

A computing architecture enabling economical safety licensing of software embedded in safety-critical technical systems is defined. The architecture relies on mature methods and technology only. In particular, it includes a highly ergonomic but rigorous validation method, called diverse back translation. For safety-related program controlled electronic systems, safety licensing of software is extremely critical, since it is far from being as dependable as hardware. The presented approach deviates from classical construction and validation techniques by enforcing the re-use of pre-engineered and verified off-the-shelf application-oriented standard software function modules and by employing a graphical programming paradigm.

Adaptive Tuning of PID Controller Using Template Surfaces

Abstract Adaptive tuning method used in a РID industrial controller is described. The purpose is generally similar as in the well-known Foxboro EXACT algorithm, i.e. find the settings which yield transients having prescribed overshoot and short settling time. Method employed here may be called “walk on template surfaces”. The surfaces are overshoot and frequency functions of controller settings. They have been obtained by Matlab simulations from a template plant (inertia with delay) and found suitable for typical industrial processes.

Adaptive Control Algorithm of the RF-537 Controller

Abstract Adaptive algorithm employed in the RF-537 industrial controller is presented. Objective is the same as in well-known Foxboro EXACT algorithm, i.e. by analyzing disturbance oscillatory responses, find the settings which yield specified damping and overshoot, simultaneously minimizing settling time. The algorithm gradually increases controller sensitivity proceeding along the line of constant damping. Root locus and simplex-like method are used.

A PID INSTRUMENT WITH SELF-TUNING

Abstract A self-tuning algorithm for PID controllers that allows to specify closed-loop reference and disturbance responses is described. The algorithm consists of two phases, pretune and fine-tune , imitating the trials of field engineers who perform manual tuning. The first phase involves relay-generated oscillations, the latter one or two load disturbance rectangular pulse responses. Frequency, root-locus, and least-squares method are employed. The algorithm is implemented in RF-537 general purpose PlO control instrument.

Root-locus Design of PID Controller for an Unstable Plant

Unstable plant considered in the paper consists of an integrator and 1st order component with positive pole. PID controller is used, so the feedback system becomes of 3rd order. Root-locus design method is applied which for such system gives analytic expressions for controller settings. If weak control action is required, the design provides better responses than conventional one. Unstable ships, particularly oil tankers, require weak control.

LD Graphic Editor Implemented in CPDev Engineering Environment

Process of creating a diagram in LD graphical language in CPDev environment, translation to ST textual program, compilation into VMASM executable code and, finally, simulation is overviewed by means of typical example. Earlier version of CPDev LD editor did not suit industrial applications, particularly with respect to processing other variables than boolean. Basic functionalities of LD in CPDev are now not far apart from those of renown CODESYS package.