Zhaojun Yang

Bio: Zhaojun Yang is an academic researcher from Jilin University. The author has contributed to research in topics: Reliability (statistics) & Machine tool. The author has an hindex of 12, co-authored 101 publications receiving 506 citations. Previous affiliations of Zhaojun Yang include Chinese Ministry of Education.

A novel driving principle by means of the parasitic motion of the microgripper and its preliminary application in the design of the linear actuator.

Abstract: This paper presents a novel driving principle by means of the parasitic motion of the microgripper. Actuators based on this principle can realize the large displacement range and high speed easily. Also the structure can be simple. A parasitic motion principle linear actuator mainly consisting of two piezoelectric stacks, two microgrippers and a mover was designed. Experimental results indicate that at a low driving frequency of 5 Hz, large velocity over 40 μm/s is obtained with the driving voltage of 100 V. Backward motion was observed and analyzed. Experimental results verify the feasibility of the new principle and it can be used to design new linear or rotary actuators.

New domain adaptation method in shallow and deep layers of the CNN for bearing fault diagnosis under different working conditions

Abstract: Deep learning models are widely used in fault diagnosis to learn hierarchical representations from collected signals. However, most of the models depend considerably on the assumption that training (source domain) and test (target domain) data sets are from the same feature distribution. This assumption is difficult to meet in practical scenarios of industrial applications because the working conditions of rotating machinery change with different machining tasks and labelled data with fault information are difficult and expensive to collect. Therefore, a novel fault diagnosis method, called multilayer adaptation convolutional neural network (MACNN), is constructed to solve the above-mentioned problems. The method regards raw temporal signals as input and uses wide kernels following a multiscale convolutional module to capture low-frequency features at multiple scales in shallow layers. Then, small convolutional kernels are used to implement multilayer nonlinear mapping in deep layers. Adaptive batch normalisation and multi-kernel maximum mean discrepancy are combined to reduce the feature distribution discrepancy in shallow and deep layers of the model, respectively, which improves the domain adaptation capability of the model. The proposed method is validated through 12 fault diagnosis experiments. The average 99.21% diagnosis precision demonstrates the reliability and stability of the method under different working loads.

Experimental research on a modular miniaturization nanoindentation device.

Abstract: Nanoindentation technology is developing toward the in situ test which requires miniaturization of indentation instruments. This paper presents a miniaturization nanoindentation device based on the modular idea. It mainly consists of macro-adjusting mechanism, x-y precise positioning platform, z axis precise driving unit, and the load-depth measuring unit. The device can be assembled with different forms and has minimum dimensions of 200 mm × 135 mm × 200 mm. The load resolution is about 0.1 mN and the displacement resolution is about 10 nm. A new calibration method named the reference-mapping method is proposed to calibrate the developed device. Output performance tests and indentation experiments indicate the feasibility of the developed device and calibration method. This paper gives an example that combining piezoelectric actuators with flexure hinge to realize nanoindentation tests. Integrating a smaller displacement sensor, a more compact nanoindentation device can be designed in the future.

A new failure mode and effects analysis model of CNC machine tool using fuzzy theory

Abstract: Failure mode analysis is important in CNC machine tool. In order to assess the failure mode of CNC machine tool, this paper described a new fuzzy FMEA model integrating with fuzzy linguistic scale method. The model proposed a risk-space diagram to explicit the relationship of S,O and D. On the basis of the risk-space diagram, risk priority number is calculated by weighted Euclidean Distance formula and centroid defuzzification based on Alpha-level. This study is used to analysis a type of CNC lathe. Compared with the criticality ranking about another similar type of CNC lathe, the risk ranking of FMEA model revealed that the method is basically same with the actual situation. The results indicated that the fuzzy FMEA used in CNC lathe is a reasonable method corresponding to the manufacturing, and it is a validity foundation for constructing reliability design model or supporting control plan of manufacturing.

