Parametrization of manual work in automotive assembly for wearable force sensing

This research aims to model manual assembly processes by parameterizing operator force readings, specifically for engine and coolant hose connections in an automotive manufacturing line. During automotive assembly, many processes are still performed manually by the human operator due to the complexity of automating the process or product with current technology. Processes include completing hose connections and subsequent “push–pull–push” verification testing. Manual work introduces an opportunity for human error because of natural variation when completing tasks; even a slight inconsistency in operation can lead to an incomplete or missed process. These incomplete processes can pass post-production checks, such as a pressure test, but later loosen and fail, causing rework or warranty issues. To minimize human error, operator force is parameterized to provide real-time feedback to the connection status. The operator force was chosen to classify connections and to verify testing quantitatively. The parametrization was completed by partitioning the shear and normal forces using custom fixtures, with shear being the primary force type required by the process. The varying finger and hand engagement for the different connector locations were factored into the parametrization to encompass a broader range of manually completed tasks. It was found that operator forces in finger engagement for manual assembly could be effectively represented by a limited set of measurable parameters.     

Systematic usability evaluation on two harnesses for a wearable chairless exoskeleton

Harnesses are used in wearable robots in safety, sports, medical, and industrial environments. Wearable robot harnesses for lower extremities should be designed to prevent musculoskeletal disorders caused by excessive strain on the spine and lower extremities when users wear these robots for prolonged periods. Therefore, this study compares and analyzes the usability of the two harnesses—the former (old design) and the latter (new design)—for the Hyundai chairless exoskeleton (CEX). In total, 27 participants took part in this study. The wearability, stability, and overall wearing satisfaction of the former and the latter harnesses were compared. We conducted an experiment where the participants wore the former and the latter harnesses while completing a series of tasks that resembled the ones performed by the workers on a front-end module assembling line of an automobile factory. After the experiment, the participants took part in a survey and semi-structured interviews. The data was analyses by t-test, correlation, and regression analyses. The survey results demonstrated that for the latter harness the cushioning sensation (thigh r = 0.539; calf r = 0.516) had the strongest effect on the overall wearing satisfaction. In addition, the latter harness scored higher in overall wear satisfaction than the previous harness. This study was able to verify the difference between the new and old designs according to the usability evaluation of the harness. The results of this study are considered to be helpful in design to improve the usability of the harness in the future.     

WeHAPTIC-light: A cable slack-based compact hand force feedback system for virtual reality

Various force feedback devices for the hand have been developed for the virtual reality field, but many systems are heavy, and various functions have not been fully developed with respect to finger motion measurement and stiffness generation. We propose a light and wearable force feedback device that can measure finger motion without calibration and can implement different stiffnesses using a cable slack-based mechanism. The proposed system has a small weight of 298 g, using a 10 g motor. To measure finger motion without calibration, an equation for each finger joint angle is derived from the three-dimensional position and orientation information of the fingertip. To realize different stiffnesses, the proposed system connects a motor and a finger structure with a cable; zero impedance is realized by maintaining a slack. The adjustable cable slack mechanism ensures to restrict the finger motion when the fingertip touches the surface of a virtual object even in fast motion; different stiffnesses are realized by proportional control input to the motor according to the deformation of the virtual object. We manufactured a prototype for three fingers and experimentally verified the performance of the proposed system.     

Multiple comparator classifier framework for accelerometer-based fall detection and diagnostic

There are a significant number of high fall risk individuals who are susceptible to falling and sustaining severe injuries. An automatic fall detection and diagnostic system is critical for ensuring a quick response with effective medical aid based on relative information provided by the fall detection system. This article presents and evaluates an accelerometer-based multiple classifier fall detection and diagnostic system implemented on a single wearable Shimmer device for remote health monitoring. Various classifiers have been utilised within literature, however there is very little current work in combining classifiers to improve fall detection and diagnostic performance within accelerometer-based devices. The presented fall detection system utilises multiple classifiers with differing properties to significantly improve fall detection and diagnostic performance over any single classifier and majority voting system. Additionally, the presented multiple classifier system utilises comparator functions to ensure fall event consistency, where inconsistent events are outsourced to a supervisor classification function and discrimination power is considered where events with high discrimination power are evaluated to further improve the system response. The system demonstrated significant performance advantages in comparison to other classification methods, where the proposed system obtained over 99% metrics for fall detection recall, precision, accuracy and F-value responses.     

Triaxial joint moment estimation using a wearable three-dimensional gait analysis system

We developed a wireless sensor system composed of a mobile force plate system, three-dimensional (3D) motion sensor units and a wireless data logger. Triaxial joint moments of the ankle, knee and hip joints were calculated using measurements of the sensor system. The accuracy of the joint moment estimation is validated against results obtained from the reference measurement system composed of a camera based motion analysis system and force plates. Triaxial joint moments measured by the sensor system showed normalized root mean square error (NRMSE) and correlation coefficient (R) of less than 22% and more than 0.80 in comparison with the stationary system.     

