Zhuohua Lin

A Methodology for the Performance Evaluation of Inertial Measurement Units

This paper presents a methodology for a reliable comparison among Inertial Measurement Units or attitude estimation devices in a Vicon environment. The misalignment among the reference systems and the lack of synchronization among the devices are the main problems for the correct performance evaluation using Vicon as reference measurement system. We propose a genetic algorithm coupled with Dynamic Time Warping (DTW) to solve these issues. To validate the efficacy of the methodology, a performance comparison is implemented between the WB-3 ultra-miniaturized Inertial Measurement Unit (IMU), developed by our group, with the commercial IMU InertiaCube3™ by InterSense.

Development of the wireless ultra-miniaturized inertial measurement unit WB-4: Preliminary performance evaluation

This paper presents the preliminary performance evaluation of our new wireless ultra-miniaturized inertial measurement unit (IMU) WB-4 by compared with the Vicon motion capture system. The WB-4 IMU primarily contains a mother board for motion sensing, a Bluetooth module for wireless data transmission with PC, and a Li-Polymer battery for power supply. The mother board is provided with a microcontroller and 9-axis inertial sensors (miniaturized MEMS accelerometer, gyroscope and magnetometer) to measure orientation. A quaternion-based extended Kalman filter (EKF) integrated with an R-Adaptive algorithm for automatic estimation of the measurement covariance matrix is implemented for the sensor fusion to retrieve the attitude. The experimental results showed that the wireless ultra-miniaturized WB-4 IMU could provide high accuracy performance at the angles of roll and pitch. The yaw angle which has reasonable performance needs to be further evaluated.

Development of an ultra-miniaturized inertial measurement unit WB-3 for human body motion tracking

Real-time tracking of human body motion is an important technology in synthetic environments, robotics, and other human-computer interaction applications. This paper presents an ultra-miniaturized inertial measurement unit (IMU) named WB-3 for real-time attitude estimation of human limb segments. The WB-3 IMU is provided with a 32-bit microcontroller and 9-axis inertial sensors (miniaturized MEMS accelerometer, gyroscope and magnetometer). The quaternion-based Extended Kalman Filter (EKF) was implemented for the sensor fusion to retrieve the attitude of the human segment. An upper body motion capture system with 12 WB-3 IMUs was elaborated for tracking human movements in real time scenarios.

Development of the miniaturized wireless Inertial Measurement Unit WB-4: Pilot test for mastication analysis

Mastication analysis can provide an objective basis for studying and diagnosing jaw musculoskeletal disorders. Therefore, the use and development of devices for quantitatively measuring and analyzing jaw movement have become very popular in the consulting room. This paper proposes a simple to be used jaw tracking prototype by using the new miniaturized wireless Inertial Measurement Unit (IMU) named WB-4. The WB-4 EVTU primarily contains a mother board, a Bluetooth module and a Li-Polymer battery. The mother board is provided with a microcontroller and 9-axis inertial sensors (miniaturized MEMS accelerometer, gyroscope and magnetometer) to measure the jaw motion. The data transmission between WB-4 and PC is based on the Bluetooth module to realize the wireless communication. The IMUs extremely reduced weight and size allows it to be easily attached to mandible during normal mastication tests without physical restriction to the subjects. Three pilot experiments for mastication analysis of chewing gum were elaborated. A group of 9 healthy subjects kindly participated in the experiment. The preliminary results show that WB-4 IMU can efficiently evaluate the jaw movement and mastication pattern of different subjects, which could provide quantitative information to the doctors for the diagnosing and clinical treatment of different jaw diseases.

Waseda Bioinstrumentation System #3 as a tool for objective rehabilitation measurement and assessment - Development of the inertial measurement unit -

In our elderly-dominated society, there is considerable expectation for a growing need for home, medical, and nursing care services to assist this aging society, both from the physical and psychological points of view. Among these services, special importance has the rehabilitation process and specifically the clinical assessments of motor abilities. The current rehabilitation process, however, lacks of objectiveness. Our research is aimed at the development of a portable Bioinstrumentation System that can objectively measure and assess the physical and physiological effects of the rehabilitation therapy, both in the hospital/rehabilitation center and at home, by integrating the analysis of human motion into the analysis of physiological indexes. More specifically, objective of this research is to develop a wearable bioinstrumentation system capable of an objective analysis of the physical and psychological conditions of the user during the activities of daily life.

Development of the Ultra-Miniaturized Inertial Measurement Unit WB3 for Objective Skill Analysis and Assessment in Neurosurgery: Preliminary Results

In recent years there has been an ever increasing amount of research and development of technologies and methodologies aimed at improving the safety of advanced surgery. In this context, several training methods and metrics have been proposed, in particular for laparoscopy, both to improve the surgeons abilities and also to assess her/his skills. For neurosurgery, however, the extremely small movements and sizes involved have prevented until now the development of similar methodologies and systems. In this paper we present the development of the ultra-miniaturized Inertial Measurement Unit WB3 (at present the smallest, lightest, and best performing in the world) for practical application in neurosurgery as skill assessment tool. This paper presents the feasibility study for quantitative discrimination of movements of experienced surgeons and beginners in a simple pick and place scenario.

