P. Balda

Raspberry Pi and Arduino Boards in Control Education

Abstract Nowadays the control education usually heavily relies on the available simulation packages and virtual laboratories, both of which have their irreplaceable position in the educational process. But unfortunately the closed loop experiments are way too often limited to these virtual domains and the students lack the physical feedback about the impact of control algorithms and its parameters. The reasons might be the price of the hardware setup to demonstrate the control algorithms physically or a complicated transition from simulation to real-time platform. This paper describes an extremely inexpensive, straightforward and surprisingly powerful platform for implementation of real-time control algorithms. The platform consists of an Arduino board and a Raspberry Pi running the REX Control System. The Arduino board is used for interaction with the physical world via its inputs and outputs. The REX Control System allows the students to develop and verify the control algorithms in Simulink and then run it in real-time by a few mouse clicks. However, the REX Control System is by no means dependent on Simulink, it is fully functional even if Simulink license is not available. The platform further bridges the gap between the virtual and physical worlds as it is tightly connected to PIDlab.com and Contlab.eu portals, which makes it an ideal choice for control education purposes.

ADVANCED CONTROL ALGORITHMS + SIMULINK COMPATIBILITY + REAL-TIME OS = REX

Abstract This paper describes the structure and features of a new industrial control system called REX. During the system design, special attention was paid to the simulation facility of the control algorithms. The equivalent behavior of simulation and real-time control is guaranteed by a large function blocks library which is implemented for both Simulink and each target platform. REX is suitable for building real-time control systems of real, virtual and remote laboratories. REX does not utilize Real Time Workshop by The Mathworks.

Advanced PID Control Algorithms Built into the REX Control System

Abstract REX is an industrial control system which has been developed by the authors of this paper and by several their colleagues during the last decade. Control algorithms of REX are contained in a large function block library (block set). Controller blocks, including various PID controllers, cover a significant part of the library. This paper briefly explains main ideas of REX and it focuses on description of two advanced PID controller function blocks with built-in auto-tuning facilities. Both of these controllers use active identification experiment for the process identification, first of them uses a pulse experiment, second of them uses a relay experiment. After finishing of the identification experiment, the designed controller parameters are immediately computed in both cases. These controllers and some additional function blocks are presented in several examples demonstrating various control structures.

New tools for teaching vibration damping concepts: ContLab.eu

Abstract In last two decades, virtual laboratories help to teach students and train technicians in a broad range of engineering areas including automation and control. However, there is still a lack of laboratories that present more complex control schemes directly related to industrial problems. In this paper, new virtual laboratories presenting feedback and feedforward vibration damping techniques are described. Thanks to the automatic code generation, the presented algorithms are directly deployable to various real-time platforms suitable for teaching/training or professional industrial applications ranging from industrial PCs towards deep embedded boards like Raspberry Pi. The interactive tools are freely accessible at www.ContLab.eu . The authors believe that those virtual labs may be useful for both academic and industrial sphere.

Real-time simulator of component models based on Functional Mock-up Interface 2.0

This paper deals with a real-time simulator of component models. The simulator imports models compatible with Functional Mock-up Interface for Model Exchange and Co-Simulation 2.0 standard (FMI 2.0) which can be generated from various versions of Modelica (e.g. OpenModelica, Dymola, SimulationX) or from several other tools. The present version of the simulator works with FMI 2.0 Co-Simulation models in which the solver is a part of the exported executable model. The simulator is integrated into RexCore — the real-time control runtime, which allows to simulate the model itself, the model and the control algorithm on the same computer (Software in the Loop, SIL) and also the model on a single computer with physical inputs and outputs connected to outputs and inputs of the second computer for control (Hardware in the Loop, HIL).

Novel tools for model-based control system design based on FMI/FMU standard with application in energetics

The paper presents novel tools for model-based control system design based on FMI/FMU standard (Functional Mock-up Interface / Unit). It is focused on application of FMI standard for easy integration of control system development cycle starting with Model-in-the-Loop (MIL) simulation and finishing with Hardware-in-the-Loop (HIL) simulation. It is shown, how the Functional Mock-up Units (FMU) containing dynamic differential-algebraic equations of various parts of the device (mechanical, electrical, hydraulic, thermal, etc.) can be easily deployed to unified simulation environment where the control system is designed, consequently. The procedure allows to combine inputs from various Modelica-based tools at the process model side, utilizing power of Matlab/Simulink for design, analysis and optimization of control system and perform final test via HIL scenario where both the model and control system are simulated in real-time on separated HW units. The pros and cons of both FMI concepts, i.e. Co-Simulation and Model Exchange are discussed in detail. The whole procedure is demonstrated on a steam turbine example combining component-based and equation based modeling. Both the turbine model and the full control loop are validated in all phases of control system development. It is shown, that monolithic simulation block with proprietary solver reduces computational burden compared to automatic FMU concept.

Steam turbine hardware in the loop simulation

In this paper, a new tool for teaching purposes is presented. The tool is a low-cost Hardware in the Loop simulation with separated process model and control algorithm on standalone hardware which runs in real-time. In this paper, the simulation is used to control the steam turbine model with shaft and generator, but it can be used on wide range of complex physical models. The used model is evaluated on ramp-up simulation in Simulink, and after that mathematical equations are implemented in Modelica language and exported into Functional Mock-up Unit (FMU). The controlled and control models are both simulated on Raspberry Pi minicomputers in real-time and one can observe the control strategy on the second Raspberry with prepared control task and Human Machine Interface (HMI). Both Raspberries are connected through the Modbus over TCP/IP protocol and one can get familiar with this wide-used communication. Furthermore, there is possibility to control the system, change regulators parameters and handle the trade-off between various performances. Regulation can be operated in so-called island or grid mode. The aim of system control is to comply shaft speed demands described in norms.

eScop project physical layer development: INCAS conveyor line pilot case study

This article describes the development of software for control of factory floor production equipment which is developed in the eScop project (Embedded systems Service-based Control for Open manufacturing and Process automation). The software is running on a network of configurable embedded devices called RTUs (Remote Terminal/Telemetry Units) which are communicating with upper layers via RESTful web service interface. The overall development methodology including simulation using model based design technique (software in the loop) is demonstrated on the pilot conveyor system application in INCAS Group, Biella, Italy.

A new extensive source for web-based control education – ContLab.eu

Abstract In last two decades, virtual laboratories help to teach students and train technicians in a broad range of engineering areas including automation and control. However, there is still a lack of laboratories that present more complex control schemes directly related to industrial problems. This paper presents a new virtual laboratory portal ContLab.eu. It was born on the basis of popular PIDlab web where only the algorithms related to PID control are demonstrated. ContLab will cover broader range of automation topics, including vibration damping, motion control and robotics. A novel technique is being used to create each individual laboratory. The simulation core is designed in Matlab/Simulink and then automatically deployed into Java. Similarly, the core can be sent to real-time target for controlling real machine or plant. This ensures that all the three platforms (virtual lab, Matlab/Simulink and real-time target) behave exactly the same way including function block algorithms, parameters and their mutual signal connection. This paper describes several ContLab virtual laboratories which are related to PID control in particular (PID autotuners, Smith predictor, floating control, center seeking control, etc). The authors believe, that the laboratories will be useful for both industrial and academic sphere.

Control system design of robotic manipulator for testing of shifting system

The paper deals with robotic manipulator for automated testing of shifting system which was developed for automotive industry. Procedure of modelling and control design for hybrid force/position motion control as well as construction of the test stand and experimental results are presented. The proposed control structure with minimum set of feature-based parameters allows rapid online tuning in case of variable testing conditions even by an unskilled operator.