The paper puts forward a method that the internal force greatly improves the actual accuracy of parallel machine tools, and a-2DOF redundantly actuated parallel mechanism is designed. The position and speed harmonious control conditions is studied and the force control system is devised in this paper. The experiments show that this method can greatly improve the accuracy of parallel machines. Therefore, the results provide the theoretical and experimental foundation for improving the accuracy of parallel machines by internal force.
Based on the structure of TFT_LCD controller in S3C2440A, the hardware design of a special LCD display system is completed which is composed of S3C2440A and liquid crystal display modules of TFT_LCD. The reliable control of TFT-LCD is achieved through SPI &RGB interface mode, and the methods of the display program and register initialization of display system are presented. The system can be applied to TFT_LCD module of different resolutions for testing instruments data-showing. The design can also be made as a reference for engineer in developing the LCD display system to shorten the development cycle and save cost.
For patients with hand movement dysfunction caused by diseases such as stroke and hemiplegia, a portable hand and wrist integrated rehabilitation robot is presented based on the human factor engineering. The rehabilitation robot can achieve rehabilitation training of 14 DOFs of fingers and 2 DOFs of wrist. The four-channel sEMG signals of finger and wrist movements are collected by DELSYS equipment, and the pre-processing operations such as denoising and segmentation are carried out by MATLAB. Three kinds of time domain signal features are extracted and combined. The classification training model is obtained by LDA, CNN and LSTM classification method, respectively for different hand movements. Comparisons of the accuracy and learning speed of the three methods show that the CNN method has the highest accuracy and the fastest learning speed. The prototype model of the rehabilitation robot is generated by 3D printing, then the CPM rehabilitation and sEMG control experiments are carried out. Experiment results verify the effectiveness and efficiency of the proposed multi-function rehabilitation robot.
The formation of shear localized chips in orthogonal machining of Ti-6Al-4V was investigated. The chips in different cutting velocities were collected and the structure of the adiabatic shear localization was examined by optical microscope and SEM after polishing and eroding. The serrated coefficient, serrated frequency and fibred coefficient were proposed in this paper to characterize the degree of serration and plastic shear flow of the chip quantitatively. Experimental results show that the width of the shear band decreased and the fibred coefficient of the shear band increased as cutting speed increased. The serrated and frequency, the serrated coefficient increased with the increase of cutting speed in the experimental range of cutting speeds.
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