Permanent Magnet Synchronous Torque Motor (PMSTM) has the main characteristics of low speed, high torque, high precision and excellent stability, which can be applied to implement the direct driving technology for CNC (Computer Numerical Control) machine tool. In this paper, the mathematical model of PMSTM is simply introduced, and the various control strategies are discussed in detail. According to the requirement of high performance for PMSTM driving servo system in CNC machine tool, the corresponding suitable control method is employed in the feed servo system. The proposed scheme is also promoted to apply in the spindle system, the tool holder and the turntable of machine tool.

Permanent magnet linear synchronous motors (PMLSM) can serve as direct drive actuators for machine tools. However, PMLSM is more easily affected by load disturbance, force ripple and parameter variation. As a result, the design of an appropriate controller and research on dynamic performance are very important for PMLSM. In this paper, a feedback controller based on pole-placement is proposed to achieve desired tracking performance. The effectiveness and feasibility of the proposed method are demonstrated through theoretical analysis. The dynamic response and disturbance rejection ability for linear servo system were researched and the parameters which influence the dynamic performance of the system were discussed.

The aim of this paper is to investigate the time dependence distribution of workpiece cutting temperature in milling process. An experimental system used to achieve a measurement of cutting temperature in high speed milling is designed by use of the thermocouple and infrared thermal imager. The general regularity of temperature distribution is concluded, and the influence of the process variables such as cutting speed, cutting depth, etc. on the temperature distribution was investigated in detail. All the experiment results can be effective used to develop a new non-contact soft-sensing method for high speed cutting temperature prediction.

In order to select the best possible design from various candidates based on structure configurations of traveling components, it is essential to evaluate the effects of traveling joints on dynamic behavior of large machine tools. Firstly, regression analysis and energy method were used to determine the nonlinear parameters of the metal-plastic joints. Then, a nonlinear receptance coupling approach was used to establish a simplified model of a large machine tool including nonlinear joints. The evaluations of the large machine tool were analyzed with different milling forces. The results show that the nonlinearity of traveling joints significantly influences the resonant frequency and the response amplitudes. Experimental verifications were performed on a prototype of a large machine tool for milling large gears.

The cotton recognition would become rather difficult during the application of the cotton harvesting robot (CHR) in the case where the cotton is sheltered or covered by other objects. In this paper, a novel approach of cotton detection based on the improved randomized Hough transform (IRHT) for this case is proposed. Based on the contour information from the boundary trace, the mathematic model-based IRHT is derived based on a modified circular detection technique. It yields a well agreement with the requirements of the precision and rating of CHR.