Tsuneo Kawano

Speech offsets activate the right parietal cortex

Speech offsets, i.e., sudden transitions from continuous speech sound to silence, activated both hemispheres differently. In addition to peak activities in the bilateral temporal cortices at about 120 ms after the offsets, the right parietal cortex was activated later irrespective of the stimulated ear. The result was discussed in the context of auditory attention.

Estimation Method of Muscle Fatigue and Recovery Progress Using a Muscular Fatigue Model

This study investigated a mechanism of muscle fatigue and proposed a muscular fatigue model to evaluate muscle fatigue progress under several muscular force patterns. Previous studies have already proposed a muscular fatigue model. However, these previous studies discussed about the condition of the maximum voluntary contraction. The new point of this study is considering several muscular force patterns including muscle recovery progress. This study proposed the method to estimate the endurance time for keeping constant forces considering the physical characteristics. This study also proposed the method to estimate the iteration numbers for keeping constant forces with interval. To validate the effectiveness of the proposed method, experimental verifications were conducted. The experimental results had a good agreement with the evaluation of muscle fatigue progress using the proposed method. The results of this study will provide ergonomically safe and efficient working environments considering the physical properties of each worker.

Method of Movement Simulation in Lifting Operation Considering theRole of Antagonistic Muscles and Biarticular Muscle

The efficiency priority working environments without considering the physical property of workers make the workload of workers increased and make the efficiency of workers decreased unintentionally under an aging society with a declining birth-rate. Therefore, it is necessary for plant managers to design the safe and efficient working environment considering the physical characteristic. This study suggested the method to simulate various motion patterns in the lifting operation with the parameters obtained from the actual lifting operations. This study also evaluated the muscle force of each muscle during simulated motions using the musculo-skeletal model considering the role of antagonistic muscles and biarticular muscle. Therefore, this study evaluated the quality of various lifting operation patterns from the muscle force point of view. As a result, this study succeeded to simulate various motions considering the role of antagonistic muscles and biarticular muscle related to the physical characteristic. The results of this study will make it possible to allocate workers optimally and result in a productivity improvement of industry.

EVALUATION METHODS FOR DRIVING PERFORMANCE USING A DRIVING SIMULATOR UNDER THE CONDITION OF DRUNK DRIVING OR TALKING DRIVING WITH A CELL PHONE

ABSTRACT The purpose of this study is to fabricate a driving simulator and establish the methods to evaluate the driving performance using the simulator under the condition of drunk driving or talking driving with a cell phone. Two indices are proposed to evaluate the driving performance. One is the degree of unsteadiness of the driving path and the other is the reaction time in pressing the brake pedal with a foot. The degree of unsteadiness is defined as composition of the degree of weaving from side to side and the degree of fluctuating of the distance between cars. Using the driving simulator experiments were carried out for six subjects. As a result it is demonstrated that the drunk driving or the talking driving with a cell phone are evaluated appropriately.

Physical and Physiological Synchrony Between Care Worker and Care Recipient During Care Operation

Musculoskeletal disorders are a widespread affliction among nurses at nursing-care facilities in general. Nursing proficient skills are supposed to make the disorders reduce and also to lead to tender care for the care recipients. Tacit knowledge such as “proficient skills” and “knacks” in nursing care skills seems not to be applied by care worker alone but by the interaction between care worker and care recipient. The purpose of this study is to examine the physical and physiological synchrony between care worker and care recipient during care operation. It is also to reveal the relationship between the synchrony and physical loads, and the relationship of cerebral activities between them. Experiments of the care operations were carried out in the care worker-recipient pairs. In the experiments the care recipient gave two kinds of roles. One was to act a physically unimpaired person, and the other was to act a bedridden person that was unable to move on his/her own. The body motions, muscle loads, and cerebral activities of the care worker and care recipient were measured using two sets of motion capture, EMG device, and near-infrared spectroscopy (NIRS), respectively. Experimental results indicated that the muscle loads of care worker decreased when the temporal changes of physical and physiological data of the care worker and care recipient got into synchronization. Furthermore, in that case the cerebral activities of the care recipient were synchronized with those of the care worker.

