Materials Science Forum Vols. 626-627

Abstract: Redundant actuation has good performance in eliminating singularities and optimizing force distribution, a 2-DOF redundantly actuated parallel robot is taken as the object of study. The dynamic model of the parallel robot is derived. Because the parallel robot is an uncertain nonlinear system, the sliding mode variable structure controller is designed considering its fast response and robustness. Then the stability of the proposed controller is analyzed. The saturation function is used instead of the sign function to eliminate the chattering of the sliding mode control. The simulation results show that the torque of each servo motor changes smoothly when using the quasi-sliding mode control. So the damage of the servo motors and robot arms is decreased. The results of the trajectory tracking demonstrate the effectiveness of the quasi-sliding mode control.

Abstract: To attain the optimal shape of the robot arm with the minimum compliance and the suitable weight and lower the possibility of vibration, this paper applies the homogenization method to describe the topology optimization design of the wafer handling robot arm which modal analysis is carried out subsequently. We deduce and establish the mathematical model of the topology optimization based on the homogenization method and calculate it by ANSYS. The results suggested that the compliance and the weight were reduced. Then we calculated the modal analysis of the optimized and non-optimized robot arms, and it was found that the first sixth natural frequencies of the optimized robot arm all increased whereas the probability of the natural vibration declined. It is concluded that the topology optimization design of the wafer handling robot has been shown to be effective in improving the stability of the robot arm.

Abstract: In order to resolve the problem of cutter rotation controlling in the process of cutting using in CNC cutting machine tool, the principle of cutting of CNC cutting machine-tool is analyzed and the coordinate of the machine tool’s motion is built. Tangent Following interpolation of arc based on data sampling algorithm is researched. Interpolation formula is educed and its arithmetic flow chart is given. Two kinds of inaccuracy are analyzed and their comparison graph is studied. PC and Controller motion control system is used in this paper and close-loop speed control system is selected. Dynamic simulation of this interpolation is realized by testing the program written by VC++6.0 under the Googol motion control platform. The result shows that the Tangent Following interpolation can satisfy the need of cutting control process well.

Abstract: This study is on the configuration of deep hole drilling system for machining of extra-large common rail fuel supply pipes. Machining conditions for deep hole drilling were deduced and stability of the developed system was verified through measurement of machining surface roughness. Also, a tilt sensor was used for real-time monitoring on machining of deep hole drilling. Machining state was evaluated through composition of a control system for signal feedback.

Abstract: This paper presents the passivity-based rotor resistance and mechanical paramters estimation, and the position control for induction motors. Firstly, the input-output linearization theory is employed to decouple the rotor flux amplitude and the rotor position at the transient state. An open-loop current model flux observer then estimates the rotor flux. Furthermore, we adopted the gradient algorithm to design adaptive laws to estimate the rotor resistance, moment of inertia, viscous coefficient, and load torque. The passive properties of the feedback connection of the rotor flux observer to the rotor resistance estimator, and the position controller are analyzed by the passivity theorem. According to the properties, the overall control system is proved to be globally stable without using Lyapunov-type arguments. Finally, experimental results are provided to show that the proposed method is robust to variations of the mechanical parameters and load torque disturbances. Moreover, good position tracking response and parameters estimating characteristic can be obtained.

Abstract: Experimentation modal analysis is the major technique for the mechanism dynamic properties. This study proceeds dynamic analysis in XK7132 NC Drill and Milling Machine with experimentation modal analysis. Thereby it gets the modal parameter of the tool of main shaft systems. It takes clearly reference for the rationalization design of main shaft systems in NC drill and milling tool.

Abstract: In order to realize the precise ignition control of gasoline engine, an ignition advance angle BP (Back Propagation) neural network model is built. The improved LM (Levenberg-Marquardt) learning algorithm is used in the model to increase the neural network performance. The neural network model is trained and tested by matlab program. For a variety of inputs, the trained ignition advance angle neural network can carry out correct outputs. Compared with the experimental ignition advance angle, the maximum error of the neural network ignition advance angle is less than 5%. Compared with the experimental map method, the ignition advance angle neural network has the advantage of online modifying the value of ignition advance angle, so it can make the gasoline engine acquire the best ignition advance angle on various working conditions. The results show that the ignition advance angle neural network model established in this paper is effective and accurate. The performance of gasoline engine can be improved ultimately.

Abstract: There are many inclined holes in modern manufacturing industry. Due to the special machining state of drilling out, the drilling jigs and other auxiliary mechods can not been used. There is intermittent cutting for a long time during drilling out, and the axial force and torque are also impact force, which cause the drill to break. The experiments results showed that the axial force and torque were also been incresed, especially the later, which is the principal factor of the drill fracture. So it is the experimental foundation for further to control and protect the dill to break.

Abstract: In this study, a fault diagnosis system is proposed for rolling ball bearing race using wavelet packet transform(WPT) and artificial neural network(ANN)technique. Vibration signal from ball bearings having defects on inner race and outer race is considered and the extraction method of feature vector based on wavelet packet transform with frequency band energy is used. The vibration signal is decomposed into the individual frequency bands. The variations of the signal energy in these bands reflect the different fault locations. Further, the artificial neural network is proposed to develop the diagnostic rules of the data base in the present fault identification system. The experimental work is performed to evaluate the effect of fault diagnosis in a rolling ball bearing platform under different fault conditions. The experimental results indicate the effectiveness of the proposed method in fault bearing identification.

Abstract: In this paper, the dynamic model of rotor bearing system with rub-impact and oil whirl is formulated. Continuation-shooting method for the periodic solution of nonlinear non-autonomous system is used to obtain the bifurcation and stability of the periodic motion of the rotor-bearing system. The effect of the unbalance and rotor/stator clearance on the bifurcation and stability of the periodic motion of the rotor bearing system are analyzed respectively. The results obtained are compared with those of rotor-bearing system with oil whirl fault.