Xijun Chen

A locomotion mechanism with external magnetic guidance for active capsule endoscope

Gastrointestinal (GI) disorder is one of the most common diseases in human body. The swallowable wireless capsule endoscopy has been proved to be a convenient, painless and effective way to examine the whole GI tract. However, lack of motion control makes the movement of the capsule substantially random, resulting in missing diagnosis. In this paper, a locomotion mechanism is developed for the next-generation active capsule endoscope. An internal actuator integrated on-board the capsule is designed to provide driving force and improve the dexterity. A small permanent magnet enclosed inside the capsule interacts with an external magnetic field to control the capsules orientation and offer extra driving force. This mechanism avoids sophisticated and bulky control system and reduces power consumption inside the capsule. Ex-vivo experimental results showed that it can make a controllable movement inside the porcine large intestine. The mechanism also has the potential to be a platform for further development, such as devices of operations, spraying medicine, biopsy etc.

Cross-Layer Optimization Schemes for Wireless Biosensor Networks

Wireless biosensor networks will enhance the medical performances due to its many advantages such as long term monitoring, fast network establishment, untethered connectivity and ambulatory diagnosis. The network protocol plays a paramount role in performing the medical tasks. Due to many unique challenges imposed on the network design in wireless biosensor networks, especially when it is related to healthcare, there are a lot of network optimization problems to be solved in the network design such as congestion control, medium access control, power control and bioeffects control, etc. These issues involve several layers of the network protocol stack so that it is not practical to consider every single optimization problem independently. It is better to consider the whole network stack as adaptive cross layer optimization problem in a holistic view. The main contribution of this paper is the employment of cross layer optimization methods to combat the unique challenges posed to the WBSN. Two preliminary optimization schemes are proposed: one is for joint congestion control and medium access control, and the other for joint power and bioeffects control. In the later scheme, we introduce the biological effects into the utility model for two purposes, one is to evaluate and control the bioeffects caused by higher power radiofrequency, and the other is to use it as the cost of non-cooperative game for each node. This position paper also briefly outlines the current methodologies exploited for wireless network cross layer design and investigates the theoretical problems

A 3G based Network Solution to the Telehealthcare Robotic System

Mobile wireless telemedicine is the latest area that exploits novel advance in telecommunication technology which provides health care delivery to the inaccessible areas that are hampered by the limitation of the conventional telecommunication technologies. To provide intelligent and high quality monitoring services to patients, best-practice decision support to the professionals and cost-effective maintenance for the management, a third generation (3G) wireless based solution to the telemedicine system is proposed in this paper to support regular and ad-hoc monitoring for the high-frequency interactive contacts between patients and professionals. This paper presents some of the relevant design issues for integration telehealthcare applications with current 3G mobile telecommunication technologies

Investigating Network Optimization Approaches in Wireless Sensor Networks

More and more wireless mobile sensor networks are employed by robotics to perform harsh tasks such as disaster rescue, emission sources localization or hazardous contaminants localization. There are a lot of network optimization problems to be solved in the protocol design of wireless mobile sensor networks (WMSN), such as rate control, flow control, congestion control, medium access control, queue management, power control and topology control etc. These issues involve several layers of the network protocol stack so that its quite difficult to consider every single optimization problem of them in a holistic view. The majority of contemporary research works mainly deal with one or some of them in terms of certain applications or objectives. However, most of the proposed protocols are based on simulations or experiments which lack of sufficient mathematical or theoretical analysis to fully understand the convergence or stability. In order to study the theoretical basis of network algorithms, this paper briefly outlines the current methodologies exploited to design and optimize the performance of sensor networks. In addition, the paper investigates the theoretical aspects to make sense of the network optimization algorithms and give a survey mainly in terms of convex optimization, game theory and artificial intelligence

Developing a Bioeffect Metric for Wireless Biomedical Sensor Networks

The adverse biological effects may be caused by wireless biosensor networks in long term monitoring. This is the first paper that specifically derives a bioeffect metric to evaluate the performance of wireless biosensor networks in terms of health effect consideration. This paper investigates the bioeffects caused by radiofrequency transmission of sensor node, including thermal effects and athermal effects. The bioeffects model is studied in both near-field and far-field, in relation to specific absorption rate (SAR). The main contribution of this work is that a normalized bioeffect metric, equivalent coefficient-of-absorption-and-bioeffects (CAB), is derived to evaluate and design the communication protocols for wireless biosensor networks. After analyzing the simulation results, we identify the factors that can reduce the adverse health effects when designing the communication system. Finally we suggest that a bioeffect aware power scheduling algorithm is paramount for the system

Robot aided object segmentation without prior knowledge

In robot perception system, distinguishing objects from complex environment is a difficult problem if without prior information. In this article, we study three cases that a robot may encounter in real-world application, no movable object, one object, or multiple objects, and then provide an object segmentation strategy through manipulation for each condition. The result shows that this method can provide sufficient prior information for accurate objects segmentation from robots observation. Through this unsupervised algorithm, a robot can learn objects around reliably.

Wireless Assistive Sensor Networks for the Deaf

In this paper, a wireless sensor network based assistive system (WASN) is developed to help the deaf or the hearing-impaired people, particularly, help them to be aware of their environments. A brief review on the current assistive devices is also addressed first. The system architecture, components and specifications are presented for two typical application scenarios: smart home and smart school playground. A node platform is developed to implement the system. Finally, the system performance is evaluated by simulations, followed by the analysis of the feasibility and availability

Radio efficiency evaluation of a body sensor platform

Networking various tiny biosensors via wireless communication will help improve the performance of medical care system. One of the key components of the biosensor networks is communication platform. This paper investigates the radio characteristics of a body sensor platform named Medi for the wearable body sensor networks. The radiofrequency signal efficiency of proposed Medi platform is evaluated through experiments. In order to investigate possible adverse health effects of wireless radiation on the human body, we further look into the electric field distribution of Medi sensor node.

System architecture of a body area network and its web service based data publishing

Wireless Sensor Networks (WSN) is a research hotspot in recent years and has yielded many fruitful results. However, the biomedical applications of WSN haven’t received significant development due to its many unique challenges for the engineers and physicians. In this paper, a system architecture solution of body area network (BAN), our so called project “MediMesh”, is presented. A biomedical dedicated BAN node hardware platform is devised to fit the medical monitoring application. The sensor node is built up especially for healthcare monitoring while the biocompatibility and portability are considered. A light weight network protocol is designed considering the radiation effect and communication overhead. After data acquisition from sink stations, a data publishing system based on web service technology is implemented for typical hospital environment. The publishing of biomedical data is realized through 3 phases: first storing the data automatically in a database, then creating information sharing service by using Web Service technology, and finally allowing data access by the physicians and end users.

Robot aided object segmentation based on kinect without prior knowledge

As a significant step in artificial intelligence, robot aided object segmentation has drawn increasing attention in past decades. In this paper, a new object segmentation method is proposed based on 3-D information and robot manipulation. We use the Kinect to get the depth information of the object directly as well as the detected contours of it, with which both the primary object segmentation and the 3-D localization of the object can be formed. The usage of Kinect will not only simplify the segmentation process but also improve the performance. Next, the robot arm WAM (Whole Arm Manipulator) with a larger payload is chosen as the manipulator to make further judgment, making it possible to deal with a heavier object. After the manipulation, object segmentation can be accomplished according to the different occasions. Experiments are conducted to prove the effectiveness of this approach.