In-Suit Sensor Systems for Characterizing Human-Space Suit Interaction
Abstract
Although the U.S. has studied space suit performance for decades, relatively little is known about how the astronaut moves and interacts within the space suit. We propose the use of in-suit sensor systems to characterize this interaction and present our results using pressure sensors and inertial measurement units (IMUs) inside the David Clark Mobility Mock-Up and the Mark III space suit from NASA’s Advanced Space Suit Lab at the Johnson Space Center. A network of 12 low-pressure sensors are distributed over the arm to measure the pressure between the arm and the suit soft goods. A high-pressure sensor mat is used to detect the pressure between the shoulder and the suit hard upper torso (HUT). Finally, we place three IMUs inside directly on the person’s lower arm, upper arm and torso, with three corresponding IMUs outside on the space suit to measure joint angles. We perform two human subject experiments with 5 movement tasks focusing on upper body motions. The 5 motions include 3 isolated joint movements (elbow flexion/extension, shoulder flexion/extension, and shoulder abduction/adduction) and 2 functional tasks (overhead hammering and multi-join cross body reach). We discuss the implementation of this experiment, our lessons learned, quality of the data, and follow-on work. Finally, we propose future improvements for the characterization of human biomechanics and injury mechanisms from a human-space suit perspective.
... Spacesuits use multiple layers of material; the inner layer that maintains the pressure is a polyurethanecoated nylon pressure suit, the outer layer includes neoprene-coated nylon lining aluminized polyester film insulation, and the outer fabric. In order to give astronauts good mobility, the spacesuit usually uses soft joints in the shoulders, elbows, wrists, and knees Soft joints have a high tensile strength and are made of fabric, rubber, and polymer Extravehicular missions require the astronaut to perform delicate activities, so there is a lot of movement in the joints, as such, the design of the soft structure part is very important [29,30]. The joints are too soft for protection and too hard for flexibility. ...
... Soft joints have a high tensile strength and are made of fabric, rubber, and polymer. Extravehicular missions require the astronaut to perform delicate activities, so there is a lot of movement in the joints, as such, the design of the soft structure part is very important [29,30]. The joints are too soft for protection and too hard for flexibility. ...
The special use environment and uncertainty of extravehicular activities (EVAs) make it difficult to predict the lifetime consumption of extravehicular spacesuits in the traditional way. This paper presents a flexible reliability dynamic simulation model to predict the life loss of extravehicular spacesuits. Based on the images of traditional reliability change curves, new life assessment parameters, based on geometric analysis, are proposed as indicators of spacesuit life loss. Multiple influence factors are used to correct the spacesuit failure rate. The results of the study show that mission intensity is the main factor affecting the health status of the spacesuit, and the higher the mission intensity, the higher the failure rate. Additionally, the more frequently the spacesuit is used, the more times it is available, however, the overall service time will decrease. Concentrating on the mission at an early stage would lead to a significant and irreversible loss of life. Reliability is higher when more intense work is scheduled later in the EVA. Therefore, it is important to rationalize the mission duration, frequency, and work intensity of spacesuits. These reliability models predict the health status of the spacesuit and assist in optimizing the scheduling of EVA.
... Threats to mission success can arise from inefficient EVA due to decreased astronaut range of motion and increased injury risk in the EMU [4]. Work has also been performed analyzing how the biomechanical interaction between the astronaut and space suit impacts the fatigue and discomfort that astronauts experience [13]. Though more recent space suits, such as the Mark III, have been developed to further planetary exploration capabilities, excessive joint torques in the hip lead to impeded mobility and agility of astronauts during locomotion [14]. ...
... The major advantage of hard joint is that torque moment derived by bearing friction is less than other kinds of hip joint. Therefore, hard hip joint has been widely applied to some spacesuits, such as the Z series spacesuit [3] and Mark III spacesuit [4]. On the other hand, the primary problem of hard joint is that the placement of bearings causes programming and potentially unnatural movement and stances. ...
Spacesuit hip joint plays an important role on astronaut activities, such as planetary walking and surveying. This paper proposes a conceptual design of hard hip joint in consideration of the coupling effect of spacesuit hip joint and astronaut thigh. Firstly, lower extremity activities are introduced to illustrate the mobility of hard hip joint, such as walking, kneeing, and abduction. A conceptual design of hard hip joint is explained in detail, including geometric structure, components, design parameters, and mechanism models. Secondly, a 3-linkage coupling mechanism model is built up by synthesizing that conceptual design of hard hip joint. An equiangular dual-perpendicular representation method is brought out to parameterize that mechanism model of hard hip joint. Particularly, four geometric constraints are, respectively, given out to avoid impact between the hip joint and the thigh and to ensure the continuity of thigh motion. Finally, motion equations of hip joint parts are established by using coordinate transformation and vector representation. A case study is conducted to verify the correctness of the proposed representation method and that coupling mechanism model.
