Yinghui P.,Tianjin University of Technology and Education
Proceedings of 2016 IEEE Advanced Information Management, Communicates, Electronic and Automation Control Conference, IMCEC 2016 | Year: 2016
This project for vocational skills certification examination in different professions, different types and different levels has developed vocational skills certification exam management system. Using Ant colony optimization (ACO) algorithm intelligently make skills identification papers has solved the multi-objective problem; so determine vocational skills certification examination test of the different professions, different types, different levels of difficulty with normal distribution, meet different groups requirements of vocational skills certification examination. © 2016 IEEE.
Li K.,Tianjin University of Technology and Education
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2017
The compatibility problem between rapidity and overshooting in the traditional predictive current control structure is inevitable and difficult to solve by reason of using PI controller. A novel predictive current control (PCC) algorithm for permanent magnet synchronous motor (PMSM) based on linear active disturbance rejection control (LADRC) is presented in this paper. In order to displace PI controller, the LADRC strategy which consisted of linear state error feedback (LSEF) control algorithm and linear extended state observer (LESO), is designed based on the mathematic model of PMSM. The purpose of LSEF is to make sure fast response to load mutation and system uncertainties, and LESO is designed to estimate the uncertain disturbances. The principal structures of the proposed system are speed outer loop based on LADRC and current inner loop based on predictive current control. Especially, the instruction value of qaxis current in inner loop is derived from the control quantity which is designed in speed outer loop. The simulation is carried out in Matlab/Simulink software, and the results illustrate that the dynamic and static performances of proposed system are satisfied. Moreover the robust against model parameters mismatch is enhanced obviously. © 2017 SPIE.
Xu L.-X.,Tianjin University of Technology and Education |
Li Y.-G.,Tianjin University of Technology and Education
Robotics and Computer-Integrated Manufacturing | Year: 2014
In this study, the effects of joint clearance on the dynamic performance of a planar 2-DOF pick-and-place parallel manipulator are investigated. The parallel manipulator is modeled by multi-body system dynamics. The contact effect in revolute joints with clearance is established by using a continuous analysis approach that is combined with a contact force model considering hysteretic damping. The evaluation of the contact force is based on Hertzian contact theory that accounts for the geometrical and material properties of the contacting bodies. Furthermore, the incorporation of the friction effect in clearance joints is performed using a modified Coulomb friction model. By numerical simulation, variations of the clearance joint's eccentric trajectory, the joint reaction force, the input torque, the acceleration, and trajectory of the end-effector are used to illustrate the dynamic behavior of the mechanism when multiple clearance revolute joints are considered. The results indicate that the clearance joints present two obvious separation leaps in a complete pick-and-place working cycle of the parallel manipulator, following a collision. The impact induces system vibration and thus reduces the dynamic stability of the system. The joint clearances affect the amplitudes of the joint reaction force, the input torque, and the end-effector's acceleration, additionally the joint clearances degrade the kinematic and dynamic accuracy of the manipulator's end-effector. Finally, this study proposes related approaches to decrease the effect of joint clearances on the system's dynamic properties for such parallel manipulator and prevent "separation-leap-impact" events in clearance joints. © 2013 Published by Elsevier Ltd. All rights reserved.
Xu L.X.,Tianjin University of Technology and Education
Multibody System Dynamics | Year: 2016
Contact impact has been widely found in the operation of various mechanical systems. These mechanical systems include the type of mechanism typically characterised by circular–non-circular geometric contact. They consist of the mechanisms of the cam with a roller follower, a Geneva wheel with intermittent motion, a cog belt drive with circular-arc teeth, a cycloidal-pin wheel gear, and a roller chain drive. For the two components in contact, one component needs to have an ideal circular shape, while the other is characterised by its non-circular geometry, that is, the contact shape may present varying radii of curvature. Taking this kind of contact mechanical system as a research object, this work proposes a general method for analysing the problems concerning contact impact on this circular–non-circular geometry. This method discretises continuous non-circular geometries to acquire a series of discrete points. Then, the contact areas of components are determined by repeatedly judging the relationships between the positions for various discrete points and the circular geometric centres thereof. In the contact areas, the maximum depth of the contact is measured, and the positions of the contact points between components, in a direction along the maximum contact depth, are determined. Finally, the normal contact force and tangential friction force between contacting components are established at the contact points. This method can be applied to analyse the problems concerning single contact and multi-point contact among various contact components. To verify the validity of this method, this work takes an offset translational roller follower disc cam mechanism (with a single contact) and a cycloidal-pin wheel gear mechanism (with multi-point contact) as examples and investigates the dynamic characteristics of the contact impact for the aforementioned mechanical systems, respectively. © 2016 Springer Science+Business Media Dordrecht
Chen J.,Tianjin University of Technology and Education
Proceedings of the World Congress on Intelligent Control and Automation (WCICA) | Year: 2016
In this paper, a self-organizing cerebellar instrumental learning algorithm (SOCILA) is proposed for a self-balancing robot to achieve the balance control based on the counter-propagation network (CPN), which combined unsupervised and supervised learning. Due to the cerebellar contributions to instrumental learning, the instrumental learning algorithm is designed to change the weights from competitive layer to output layer of CPN, while the clustering to input state is implemented by fuzzy self-organizing map layer (from input layer to competitive layer)of CPN. In order to save the learning results, curiosity parameter is introduced, which is useful to instrumental learning and simulate the biological learning process. Simulations on balance learning of a two-wheeled self-balancing robot is given to illustrate the performance and applicability of the proposed learning scheme, and, as a result, progressive learning process of balance can be achieved using the proposed SOCILA method. Finally, in order to compare the learning performances we choose different number of rules to test the learning performance in balance learning. © 2016 IEEE.