Model based processing of signals : a state space approach. Prolog

Abstract: This paper is a tutorial on linear, state space, model-based methods for certain nonlinear estimation problems commonly encountered in signal and data analysis. A prototypical problem that is studied is that of estimating the frequencies of multiple, superimposed sinusoids from a short record of noise-corrupted data. The approach expounded however, is applicable to a vast range of nonlinear signal analysis problems and applications in direction finding and damped sinusoid retrieval are dealt with in some detail. The benefits that result from using a state space description of the signal are highlighted in this paper. It is shown that state space models provide an elegant tool for exposing the structure present in the problem. The approach also allows for robust parameterization of the model with respect to finite precision errors. The robustness of the parameter set is complemented by the availability of numerically robust tools to estimate the parameters. The resulting algorithms are compatible with multiprocessor implementations. >

Stepping piezoelectric actuators with large working stroke for nano-positioning systems: A review

Abstract: Precision positioning systems with large working stroke (millimeter or more) and micro/nano-scale positioning resolution are widely required in both scientific research and industries. For this kind of applications, piezoelectric materials based actuators show unique advantages and have been widely employed. To overcome the demerit of the limited working stroke for single piezoelectric element, various stepping motion principles have been proposed in the past years, and accordingly, stepping piezoelectric actuators with various structures have been designed and evaluated. This review is aimed to summarize the recent developments and achievements in stepping piezoelectric actuators with large working stroke. Especially, the emphasis is on three main types of stepping piezoelectric actuators, i.e., inchworm type, friction-inertia type, and parasitic type. The motion principles of these three types of piezoelectric actuators and the corresponding developments of various actuators are discussed respectively, followed by pointing out the existing problems in these three types of piezoelectric actuators and proposing some potential research directions in this topic. It is expected that this review is helpful for relevant researchers to understand stepping motion principles as well as piezoelectric actuators, and to successfully select and design stepping piezoelectric actuators for specific applications.

A Novel Trapezoid-Type Stick–Slip Piezoelectric Linear Actuator Using Right Circular Flexure Hinge Mechanism

Abstract: A trapezoid-type stick–slip piezoelectric linear actuator using a right circular flexure hinge mechanism was proposed, designed, fabricated, and tested with the aim of accomplishing linear driving based on stick–slip motion. The angle adjustment of the trapezoid beam was used for generating lateral motion on the driving foot of the flexure hinge mechanism. A method of tuning the lateral motion of the flexure hinge mechanism was discussed. Based on the finite-element method, a proper angle of the trapezoid beam was obtained. The analysis results proved that asymmetrical flexure hinge mechanism can increase static friction force in slow extension stage and decrease kinetic friction force in quick contraction stage by lateral motion of the driving foot. A prototype was fabricated and its experimental system was established. The mechanical output experiments showed that the prototype achieved maximum output velocity and load of 5.96 mm/s and 3 N at a voltage of 100 V $p-p$ and a frequency of 500 Hz, respectively.

Design and Control of a Compliant Microgripper With a Large Amplification Ratio for High-Speed Micro Manipulation

Abstract: The design and control of a novel piezoelectric actuated compliant microgripper is studied in this paper to achieve fast, precise, and robust micro grasping operations. First, the microgripper mechanism was designed to get a large jaw motion stroke. A three-stage flexure-based amplification composed of the homothetic bridge and leverage mechanisms was developed and the key structure parameters were optimized. The microgripper was manufactured using the wire electro discharge machining technique. Finite element analysis and experimental tests were carried out to examine the performance of the microgripper mechanism. The results show that the developed microgripper has a large amplification factor of 22.6. Dynamic modeling was conducted using experimental system identification, and the displacement and force transfer functions were obtained. The position/force switching control strategy was utilized to realize both precision position tracking and force regulation. The controller composed of an incremental proportional-integral-derivative control and a discrete sliding mode control with exponential reaching law was designed based on the dynamic models. Experiments were performed to investigate the control performance during micro grasping process, and the results show that the developed compliant microgripper exhibits good performance, and fast and robust grasping operations can be realized using the developed microgripper and controller.