Principle of Superposition for Controlling Pinch Motions by Means of Robot Fingers with Soft Tips

Arimoto, Suguru; Tahara, Kenji; Yamaguchi, M.; Nguyen, Pham Thuc Anh; Han, Hyun-Yong

doi:10.1016/s1474-6670(17)37920-x

Cited by 31 publications

(39 citation statements)

References 3 publications

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“…Tangential forces: In all cases the sum of the thumb and VF tangential forces was very close to the weight of the apparatus, as it should be expected from equation (2). In contrast to the normal force changes, the change in the tangential forces of the thumb and VF depended on which finger was manipulated, not on the finger function in the task -whether the finger served as torque agonist or antagonist.…”

Section: The Vf Level Steady Statesupporting

confidence: 60%

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Digit force adjustments during finger addition/removal in multi-digit prehension

2008

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We explored adjustments in multi-digit coordinated action on a hand-held object with finger addition and removal. The subjects (n= 7) kept a vertically oriented handle at rest using a prismatic grasp as if holding a glass of liquid and then either added one finger to the grasp-the index (I) or little (L) finger-or removed one finger. Three external torques were applied on the apparatus: clockwise, counterclockwise, and no torque. The individual digit forces and moments were recorded with 6-component sensors. The change in grasping force depended on the function of the manipulated finger, i.e. on whether the finger resisted external torque (torque agonist) or assisted it (torque antagonist). There was a significant increase of the grasping force when an antagonist was added or when an agonist was removed. These force increases were not necessary for slipping prevention: the normal forces prior to the manipulation were large enough to prevent slipping. All other finger manipulations exhibited no significant change in the grip force, except for the antagonist removal during the supination efforts (after removing the I finger the grasping force decreased). In contrast, the changes in the tangential force depended on the manipulated finger, not on the finger function with respect to external torque. There was a significant thumb force increase when the I finger was added or when the L finger was removed; opposite changes were seen when the L finger was added or the I finger was removed. The changes of the virtual finger (VF) tangential force were equal and opposite to the thumb tangential force alterations; these opposite changes caused changes in the moments these forces generated. The changes in the moments of the tangential forces were counterbalanced by the opposite changes in the moments of normal forces such that the total moment remained constant and the handle orientation was maintained. At the level of individual finger (IF) forces two strategies of error compensation were found: (a) local error compensation -the opposite action of the neighboring finger, i.e. force decrease in response to a force increase (finger addition), and vice versa, and (b) distant error compensation -similar action by a finger that is a torque antagonist to the manipulated finger. During the transient periods, the changes in the thumb and VF forces were simultaneous and equal in magnitude. The normal forces increased or decreased concurrently while the changes in the tangential forces were opposite in direction. The data support the existence of chain effects in the digit force adjustments to finger addition or removal. We conclude that the digit force adjustments during the object manipulation are controlled mainly in a feed-forward manner. The obtained data agree with the principle of superposition reported previously. The findings agree with earlier reports on the limited ability of CNS to organize synergies at two levels of a control hierarchy simultaneously.

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Section: The Vf Level Steady Statesupporting

confidence: 60%

“…The principle was first suggested in robotics (Arimoto et al 2001) and then confirmed for human grasping (Zatsiorsky et Shim et al 2005a). According to the principle, the central controller employs two commands for grasping control: (1) grasp the object stronger or weaker to prevent slipping, and (2) prevent tilting of the object.…”

Section: Introductionmentioning

confidence: 98%

Digit force adjustments during finger addition/removal in multi-digit prehension

2008

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“…In particular, studies of finger force co-variation across static tasks withholding an object have suggested that the control of the hand action can be represented as a superposition of two processes, the control of the gripping action and the control of the rotational action (Shim et al 2003(Shim et al , 2004a). As such, hand control seems to obey the principle of superposition introduced in robotics (Arimoto et al 2000(Arimoto et al , 2001; according to this principle, some complex tasks performed by a set of effectors may be more efficiently controlled if they are decomposed into sub-tasks that have their own controllers with no interference with each other. In all those studies, however, the production of a particular moment of force was an implicit task component, and the magnitude of the moment was not changed during the trial.…”

