Extravehicular Activity Glove Research Articles

Effects of EVA glove on hand dexterity at low temperature and low pressure

Hand dexterity is an important index to assess whether extravehicular activity (EVA) gloves are appropriately designed. Pressurized gloves and low temperature environments can both cause a decrease in hand dexterity. However, due to the difficulty in performing tests under extreme conditions, there has been no report on dexterity tests with gloves under pressure and low temperature. To fill this gap, we performed a dexterity test of EVA gloves with twelve male volunteers involved under the extreme conditions, which were created in the low-pressure simulation cabin with vaporized liquid nitrogen used to cool it down. A total of nine conditions were designed. Purdue pegboard test and nut fastening test were improved before being applied in a hand dexterity test. Completion times for both tests, finger temperatures and cold feeling of the hand were recorded and analyzed. Results showed that the completion times for both tests increased either as the temperature decreased or as the pressure increased. Furthermore, a combined effect of low temperature and pressure was observed. The study provides evidence in support of astronaut training and optimization of EVA glove productivity.

WSGC NASA Internship Final Report

This report describes the activities carried out during a 10-week, full-time internship at NASA’s Johnson Space Center (JSC) in Houston, Texas. As an intern on the Space Suit Assembly (SSA) Development Engineering team, I contributed to several ongoing projects related to the advancement of Extravehicular Activity (EVA) space suits. Current EVA suits were designed for limited activities and usage time, and projected requirements of future exploration missions necessitate research into new suit components and materials. During my internship, I contributed mainly to the testing protocol for upcoming High-Performance EVA Glove (HPEG) testing, tasks for Z-2 suit testing, and studied the effects of radiation on space suit materials.

WSGC NASA Internship Final Report

This report describes the activities carried out during a 10-week, full-time internship at NASA’s Johnson Space Center (JSC) in Houston, Texas. As an intern on the Space Suit Assembly (SSA) Development Engineering team, I contributed to several ongoing projects related to the advancement of Extravehicular Activity (EVA) space suits. Current EVA suits were designed for limited activities and usage time, and projected requirements of future exploration missions necessitate research into new suit components and materials. During my internship, I contributed mainly to the testing protocol for upcoming High-Performance EVA Glove (HPEG) testing, tasks for Z-2 suit testing, and studied the effects of radiation on space suit materials.

Effects of EVA gloves on grip strength and fatigue under low temperature and low pressure

ObjectiveTo study the effects of wearing extravehicular activity (EVA) gloves on grip strength and fatigue in low temperature, low pressure and mixing of two factors (low temperature and low pressure). MethodsThe maximum grip strength and fatigue tests were performed with 10 healthy male subjects wearing gloves in a variety of simulated environments. The data was analysed using the normalization method. ResultsThe results showed that wearing gloves significantly affected the maximum grip strength and fatigue. Pressure (29.6, 39.2 kPa) had more influence on the maximum grip compared with control group while low temperatures (−50, −90, −110 °C) had no influence on grip but affected fatigue dramatically. The results also showed that the maximum grip strength and fatigue were influenced significantly in a compound environment. ConclusionsSpace environment remarkably reduced strength and endurance of the astronauts. However, the effects brought by the compound environment cannot be understood as the superimposition of low temperature and pressure effects.

Towards an underactuated finger exoskeleton: An optimization process of a two-phalange device based on kinetostatic analysis

The current paper deals with the kinetostatic analysis and consequent optimization of an underactuated mechanism, whose aim is to constitute an exoskeleton device, designed to enhance the force of the human finger with whom it is coupled. Given an exoskeleton architecture, optimal from the point of view of the simplicity, the geometric parameters are further optimized, to let the transmitted forces be as similar as possible to the specific force profile, set as a reference for the device. In particular, extra-vehicular activity (EVA) for astronauts is recognized as a possible field for hand exoskeletons, since EVA gloves are very demanding in terms of strength and fatigue. Thus, the force profile for a specific EVA glove is provided as an example, and different optimized devices are obtained from the stochastic optimization process. Their kinetostatic performances are hence analyzed and discussed, thanks to a properly defined performance index. Finally, a verification of the actual encumbrance of the synthesized structure is performed, with respect to EVA-specific constraints.

