Mar 2011, Volume 6 Issue 1
    

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  • EDITORIAL
    I-Ming CHEN
  • FEATURE ARTICLE
    I-Ming CHEN, Soo Jay PHEE, Zhiqiang LUO, Chee Kian LIM

    With the advancement in micro- and nanotechnology, electromechanical components and systems are getting smaller and smaller and gradually can be applied to the human as portable, mobile and even wearable devices. Healthcare industry have started to benefit from this technology trend by providing more and more miniature biomedical devices for personalized medical treatments in order to obtain better and more accurate outcome. This article introduces some recent development in non-intrusive and intrusive biomedical devices resulted from the advancement of niche miniature sensors and actuators, namely, wearable biomedical sensors, wearable haptic devices, and ingestible medical capsules. The development of these devices requires carful integration of knowledge and people from many different disciplines like medicine, electronics, mechanics, and design. Furthermore, designing affordable devices and systems to benefit all mankind is a great challenge ahead. The multi-disciplinary nature of the R&D effort in this area provides a new perspective for the future mechanical engineers.

  • RESEARCH ARTICLE
    Chee Kian LIM, Zhiqiang LUO, I-Ming CHEN, Song Huat YEO

    Widely used in the fields of physical and occupational therapy, goniometers are indispensible when it comes to angular measurement of the human joint. In both fields, there is a need to measure the range of motion associated with various joints and muscle groups. For example, a goniometer may be used to help determine the current status of the range of motion in bend the arm at the elbow, bending the knee, or bending at the waist. The device can help to establish the range of motion at the beginning of the treatment series, and also allow the therapist to monitor progress during subsequent sessions. Most commonly found are the mechanical goniometers which are inexpensive but bulky. As the parts are mechanically linked, accuracy and resolution are largely limited. On the other hand, electronic and optical fiber-based goniometers promise better performance over its mechanical counterpart but due to higher cost and setup requirements does not make it an attractive proposition as well. In this paper, we present a reliable and non-intrusive design of an optical-based goniometer for human joint measurement. This device will allow continuous and long-term monitoring of human joint motion in everyday setting. The proposed device was benchmarked against mechanical goniometer and optical based motion capture system to validate its performance. From the empirical results, it has been proven that this design can be use as a robust and effective wearable joint monitoring device.

  • RESEARCH ARTICLE
    Zhiqiang LUO, Chee Kian LIM, I-Ming CHEN, Song Huat YEO

    This paper presents a virtual reality (VR) system for upper limb rehabilitation. The system incorporates two motion track components, the Arm Suit and the Smart Glove which are composed of a range of the optical linear encoders (OLE) and the inertial measurement units (IMU), and two interactive practice applications designed for driving users to perform the required functional and non-functional motor recovery tasks. We describe the technique details about the two motion track components and the rational to design two practice applications. The experiment results show that, compared with the marker-based tracking system, the Arm Suit can accurately track the elbow and wrist positions. The repeatability of the Smart Glove on measuring the five fingers’ movement can be satisfied. Given the low cost, high accuracy and easy installation, the system thus promises to be a valuable complement to conventional therapeutic programs offered in rehabilitation clinics and at home.

  • RESEARCH ARTICLE
    Lin LIN, Mahdi RASOULI, Andy Prima KENCANA, Su Lim TAN, Kai Juan WONG, Khek Yu HO, Soo Jay PHEE

    The recent advances in integrated circuit technology, wireless communication, and sensor technology have opened the door for development of miniature medical devices that can be used for enhanced monitoring and treatment of medical conditions. Wireless capsule endoscopy is one of such medical devices that has gained significant attention during the past few years. It is envisaged that future wireless capsule endoscopies replace traditional endoscopy procedures by providing advanced functionalities such as active locomotion, body fluid/tissue sampling, and drug delivery. Development of energy-efficient miniaturized actuation mechanisms is a key step toward achieving this goal. Here, we review some of the actuators that could be integrated into future wireless capsules and discuss the existing challenges.