Section: Multi-finger Synergies Stabilizing Rotational Hand Actionmentioning

confidence: 99%

Finger synergies during multi-finger cyclic production of moment of force

2006

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We investigated multi-finger synergies stabilizing the total moment of force and the total force when the subjects produced a quick cyclic change in the total moment of force. The seated subjects performed the task with the fingers of the dominant arm while paced by the metronome at 1.33 Hz. They were required to produce a rhythmic, sine-like change in the total pronation-supination moment of force computed with respect to the midpoint between the middle and ring fingers. The framework of the uncontrolled manifold hypothesis was used to compute indices of stabilization of the total moment and of the total force across 20 cycles. Variance of the total moment showed a cyclic pattern with peaks close to the peak rate of the moment change. Variance of the total force was maximal close to peak moment into supination. Higher magnitudes of the moment directed against the required moment direction (antagonist moment) were produced by individual fingers during supination efforts as compared to pronation efforts. Indices of multi-finger synergies showed across-trials stabilization of the total moment over the whole cycle but not of the total force. These indices were smaller during supination efforts. We conclude that the central nervous system facilitates multi-finger synergies stabilizing the total rotational action across a variety of tasks. Synergies stabilizing the total force are not seen in tasks that do not explicitly require accurate force control. Pronation efforts are performed more efficiently and with better stabilization of the action.

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“…The leading studies of function based control is proposed by by Tsuji, Nishi and Ohnishi in [2]. Arimoto and Nguyen in [3] investigated decentralized control with concepts such as linear superposition. The implementation of sliding mode control in bilateral systems is studied by Onal and Sabanovic in [4].…”

Section: Introductionmentioning

confidence: 99%

Task Based Bilateral Control for Microsystems Application

et al. 2011

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Original scientific paperDesign of a motion control system, convenient for a wide range of applications in industry, space, biology, medicine, particularly including more than one physics environment is very important. Well known control architectures like trajectory tracking, compliance control, interaction force control are scientific milestones which has common control task: to maintain desired system configuration. In this concept, motion control system can be an unconstrained motion-performed interaction with neither environment nor any other system, or constrained motionsystem in contact with environment and/or other systems. This paper provides the function based design approach to formulate control of constrained system particularly bilateral systems in micromanipulation applications. The control objective aimed to maintain desired functional relations between human and environment defining convenient tasks and their proper relations on master and slave motion systems. Preliminary results concerning position tracking, force control and transparency between master and slave systems are clearly demonstrated. Key words: Bilateral control, Motion control, Micromanipulation, TeleoperationBilateralno upravljanje zasnovano na zadacima za primjene u mikrosustavima. Sinteza slijednog sustava prikladnog za široki raspon primjena u industriji, svemiru, biologiji, medicini te posebno za primjene koje obuhvaćaju više raličitih fizikalnih okruženja, vrlo je važna. Dobro poznate strukture upravljanja poput slijeenja trajektorije, usklaenog upravljanja i upravljanja interakcijskom silom predstavljaju znanstvene prekretnice koje imaju zajednički upravljački cilj: održavanje željene konfiguracije sustava. U ovom konceptu, slijedni sustav može biti sustav bez ograničenja i bez interakcije s okolinom ili ostalim sustavima, odnosno može biti sustav s ograničen-jima koji je spregnut s okolinom i/ili drugim sustavima. Ovajčlanak opisuje funkcijski zasnovanu sintezu sustava upravljanja za sustav s ograničenjima, a posebno za bilateralne sustave u mikromanipulacijskim primjenama. Cilj upravljanja je održavanje željenih funkcionalnih relacija izmežučovjeka i okoline definirajući prikladne zadaće i njihove odgovarajuće relacije za glavni i podreeni slijedni sustav. Preliminarni rezultati vezani uz upravljanje pozicijom, upravljanje silom te veza izmeu glavnog i podreenog sustava su jasno prezentirani.

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Principle of Superposition for Controlling Pinch Motions by Means of Robot Fingers with Soft Tips

Cited by 31 publications

References 3 publications

Digit force adjustments during finger addition/removal in multi-digit prehension

Digit force adjustments during finger addition/removal in multi-digit prehension

Finger synergies during multi-finger cyclic production of moment of force

Task Based Bilateral Control for Microsystems Application

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