A reduced-gravity simulator for physically simulating human walking in microgravity or reduced-gravity environment

Abstract

Astronauts must go through extensive training of their tasks in a simulated microgravity or reduced-gravity environment before they can perform the same tasks in space. Scientists and engineers also need simulated reduced-gravity facilities to study human performance and factors in space. This paper presents a novel design and prototype test of a multi-DOF reduced-gravity simulator which can be used for training astronauts and studying human factors in zero or partial gravity environment. Designed based on the passive static balancing technology, the simulator can passively compensate the gravity force applied to a human to any level from 0 to 100% at all the configurations within its workspace. Therefore, a person attached to the simulator can biomechanically feel like he/she were in a real reduced-gravity environment while doing a physical activity such as walking or jumping. A prototype of the simulator was developed to study the feasibility and dynamic performance of the system. The prototype study demonstrated the reduced-gravity simulation capability of the system. It also revealed some interesting findings which motivate further research in the future.

Use of Pressure-Measuring Insoles to Characterize Gait Parameters in Simulated Reduced-Gravity Conditions

“…In this study, we found that the effect of lower-body positive-pressure treadmill (LBPPT) walking, specifically an increase in body weight support, or a reduction in gravity from 100% (normal gravity) to 40% and 20% (reduced gravity) body weight (BW), is mainly characterized by a significant decrease in center of pressure (COP) anterior–posterior segment length and simultaneous significant increase in COP medial–lateral segment width. The calculated COP location and its movement during the stance phase of each cycle are typically reported as indicators of marked gait stability during dynamic tasks such as walking [ 20 , 21 ]. This alteration in gait stability may be suggestive of a shift in walking patterns as gravity conditions are reduced.…”

“…COP, when examining kinetic plantar pressure measures, is typically used to identify and assess any issues with an individual’s foot pathology during gait. The calculated COP location and its movement during the stance phase of each cycle is reported as an indicator of marked gait stability during dynamic tasks such as walking [ 20 , 21 ]. It was suggested that the assessment of plantar pressure could be an appropriate substitute for measuring foot trauma.…”

Fast reoptimization of human motor patterns in non-Earth gravity fields locally induced by a robotic exoskeleton

“…Moreover, while very relevant to space exploration (29)(30)(31)(32)(33), completely immersing participants in a novel gravity field is not representative of other applications. For instance, it is common to use devices to support a patient's limb and reduce their muscle effort required to counteract gravity in rehabilitation (34)(35)(36)(37)(38)(39)(40)(41)(42).…”

“…Studies in parabolic flights have allowed to test this theory in a couple of hypo- and hyper-gravity fields with a limited number of trials and participants ( 5, 9, 12, 13 ). Moreover, while very relevant to space exploration ( 29–33 ), completely immersing participants in a novel gravity field is not representative of other applications. For instance, it is common to use devices to support a patient’s limb and reduce their muscle effort required to counteract gravity in rehabilitation ( 34–42 ).…”

Design, modelling and characterisation of a magnetic variable stiffness mechanism

“…For this configuration to function properly, the elastic element and the link between the elastic element and the motor need to be carefully selected and designed to result in an appropriate equilibrium position and torque profile [165]. They have been used for gravity compensation [166,167], in exoskeletons to reduce motor torque and power requirements during load lifting [168], and for efficient locomotion with large payloads [169].…”