Silvano Balemi

Rapid controller prototyping with Matlab/Simulink and Linux

Abstract This paper presents a Rapid Controller Prototyping System based on Matlab, Simulink and the Real-Time-Workshop toolbox. Executable code is automatically generated for Linux RTAI, a hard real-time extension of the Linux Operating System. The generated code runs as a normal user space hard real-time application on a standard personal computer with the RTAI extension of the Linux Operating System. This environment can be used to quickly implement real-time controllers. Moreover, standard hardware allows the use of rapid prototyping techniques not only during development activities but also during system operation. A didactic and an industrial application are presented which demonstrate the capabilities and the performance of the environment.

Scilab/Scicos and Linux RTAI - a unified approach

This paper presents a rapid controller prototyping environment completely based on open source software. GNU/Linux with the RTAI extension is used as a hard real-time operating system. The Scilab/Scicos suite permits performance of all phases of the control system design. A modified Scicos code generator directly generates the C-code for the Linux RTAI environment. Finally, the generated hard real-time task runs as a user space application on a standard PC using the COMEDI drivers to interface with the real plant. A GUI application facilitates the user to interact with the running real-time task (data visualization, data collection, parameters tuning) directly from any PC in the network. All needed software is available on the Web and can be freely downloaded. Some applications are presented to demonstrate the potentialities of the presented suite

Automatic calibration of sinusoidal encoder signals

Abstract Precision positioning and manipulation systems often rely on data from sensors delivering a sinusoidal signal pair. These signals can be interpolated to provide a high resolution measurement. The paper presents a novel method for removing signal differences and drifts by automatic self-calibrating the sinusoidal signal pair. Then, manual calibration is avoided and slow varying effects, like thermal drifts or imprecise sensor mounting, can be effectively compensated. The proposed method can be implemented on a DSP. It uses an on-line gradient search to minimize a given performance index.

ZIMPOL-3: a powerful solar polarimeter

The area of high precision solar spectropolarimetry has made great advances in recent years and the Zurich IMaging POLarimeter (ZIMPOL) systems have played a major role in that. ZIMPOL reaches a polarimetric accuracy of 10-5 by using fast (kHz) polarization modulation/demodulation of the light beam in combination with large-area array detectors. A new generation of improved cameras (ZIMPOL-3) are being implemented for the scientific observations at the solar observatory at Istituto Ricerche Solari Locarno. The new system is based on a flexible and compact modular design, which easily adapts to new applications. A faster electronics and new sensors with higher quantum efficency compared to the previous ZIMPOL versions, allow to achieve a better overall efficency. Future plans include observing campaigns at foremost large telescopes and the exploration of new technologies (e.g. CMOS).

Rapid Controller Prototyping with Matlab/Simulink and Linux

This paper presents a Rapid Controller Prototyping System based on Matlab, Simulink and the Real-Time-Workshop toolbox. Executable code is automatically generated for Linux RTAI, a hard real-time extension of the Linux Operating System. The generated code runs as a normal user space hard real-time application on a standard personal computer with the RTAI extension of the Linux Operating System. This environment can be used to quickly implement real-time controllers. Moreover, standard hardware allows the use of rapid prototyping techniques not only during development activities but also during system operation. A didactic and an industrial application are presented which demonstrate the capabilities and the performance of the environment.

Free open source software in control engineering education: A case study in the analysis and control design of a rotary inverted pendulum

The present paper aims to show the advantages of using Free and Open Source Software for control systems in education. Accordingly, this paper presents a control assignment for an introductory control theory course that can be done entirely with FOSS. This assignment consists of the control of a rotary inverted pendulum.

CAN-bus based rapid control prototyping system for education laboratories

The central element of the educational activities in mechatronics at SUPSI is the mechatronics laboratory, where students integrate the topics introduced by various courses. In order to increase the value of the laboratory to students and to reduce the cost of its creation and operation, a modular approach has been implemented, which relies on sensors and actuators communicating through the CAN bus as a standard communication protocol. A library of interfaces for many CAN capable devices has been implemented both for Matlab/Simulink and for Scilab/Scicos. Rapid control prototyping techniques can be used to generate code for existing applications or to build new applications based on available devices. Additional devices can also be easily added thanks to a 4-tier design of the interfaces.

High-bandwidth three-phase phase-locked loop

Phase-locked loops (PLLs) generate sinusoidal signals in phase with periodic reference signals.

Adaptive optics system for the IRSOL solar observatory

We present a low cost adaptive optics system developed for the solar observatory at Istituto Ricerche Solari Locarno (IRSOL), Switzerland. The Shack-Hartmann Wavefront Sensor is based on a Dalsa CCD camera with 256 pixels × 256 pixels working at 1kHz. The wavefront compensation is obtained by a deformable mirror with 37 actuators and a Tip-Tilt mirror. A real time control software has been developed on a RTAI-Linux PC. Scicos/Scilab based software has been realized for an online analysis of the system behavior. The software is completely open source.

Partial-order reduction of observers for linear systems

Full-state observers for linear systems use available measurements for the estimation of the entire state of a system. Reduced-order observers instead deliver an estimate only in the unmeasured state subspace while the state values in the measured subspace are taken directly from the measurements. This paper presents a combination of both types of observers which directly uses only part of the measured subspace and estimates/filters the rest of the state space. The order of this new observer is freely selectable between that of the full-state observer and of the reduced-order observer. A practical example demonstrates the validity of the new observer form. The results show that the performance of a state-feedback controller with the new observer is similar to that with the full-state observer.