Neural network contour error prediction of a bi-axial linear motor positioning system

In the article a method of predicting contour error using artificial neural network for a bi-axial positioning system is presented. The machine consists of two linear stages with permanent magnet linear motors controlled by servo drives. The drives are controlled from a PC with real-time operating system via EtherCAT fieldbus. A randomly generated Non-Uniform Rational B-Spline (NURBS) trajectory is used to train offline a NARX-type artificial neural network for each axis. These networks allow prediction of following errors and contour errors of the motion trajectory. Experimental results are presented that validate the viability of the neural network based contour error prediction. The presented contour error predictor will be used in predictive control and velocity optimization algorithms of linear motor based CNC machines

Real-Time Jerk Limited Feedrate Profiling and Interpolation for Linear Motor Multiaxis Machines Using NURBS Toolpaths

In this article, a NURBS toolpath feedrate profile generation algorithm for a biaxial linear motor control system is presented. High achievable velocities and accelerations of linear motor machines present new computational challenges in implementing feedrate generation and toolpath interpolation algorithms in real-time controllers. The proposed algorithm is capable of online generation of the feedrate profile with axial acceleration and jerk constraints. Each stage of the feedrate profiling algorithm is described with attention being given to both performance and implementation aspects. Furthermore, an alternative to the commonly used Taylor series interpolation method is also tested to ensure minimal interpolation errors. The feedrate profiling and interpolation algorithms’ implementation in a PC-based controller with real-time Linux kernel is described. Experimental results are presented that confirm that the algorithm is capable of limiting acceleration and jerk in the machine’s axes and it is low computation time enables real-time on-line operation in a PC-based CNC controller

Neural Network Contour Error Predictor in CNC Control Systems

Paper presented as poster presentation at MMAR 2016 conference (Międzyzdroje,Poland, 29 Aug.-1 Sept. 2016)This article presents a method for predicting contour error using artificial neural networks. Contour error is defined as the minimum distance between actual position and reference toolpath and is commonly used to measure machining precision of Computerized Numerically Controlled (CNC) machine tools. Offline trained Nonlinear Autoregressive networks with exogenous inputs (NARX) are used to predict following error in each axis. These values and information about toolpath geometry obtained from the interpolator are then used to compute the contour error. The method used for effective off-line training of the dynamic recurrent NARX neural networks is presented. Tests are performed that verify the contour error prediction accuracy using a biaxial CNC machine in a real-time CNC control system. The presented neural network based contour error predictor was used in a predictive feedrate optimization algorithm with constrained contour error

PSO based feedrate optimization with contour error constraints for NURBS toolpaths

Paper presented at MMAR 2016 conference (Międzyzdroje, Poland, 29 Aug.-1 Sept. 2016)Generation of a time-optimal feedrate profile for CNC machines has received significant attention in recent years. Most methods focus on achieving maximum allowable feedrate with constrained axial acceleration and jerk without considering manufacturing precision. Manufacturing precision is often defined as contour error which is the distance between desired and actual toolpaths. This paper presents a method of determining the maximum feedrate for NURBS toolpaths while constraining velocity, acceleration, jerk and contour error. Contour error is predicted during optimization by using an artificial neural-network. Optimization is performed by Particle Swarm Optimization with Augmented Lagrangian constraint handling technique. Results of a time-optimal feedrate profile generated for an example toolpath are presented to illustrate the capabilities of the proposed method

CNC machine laboratory stand with H-Bot parallel kinematics using the EtherCAT bus

This paper presents an H-Bot kinematics machine control system. The H-Bot machine accuracy depends on the servo drives' synchronous operation and mechanical design. Therefore, the mechanical axes' movement quality is influenced by the communication bus and the ability to detect backlash and elasticity in the machine axes. EtherCAT – an industrial bus will be used for communication between the controller and other machine control system elements. Each mechanical axis at the H-Bot machine is equipped with a position measurementsystem. The laboratory stand was equipped with accelerometers. It is planned to perform research in the Predictive Maintenance and Trajectory Optimization field

Moduł komunikacyjny magistrali EtherCAT przeznaczony dla napędów elektrycznych

Badania zostały sfinansowane przez Zakład Energoelektroniki "TWERD" Sp. z o.o., w ramach grantu Voucher Badawczy województwa Kujawsko-Pomorskiego „Moduł komunikacyjny EtherCAT do inwerterów dla energetyki odnawialnej”W artykule przedstawiono moduł komunikacyjny magistrali EtherCAT przeznaczony dla napędów elektrycznych. Omówiono standard komunikacji EtherCAT wraz z opisem działania urządzenia podrzędnego wykorzysującego profil komunikacyjny CiA402. Omówiono budowę i działanie modułu komunikacyjnego. Przedstawiono opis stanowiska badawczego oraz badania weryfikujące poprawność działania opracowanego modułu