A new method of measuring the stiffness of astronauts' EVA gloves

Hand fatigue is one of the most important problems of astronauts during their missions to space. This fatigue is due to the stiffness of the astronauts' gloves known as Extravehicular Activity (EVA) gloves. The EVA glove has a multilayered, bulky structure and is pressurized against the vacuum of space. In order to evaluate the stiffness of EVA gloves, different methods have been proposed in the past. In particular, the effects of wearing an EVA glove on the performance of the hands have been published by many researchers to represent the stiffness of the EVA glove. In this paper, a new method for measuring the stiffness of EVA gloves is proposed. A tendon-actuated finger probe is designed and used as an alternative to the human index finger in order to be placed inside an EVA glove and measure its stiffness. The finger probe is equipped with accelerometers, which work as tilt sensors, to measure the angles of its phalanges. The phalanges are actuated by applying different amount of torque using the tendons of the finger probe. Moreover, a hypobaric glove box is designed and realized to simulate the actual operating pressure of the EVA glove and to measure its stiffness in both pressurized and non-pressurized conditions. In order to prove the right performance of the proposed finger probe, an Orlam-DM EVA glove is used to perform a number of tests. The equation of stiffness for the PIP joint of this glove is extracted from the results acquired from the tests. This equation presents the torque required to flex the middle phalanx of the glove. Then, the effect of pressurization on the stiffness is highlighted in the last section. This setup can be used to measure the stiffness of different kinds of EVA gloves and allows direct, numerical comparison of their stiffness.

Cursor Control Device Test Battery: Development and Application

A test battery was developed for cursor control device evaluation. Four tasks were taken from ISO 9241–9, and three from previous studies conducted at NASA. The tasks focused on basic movements such as pointing, clicking, and dragging. Four cursor control devices were evaluated with and without Extravehicular Activity (EVA) gloves to identify desirable cursor control device characteristics for NASA missions: a large trackball, a Hulapoint mouse, a small trackball, and an aircraft trackball. Conclusions include: 1) the test battery is an efficient tool for differentiating among input devices; 2) devices used with gloves have to be larger, and should allow good hand positioning to counteract the lack of tactile feedback; 3) none of the devices, as designed, were ideal for operation with EVA gloves.

Study on functional relationships between ergonomics indexes of manual performance

This paper investigates functional relationships between some of the key ergonomics indexes in manual performance, and attempts to condense the ergonomics appraisal indexes system and thus evaluate hand performance wearing EVA (extravehicular activity) glove, design and improve EVA glove's performance. Four types of ergonomics indexes were studied, i.e., dexterity, tactile sensibility (TS), strength and fatigue. Two test items of insert sticks into a holes-board (ISIHB) and nuts–bolts assembly task (NBAT) were used to measure dexterity, while shape discrimination (SD) was employed for TS, and grip force (GF) for strength and fatigue. The variables measured in this investigation included accomplishing time (AT) of ISIHB and NBAT, correct rate (CR) of SD, maximal grip force (MGF), instant grip force (IGF) and endurance time of grip force ( ET GF ) . Experiments were conducted on 31 undergraduates (eight female and 23 male) with two experiment conditions of bare-hand group and gloved hand group. Results demonstrated that dexterity and TS performance of gloved hand group declined significantly compared with those of bare-hand group ( p < 0.001 ) . There were not significant differences in strength and fatigue between two conditions ( p > 0.05 ) . Four effective functional relationships were developed between four pairs of ergonomics indexes in bare-hand group. In gloved hand group, in addition to above-mentioned four pairs of relationships, another formula was found, which was y ^ = 0.02061 + 0.01233 x ( p < 0.01 , dexterity and TS).

Proposal of a SkilMate Hand and its component technologies for extravehicular activity gloves

In this study, we propose a SkilMate Hand for space extravehicular activity gloves which is equipped with devices of both a power assist and a tactile media. The paper focuses on development of component technologies for constructing a SkilMate Hand, which is proposed for recovering deteriorated haptic sensation in human hands. First, we manufacture a power assist device which compensates the bending moment exerted at a human finger joint utilizing a standing-wave-type ultrasonic motor. We plot the examined characteristics, propose a control policy of the actuators and show some control perforce in Bode plots. Second, we produce a tactile media device which is composed of a vibrotactile sensor element on the outer side and a vibrotactile display element on the inner side at the fingertips of the SkilMate Hand. Piezo-rubber is chosen to be used as a vibrotactile sensing transducer whose sensing performance is examined in the extremely high/low-temperature regions. We locate SkilMate in a wider framework of wearable intelligent machines which assist in affording such working surroundings that they can exhibit their skills in spite of their necessity for wearing special suits typical in hazardous environments. A proposal of a wearable intelligent machine such as that of a SkilMate with its concept has not been made before.

