Fault Detection for Motor Drive Control System of Industrial Robots Using CNN-LSTM-based Observers

The complex working conditions and nonlinear characteristics of the motor drive control system of industrial robots make it difficult to detect faults.In this paper,a deep learning-based observer,which combines the convolutional neural network(CNN)and the long short-term memory network(LSTM),is employed to approximate the nonlinear driving control system.CNN layers are introduced to extract dynamic features of the data,whereas LSTM layers perform time-sequential prediction of the target system.In terms of application,normal samples are fed into the observer to build an offline prediction model for the target system.The trained CNN-LSTM-based observer is then deployed along with the target system to estimate the system outputs.Online fault detection can be realized by analyzing the residuals.Finally,an application of the proposed fault detection method to a brushless DC motor drive system is given to verify the effectiveness of the proposed scheme.Simulation results indicate the impressive fault detection capability of the presented method for driving control systems of industrial robots.

A novel two-degree-of-freedom spherical ultrasonic motor using three travelling-wave type annular stators

In order to promote the tolerance and controllability of the multi-degree-of-freedom(M-DOF) ultrasonic motor, a novel two-degree-of-freedom(2-DOF) spherical ultrasonic motor using three traveling-wave type annular stators was put forward. Firstly,the structure and working principle of this motor were introduced, especially a spiral spring as the preload applied component was designed for adaptive adjustment. Then, the friction drive model of 2-DOF spherical motor was built up from spatial geometric relation between three annular stators and the spherical rotor which was used to analyze the mechanical characteristics of the motor.The optimal control strategy for minimum norm solution of three stators' angular velocity was proposed, using Moore-Penrose generalized inverse matrix. Finally, a 2-DOF prototype was fabricated and tested, which ran stably and controllably. The maximum no-load velocity and stall torque are 92 r/min and 90 m N·m, respectively. The 2-DOF spherical ultrasonic motor has compact structure, easy assembly, good performance and stable operation.

A Review of Drive Techniques for Multiphase Machines

Multiphase machines are gaining increasing popularity because of their distinct advantages over three-phase counterparts,such as reduced per phase power rating,improved reliability and increased degrees of freedom.This paper overviews the development history of multiphase machines and drive techniques in Section II.Three kinds of drive algorithms,including Field-Oriented Control(FOC),Direct Torque Control(DTC)and Model Predictive Control(MPC),are introduced in Section III.Then two types of fault-tolerant methods are compared in Section IV,which are the Vector Space Decomposition(VSD)strategy and Optimal Current Control(OCC)method.Furthermore,different types of existing multiphase converter topologies are listed in Section V,and various kinds of multiphase PWM methods are discussed in Section VI.Finally,based on the review,developing trends of multiphase drive techniques are forecasted.

Development of Super-Synchronization Speed Control Assembly in Two 80 MVA Motor Generators of HL-2A Tokamak

The power of the toroidal field （TF） coil in HL-2A is supplied with two 80 MVA motor generators （MGs） together through a diode rectifier. The TF system is designed to obtain the parameters as follows： the highest toroidal filed of 2.8 T, the biggest coil current of 45 kA, the fiat top time of 3-5 s. So the released energy of each MG set for one pulse discharge mast be more than 500 MJ.

Digital Design of Multi-Functional Rehabilitation Robot

The mechanical structure as well as the schematic organization has been designed to achieve lower limb rehabilitation training function; Solidworks has been used to model the robot. And the robot has been optimized by the means of human-interference engineering. The primary components of the robot have been analyzed by Ansys workbench.