Investigation of the relationship between Ironworker’s gait stability and different types of load carrying using wearable sensors

Load carrying can cause changes in gait stability. Maintaining gait stability (body balance) on a steel frame is an important factor in the prevention of accidents. However, the effects of load carrying on a restricted surface (width), where ironworkers usually perform their jobs, have rarely been investigated. In this context, this study investigates the effect of different types of load-carrying scenarios on the gait stability of ironworkers. Accordingly, to identify the relationships between the weight of load, type of load-carrying method, type of load-carrying tools, and gait stability, represented as the dynamic time warping (DTW) values, an experiment was conducted under 15 different load-carrying conditions. The change in DTW according to the different load conditions was as follows: For one-handed load-carrying using a toolbox, the average DTW values were 23.31 at a weight of 3 kg, 23.80 at 6 kg, 33.20 at 10 kg, 65.84 at 16 kg, and 103.50 at 20 kg. Moreover, for one-handed load-carrying using a bucket, the average DTW values were 23.07 at 3 kg, 24.76 at 6 kg, 34.35 at 10 kg, 77.52 at 16 kg, and 108.28 at 20 kg. Finally, in the case of both-handed load carrying, the average DTW values were 24.31 at 6 kg, 28.11 at 10 kg, 27.23 at 16 kg, 37.90 at 20 kg, and 40.96 at 32 kg. As the weight of the load increased, the DTW values in almost all the experimental cases also increased. Furthermore, the DTW values for bucket carrying and tool box carrying showed clear differences above a certain weight (16 kg). Thus, the results of the experiments indicate that different types of load-carrying conditions significantly affect the ironworkers’ gait stability as they walk on a steel frame. Finally, the calculated DTW values were compared with the subjective perceived ratings to validate the experimental results. The DTW value was highly correlated with the subjective perceived rating scores (Pearson coefficient: 0.929). The results of this study will facilitate the use of gait stability measurements to enhance the construction safety of ironworkers.     

Decoupling data-at-rest encryption and smartphone locking with wearable devices

Smartphones store sensitive and confidential data, e.g., business related documents or emails. If a smartphone is stolen, such data are at risk of disclosure. To mitigate this risk, modern smartphones allow users to enable data encryption, which uses a locking password to protect the data encryption key. Unfortunately, users either do not lock their devices at all, due to usability issues, or use weak and easy to guess 4-digit PINs. This makes the current approach of protecting confidential data-at-rest ineffective against password guessing attackers. To address this problem we design, implement and evaluate the Sidekick system — a system that uses a wearable device to decouple data encryption and smartphone locking. Evaluation of the Sidekick system revealed that the proposal can run on an 8-bit System-on-Chip, uses only 4 Kb/20 Kb of RAM/ROM, allows data encryption key fetching in less than two seconds, while lasting for more than a year on a single coin-cell battery.     

Measuring human–robot interaction on wearable robots: A distributed approach

This paper presents a novel, distributed approach to monitor physical interaction between a user and a wearable robot. We propose to apply a matrix of optoelectronic sensors embedded in a thin and compliant silicone bulk onto the user-robot contact surface. This distributed tactile sensor can measure the pressure distribution on the interaction area without affecting the comfort of the user, and does not require the robot to be specifically designed to house it. Besides the estimation of the interaction force/torque, the distributed approach allows to monitor the pressure on the user’s skin. This information is fundamental to assess the comfort and safety of the users which determine the final acceptability of the robot-mediated rehabilitation. The proposed method is preliminary evaluated on an elbow active orthosis during a repetitive rehabilitation task. Experimental results prove the relevance of this approach for the detection of the user motion intention through a measurement of the interaction force distribution.     

基于针织导电织物可演奏音乐的智能服装研究

采用针织方法将导电纱线编织到服装面料中,结合控制芯片和计算机编程,利用微电流触控原理,开发出可演奏音乐的电子智能服装。介绍该智能服装的总体设计思路和系统结构,阐述该智能服装开发过程中的关键技术,包括织物连接件、微电流触控芯片、模块集成与无线连接、以及Action Scrip语言编程。最后举例说明该智能服装的应用,指出该智能服装系统虽然稳定性较好,能满足智能服装的设计要求,但是若要转化为产品在市场上销售,还面临着许多问题,其中芯片的二次研发和小型化问题、无线收发系统的稳定性问题以及软件的深入开发及封装问题有待于进一步完善。     

入球监控技术

显示技术是电子技术领域中发展最快的技术,从最早的CRT显示技术,到液晶显示技术,等离子显示技术、有机发光显示技术等,这些显示技术应用到各种电子产品中,提高了电子产品的性能。近年来,随着可穿戴设备的开发,用于可穿戴设备中的透明显示和柔性显示技术相应成为显示技术的研发热点。本文基于专利文献,对透明显示和柔性显示技术领域的主要申请人以及相关专利技术进行了介绍