Effect of added inertia on the pelvis on gait.
ABSTRACT Gait-training robots must display a low inertia in order to allow normal-looking walking. We studied the effect of inertia added to the pelvis during walking. We attached subjects to a mechanism that displays inertia to the pelvis in the anterior/posterior (AP) direction and the lateral direction independently. During walking we measured EMG, metabolic rate and kinematics of nine subjects. We found that inertias up to 5.3 kg added in lateral direction had no significant effect on gait. We found that 4.3 kg added in the AP direction had a significant but not relevant effect on the range of motion (RoM) of pelvis AP displacement and acceleration, and on hip flexion. 10.3 kg caused a significant and relevant difference in pelvis acceleration RoM. 6 kg is estimated as the maximum inertia that gait-training robots can add to the pelvis, without affecting the gait.
Conference Paper: GaitEnable: An omnidirectional robotic system for gait rehabilitation[Show abstract] [Hide abstract]
ABSTRACT: This paper introduces GaitEnable, a robotic gait trainer composed of an actuated omnidirectional mobile base, a passive body weight support (BWS) system, and a reactive control system that can initiate, sustain, stabilize or perturb a user's gait. The device is designed to provide minimal constraints to the user's natural motion, and its actuated mobile base can move cooperatively with the user in any direction. Data from preliminary experiments performed by a healthy male subject confirm that the reactive control system can compensate for the device's inertial effects and that the device's omnidirectional mobile base reduces pelvis and torso motion constraints. The results also demonstrate that GaitEnable can easily be programmed to simulate different types of behaviours or motion constraints.Mechatronics and Automation (ICMA), 2012 International Conference on; 01/2012
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ABSTRACT: The application of external constraints and/or applied forces during movement can lead to reactive as well as adaptive changes in human motion. Previous research has shown adaptation in walking kinematics when external forces were applied to a leg. This work aims to study adaptation in human walking when externally applied forces were present on the pelvis during the swing and stance phases of both legs. A novel tethered pelvic assist device (TPAD) was used to passively apply symmetric downward forces on the human pelvis while walking. During the experiment, eight healthy subjects walked on a treadmill at a constant speed while their kinematics and foot pressure data were recorded. Data analysis revealed that the healthy subjects exhibited both reactive as well as adaptive changes in their gait parameters. The immediate response of the subjects was to increase their hip flexion to clear their foot off the ground as they were unable to lift their pelvis to their usual height in the presence of downward forces. Seven out of eight subjects resisted the downward forces to move their pelvis up. Eventually, they reached a level of downward force that they could sustain over the training session. This adaptation to the downward force was reflected in the heel peak pressure values during the cycles of the gait. On removing the tethers, aftereffects in heel peak pressure values were observed as a result of higher magnitude of pelvic acceleration in vertical direction. In summary, symmetrically applied external forces on the pelvis of healthy subjects, resulted in reactive changes in the gait kinematics and adaptive changes in the gait kinetics and the foot interaction forces with the ground.IEEE transactions on neural systems and rehabilitation engineering: a publication of the IEEE Engineering in Medicine and Biology Society 03/2013; · 2.42 Impact Factor
Conference Paper: Gyroscopic Assistance for Human Balance[Show abstract] [Hide abstract]
ABSTRACT: Falls are an urgent challenge in aging societies, and balance dysfunction is a major risk factor. Current robotic technology that assists human locomotion, however, aims at versatile functionality, particularly in the assistance of weak muscles. Such versatile design leads to heavy, bulky devices that are impractical in daily life for most elderly subjects. In this paper, we investigate the use of minimalistic robotic technology that focuses exclusively on stabilizing human balance during gait. This task-specific device is novel in its combination of portability and simplicity. Our initial simulations show that it is possible to return a person to a vertical position from an engagement angle of 10 degrees from vertical.Proceedings of the 12th International Workshop on Advanced Motion Control (AMC); 03/2012