In order to obtain the inherent law of the structure and performance of the SMA actuator of the bionic flexible dexterous hand. Four phase transition temperature parameters of SMA wire were obtained by temperature test. The Brinson constitutive model was used to describe the material relationship of SMA. The finite element model of SMA mechanical properties was established by user material subroutine (UMAT). The validity of the secondary development was verified by comparing the results with the literature. Based on this, the parametric finite element modeling and simulation of SMA actuator were carried out, and the influencing factors of mechanical properties of SMA actuator were analyzed. The results show that the SMA wire diameter of the dexterous hand actuator has a great influence on the performance of the actuator, while the structural parameters such as the winding spacing and the actuator diameter have little effect on the driving performance of the SMA wire. The pre-stretching force and output force of the actuator increase with the increase of the diameter of the SMA wire. The research results provide a reference for the design of related SMA actuators.
Continuously Operating Reference Station (CORS) is an integrated service system constructed based on multi-base station network Real Time Kinematic (RTK) technology. CORS system is composed of several fixed and continuously operating GNSS reference stations which form a network automatically providing different types of GNSS observations such as carrier phase and pseudorange, various correction numbers, status information and other GNSS services through computers, data communication and Internet (LAN/WAN) technology. This article selects an appropriate location and sets up a reference station to receive Beidou, GPS, GLONASS satellite data basing on CORS system, establishes an All-Terrain inspection field, designs a set of mobile positioning terminals, and develops a set of real time inspection software for the calibration of navigation products. Experimental verification results shows that the calibration system designed by this article is applicable to calibrate navigation products and worthy of extensive promotion.
The article studies the key technical parameters such as "horizontal position deviation", "distance-counting error", "velocity measurement error", and "time-counting error" of intelligent service terminal of cruising taxi, and determines the appropriate standards for the calibration of the parameters The novel calibration procedure presented in this article has been performed on several typical types of intelligent service terminals of cruising taxis widely used in China. The experimental and the uncertainty analysis results show that the calibration method presented in this article can be adopted for the periodic calibration of the intelligent service terminal of cruising taxi, in order to establish the metrological traceability system of the instrument.
In this paper, an automated edge detection model is developed for large irregular circular using a laser scanning approach. Some key influencing factors, just like surface quality, surface orientation and scan depth, have been respectively considered in this model. By consider of the limited of field of view and corresponding optical constraints, only a small part of key region is effectively captured by laser scanner at a specific posture. In term of specified view angles of laser scanner, the position of laser scanner approximate to the stand-off distance with respect to edge area can be determined and then high-quality point clouds of large irregular circular edge feature can be effectively obtained. Finally, a series of experiments are performed on workpieces with different large irregular circular features. The experimental result shows our method features high automation and high efficiency. Those results are most promising for on-machine applications in dimensional measurement of large-scale workpiece.
In order to meet high quality measurement requirements with less cost and lesser time consumption, the sampling strategy has to be planned before the measuring device is already available. In this paper, a common 3D geometric measuring system based on laser scanning technique is presented. An measurement cost model is established by consider of several cost sources in 3D geometric measurement process. In terms of view angle of laser scanner, an optimal inspection strategy planning is developed on a circular feature too. Finally, a series of experiments on typical circular of workpieces are performed based on coordinate measuring system equipped with a laser line scanner. In case of desired measurement accuracy for the measured feature, the minimum inspection cost can be obtained by the iterative optimization algorithm, thus generating a reliable and an efficient sampling path planning. Those results are most promising for on-machine applications in optimal inspection strategy of 3D geometric of workpiece.
Nowadays, with 3D topographic features increasingly complicated and complex, scanning probe microscopes have widely been used of nano-scale dimensional measurement in the semiconductor manufacturing and space industry, which can create three-dimensional data over almost all solids in a wide range of ambient. Although scanning probe microscopes readily achieve nanometer level resolution images of measured surfaces, there are several aspects of their behavior that can cause them to yield large measurement errors. In this paper, according to possible traceability pathways for calibration of lateral axes and z axis, both pitch and step height measurements are respectively performed and axis error self-correction model is proposed. The influence of thermal stability on drift error is also discussed. Experimental results show that our method will be helpful for a fast performance evaluation test for scanning probe microscope.
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