Artificial balancer – Supporting device for postural reflex

Abstract-Gyroscopic actuation is appealing for wearable applications due to its ability to impart free moments on a body without exoskeletal structures on the joints. We recently proposed an unobtrusive balancing aid consisting of multiple parallelmounted control moment gyroscopes (CMGs) contained within a backpack-like orthopedic corset. Using conventional CMG control techniques, geometric singularities result in a number of performance issues, including either unintended oscillations or freezing of the gimbals at certain alignments, which are typically mitigated by the addition of redundant actuators or by allowing errors in the generated moment; however, because of the minimalistic design of the proposed device and focus on accurate moment tracking, a new methodology is required.In this paper, a control scheme is proposed for non-redundant CMG systems in which oscillations at saturated states are avoided and all remaining singularities are efficiently escaped by exploiting the system geometry; due to its use of classification-specific singularity proximity measures that account for the command moment orientation, it is named the directional singularity-robust (DSR) control law. The performance of this control law is assessed in both simulations and hardware testing. The proposed method is suitable for a wide range of CMG systems, including both balancing and aerospace applications.

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“…[2]), we described first a device utilizing CMGs and harnessing the above benefits [3]. In this concept, a wearable backpack-like device ( Fig.…”

Section: Introductionmentioning

confidence: 99%

Directional Singularity-Robust Torque Control for Gyroscopic Actuators

Berry

Lemus

Babuška

2016

IEEE/ASME Trans. Mechatron.

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“…The importance of studying this task has been reported by many researchers due to its close relationship to the overall posture balance of the human body (Tsuruike et al, 2003; Torres-Oviedo and Ting, 2007; Wojtara et al, 2012b). Understanding the neural basis underlying posture balance control is a challenging research topic that can provide insight into properties of motor neural dynamics, as well as assistance in predicting and preventing the risk of falls and thus, their consequent harm (Tinetti et al, 1986; Bloem et al, 2003; Vassallo et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Muscle synergy space: learning model to create an optimal muscle synergy

Alnajjar¹,

Wojtara

Kimura³

et al. 2013

Front. Comput. Neurosci.

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Muscle redundancy allows the central nervous system (CNS) to choose a suitable combination of muscles from a number of options. This flexibility in muscle combinations allows for efficient behaviors to be generated in daily life. The computational mechanism of choosing muscle combinations, however, remains a long-standing challenge. One effective method of choosing muscle combinations is to create a set containing the muscle combinations of only efficient behaviors, and then to choose combinations from that set. The notion of muscle synergy, which was introduced to divide muscle activations into a lower-dimensional synergy space and time-dependent variables, is a suitable tool relevant to the discussion of this issue. The synergy space defines the suitable combinations of muscles, and time-dependent variables vary in lower-dimensional space to control behaviors. In this study, we investigated the mechanism the CNS may use to define the appropriate region and size of the synergy space when performing skilled behavior. Two indices were introduced in this study, one is the synergy stability index (SSI) that indicates the region of the synergy space, the other is the synergy coordination index (SCI) that indicates the size of the synergy space. The results on automatic posture response experiments show that SSI and SCI are positively correlated with the balance skill of the participants, and they are tunable by behavior training. These results suggest that the CNS has the ability to create optimal sets of efficient behaviors by optimizing the size of the synergy space at the appropriate region through interacting with the environment.

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“…Interestingly, the two robotic devices found to most similarly assist postural control via the upper body also used posture-independent controllers. For a walking task similar to Experiment 1 and with a wearable reaction wheel fixed to the trunk, Wojtara et al implemented an anisotropic (and potentially discontinuous) damping controller to generate a velocity-dependent moment opposing motion of the trunk only when moving away from upright posture 82 ; the selection of the viscous controller was justified with the anecdote that while 'standing in shoulder-deep water, it is easy to keep balance' . In the second instance, Wu et al used a cable robot attached to a hip harness where lateral forces proportional to the CoM velocity were applied to either assist or perturb subjects as they follow a straight line on a treadmill 35 ; here the selection of the viscous field was made due to avoid www.nature.com/scientificreports www.nature.com/scientificreports/ imparting position constraints on the subject.…”

Section: Subjects Interact Better With Predictable Controllersmentioning

confidence: 99%

Controller synthesis and clinical exploration of wearable gyroscopic actuators to support human balance

Lemus

Berry

Jabeen

et al. 2020

Sci Rep

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Gyroscopic actuators are appealing for wearable applications due to their ability to provide overground balance support without obstructing the legs. Multiple wearable robots using this actuation principle have been proposed, but none has yet been evaluated with humans. Here we use the GyBAR, a backpack-like prototype portable robot, to investigate the hypothesis that the balance of both healthy and chronic stroke subjects can be augmented through moments applied to the upper body. We quantified balance performance in terms of each participant's ability to walk or remain standing on a narrow support surface oriented to challenge stability in either the frontal or the sagittal plane. By comparing candidate balance controllers, it was found that effective assistance did not require regulation to a reference posture. A rotational viscous field increased the distance healthy participants could walk along a 30mm-wide beam by a factor of 2.0, compared to when the GyBAR was worn but inactive. The same controller enabled individuals with chronic stroke to remain standing for a factor of 2.5 longer on a narrow block. Due to its wearability and versatility of control, the GyBAR could enable new therapy interventions for training and rehabilitation.

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Artificial balancer – Supporting device for postural reflex

Cited by 16 publications

References 13 publications

Directional Singularity-Robust Torque Control for Gyroscopic Actuators

Directional Singularity-Robust Torque Control for Gyroscopic Actuators

Muscle synergy space: learning model to create an optimal muscle synergy

Controller synthesis and clinical exploration of wearable gyroscopic actuators to support human balance

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