King Pui Louis Liu

Tele‐operated climbing and mobile service robots for remote inspection and maintenance in nuclear industry

Purpose – Aims to report on the various types of tele‐operated mobile service robots for remote inspection and maintenance, especially in the field of nuclear industry.Design/methodology/approach – Describes nuclear electric robot operator (NERO), Sizewell A duct inspection equipment (SADIE), Robug‐IIs (all leg‐based) and Roboslave (wheel‐based).Findings – That these robots can handle a significant portion of inspection and maintenance tasks in a typical nuclear plant, though, given that they are primarily tailor‐made, they are still too expensive for ordinary industries.Originality/value – As the interests of health and safety and paramount, this study sees the use of such robots expanding and diversifying, irrespective of cost.

Demonstrated trajectory selection by hidden Markov model

This paper proposes an automatic selection scheme to choose the most consistent trajectory among a number of human-demonstrated ones. The consistency-determination is based on the hidden Markov model (HMM) technique. There are three stages involved. The first stage is preprocessing of the human-generated trajectories. It includes short-time Fourier transform and vector quantization. The former maps the trajectories from the time domain to the frequency domain, and the latter quantizes a list of frequency spectra to a finite number of prototype spectrum-vectors, called symbols. The second stage is training of the HMM. The unknown model parameters in the HMM are tuned by the concept of counting event occurrences. The quantized symbols are counted so that probabilities of occurrences are applied to train the HMM. The third stage is measurement of the consistency of every trajectory. Each trajectory is sent through the trained HMM. A probability-based likelihood index is evaluated which reflects the consistency of the trajectory with the HMM. The trajectory giving the largest likelihood index is considered to be the most consistent one and will be selected.

Modelling of the B-field effect on the free surface of magneto-rheological fluids

The free surface of magneto-rheological fluids (MRFs) can be disturbed by an external magnetic field to form peaks along the field direction. The protruding volume is largely related to the magnitude of the applied B-field. This paper presents a theoretical analysis of the effects of this type of magnetic field on the protruding height (volume) of MRFs. A theoretical model of the protruded volume of MRFs is used according to the Euler equation and the boundary conditions for equilibrium and based on an ideal ellipsoidal shape. The surface profile due to the presence of a magnetic field is also experimentally analysed.

The response of excited magneto-rheological fluid along field direction

This paper describes an experimental study on the characteristics of an excited magneto-rheological fluid in the field direction using a self-developed two-plate rheometer. The effects of B-fields and shearing are investigated. The normal force can be built up by B-fields and further increased by imposing an additional shear action. The rate at which the normal force changes in response to an increasing B-field and shearing is quite rapid. In addition, the shear-enhanced normal force can be sustained even when the shear is stopped. An explanation based on chain rotation and slippage effects is proposed.

Application of service robots for building NDT inspection tasks

Purpose – Building inspection tasks usually involve working at life‐threatening height, especially for high‐rise buildings. The purpose of this paper is to introduce two service robots which are designed for high‐rise building inspection applications.Design/methodology/approach – The first service robot, equipped with independent‐climbing capability, is applied to gas pipe inspection. The robot requires very little setup time and is suitable for some small inspection tasks. The second, which shares some similarities of industrial gondolas, is applied to check the health conditions of tile‐walls of high‐rise buildings. This robot requires more initial setup time but can provide faster inspection operations. In addition, it can be programmed to carry out the inspection task automatically. So, it is more suitable for large‐scale inspection tasks.Findings – For tile‐wall inspection, a fast, low‐cost and effective non‐destructive testing technique based on impact acoustic method has been developed for the robo...

An Intelligent Networking and Automation System for Home and SOHO Environments

The ever increasing desires for improvement in efficiency and comfort for individuals’ home and office environments have provided the driving force for the recent development in Home/SOHO automation and networking systems. This paper presents a new Home/SOHO automation system which is designed for handling heterogeneous network systems. The laboratory-built system makes use of OSGi (Open Service Gateway Initiative) open standard to provide a flexible framework for adding and removing devices and appliances in an ad hoc manner. Since end users of the system may not necessarily be very computer literate, UPnP (Universal Plug and Play) open standard is being used to make the network connection of various devices as transparent to the users as possible. The current experimental Home/SOHO system can support Bluetooth wireless network, Lonworks, IR, C-bus, 315MHz, 418MHz and 433MHz ISM band RF, and broadband Internet communication. The proposed system can certainly provide a platform for developing Home/SOHO commercial products and it is also flexible enough for developing and experimenting with other Home/SOHO automation technologies

Equalization of ultrasonic transducers based on evolutionary algorithm and IIR lattice filter

In ultrasonic non-destructive evaluation (NDE) application, band-pass ultrasonic transducer is recognized as a main factor degrading the time fidelity of inspection. Due to low computational complexity and simplicity, finite impulse response (FIR) equalizer techniques have been applied to undo the band-pass response of the narrowband ultrasonic transducers in our previous work. Compared to FIR filters, infinite impulse response (IIR) structures exhibit considerable advantages including the potential reduction of computational complexity and the increased accuracy with equivalent order. However, the application of the IIR filters is seriously hindered by their drawbacks such as the multimodal performance surface and stability issue. Aiming to mitigate the limitations posed by the IIR filters, this paper introduces an evolutionary algorithm-based IIR filter implemented as the lattice structure which greatly simplifies the stability control and then applies it in the physical ultrasonic transducer equalization. The experimental results on numerical data as well as the practical ultrasonic NDE signals are provided to demonstrate the effectiveness of the proposed method.

General representation of human demonstration using differential-geometry properties

This paper proposes a new demonstrated-trajectory modelling technique for human-skill representation based on differential-geometry properties. It satisfies three desirable criteria for generalization of the captured human trajectory for trajectory comparison and robot-command mapping. The important criteria are spatial independence, temporal independence, and suitability for similarity measurement. The differential geometry properties extracted for use are curvature and torsion which adequately describe the trajectory shape and fulfil the first two criteria. The last criterion is met by introducing a suitable form of model function derived from the curvature and torsion functions.