Tan Kok Kiong

Precision Motion Control: Design and Implementation

Precision Tracking Motion Control.- Automatic Tuning of Control Parameters.- Co-ordinated Motion Control of Gantry Systems.- Geometrical Error Compensation.- Electronic Interpolation Errors.- Vibration Monitoring and Control.- Other Engineering Aspects.

Precision Motion Control

PI offers the world’s largest portfolio of precision motion technologies for positioning in the accuracy range from one micrometer down to below one nanometer. Fast settling or extremely smooth low speed motion, high positional stability, high resolution and high dynamics – the requirements placed on piezo mechanisms vary greatly and need drivers and controllers with a high degree of flexibility. PI provides a broad spectrum of piezo electronics from versatile general purpose controllers to highly specialized devices. Units come in different levels of integration from customized OEM boards and a plug & play bench-top devices to modular controllers to scalable to almost any number of axes. Piezo mechanisms directly respond to the smallest change in the drive voltage with a change in displacement. Response times of a few microseconds are possible, depending on the mechanical design and the performance of the piezo controller.

MEETING ROOM - A secure multi-access, cross-platform telemedicine application

The high costs and inconvenience of visiting a doctor for medical advice have deterred a sizable number of elderly and needy from seeking proper medical treatment promptly and this may cause their conditions to deteriorate and possibly resulting in a more severe impact on their daily lives. Thus, this application is designed with the aim to bring more convenience and health care services to these less privileged segments of the community. In this paper a secure multi-access cross-platform telemedicine application, known as MEETING ROOM, has been designed and developed to provide easily accessible health care services. The MEETING ROOM application adopts a web-based approach in general to provide the flexibility to run on cross-platform devices. Computing devices with network connectivity can be placed in clinics, day care centers, community centers or right at their homes so that they can easily access the application with those devices. It is a hybrid application, comprising of a web portal and a video conferencing application. The web portal is used to manage the system and the users in a secure manner while the video conferencing application provides a convenient communication platform for the patients to consult a doctor on their conditions and for the doctors to hold online meetings. A web-based version and mobile Android version of the video conferencing application are developed to provide the flexibility.

Dead Time Compensators

Dead time compensators were among the first predictive controllers formulated. This is not surprising since for time-delay systems, prediction of the behaviour of the system in the future is necessary to formulate the appropriate control action. For a non-predictive controller, the control action or the effect of control action cannot be realised until some time in the future when the system variables may have changed considerably such that the control action is no longer appropriate. While the proportional-integralderivative (PID) controller is widely used in industry, its performance when used in time-delay systems is known to be limited. If a time-delay system is controlled by a PID controller, the derivative action is often disabled to reduce excessive overshoot and oscillations, due largely to misinterpretation of the non-responsiveness of the system (Hagglund and Astrom, 1991). On the other hand, with no derivative action, there is no predictive capability in the remaining PI control action, which is precisely what is needed for these systems. Dead time compensators are employed when better performance is demanded.

Overview of Nanotechnology

This introductory chapter will briefly explain what nanotechnology is, briefly trace its origins and recent historical developments and then to describe representative nanotechnology processes and applications.

Comprehensive lane keeping system with mono camera

One to three percentage of worlds gross domestic product is being wasted due to automotive accidents and this figure will be increased further without any new commitments to prevent them. Automated driving system is one of the promising commitments and the road detection technology and the steering control technology are two essential technologies for realizing such a system. In this paper, a novel lane detection algorithm as well as lane keeping system are proposed. These two proposed methods are verified, through both simulation and experiments, to provide a satisfactory performance for the automated driving systems.

Optimal PID Control Based on a Predictive Control Approach

Proportional-integral-(derivative) (PI(D)) controllers have remained the most commonly used controllers in industrial process control for more than fifty years, despite the advance in mathematical control theory. The main reason is that they have a simple structure, which is easily to be understood by engineers, and under practical conditions it performs more reliably than more advanced and complex controllers.

Precision Tracking Motion Control

Among the electric motor drives, permanent magnet linear motors (PMLM) are probably the most naturally akin to applications involving high speed and high precision motion control. The increasingly widespread industrial applications of PMLM in various semiconductor processes, precision metrology and miniature system assembly are self-evident testimonies of the effectiveness of PMLM in addressing the high requirements associated with these application areas. The main benefits of a PMLM include the high force density achievable, low thermal losses and, most importantly, the high precision and accuracy associated with the simplicity in mechanical structure. PMLM is designed by cutting and unrolling their rotary counterparts, literally similar to the imaginary process of cutting a conventional motor rotary armature and rotary stator along a radial plane and unroll to lay it out flat, as shown in Fig. 2.1. The result is a flat linear motor that produces linear force, as opposed to torque, because the axis of rotation no longer exists. The same forces of electromagnetism that produce torque in a rotary motor are used to produce direct linear force in linear motors.

Feasibility of adaptive streaming technologies in developing an integrated learning platform

Education system is going through a reform in terms of delivering lectures, with recent studies suggesting that shorter lectures help students to focus on the concepts thoroughly as well as effectively as they are found to be more engaging than the longer ones. However, making it a reality in traditional classroom settings is a big challenge. One possible alternative is to deliver lecture through short, bite-sized chunks of videos over the Internet which the students can access using their own devices at their own time, thus creating a flexible learning environment. This again posts another challenge in terms of its functionalities in bandwidth-scarce situations. This paper conducts a feasibility study of developing such a system, termed integrated learning platform, or iLEAP, by utilising adaptive streaming technology algorithms. iLEAP is intended to host lecture videos as well as discussion forums for students to engage in active discussions among themselves. This paper discusses the methods by which the data size can be reduced so as to enable the platform to work satisfactorily under varying network conditions. Evaluation of some of these techniques is done to show the viability of such a system which can enhance the learning experience of students. The paper concludes with further insights on the possibility of such techniques in other useful areas such as telemedicine.

Development for precise positioning of air bearing stages

In this paper, we propose control approaches for air bearing stages. First, we consider the case in which air bearing system is a linear stage. A control scheme incoporated with eddy current braking is proposed, where two control inputs are introduced to handle the nonlinear air bearing system. Secondly, we consider the case in which air bearing system is a spherical stage. The control scheme involves Kalman filter and optimal control designs. Finally, experimental results are given to further verify the effectiveness of the proposed methods.