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Effects of a fully natural aging of MEMS accelerometers are evaluated with regard to changes in their performance. Two models of commercial dual-axis accelerometers (two pieces of ADXL 202E and 203 by Analog Devices Inc.) with analog outputs were tested over a period of about 10 and 4 years, respectively. A custom computer controlled test rig was used for performing relevant experimental studies, employing the gravitational acceleration as the reference source. A methodology of determining the proposed indicators of aging phenomena is presented and discussed. Changes of the offset voltage and the scale factor were observed and a way of evaluating the overall error due to combined influence of these two parameters is proposed. It was found out that the changes of the output voltage generated by the tested accelerometers were considerable, resulting in respective maximal errors of about 52 mg (2.6%) (ADXL 202E) or 20 mg (1%) (ADXL 203). Simple ways of reducing the effects of aging are proposed.

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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.

Abstract. The presented works concerned launching of an angular positioner powered by an electromagnetic actuator, designed for performing angular micromovements within a range of few microradians. The principle of operation is based on balancing the electromagnetic torque of the motor with a torque that is twisting a compliant element. As electrodynamic actuators have no distinguished controlled positions, therefore in typical positioning systems desired positions are obtained applying a closed-loop position control. Usually, such systems employ also a feedback (dumping) related to velocity of the moving elements, what simplifies forming of dynamics of the system. The design of the physical model employs a DC micromotor, whose rotor is coupled with a torsional torquemeter. A feedback signal is generated by resistive strain gauges. The paper presents a mathematical model of the positioning system, results of simulation study as well as results of experimental study. The simulation study indicates that it is possible to select such design features and such type of the micoromotor that a high dynamics of positioning is ensured.

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