Wybrane problemy zadawania obciążenia w trakcie badań silników bezszczotkowych o dużych prędkościach obrotowych

Following paper presents some considerations about modern small high-speed permanent magnet brushless direct current motors and possibilities of testing their mechanical characteristics. Usage of eddy current brake is described as well as a testbed and an experiment. Measured characteristic of tested motor is shown with some remarks about usage and design of eddy current brake intended to work with speed up to 50000 rpm.Artykuł przestawia rozważania dotyczące możliwości badania charakterystyk miniaturowych silników bezszczotkowych. Przeanalizowano możliwości zadawania obciążenia w czasie takich badań. Analizy te doprowadziły do zaprojektowania stanowiska testowego wykorzystującego hamulec wiroprądowy z magnesami trwałymi. Wyniki badań ilustrują przykładowe charakterystyki jednego z badanych silników. W podsumowaniu podano spostrzeżenia i wnioski na temat wykorzystania hamulców wiroprądowych z magnesami trwałymi do badania silników o prędkościach obrotowych do 50000 obr/min

Methods and devices for measurement of dynamic characteristics of stepping motors

W artykule przedstawiono modułowy system do wyznaczania charakterystyk częstotliwościowych silników skokowych. Pomiar momentu może być prowadzony bezpośrednio "na wałku" silnika (momentomierzem obrotowym serii OPM lub poprzez pomiar reakcji stojana (momentomierzem dynamometrycznym z piezoelektrycznym czujnikiem siły. Oprócz badań konkretnych silników i sterowników stanowisko umożliwiło weryfikację metod badawczych i doskonalenie opisu formalnego mikromaszyn i procedur sterowania.The paper presents a modular test system designed in the Division of Fine Mechanics Design - the Institute of Micromechanics and Photonics, intended for setting frequency depended characteristic curves of a stepper motors. There is a possibility of measurement of two kinds of characteristics (pull-in and pull-out), both according to two different methods (see Fig. 1). During determination of characteristics the torque metering can be taken directly from a motor shaft with use of optoelectronic OPM series rotary torque meters or it can be processed also as a stator reaction force measurement made with use of a dynamometric torque meter equipped with a piezoelectric force transducer. Figs. 2-5 present possible configurations of a test bed and a set of transducers. The photo of the selected configuration is shown in Fig. 6 and view of the electronic module in Fig.7. Control and measurements can be made by a data acquisition card installed in a personal computer. The tested motor can be driven in full-, half- and micro-step modes, depending on its own driver. The main window of a control program (see Fig .8) allows a user to select the desired test method and its parameters. Algorithms of the test bed working modes are shown in a synthetic way in Figs. 9 and 10 (for pull-in curve). The experiments results, despite its utilitarian use (tests of particular motors), can be applied to scientific research - comparison of different methods for determination of characteristics. The exemplary results are presented in Figs. 11-13

Shifted axis angular positioning mechanisms – unconventional use of exact constraint design

Paper presents some remarks about designing angular positioners having significant angular displacement and shifted axis of rotation. Those driving mechanism are useful in specific applications where mechanism wraps around other object or there is a need of rotation around virtual axis. Examples of those applications like orthotic robots or gimbals for panoramic motions where developed at Faculty of Mechatronics WUT. Usage of exact constraint method was described including its influence to a kinematic structure of designed mechanism

Shifted axis angular positioning mechanisms – unconventional use of exact constraint design

Paper presents some remarks about designing angular positioners having significant angular displacement and shifted axis of rotation. Those driving mechanism are useful in specific applications where mechanism wraps around other object or there is a need of rotation around virtual axis. Examples of those applications like orthotic robots or gimbals for panoramic motions where developed at Faculty of Mechatronics WUT. Usage of exact constraint method was described including its influence to a kinematic structure of designed mechanism

Shifted axis angular positioning mechanisms – unconventional use of exact constraint design

Paper presents some remarks about designing angular positioners having significant angular displacement and shifted axis of rotation. Those driving mechanism are useful in specific applications where mechanism wraps around other object or there is a need of rotation around virtual axis. Examples of those applications like orthotic robots or gimbals for panoramic motions where developed at Faculty of Mechatronics WUT. Usage of exact constraint method was described including its influence to a kinematic structure of designed mechanism

Flexible grippers for industrial robots – comparison of features of low-cost 3D printed component

The aim of presented work was to analyse the feasibility of using 3D-print technology in robotics based on the production of industrial robot flexible grippers. For selected geometry of gripper single finger available 3D printing techniques has been analysed. The study made by authors uses the following additive technologies and devices: SLS (Selective laser Sintering) and FDM (Fused deposition modelling). As a prior an analyses of capabilities of individual technologies were done by testing the quality of the 3D CAD model recreated on test print-outs. Based on the printed gripper, its functionality, and strength properties were examined. Strength of grapplers was tested with a use of an MTS test machine under repeating deflexion simulating standard operational cycle of a gripper. Test proved that at least few thousands of cycle are possible to be made by a 3D printed gripper. What interesting gripper made with use of the less advanced printer showed different wear behaviour than an one made on the more advanced. First one showed almost instantaneous start of slow and constant strength degradation while the second one proved to have a stable deflexional capability by almost twice an number of cycles. More isotropic structure of an SLS printed gripper caused the best results of all tested ones

Flexible grippers for industrial robots – comparison of features of low-cost 3D printed component

The aim of presented work was to analyse the feasibility of using 3D-print technology in robotics based on the production of industrial robot flexible grippers. For selected geometry of gripper single finger available 3D printing techniques has been analysed. The study made by authors uses the following additive technologies and devices: SLS (Selective laser Sintering) and FDM (Fused deposition modelling). As a prior an analyses of capabilities of individual technologies were done by testing the quality of the 3D CAD model recreated on test print-outs. Based on the printed gripper, its functionality, and strength properties were examined. Strength of grapplers was tested with a use of an MTS test machine under repeating deflexion simulating standard operational cycle of a gripper. Test proved that at least few thousands of cycle are possible to be made by a 3D printed gripper. What interesting gripper made with use of the less advanced printer showed different wear behaviour than an one made on the more advanced. First one showed almost instantaneous start of slow and constant strength degradation while the second one proved to have a stable deflexional capability by almost twice an number of cycles. More isotropic structure of an SLS printed gripper caused the best results of all tested ones

Modelling of mechatronic devices supported by 3D engineering software

Modelling is considered to be an inherent part of design process of mechatronic devices and systems, in particular when solving problems of dynamics and accuracy of actuators and sensors. Mathematical software packages such as Matlab/Simulink are commonly used for this purpose. Engineers and designers who integrate mechanical components of devices under design, usually employ special computer software known as 3D CAD for creating three dimensional images. Typically it is used to generate technical drawings and layouts but its usability is more extensive. The paper presents ability of such software to support simulation where a linear stepping actuator is an example of a device under design