  • RESEARCH ARTICLE
    Mahdi RASOULI, Andy Prima KENCANA, Van An HUYNH, Eng Kiat TING, Joshua Chong Yue LAI, Kai Juan WONG, Su Lim TAN, Soo Jay PHEE

    Wireless capsule endoscopy has become a common procedure for diagnostic inspection of gastrointestinal tract. This method offers a less-invasive alternative to traditional endoscopy by eliminating uncomfortable procedures of the traditional endoscopy. Moreover, it provides the opportunity for exploring inaccessible areas of the small intestine. Current capsule endoscopes, however, move by peristalsis and are not capable of detailed and on-demand inspection of desired locations. Here, we propose and develop two wireless endoscopes with maneuverable vision systems to enhance diagnosis of gastrointestinal disorders. The vision systems in these capsules are equipped with mechanical actuators to adjust the position of the camera. This may help to cover larger areas of the digestive tract and investigate desired locations. The preliminary experimental results showed that the developed platform could successfully communicate with the external control unit via human body and adjust the position of camera to limited degrees.

  • RESEARCH ARTICLE
    Guilin YANG, Shabbir Kurbanhusen MUSTAFA, Song Huat YEO, Wei LIN, Wen Bin LIM

    In this paper, an anthropomimetic design of a 7-DOF dexterous robotic arm is proposed. Similar to the human arm, the arm consists of three sequentially connected modules, i.e., a 3-DOF shoulder module, a 1-DOF elbow module, and a 3-DOF wrist module. All three arm modules are also driven by cables in order to mimic the driving scheme and functionality of the human muscles. This paper addresses three critical design analysis issues, i.e., the displacement analysis, the tension-closure analysis, and the workspace analysis. A closed-form solution approach is presented for the forward displacement analysis, while the inverse displacement solution is obtained through an efficient optimization algorithm, in which both task-decomposition and dimension-reduction techniques are employed. An effective tension-closure analysis algorithm is also formulated based on the theory of convex analysis. The orientation workspace for the 3-DOF shoulder and wrist modules are then analyzed using a new equi-volumetric partition scheme based on the intuitive Tilt-and-Torsion angle parameterization. An optimization approach is then investigated for the kinematic design of the three joint modules, in which the design objective is to maximize the matched workspace of the robotic arm joints with that of the human arm joints. A research prototype of the 7-DOF cable-driven robotic arm has also been developed in order to demonstrate the anthropomimetic design concept. With a lightweight structure of 1 kg, the cable-driven robotic arm can carry a payload of 5 kg and has motion repeatability of±2.5mm.

  • RESEARCH ARTICLE
    Fabrizio SERGI, Dino ACCOTO, Nevio L. TAGLIAMONTE, Giorgio CARPINO, Eugenio GUGLIELMELLI

    The choice of non-anthropomorphic kinematic solutions for wearable robots is motivated both by the necessity of improving the ergonomics of physical Human-Robot Interaction and by the chance of exploiting the intrinsic dynamical properties of the robotic structure so to improve its performances. Under these aspects, this new class of robotic solutions is potentially advantageous over the one of anthropomorphic robotic orthoses. However, the process of kinematic synthesis of non-anthropomorphic wearable robots can be too complex to be solved uniquely by relying on conventional synthesis methods, due to the large number of open design parameters. A systematic approach can be useful for this purpose, since it allows to obtain the complete list of independent kinematic solutions with desired properties. In this perspective, this paper presents a method, which allows to generalize the problem of kinematic synthesis of a non-anthropomorphic wearable robot for the assistance of a specified set of contiguous body segments. The methodology also includes two novel tests, specifically devised to solve the problem of enumeration of kinematic structures of wearable robots: the HR-isomorphism and the HR-degeneracy tests. This method has been implemented to derive the atlas of independent kinematic solutions suitable to be used for the kinematic design of a planar wearable robot for the lower limbs.

