Advanced Materials Research Vols. 139-141

Abstract: In order to solve the problem that the tension measurement data of mine hoist wire-rope is inaccurate and the method of fault diagnosis of multi-rope hoist rope tension imbalance is non-standard, the systematic study of monitoring, forecasting and fault diagnosis of rope tension imbalance was made by using the principles of vibration wave method in mechanical dynamics. A set of new methods about monitoring, forecasting and fault diagnosis were developed, which the test method of hoist wire-rope tension based on inhomogeneous chord vibration and the methods for fault diagnosis of steel rope unbalance tension were described deeply. The vibration wave method was also used in these methods. The field test indicated that these methods were simple to operate and had higher accuracy and reliability.

Abstract: Drill wear or breakage often damages the work piece and/or machine tool. Spindle motor current reflects the cutting process and the signal can be easily and inexpensively obtained. This paper presents a strategy for on-line drilling tool wear and breakage monitoring. It employs Wavelet Transform (WT) of the spindle current signature to perform monitoring. A moving window technique is used to extract the cutting portion of data from the entire data sequence. A low pass de-nosing filter is employed to remove noise from the current signal. Features were extracted using WT node energy and selected based on their ability to detect tool wear and chipping. The Progression of tool wear based on feature of WT detail level 4 is analyzed and pointed out status of worn or chipped tool. Experimental results validate performance of the proposed algorithm.

Abstract: Fault diagnosis is a kind of pattern recognition problem and how to extract diagnosis features and improve recognition performance is a difficult problem. Local Linear Embedding (LLE) is an unsupervised non-linear technique that extracts useful features from the high-dimensional data sets with preserved local topology. But the original LLE method is not taking the known class label information of input data into account. A new characteristics similarity-based supervised locally linear embedding (CSSLLE) method for fault diagnosis is proposed in this paper. The CSSLLE method attempts to extract the intrinsic manifold features from high-dimensional fault data by computing Euclidean distance based on characteristics similarity and translate complex mode space into a low-dimensional feature space in which fault classification and diagnosis are carried out easily. The experiments on benchmark data and real fault dataset demonstrate that the proposed approach obtains better performance compared to SLLE, and it is an accurate technique for fault diagnosis.

Abstract: The research on support vector machine in fault diagnose has already obtained a lot of breakthroughs, such as the mode identify problems in small sample, nonlinearity, high dimension and so on. However, there are some limitations in the traditional support vector machine. In this paper, in allusion to the current rotating machinery fault diagnosis problem, the basic principles of support vector machine are studied. According to the complex characteristics of rotating machinery vibration fault, a fault extraction method is proposed based on the K-L transform. Multi-classification algorithm of support vector machine is improved, and the algorithm is used to analyze the rotating machinery vibration. By using its capabilities of model identification and system modeling, the initial symptom, occurrence, development of the typical faults are dynamically analyzed. These provide new ideas and methods for fault diagnosis of rotating machinery.

Abstract: Hydraulic system is consists of mechanical, hydraulic and electrical devices. Therefore, hydraulic system malfunction are a lot of types. Based on the complexity and all-around of hydraulic system malfunction, it is very difficult to solve the hydraulic system malfunction. Hence how to quickly and accurately identify the mechanical is the forefront of current research projects. With the rapid development of computer communication technology, computer-aided diagnosis technology can solve the problem of fault diagnosis of hydraulic systems. In order to solve the hydraulic station mechanical, according to the existing hydraulic system failure analysis, it makes visual dynamic diagnosis. In this paper, the visual dynamic diagnostic technology is introduced, which works in the technical feasibility and tastes its convenience and practicality in the actual practice.

Abstract: The superiority and feasibility of piezoelectric impedance method used in damage detecting was expounded, and the research status of the technical was summarized. Then, the rationale of the basic theory of the technique used in damage identification and health monitoring was analyzed here. The experiment of the damage change of loaded beam was researched. The experiment of the beam which was loaded by a material property, the value of the beam was got by an impedance analyzer, while the beam with different pull force. The research indicates that while the testing frequency range should elect as 300k-800k, with the increasing of loading force, the value of real part impedance is descending, the damage index of beam is increasing. PZT can sensitively catch the influence brought by stress varying

Abstract: The stiction of control valve is one of main causes which make control loop instable in the process industry. Now a number of studies on the diagnosis of control valves are based on stiction. It needs developing a proper method which can detect, quantify, and compensate stiction. A non-invasive method has been used into the fault diagnosis for stiction of pneumatic control valve. Firstly, a two-parameter data-driven model about stiction has been established, and on the basis of separable least squares method, combined with the global search algorithm to deduce the model identification method. Secondly, ellipse fitting method has been adopt to confirm whether the stiction existed, thus the stiction could be quantified, and on this basis, the stiction was compensated. So it improved the performance of control system. Thirdly, the validity of the method was confirmed by simulation.

Abstract: Road friction coefficient is a critical component in traffic safety. The estimation of tire–road friction coefficient at tires allows the control algorithm in vehicle activity system to adapt to external driving conditions. This paper develops a new tire–road friction coefficient estimation algorithm based on tire longitudinal force estimation and tire slip estimation. Vehicle tire longitudinal forces are estimated by sliding mode observer combined with Kalman filter. Based on the tire forces estimation, road friction coefficient is estimated by recursive least squares algorithm (RLS). The test conditions which contain different friction level road are established in ADAMS/Car. The conclusions validate the reliability and efficiency of the proposed method for estimating the friction coefficient in different adhesion level roads. The research also indicates the theory of slip slope can also be reappeared in virtual experiment based on ADAMS.

Abstract: In order to get good car rideability, the electronic air suspensions(EAS) are now used in some advanced automotives. Although ABS systems are used in automotives for a long time, in some limit cases such as cornering at high speeds, cars may be still in great dangerous states. It is considered that if electronic air suspensions(EAS) can be adjusted with ABS during some extreme conditions, the cars may become safer. To investigate this possibility and then find out a specific control scheme, some research work is done in the paper. The research work begins from the dynamic analysis for cars with EAS and ABS both, and then based on it an integration control scheme for EAS and ABS is put forward. By means of Matlab/Simulink simulation study, it is found that the braking performances such as braking distance, braking deceleration, and the car vertical acceleration are improved obviously with the integration control technique for both of EAS and ABS during high speed cornering. Therefore the integration control method developed here can work well and improve the car performances obviously.

Abstract: This paper proposes a design of a new shock absorber with combined mechanical- electromagnetic- hydraulic structure, and expounds its working principles. This new type of absorber can recyle the vibration energy and transform it into electrical energy for use. However, in its working process, the damping force in extension stroke is always smaller than that in compression stroke, which is determined by the inner structure, while in traditional absorbers, it is just the opposite. This does not meet the practical demands. Directing at this problem, the paper puts out a way to make real-time adjustment to the damping force by controlling the generator load, and tests the feasibility with a simulation model built with AMESim. The test result reveals that the method is feasible. This contributes a lot to the future further research on active control.