Stanowisko badawcze układów sterowania wieloosiowego napędami liniowymi poprzez magistralę EtherCAT

W artykule przedstawiono stanowisko badawcze przeznaczone do badania wieloosiowych układów sterowania z serwonapędami liniowymi. Stanowisko składa się z komputera pełniącego rolę sterownika nadrzędnego, serwosterowników oraz silników liniowych. Sterownik pracuje pod kontrolą systemu Linux z jądrem czasu rzeczywistego. Zaimplementowano również programowy stos EtherCAT do komunikacji z napędami. Przedstawiono budowę układu sterowania oraz strukturę oprogramowania sterownika. Przedstawiono również planowane badania, które będą realizowane na stanowisku dotyczące metod generacji optymalnych trajektorii ruchu, implementacji algorytmów regulacji położenia i prędkości w sterowniku oraz wpływu magistrali EtherCAT na jakość sterowania

Application of Ethernet Powerlink for communication in a Linux RTAI open CNC control system

In computerized numerical control (CNC) systems, the communication bus between the controller and axis servo drives must offer high bandwidth, noise immunity, and time determinism. More and more CNC systems use real-time Ethernet protocols such as Ethernet Powerlink (EPL). Many modern controllers are closed costly hardware-based solutions. In this paper, the implementation of EPL communication bus in a PC-based CNC system is presented. The CNC system includes a PC, a software CNC controller running under Linux Real-Time Application Interface real-time operating system and servo drives communicating via EPL. The EPL stack was implemented as a real-time kernel module. Due to software-only implementation, this system is a cost-effective solution for a broad range of applications in machine control. All software systems are based on GNU General Public License or Berkeley Software Distribution licenses. Necessary modifications to the EPL stack, Linux configurations, computer basic input/output system, and motherboard configurations were presented. Experimental results of EPL communication cycle jitter on three different PCs were presented. The results confirm good performance of the presented system

Układ sterowania CNC bazujący na komputerze PC z magistralą EtherCAT

W artykule przedstawiono układ sterowania numerycznego maszyn zbudowany na bazie komputera PC, komunikujący się z serwonapędami i układami wejścia/wyjścia sterującymi wyposażeniem maszyny poprzez magistralę komunikacyjną EtherCAT. W komputerze zaimplementowano system operacyjny czasu rzeczywistego Linux RTAI wraz ze zmodyfikowanym oprogramowaniem sterującym LinuxCNC. Opracowano programowy moduł komunikacyjny magistrali EtherCAT i zintegrowano go z oprogramowaniem LinuxCNC. Opracowany moduł EtherCAT umożliwia komunikację z serwonapędami zgodnie ze standardem CiA 402 oraz modułami wejść/wyjść zgodnie ze standardem CiA 401. Opracowany układ sterowania cechuje się prostą budową i łatwym montażem. Pozwala na bardzo szybką dwukierunkową komunikację z napędami i układami wejścia/wyjścia. Jest układem elastycznym, który można łatwo zaimplementować do sterowania maszynami wieloosiowymi o różnej konfiguracji

Implementation of extended cardiopulmonary resuscitation procedure in in-hospital cardiac arrest: a preliminary simulated study

INTRODUCTION: The survival rate of patients after in-hospital cardiac arrest (IHCA) is poor. The implementation of novel technologies to conventional cardio-pulmonary resuscitation (CPR) may improve clinical outcomes.   Aim: To evaluate efficacy of extended CPR (ECPR) performed by physicians in the simulated scenario of IHCA.   MATERIAL AND METHODS: High-fidelity simulations were performed in a simulation room equipped with a full spectrum of emergency devices. Earlier, the physicians (n = 60, five courses) participated in a threeday training in the use of extracorporeal techniques. Eventually, 12 participants were divided into 4-member teams that were involved in three stages (assessed in terms of duration and quality) of scenario such as 1. Advanced Life Support (ALS) activities; 2. preparation of the extracorporeal membrane oxygenation device (ECMO); 3. cannulation and activation of ECMO.   RESULTS: All teams completed successfully scenario within recommended time of 60 minutes (ranged from 33 min. 55 sec. to 37 min.) after IHCA. In details, decision to activate ECMO team was taken between 8 min. 45 sec. and 14 min. 15 sec of scenario, ECMO device prepared within 10 min. 5 sec. to 15 min. 30 sec. whereas peripheral vessels cannulated in 4 min. 14 sec. to 6 min. 10 sec. Of note, all evaluated times were the shortest for teams with decisive leaders.   CONCLUSIONS: Implementation of ECPR procedure is possible within recommended time after IHCA. It has also been shown that training with application of high-fidelity simulation techniques is of paramount importance in achievement and maintenance of ECPR skills, not only manual but also in effective communication