  • RESEARCH ARTICLE
    Hock Guan TAN, Cheng Yap SHEE, Keng He KONG, Cuntai GUAN, Wei Tech ANG

    This paper describes the Brain Computer Interface (BCI) system and the experiments to allow post-acute (<3 months) stroke patients to use electroencephalogram (EEG) to trigger neuromuscular electrical stimulation (NMES)-assisted extension of the wrist/fingers, which are essential pre-requisites for useful hand function. EEG was recorded while subjects performed motor imagery of their paretic limb, and then analyzed to determine the optimal frequency range within the mu-rhythm, with the greatest attenuation. Aided by visual feedback, subjects then trained to regulate their mu-rhythm EEG to operate the BCI to trigger NMES of the wrist/finger. 6 post-acute stroke patients successfully completed the training, with 4 able to learn to control and use the BCI to initiate NMES. This result is consistent with the reported BCI literacy rate of healthy subjects. Thereafter, without the loss of generality, the controller of the NMES is developed and is based on a model of the upper limb muscle (biceps/triceps) groups to determine the intensity of NMES required to flex or extend the forearm by a specific angle. The muscle model is based on a phenomenological approach, with parameters that are easily measured and conveniently implemented.

  • RESEARCH ARTICLE
    Domenico CAMPOLO, Fabrizio TAFFONI, Domenico FORMICA, Flavio KELLER, Eugenio GUGLIELMELLI

    This paper describes an interdisciplinary approach to the assessment on infants’ behavior, with a focus on the technology. The goal is an objective, quantitative analysis of concurrent maturation of sensory, motor and cognitive abilities in young children, in relation to the achievement of developmental milestones. An instrumented block-box toy specifically developed to assess the ability to insert objects into holes is presented. The functional specifications are derived from experimental protocols devised by neuroscientists to assess spatial cognition skills. Technological choices are emphasized with respect to ecological requirements. An ad hoc calibration procedure is also presented which is suitable to unstructured environments. Finally, preliminary tests carried out at a local day-care with 12–24 months old infants are presented which prove the in-field usability of the proposed technology.

  • RAPID COMMUNICATION
    Xinjun LIU, Chao WU, Fugui XIE
  • RAPID COMMUNICATION
    Xu PEI, Jingjun YU
  • RAPID COMMUNICATION
    Zhihuai MIAO, Yanan YAO
  • RESEARCH ARTICLE
    Xiancheng ZHANG, Fuzhen XUAN, Shantung TU, Binshi XU, Yixiong WU

    The aim of this paper was to address the rolling contact fatigue (RCF) failure mechanisms of plasma-sprayed Cr3C2-NiCr coatings under different tribological conditions of contact stress. Weibull distribution plots of fatigue lives of the coated specimens at different contact stresses were obtained. The failure modes of coatings were identified on the basis of wore surface observations of the failed coatings. Results showed that the RCF failure modes can be classified into four main categories, i.e., surface abrasion, spalling, cohesive delamination, and interfacial delamination. The probabilities of the surface abrasion and spalling type failures were relatively high at low contact stress. When the coatings were subjected to abrasion and spalling type failures, the failure of the coating was depended on the microstrcture of the coating. The stress concentration near the micro-defects in the coating may be the may reason for the formation of spall. The coatings were prone to fail in delamination under higher contact stresses. However, the delamination of coating may be related to distribution of shear stress amplitude within coating. The location of maximum shear stress amplitude can be used as a key parameter to predict the initiation of subsurface cracks within coating in rolling contact.

  • RESEARCH ARTICLE
    Xinjun LIU, Zhidong LI, Liping WANG, Jinsong WANG

    Finding a good solution method for topology optimization problems is always paid attention to by the research field because they are subject to the large number of the design variables and to the complexity that occurs because the objective and constraint functions are usually implicit with respect to design variables. Guide-Weight method, proposed first by Chen in 1980s, was effectively and successfully used in antenna structures’ optimization. This paper makes some improvement to it so that it possesses the characteristics of both the optimality criteria methods and the mathematical programming methods. When the Guide-Weight method is applied into topology optimization, it works very well with unified and simple form, wide availability and fast convergence. The algorithm of the Guide-Weight method and the improvement on it are described; two formulations of topology optimization solved by the Guide-Weight method combining with SIMP method are presented; subsequently, three numerical examples are provided, and comparison of the Guide-Weight method with other methods is made.