The effects of extra vehicular activity (EVA) gloves on human performance

Human strength and capabilities such as dexterity, manipulability, and tactile perception are unique and render the hand as a very versatile, effective, multipurpose tool. This is especially true for unknown microgravity environments such as the EVA environment. Facilitation of these activities, with simultaneous protection from the cruel EVA environment, are the two, often conflicting, objectives of glove design. The objective of this study was to assess the effects of EVA gloves at different pressures on human hand capabilities. A factorial experiment was performed in which three types of EVA gloves were tested at five pressure differentials. The independent variables tested in this experiment were gender, glove type, pressure differential, and glove make. Six subjects participated in an experiment in which a number of dexterity measures such as time to tie a rope, and the time to assemble a nut and bolt, were recorded. Tactility was measured through a two-point discrimination test. The results indicate that (a) With EVA gloves there is a considerable reduction in both strength and dexterity performance; and (b) performance decrements increase with increasing pressure differential. Some interesting gender glove interactions were observed, some of which may have been due to the extent (or lack of) fit of the glove to the hand. The implications for the designer are discussed.

The Effects of Extra Vehicular Activity (EVA) Gloves on Dexterity and Tactility

Human capabilities such as dexterity, manipulability, and tactile perception are unique and render the hand as a very versatile, effective and a multipurpose tool. This is especially true for unknown microgravity environments such as the EVA environment. Facilitation of these activities, with simultaneous protection from the cruel EVA environment are the two, often conflicting, objectives of glove design. The objective of this study was to assess the effects of EVA gloves at different pressures on human hand capabilities, A factorial experiment was performed in which three types of EVA gloves were tested at five pressure differentials. The independent variables tested in this experiment were gender, glove type, pressure differential, and glove make. Six subjects participated in an experiment where a number of dexterity measures, namely time to tie a rope, and the time to assemble a nut and bolt were recorded. Tactility was measured through a two point discrimination test. The results indicate that a) With EVA gloves there is a considerable reduction in dexterity, b) performance decrements increase with increasing pressure differential, and c) some interesting gender glove interactions were observed, some of which may have been due to the extent (or lack of) fit of the glove to the hand. The implications for the designer are discussed.

The test methodology used for the evaluation of the hermes extra vehicular activity glove and preliminary results

Several spring–damper–mass models of the human body have been developed in order to reproduce the measured ground vertical reaction forces during human running (McMahon and Cheng, 1990; Ferris et al., 1999; Liu and Nigg, 2000). In particular, Liu and Nigg introduced at the lower level of their model, i.e. at the interface between the human body and the ground, a nonlinear element representing simultaneously the shoe midsoles and the ground flexibility. The ground reaction force is modelled as the force supported by this nonlinear element, whose parameters are identified from several sets of experimental data. This approach proved to be robust and quite accurate. However, it does not explicitly take into account the shoe and the ground properties. It turns out to be impossible to study the influence of shoe materials on the impact force, for instance for footwear design purposes. In this paper, a modification of the Liu and Nigg's model is suggested, where the original nonlinear element is replaced with a bi-layered spring–damper–mass model: the first layer represents the shoe midsole and the second layer is associated with the ground.Ground is modelled as an infinite elastic half-space. We have assumed a viscoelastic behaviour of the shoe material, so the damping of shoe material is taken into account. A methodology for the shoe-soles characterization is proposed and used together with the proposed model. A parametric study is then conducted and the influence of the shoe properties on the impact force is quantified. Moreover, it is shown that impact forces are strongly affected by the ground stiffness, which should therefore be considered as an essential parameter in the footwear design.

The Effect of Pressure Suit Gloves on Hand Performance

The effects of pressure gloves on human hand capabilities is a major concern in the performance of extravehicular activity (EVA) for space maintenance and construction missions. The effects of EVA gloves on six hand performance domains was investigated in this NASA sponsored research. They were range of motion, strength, tactile perception, dexterity, fatigue, and comfort. All tests were designed to be performed in a glove box using the barehand as well as the glove at 0 and 4.3 pressure differentials. Ten subjects participated in the test in a repeated measures design. The results of the experiments are summarized in this paper.