CHIMAN KWAN

A new approach to traffic incident detection is proposed in this paper. The method consists of two stages. In the first stage, a real-time adaptive on-line procedure is used to extract the significant components of traffic states, namely, average velocity and density of moving vehicles. In order to effectively and efficiently account for the time-varying and random nature of traffic incidents, it is necessary to have a real-time on-line adaptive algorithm. In the second stage, we apply a new neural network called Fuzzy CMAC to identify traffic incidents. Simulation results show that the performance is very good.

Phase-locked loops (PLL) have found applications in many industrial applications such as communication and control systems. The key requirements are stability and loop performance in terms of signal-to-noise ratio and tracking errors. Here we present a two-step approach to PLL design. First, we present a Lyapunov approach to analyze the loop stability. The parameter range that can guarantee stability can be easily derived in the process. Second, we present a multi-objective optimization method that can search a set of values within the above range of parameters to achieve an optimal trade-off between loop bandwidth, transient and steady-state performance. Simulation results are contained to illustrate the performance of our procedure.

It is well known that nonlinear distortion over a communication channel is now  a significant factor hindering further increase in the attainable data rate in high-speed data transmission. Since the recived signal over a nonlinear channel is a nonlinear function of the past values of the transmitted data pulses, it is not surprising that he linear equalizers do not work efficiently. We propose a new nonlinear equalizer that uses a new type of neural network called Fuzzy CMAC which combines the advantages of both fuzzy logic and CMAC (Cerebellar Model Arithmetic Computer) networks. The learning speed it an order of magnitude faster than conventional neural nets. Moreover, human expert knowledge in the form of linguistic rules can be easily incorporated into the scheme.

We propose two advanced control algorithms (LMS adaptive filter and Fuzzy CMAC neural network) to counteract the chatter problem for a lathe machine. Experimental results are also included. Approximately 20 dB reduction in chatter has been achieved. We have also developed a Multi-DSP board which can be used to implement any type of intelligent controllers to machine systems. Other potential applications of the proposed methods are to milling and boring machines.

A new approach to flow control in high speed communication networks is proposed where the flow control problem is modeled as a dynamic system with time delay. The main advantage is that it can assure stability of system as well as maintaining certain throughput of the communication channel. Inside the controller, there is a term which predicts the future backlogs int eh system. The controller is easy to implement. Simulation results show that the method offers significant less delay than existing methods

This paper describes a design study to determine the feasibility of integrating active control into a milling machine to enhance milling-process performance. The study described herein focuses on the active suppression of chatter instabilities in an Octahedral Hexapod Milling (OHM) machine. Structural dynamics contributing to chatter instabilities were described using calibrated finite element models, which were coupled with a tool-workpiece interaction model for purposes of determining, by simulation, machine performance enhancement due to active control. An active vibration control design to minimize vibration at the tool tip was also integrated into the simulation. Active control subcomponent and actuator size requirements were determined from the modeling arid simulations. The study showed that active control is a feasible solution for suppressing chatter instabilities, allowing the metal removal rate of the OHM machine to be increased by roughly a factor of two. I. INTRODUCTION In machining, Metal Removal Rate (MRR) is limited by the power limit of the machine and by machining instabilities. The power limit of the machine is increased by increasing the horsepower of the motor. Typically, machining instabilities are minimized by stiffening machines and tools by adding reinforcing material. However, there are many tools and machines for which stiffening by material addition may not be practical. An example of such a machine is the Ingersoll Milling Machine Company's Octahedral Hexapod Milling (OHM) machine1 .As an alternative, stiffness may be increased in selected frequency ranges through the use of active control. The problem addressed in this paper is to synthesize an active control design that will make a flexible tool look stiff at the point of cutting. The target of the active control design is the Ingersoll OHM machine. This machine has been dynamically characterized, and essential dynamic characteristics are employed to study dynamic performance of the active control by simulation. The following sections of this paper describe the OHM machine model, development of an active control design to make a flexible tool used with the OHM machine look stiff at the point of cutting, and sizing of electrostrictive ceramic actuators for this active control design. 2. OCTAHEDRAL HEXAPOD MILLING (OHM) MACHINE MODEL This section describes the development of a finite element model of the OHM machine with flexible and stiff milling tools. The model captures the local dynamic behavior of a diverse, but practical set of machine and tool configurations susceptible to chatter. Figure 1 shows an illustration of the machining head of the OHM machine, comprising a solid steel platform, spindle drive motor and spindle assembly, all supported by six servo struts. Some dynamics of this machine are inherently nonlinear and hysteretic due to the use of bolted connections, compression fittings, socketed joints and flexible 316 / SPIE Vol. 2721

This paper describes a design study to determine the feasibility of integrating active control into a milling machine to enhance milling-process performance. The study described herein focuses on the active suppression of chatter instabilities in an Octahedral Hexapod Milling ...