Performance evaluation of the wireless inertial measurement unit WB-4 with magnetic field calibration

This paper presents the performance evaluation of our wireless miniature Inertial Measurement Unit (IMU) WB-4 by compared with the Vicon motion capture system. In particular, a magnetic field calibration method is introduced to improve the sensor orientation estimate accuracy. The WB-4 IMU primarily contains a motherboard for motion sensing, a Bluetooth module for wireless data transmission with PC, and a Li-Polymer battery for power supply. The motherboard is provided with a 32-bit microcontroller and 3-axis miniaturized MEMS accelerometer, 3-axis gyroscope and 3-axis magnetometer to estimate the sensor orientation based on an extended Kalman filter algorithm. In our previous research of WB-4 IMU performance evaluation, the factory calibration parameters of the magnetometer were used for the sensor fusion, which resulted in a higher error on the yaw angle in respect to roll and pitch. This study presents a magnetic calibration method for overcoming that limitation. The experimental results showed that the wireless WB-4 IMU could achieve better orientation performance in all the directions after the implementation of the magnetic calibration method. The yaw angle accuracy was significantly improved from previous error 5.46 degree to 1.77 degree.

Baseline Adaptive Wavelet Thresholding Technique for sEMG Denoising

The surface Electromyography (sEMG) signal is affected by different sources of noises: current technology is considerably robust to the interferences of the power line or the cable motion artifacts, but still there are many limitations with the baseline and the movement artifact noise. In particular, these sources have frequency spectra that include also the low‐frequency components of the sEMG frequency spectrum; therefore, a standard all‐bandwidth filtering could alter important information. The Wavelet denoising method has been demonstrated to be a powerful solution in processing white Gaussian noise in biological signals. In this paper we introduce a new technique for the denoising of the sEMG signal: by using the baseline of the signal before the task, we estimate the thresholds to apply to the Wavelet thresholding procedure. The experiments have been performed on ten healthy subjects, by placing the electrodes on the Extensor Carpi Ulnaris and Triceps Brachii on right upper and lower arms, and performing a flexion and extension of the right wrist. An Inertial Measurement Unit, developed in our group, has been used to recognize the movements of the hands to segment the exercise and the pre‐task baseline. Finally, we show better performances of the proposed method in term of noise cancellation and distortion of the signal, quantified by a new suggested indicator of denoising quality, compared to the standard Donoho technique.

Waseda Bioinstrumentation system WB-2R as a wearable tool for an objective analysis of surgeon's performance

There has been an ever increasing amount of research and development of technologies and methods to improve the safety of surgery such as Minimally Invasive Surgery (MIS). While these new technologies and methods have many advantages for patients, they often require surgeons to undergo long and difficult training. In this context, several training methods and metrics have been proposed, both to improve the surgeons abilities and also to assess his/her skills. Our research is aimed at using WB-2R (Waseda Bioinstrumentation system NO.2 Refined), to investigate and analyze a surgeons movements and performance. In this paper, we analyze the effects of two days of laparoscopic training on a novice subject. By using the Inertial Measurement Unit (IMU) of WB-2R it is possible to evaluate the novices ability and improvement to handle surgical instruments and perform some knots of basic C-Loop suture. The preliminary analysis of the data acquired during the experiments (the mean and standard deviation of acceleration; 95% cumulated distribution of acceleration; the path length of the movements of hands and the execution time completing the knots) clearly shows the novices improvements after the training. WB-2R system could provide additional information improving to help assess the experience and performance of surgeons, and to show the effectiveness of laparoscopic training. These analyses and modeling are an important step to realize a better training/evaluation system for surgeons during MIS, to understand better how the surgery is performed.

Objective skill analysis and assessment in neurosurgery by using an ultra-miniaturized inertial measurement unit WB-3 — Pilot tests —

In recent years there has been an ever increasing amount of research and development of technologies and methods to improve the quality and the performance of advanced surgery. In several fields, such as laparoscopy, various training methods and metrics have been proposed, both to improve the surgeons abilities and also to assess her/his skills. For neurosurgery, however, the extremely small movements and target operating space involved have prevented until now the development of similar methodologies and systems. In this paper we present the development of an ultra-miniaturized Inertial Measurement Unit (IMU) and its application for neurosurgery skill assessment in a simple pick and place scenario. This analysis is a preliminary yet fundamental step to realize a better training/evaluation system for neurosurgeons, and to objectively evaluate and understand how the neurosurgery is performed.