Mei Q.,Whirlpool Corp. |
Shan M.,General Electronics |
Liu L.,Tianjin University of Technology and Education |
Guerrero J.M.,University of Barcelona
IEEE Transactions on Industrial Electronics | Year: 2011
Maximum power point (MPP) tracking (MPPT) techniques are widely applied in photovoltaic (PV) systems to make PV array generate peak power which depends on solar irradiation. Among all the MPPT strategies, the incremental-conductance (INC) algorithm is widely employed due to easy implementation and high tracking accuracy. In this paper, a novel variable step-size incremental-resistance MPPT algorithm is introduced, which not only has the merits of INC but also automatically adjusts the step size to track the PV array MPP. Compared with the variable step-size INC method, the proposed scheme can greatly improve the MPPT response speed and accuracy at steady state simultaneously. Moreover, it is more suitable for practical operating conditions due to a wider operating range. This paper provides the theoretical analysis and the design principle of the proposed MPPT strategy. Simulation and experimental results verify its feasibility. © 2010 IEEE.
Zhang J.,Tianjin University of Technology and Education
Gait and Posture | Year: 2012
A gait analysis method based on continuous wave (CW) radar is proposed in this paper. Time-frequency analysis is used to analyze the radar micro-Doppler echo from walking humans, and the relationships between the time-frequency spectrogram and human biological gait are discussed. The methods for extracting the gait parameters from the spectrogram are studied in depth and experiments on more than twenty subjects have been performed to acquire the radar gait data. The gait parameters are calculated and compared. The gait difference between men and women are presented based on the experimental data and extracted features. Gait analysis based on CW radar will provide a new method for clinical diagnosis and therapy. © 2012 Elsevier B.V.
Li Z.,Tianjin University of Technology and Education |
Zhao X.,Tianjin University of Technology and Education
Nonlinear Analysis: Real World Applications | Year: 2011
Combining adaptive control theory with an antisymmetric structure, an extended adaptive controller which is more generalized and simpler than some existing controllers is designed. Under the controller, generalized function projective synchronization of two different uncertain hyperchaotic systems is achieved, and the unknown parameters are also estimated. In numerical simulations, the scaling function factors discussed in this paper are more complicated, and they have not been discussed in other papers. Corresponding simulation results are presented to show that the controller works well. © 2011 Elsevier Ltd. All rights reserved.
Dai Y.,Tianjin University of Technology and Education
Zhongguo Jixie Gongcheng/China Mechanical Engineering | Year: 2011
A reliability evaluation test plan of NC machine tools based on exponent distribution was investigated. At first the evaluation test plan type was confirmed as timing censored lifetime test with replacement, secondly the minimum failure number was discussed to get certain confidence interval, and then the condition that the product of machine tool number and censored time should satisfied was analyzed to get the minimum failure number. At last, the optimum plan about machine tool number and censored time were put forward.
Gu Q.,Tianjin University of Technology and Education |
Gao T.,Nankai University
Digital Signal Processing: A Review Journal | Year: 2013
Reversible watermarking can be applied to the protection for important digital media, such as medical and military image, it allows the watermark to be extracted and the original image to be restored completely, but reversible watermarking with stronger robustness is seldom discussed in existing literature. In this paper, a novel reversible watermarking algorithm based on chaotic system is proposed; chaotic system is not only used to search space of reversibility of the scheme, but also used to randomly select the position of watermarking embedding. Consequently, the proposed scheme achieves larger threshold space of reversibility and better performance of security. For some specific thresholds, the proposed algorithm is not only reversible, but also has stronger robustness against image compression. The experimental results show that the ergodicity and sensitivity to initial values of chaotic system play an important role in reversible watermarking algorithm, and the proposed scheme can achieve balance between reversibility and robustness with the help of chaotic system. © 2012 Elsevier Inc. All rights reserved.