Zude Zhou

A systematic approach to integrated fault diagnosis of flexible manufacturing systems

A flexible manufacturing system (FMS) is an application of modern manufacturing techniques. Like for other manufacturing equipment, the success of an FMS is very much dependent upon its trouble-free operation. It is crucial to monitor all the possible faults or abnormalities in real time and, when a fault is detected, react quickly in order to maintain the productivity of the FMS. Because of the complexity of FMSs, the functionally complete diagnosis of an FMS should be based on all the available information and various advanced diagnostic techniques so as to get a satisfactory result. This paper proposes a systematic approach to fault diagnosis of FMSs that integrates condition monitoring, fault diagnosis and maintenance planning. An intelligent integrated fault-diagnosis system is designed with a modular and reconfigurable structure. The implementation of the integrated diagnosis system is presented in detail. The system can monitor the major conditions and diagnose the major faults of an FMS, and give corresponding maintenance planning as well. The developed system has been applied to an existing FFS-1500-2 FMS in Zhengzhou Textile Machinery Plant and has achieved good results.

Study on Coordination in Multi-Agent-Based Agile Supply Chain Management

One of the most important tasks of the agile supply chain management(ASCM) is to reconfigure a supply chain quickly based on the customers’ requirement. Without more sophisticated cooperation and dynamic formation in an agile supply chain, it cannot achieved for mass customization, rapid response and high quality services. Because of its great potential in supporting cooperation for the supply chain management, agent technology can carry out the cooperative work by inter-operation across networked human, organization and machines at the abstractive level in a computational system. A major challenge in building such a system is to coordinate the behavior of individual agent or a group of agents to achieve the individual and shared goals of the participants. In this paper, the agent technology is used to support modeling and coordinating of supply chain management. Because two types of agents, namely cooperated agents and self-interested agents, are used in the supply chain, their characteristics are analyzed and then two different methods are put forward for the solutions, that is the distributed scheduling and centered making decision(DSCM) for cooperated agents and the hierarchical distributed coordination (HDC) for self-interested agents.

An improved fuzzy system for position control of permanent magnet linear motor

In this paper, a fuzzy system with stable value is proposed to promote the traditional fuzzy controller and to be applied to position control of the permanent magnet linear motor. By a partition of error and change of error, the proposed fuzzy system can be used in a traditional fuzzy controller and can be switched to preceding a stable output control smoothly. For PMLM control system, the output of position control can be divided into a stable value and a changing one when the controlled system is close to stable state. A stable parameter value is acquired from the output of a traditional fuzzy controller when the controlled system comes into the stable state. And the stable parameter value can be tuned by a designed integral part so as to alleviate the static error. Simulation results show the improved fuzzy system has a higher performance than the traditional PID and the traditional fuzzy controller. The experiment results also verify that it has high precision in position control of PMLM.

Hierarchical fuzzy neural controller based on error iterative and approach

In this paper, a fuzzy neural networks based on hierarchical approach reasoning is proposed. The construction combining model is described by the fuzzy logic technology. The output of the antecedent part of the fuzzy logic is expressed as the input of the consequent part. The consequent part is a simple linear equation of the variables corresponding to the rule strength of the antecedent network and the output variables of the consequent network. So, the physical meaning of the proposed fuzzy neural network is clearer and its structure is simpler. We present a learning algorithm based on hierarchy error approach which utilizes a fuzzy logic function to aggregate the weight coefficients of the neural network, so the output can rapidly converge to the desired tolerable error range. Simulation results show the fuzzy neural network based on fuzzy hierarchy error approach have very good approach ability of for the complex functions through learning and training of the rule weight.

Accurate tracking control of a linear fast tool servo unit for noncircular cutting

In this paper, an accurate position tracking control scheme is proposed for a moving-coil-type linear DC motor driven fast tool servo unit for noncircular cutting application. A sliding mode tracking controller is designed to ensure the system has a fast tracking characteristic to the position command. Moreover a disturbance observer is used to estimate and compensate exogenous disturbance to improve robustness and stability of the fast tool servo unit. Because the reference input is approximately periodic in noncircular cutting process. Therefore, the periodic error can he further reduced by augmenting an iterative learning controller to the existing sliding mode controller for repetitive position tracking. The experimental results of noncircular cutting adopting the proposed control method, including tracking performance and robustness of the system, are much improved.