Safety performance of gloves using the pressure tolerance of the hand.

Two prototype gloves have been designed and developed at the University of Nebraska-Lincoln. The aim of this study was to evaluate the safety performance of the developed gloves. An experiment was conducted to assess the discomfort threshold level at 12 zones on the palmar surface of the hand for five hand conditions--bare hand, single glove, double glove and two prototype gloves. Prototype I consisted of a glove with an extra layer of glove material applied selectively to critical areas of the hand; while prototype II had up to four layers applied to critical areas. This design increases protection in critical areas without increasing bulk, provides performances comparable with single glove, and improves grip strength. The study was conducted using an algometer device to apply pressure to each of the 12 zones, for all hand conditions. The results indicated that for pressure tolerance, prototype II had the highest pressure-discomfort threshold, while prototype I had a threshold similar to the double layer glove. Pressure discomfort tolerance threshold is greatly increased by the use of gloves, and pressure-discomfort thresholds are raised by 25-65%. The two prototype gloves, although much less bulkier than the double glove, have pressure thresholds that are equal to or superior to that of a double glove. The algometer can be used to assess the safety of glove from mechanical trauma. Hence, the generalizability of the results is somewhat restricted. However, the method of selective protection, without compromising performance appears to be promising and is worth pursuing by glove designers.

The development and evaluation of an ergonomic glove.

The primary intent of this study was to determine if a hand glove could be designed on a criterion of selective protection. Force distribution patterns on the palmar side of hand were obtained from various studies to develop zones of hand that needed protection. A new design for gloves was developed based on the principle of selective protection, where protective material is introduced in varying levels over different parts of the glove, in order to provide protection where it is most needed, and at the same time preserve the desirable dexterity and strength capabilities of the barehand, optimizing the trade-off between protection and performance. Two pairs of prototype gloves incorporating different levels of protection were fabricated and tested using a battery of performance tests and an algometer test for pressure sensitivity. The test battery comprising four dexterity tasks and a maximal voluntary grip strength task was used to assess a number of glove conditions, including the two prototype gloves developed. The results indicate that the performance of the prototype gloves are comparable, and that the performance times for the double glove and the two prototype gloves tested were not significantly different. For the grip strength, the two prototype gloves were better than the double glove. The assembly task performance for the prototype II (laminar glove) was significantly lower than that of the other glove types tested. It appears that gloves of variable thickness can be developed to afford adequate protection at zones of most need. Glove manufacturers are recommended to use an ergonomic approach in the design of gloves. Such an approach, besides protecting the safety objective of gloves, could enhance productivity considerably.

Force-endurance relationship: does it matter if gloves are donned?

The human hand is a very useful multipurpose tool in all environments. However, performance capabilities are compromised considerably when gloves are donned. This is especially true for extra-vehicular activity (EVA) gloves used in a space environment. The primary aim of this study was to establish exertion and endurance limits for specific tasks. The objective of this study was to develop grip force endurance relations. Six subjects participated in a factorial experiment involving three hand conditions, three pressure differentials, and four levels of force exertion. The results indicate that while the force that could be exerted depended on the glove, pressure differential, and the level of exertion, the endurance time at any exertion level depended just on the level of exertion expressed as a percentage of maximum exertion possible at that condition. The impact of these findings for practitioners as well as theoreticians is discussed.

Cognitive ergonomics of a mail order filling company: Part 2--influence of shelf coding and address information on acquisition time.

This is the second part of a study on a mail order picking task. In the first part of the study, recognition time was addressed by varying colour, position and highlighting cues in a computer-simulated version of the picking task. This study addresses the product acquisition time. Shelf coding and continuous presentation of the address information were varied in a factorial experiment in which 14 subjects (seven experts and seven novices) had participated. Experts were slower but more accurate than the novices. Continuous display of address information appears to be a good training aid for implementing new shelf coding systems, and for new operators. Shelf coding effect appears to disappear with practice. A summary of the recommendations is given.

Cognitive ergonomics of a mail order filling company: part 1 - influence of colour, position and highlighting on recognition time.

Filling mail order request forms requires the picker to determine if the items ordered on the form are in his/her bay, reading the bin address and picking the item. An order form was investigated to determine if ergonomics improvements would result in improved productivity and accuracy. Colour, position and highlighting cues were systematically varied in a computer-simulated version of the picking task. It was concluded that colour and position significantly influence the processing time, while highlighting had no effect on processing time. Expert pickers were slower, but more accurate than the novice pickers. Recommendations for improving the order forms were made and implemented, with very encouraging results.

Information processing in assembly tasks--a case study.

In a surface wiring task the terminals of electrical components are connected by wires according to a wiring list. This series of experiments examined one such task in a batch assembly environment where production runs are short. The findings show that information theory is a good predictor of performance, that different sources of information within the task are processed in different ways, and that considerable symmetric transfer can be expected between different batches.