Abstract of Special Research Report (SRR-No.16)
National Institute of Occupational Safety and Health, Japan
Development of Devices and Working Systems for Promoting Safety of Aged Workers (Second Report)
Introduction
SRR-No.16-1 |
Shigeo UMEZAKI and Soichi KUMEKAWA |
: As the aging society becomes actuality in Japan, an expansion of working fields and promoting safety for aged workers have become matters of great concern. For this trend, the specific research on "Development of Devices and Working Systems for Promoting Safety of Aged Workers" was conducted from 1990 to 1994.
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Development of Safety Control System of Heavy Work Handing by the Cooperative Control of Crane and Manipulator
SRR-No.16-2 |
Noboru SUGIMOTO and Hiroyasu IKEDA |
: The handling of a heavy work, for example, an operation to change heavy dies of a large press machine or injection machine, is a dangerous task. A crane is one of the suitable mechanisms to handle the heavy work, but it makes the suspended work vibration. In construction sites of building, many aged workers engage in handling a crane-loaded heavy work and they suffer from accidents of impact or crushing with the heavy work. |
Development of Chasing Carriage Vehicle
SRR-No.16-3 |
Hiroyasu IKEDA and Noboru SUGIMOTO |
: There are still lots of manual handling works in which aged workers are engaged. In these manual working conditions, aged workers often use carriage vehicles, such as hand trucks and hand carts, in order to support their physical strength. |
Development of Safety Systems of Automated Warehouses for Assisting Aged Workers
SRR-No.16-4 |
Shigeo UMEZAKI,Kiyoshi FUKAYA, Soichi KUMEKAWA and Shoken SHIMIZU |
: There are many non-steady operations in automated warehouses such as trouble-shooting, picking, repairing and maintenance. In order to conduct these operations, workers are sometimes forced to climb up to the heights, to confirm safety over wide areas by their own eyes, or to carry out their work without stopping stacker cranes. They are required to have physical abilities such as good body balance, quick response and good eyesight, but these abilities naturally declines with age. As a result, aged workers sometimes meet with serious accidents during above operations.
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Development of Safety Device of Laser Beam Type for Compensating Visual Ability of Aged Workers
SRR-No.16-5 |
Shigeo UMEZAKI, Kiyoshi FUKAYA and Hiroyasu IKEDA |
: In automated warehouses, workers are forced to confirm a human absence in a movable range of a stacker crane before they operate it. Especially for aged workers, whose visual abilities decline with age, it is extremely difficult to confirm the human absence. As a result, aged workers may start it erroneously in spite of the human existence in the movable range of a stacker crane.
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Start-up Alarm System for Reducing Work Load on Aged Workers
SRR-No.16-6 |
Kiyoshi FUKAYA |
: Before a start-up of a large machine, such as an automatic warehouse and a long belt conveyor, it is indispensable to confirm the safety condition, which means nobody is in the movable zone of the machine. In many cases this safety confirmation should be conducted by the operator of the machine, but it is difficult especially for an aged worker who is weak-sighted. Because actually many accidents occurred in the start-up process, safety measures which assist the operator to confirm safety are needed.
This system consists of an operation block, an alarm generation block, a sound detection block and a control block. The start-up sequence begins by start-up operation, which makes the alarm sound. When the sound detector detects the alarm, it triggers an on-delay timer to count the time for escape. When the time is up, the machine is powered. If any element of the system fails, the sequence stops at this failure. |
Logical Study on Danger Zone Guard System in Automated Warehouses
SRR-No.16-7 |
Kiyoshi FUKAYA, Soichi KUMEKAWA and Shigeo UMEZAKI |
: Safety measures were analyzed logically from the standpoint of protection against a danger zone. In this analysis an accident is represented logically by coexistence of a man and a machine. Consequently basic principle of safety measures is a spatial or temporal separation of a man and a machine. Spatial separation means a division of the space into a danger zone in which machinery moves and a safety zone in which men exist. Temporal separation means stop of machinery during men's existence in the danger zone. To control separation, an interlock structure is needed. There are two type of interlock. One is an interlock to human and another is an interlock to machine. If there is no time delay in control system, either interlock can realize the separation. But there is a time delay in any control system and it must be compensated in control structure. There are two methods of compensation. One is "the confirmation precedence method" in which both type of interlock structure are applied, that is, a human entrance into the danger zone is permitted after confirming stop of the machine and start of machine operation is permitted after nobody's existence in the danger zone. Another is "the prediction method" in which a human approach to the danger zone is predicted and a machine is stopped. This method is an enhancement of an interlock to machine and control is based not only on the human existence in the danger zone but also on the prediction of human existence. Therefore certainty of the prediction and of control, especially stop control of machine, is needed. |
Conclusion
SRR-No.16-8 |
Shigeo UMEZAKI and Soichi KUMEKAWA |
: The aim of this specific research was to promote safety of aged workers engaged in nonsteady operations. To realize this purpose, several safety measures were proposed based on physical and mental characteristics of aged workers. Results of these studies are summarized as follows.
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