Analysis of Accuracy in Pointing with Redundant Hand-held Tools: A Geometric Approach to the Uncontrolled Manifold Method

Campolo, Domenico; Widjaja, Ferdinan; Xu, Hong; Ang, Wei Tech; Burdet, Etienne

doi:10.1371/journal.pcbi.1002978

Cited by 13 publications

(16 citation statements)

References 28 publications

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“…One important caveat for many approaches that analyze structure of variability is that these analyses are fundamentally sensitive to the chosen coordinates (Müller et al, 2007; Smeets and Louw, 2007; Sternad et al, 2010; Campolo et al, 2013). As demonstrated in our earlier study, variability analyses that rely on the covariance matrix are highly sensitive to the definition of the variables that span the space.…”

Section: Discussionmentioning

confidence: 99%

Directionality in distribution and temporal structure of variability in skill acquisition

Abe

Sternad

2013

Front. Hum. Neurosci.

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Observable structure of variability presents a window into the underlying processes of skill acquisition, especially when the task affords a manifold of solutions to the desired task result. This study examined skill acquisition by analyzing variability in both its distributional and temporal structure. Using a virtual throwing task, data distributions were analyzed by the Tolerance, Noise, Covariation-method (TNC); the temporal structure was quantified by autocorrelation and detrended fluctuation analysis (DFA). We tested four hypotheses: (1) Tolerance and Covariation, not Noise, are major factors underlying long-term performance improvement. (2) Trial-to-trial dynamics in execution space exhibits preferred directions. (3) The direction-dependent organization of variability becomes more pronounced with practice. (4) The anisotropy is in directions orthogonal and parallel to the solution manifold. Results from 13 subjects practicing for 6 days revealed that performance improvement correlated with increasing Tolerance and Covariation; Noise remained relatively constant. Temporal fluctuations and their directional modulation were identified by a novel rotation method that was a priori ignorant about orthogonality. Results showed a modulation of time-dependent characteristics that became enhanced with practice. However, this directionality was not coincident with orthogonal and parallel directions of the solution manifold. A state-space model with two sources of noise replicated not only the observed temporal structure but also its deviations from orthogonality. Simulations suggested that practice-induced changes were associated with an increase in the feedback gain and a subtle weighting of the two noise sources. The directionality in the structure of variability depended on the scaling of the coordinates, a result that highlights that analysis of variability sensitively depends on the chosen coordinates.

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Section: Discussionmentioning

confidence: 99%

Directionality in distribution and temporal structure of variability in skill acquisition

Abe

Sternad

2013

Front. Hum. Neurosci.

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“…To solve these issues, a coordinate-independent formulation of the UCM analysis was recently proposed [30]. Campolo et al exploited a particular type of kinetic energy metric originally proposed in [60] to study the level of redundancy exploitation during a static pointing task performed with an hand-handled tool.…”

Section: B Error Metricsmentioning

confidence: 99%

“…While coordinate-dependency still represents a non-negligible limitation of the present work, the comparative nature of the analysis should make it less sensitive to changes in the joints reference frames. Future studies are needed to develop a coordinate-independent metric similar to [30] that would be appropriate for our current task and for future studies with surgical tasks.…”

Section: B Error Metricsmentioning

confidence: 99%

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An Uncontrolled Manifold Analysis of Arm Joint Variability in Virtual Planar Position and Orientation Telemanipulation

Buzzi

Momi

Nisky³

2019

IEEE Trans. Biomed. Eng.

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Abstract-Objective: In teleoperated robot-assisted tasks, the user interacts with manipulators to finely control remote tools. Manipulation of robotic devices, characterized by specific kinematic and dynamic proprieties, is a complex task for the human sensorimotor system due to the inherent biomechanical and neuronal redundancies that characterize the human arm and its control. We investigate how master devices with different kinematics structures and how different task constraints influence users capabilities in exploiting arm redundancy. Methods: A virtual teleoperation workbench was designed and the arm kinematics of seven users was acquired during the execution of two planar virtual tasks, involving either the control of position only or position-orientation of a tool. Using the UnControlled Manifold Analysis of arm joint variability we estimated the logarithmic ratio between task irrelevant and the task relevant manifolds (Rv). Results: The Rv values obtained in the position-orientation task were higher than in the position only task while no differences were found between the master devices. A modulation of Rv was found through the execution of the position task and a positive correlation was found between task performance and redundancy exploitation. Conclusion: Users exploited additional portions of arm redundancy when dealing with the tool orientation. The Rv modulation seems influenced by the task constraints and by the users possibility of reconfiguring the arm position. Significance: This work advances the general understanding of the exploitation of arm redundancy in complex tasks, and can improve the development of future robotic devices.

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“…Not only does the redundancy in the neuro-mechanical system afford infinitely many ways to produce the desired movement, the task itself can also be achieved in infinitely many ways and performance improvement may proceed in a non-monotonic fashion. The manifold of solutions in the result space is typically nonlinear, with some solutions more favorable than others (Sternad et al 2011; Berret et al 2011; Campolo et al 2013; Ganesh and Burdet 2013; Sternad et al 2014). Specifically, some solutions tend to be more tolerant to perturbations and noise.…”

Section: Introductionmentioning

confidence: 99%

Implicit guidance to stable performance in a rhythmic perceptual-motor skill

Huber

Sternad

2015

Exp Brain Res

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Feedback information about error or reward is regarded essential to aid learners to acquire a perceptual-motor skill. Yet, simple error feedback does not suffice in guiding the learner towards the optimal solutions, when tasks have redundancy where the mapping between execution and performance outcome is unknown. The present study developed and tested a new means of implicitly guiding learners to acquire a perceptual-motor skill, rhythmically bouncing a ball on a racket. Due to its rhythmic nature, this task affords dynamically stable solutions that are resistant to small errors and noise, a strategy that is independent from simply reducing error. Based on the task model implemented in a virtual environment, a state-dependent manipulation was designed that shifted the range of ball-racket contacts that achieved to dynamically stable solutions. In two experiments, subjects practiced with this manipulation that guided them to impact the ball with more negative racket accelerations, the indicator for the strategy with dynamic stability. Subjects who practiced under normal conditions took longer time to acquire this skill, although error measures were identical between the control and experimental groups. Unlike in many other haptic guidance or adaptation studies, the experimental groups not only learned but also maintained the stable solution after the manipulation was removed. These results are a first demonstration that more subtle ways to guide the learner to better performance are needed to assist performance improvements, especially in tasks with redundancy, where error feedback may not be sufficient.

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Analysis of Accuracy in Pointing with Redundant Hand-held Tools: A Geometric Approach to the Uncontrolled Manifold Method

Cited by 13 publications

References 28 publications

Directionality in distribution and temporal structure of variability in skill acquisition

Directionality in distribution and temporal structure of variability in skill acquisition

An Uncontrolled Manifold Analysis of Arm Joint Variability in Virtual Planar Position and Orientation Telemanipulation

Implicit guidance to stable performance in a rhythmic perceptual-motor skill

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