Simulation Method of Working Condition in Lifting Operation Considering the Role of Antagonistic Muscles and Biarticular Muscle

The efficiency priority working environments without considering the physical property of workers make the workload of workers increased and make the efficiency of workers decreased unintentionally. Therefore, it is necessary for plant managers to design the safe and efficient working environment considering the physical characteristic. The objective of this study is to propose the method to determine the optimal working condition considering the physical characteristic of each worker in the lifting operation. To this end, this study suggested the method to simulate working condition considering muscle forces during motion in the lifting operation, and evaluated the muscle force of each muscle during motion using the musculo-skeletal model considering the role of antagonistic muscles and biarticular muscle. Accordingly, the optimized workable weight for each worker was estimated. As a result, this study can be used to simulate the optimized working condition considering the physical characteristics including muscle forces. This study may help the plant manager to design the working condition and determine personnel distribution according to physical characteristic of worker.

Promotion Methods of Job Redesigning for Elderly Workers on the Production Line

A shortage of labour force at production sites is a concern in ”an aging society with a fewer children”. In such a society, it is important to improve working environments in which workers are able to continue on the job up to the age of 65. To this end, it is necessary to effectively employ elderly workers systematically and continuously, to plan for the long term while paying attention to overall surroundings and not focusing merely on partial and temporary improvements, and to work for the empowerment of elderly workers. Therefore, job redesigning that takes into consideration the ergonomics of operations which middle-aged and elderly workers can perform on production lines easily, safely, comfortably, and without undue strain, is necessary. In light of the expansion of workplaces accommodating of elderly workers, in this study we propose four countermeasures, based upon specific evidence, with the objective of advancing the streamlining of job redesigning for middle-aged and elderly workers along the production line.

DEVELOPMENT OF MEASURING DEVICE FOR LOWER LEG SWELLING DURING STANDING WORK TASKS

ABSTRACT In this study a measuring device called as SWELL (Sensoring Wire for Edema of Lower Leg) has been developed in order to measure the lower leg swelling of the worker during the standing work tasks. The device consists of a flexible wire, a coil spring, and a flat spring with a strain gauge. The wire is wound around the lower leg with proper tension and the strain of the flat spring produces when the leg swelling develops. The characteristics of the device, such as linearity, hysteresis, drift, and thermal behavior, are demonstrated. Experiments were carried out to measure the swelling of the lower leg for thirteen subjects. The results showed that SWELL was continuously able to measure the leg swelling defined as the increase of the circumference length of the leg, the magnitudes of the swelling increased almost linearly, and the measured average magnitudes were 3.0mm after standing for 30 minutes. In addition, a strong correlation was shown between the swelling magnitude estimated by digital camera method and the one measured with SWELL.

Interferences of Semantic and Spatial Information Processing in Dual Task Performance between Cell Phone Talk and Driving

The purpose of this study is to examine the degradations of driving and talking performances due to interferences of semantic and spatial information processing during dual task performances between cell phone talk and driving. The color and geographical information fed into the ears through the cell phone is classified into semantic and spatial information in cerebral activities, respectively. The information regarding traffic signal and road scene perceived by the eyes in driving task is similarly classified. The interferences due to the combinations of their information were experimentally investigated using a driving simulator. Traveling instability and time lag of braking operation were measured as well as reaction time of listening task while driving. As a result, degradations of driving performances and reactions to listening task became more distinguished in case the same kind of information both from visual and auditory organs was processed simultaneously.

Development of micro positioning table with high functions based on pattern recognition of load and its applications to ceramic grinding.

A piezoelectrically actuated micro positioning table (MPT) which can be retrofitted to enhance the performance of the conventional ceramic grinding machine has been developed. A microcomputer-based control system for the MPT has been established to enable detection of the force acting on the MPT as well as small depth of cut; It has been attested that the increase of force acting on the MPT can be estimated with 1.25N resolution by the increase of control input voltage (CV value) to manipulate the MPT. The experimental results in grinding of ceramics show that the MPT can give better versatility to enable operations such as initial setting up of wheel depth of cut, automated surface grinding, formation of micro profiles on the surface, and in-process compensation of machining errors.