We propose a technique for remotely measuring the gap between an external wearable device/clothing surface and the underlying (visually obstructed) body surface – which we refer to as the garment-body ’air gap’ – that commonly occurs in positive ease garments (i.e., garments that are larger in dimension than the underlying body dimension). To achieve this, we developed a triple-frequency band remote measurement system based on a 77-81 GHz FMCW radar, a 40kHz ultrasound sensor, and an infrared 344 GHz proximity sensor. When used synergistically, these sensors allow for remote measurement of the uniaxial distances to multiple layered surfaces simultaneously. To validate this approach, a test setup was developed to mount multiple surfaces at variable distances from the sensor suite. The sensor suite, when activated, can provide measurements at different configurations and distances from 3-60 cm. To provide a single measurement for the infrared/ultrasonic sensors, a logistic regression-based model was utilized, reducing the surface estimation error (RMSE) from 1.610 mm and 4.728 mm for the ultrasonic and infrared sensors, respectively, to 0.41 mm. Results show that the current first-generation multi-sensor system is able to find the air gap between a fabric surface and an underlying body-like surface with an accuracy of 2.6 mm (measured in RMSE). The developed system shows potential to allow non-invasive assessment of functional garments such as hazmat suits, PPE, space suits, and everyday clothing, offering valuable wearer interaction insights without relying on post-hoc simulations or physical sensors, enabling better design and evaluation of garments.
Astronauts usually are forced to work in harsh environments, facing challenges related to living in microgravity conditions, operating in outer space, or even exploring planets with unknown pathogens and viruses. To this end, it is essential to provide astronauts easy tools to monitoring their health status with low cost and fast diagnostic methods. Indeed, undetected damages occurring at one crew member can compromise an entire mission and worst, it can cause the death for all the other crew members. In this respect, biosensors can offer valuable solutions. Among different biosensing techniques, Raman sensing can provide information on complex organic compounds like proteins, enzymes, DNA mutations etc. Here we present a low cost and totally label free Raman platform based on silver-coated zinc oxide nanostructures to reveal biomarkers and chemical alterations in human fluids like saliva or blood, without the need of sample processing.
Body compression through a garment or inflatable pneumatic mechanism has various applications in aesthetic, athletic, robotics, haptics, astronautics, and especially medical fields for treatment of various disorders such as varicose veins, lymphedema, deep vein thrombosis , and orthostatic intolerance. Traditionally, compression has been done through under-sized (e.g. elastic) or size-adjustable (e.g. inflatable) compression garments. Such systems are designed to apply substantially uniform pressure on the body. However, due to reasons such as anatomical variations and body posture change, different levels of compression may be applied to the body. Further, a high level of discomfort and non-compliance is reported among patients due to donning difficulties. Therefore, there have been some efforts to make compression garments smart by employing advanced functional soft materials and actuators (such as Shape Memory Alloy (SMA), Shape Memory Polymer (SMP), Electroactive polymer (EAP), etc.) as well as soft force-pressure sensors so that the compression level could be controlled and regulated for each person or specific tasks. However, despite these advances, there are still challenges to accurately controlling the on-body compression level that are mainly due to the inherent characteristics of the soft actuators or sensors and the sophisticated human body conditions. In this paper, we will first investigate the soft actuators and sensors that have the potential to be used for on-body compression applications. Then, integrated soft sensing-actuation systems for interfacial compression purposes are studied. Finally, the challenges that might be associated with this work are introduced.
Working inside the space suit causes injury and discomfort, but suit assessment techniques such as measuring joint torques and ranges of motion fail to evaluate injury because they fail to distinguish interactions between the human and the space suit. Contact pressure sensing would allow a quantitative assessment of the nature and location of suit-body contact where injuries occur. However, commercially available systems are not well suited for measurement inside the confined environment of the space suit during movement. We report on the design of a wearable pressure sensing system, the Polipo. The Polipo dynamically measures between 5 and 60 kPa of pressure with kPa sensitivity, is within 10% root mean square error from a known loading profile during dynamic movement, and is a standalone system able to accommodate a 50th percentile female to a 95th percentile male upper body dimensions with near shirt-sleeve mobility. This paper focuses on the upper body, but the methods may be extended to the full body as future work. It provides a pressure sensing system that could be applied beyond the field of aerospace to assess human–garment interactions, for example recommending armor protection for defense applications or to alleviate fall impacts for medical applications.
Gas-pressurized space suits are incredibly well engineered tools allowing astronauts to perform critical duties. However, current gas pressurized space suits have an inherent stiffness, causing fatigue, unnecessary energy expenditure, and in some instances injury. Prior to this research effort there was no technology allowing the human-space suit interface to be measured internally. We quantify and evaluate human-space suit interaction with a novel pressure sensing tool, focusing on the arm under different loading regimes. An experiment was performed inside the Mark III space suit at NASA Johnson Space Center. One highly experienced male subject was asked to perform a series of mission-realistic movements for planetary exploration: kneel and recover, boot tighten, and prone and recover. These motions were performed in conjunction with an upper-body motion experiment to assess human-space suit interaction during controlled movements. The subject was asked to perform these mission-realistic tasks to determine the utility of the pressure sensing system in experiments not intentionally directed at loading the sensors. Loading over the upper forearm for each task was compared against experimental video to determine motion induced loading on the subject's body and gave insight into how the system could be used to index the person's body inside the suit and determine how motion occurs and the nature of that motion. We propose future improvements for the characterization of human biomechanics and injury mechanisms inside the space suit.
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