Junichi Higuchi

Sit-to-stand assist system by using handrail and electric bed moving up and down

In this paper, we propose a user adaptive support system for sit-to-stand movement from a bed. The support system consists of a handrail and an electric bed which moves up and down. The evaluation indexes for the sit-to-stand movement based on a human model are introduced. By using these indexes, we set the parameters of the support system such as the handrail position, the height of the bed, and the foot position, for stabilizing the userpsilas posture and reducing the burdens of the userpsilas muscles. The parameters of the support system are determined according to the body size and the disability of the user, and the experimental results illustrate the validity of the method for setting the handrail position, the height of the bed, and the foot position.

Self-help standing-up method based on quasi-static motion

When supporting standing-up motion, a caregiver takes advantage of gravity force to make sufficient momentum without bearing heavy burden. The physical abilities or decision-making abilities decrease for many of elderly people who need care. We propose a self-help standing-up method for such people. The method with quasi-static motion in which the acceleration is approximated to zero, so as to keep safety at the time of emergency, is preferable. However, the quasi-static motion gives heavy burden to a caregiver because it cannot make efficient use of inertia force by the help of gravity force. Compared to human assist, mechanical system can easily realize the quasi-static motion, since a mechanical system has an ability to hold a large force. However, a quasi-static motion trajectory has to be newly-developed because it is not well known. Therefore, we propose the mechanical system and a quasi-static method for supporting standing-up motion. As an example, the method using artificial upper body constraint, and fitted to physical characteristics of each patient have been proposed. This system is found to be the effectiveness.

Identifying propagated response delays in performance monitoring of n-tier applications

One of the significant challenges on performance monitoring of an n-tier system is the “response delay propagation”, in which a response delay in a component server is propagated to other component servers due to the invoking relations among request types in different component servers of the system. It leads the operations manager of the system to misdiagnose the location of source delays and results in wasting time to investigate the root cause. We developed a response delay monitoring system that helps the operations managers distinguish the source delays from many other propagated delays. The system is able to build a model of invoking relations among request types in different component servers and use the model to diagnose the response delay propagation and pin-point the location of source response delays. To obtain such invoking relations among request-types from black-box component servers in an n-tier system, we propose a novel invoking relation estimation method which can achieve high accuracy of true invoking relation among request types by eliminating the negative influence of two spurious correlation factors through partial correlation analysis. We implemented the response delay monitoring system and evaluated the effectiveness of our invoking relation estimation method on a real in-company n-tier system which has thousands of request-types in each tier. The result (over 90% in precision) confirms our estimation method can effectively capture invoking relations in an n-tier system.