Representation of hand position prior to movement and motor variability

1995 ◽  
Vol 73 (2) ◽  
pp. 262-272 ◽  
Author(s):  
Michel Desmurget ◽  
Yves Rossetti ◽  
Claude Prablanc ◽  
Marc Jeannerod ◽  
George E. Stelmach
Keyword(s):  
Peak Velocity ◽  
Human Subjects ◽  
Hand Position ◽  
Feedback Process ◽  
Significant Modification ◽  
Movement Kinematics ◽  
Acceleration Phase ◽  
Movement Onset ◽  
Motor Variability ◽  
Deceleration Phase

Pointing accurary of six human subjects was measured in two blocked conditions where the hand was either never visible (T: target only) or only visible in static position prior to movement onset (H+T: hand + target). It was shown in condition H+T that, viewing the hand prior to movement greatly decreased end-point variability compared with condition T. This effect was associated with a significant modification of the movement kinematics: the H+T condition induced a shortened acceleration phase with a corresponding lengthened deceleration phase, compared with the T condition. These results led us to the hypothesis that viewing the hand prior to movement onset allowed a decrease of pointing variability through a feedback process. This hypothesis was further tested by turning the target off during the deceleration phase of the movement at half peak velocity. It was shown that turning the target off had no effect upon the T condition but induced a significant increase of pointing variability in the H+T condition. This result suggests that vision of the static hand enhances the proprioceptive localization of the limb and allows for a better visual to kinesthesic feedback.Key words: proprioception, vision, motor control, pointing, feedback, human.

Fusion of Visual and Proprioceptive Information about Hand Position Prior to Movement

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 127-127
Author(s):  
M Desmurget ◽  
Y Rossetti ◽  
C Prablanc
Keyword(s):  
Visual Information ◽  
Human Subjects ◽  
Visual Presentation ◽  
Accurate Estimate ◽  
Open Loop ◽  
The Body ◽  
Hand Position ◽  
Proprioceptive Information ◽  
Movement Onset ◽  
Loop Condition

The problem whether movement accuracy is better in the full open-loop condition (FOL, hand never visible) than in the static closed-loop condition (SCL, hand only visible prior to movement onset) remains widely debated. To investigate this controversial question, we studied conditions for which visual information available to the subject prior to movement onset was strictly controlled. The results of our investigation showed that the accuracy improvement observed when human subjects were allowed to see their hand, in the peripheral visual field, prior to movement: (1) concerned only the variable errors; (2) did not depend on the simultaneous vision of the hand and target (hand and target viewed simultaneously vs sequentially); (3) remained significant when pointing to proprioceptive targets; and (4) was not suppressed when the visual information was temporally (visual presentation for less than 300 ms) or spatially (vision of only the index fingertip) restricted. In addition, dissociating vision and proprioception with wedge prisms showed that a weighed hand position was used to program hand trajectory. When considered together, these results suggest that: (i) knowledge of the initial upper limb configuration or position is necessary to plan accurately goal-directed movements; (ii) static proprioceptive receptors are partially ineffective in providing an accurate estimate of the limb posture, and/or hand location relative to the body, and (iii) visual and proprioceptive information is not used in an exclusive way, but combined to furnish an accurate representation of the state of the effector prior to movement.

scholarly journals Are reaching and grasping effector-independent? Similarities and differences in reaching and grasping kinematics between the hand and foot

2021 ◽  
Author(s):  
Yuqi Liu ◽  
James Caracoglia ◽  
Sriparna Sen ◽  
Ella Striem-Amit
Keyword(s):  
Peak Velocity ◽  
Object Size ◽  
Body Parts ◽  
Acceleration Phase ◽  
Grip Aperture ◽  
Deceleration Phase ◽  
Neural Representations ◽  
Maximum Grip Aperture ◽  
Similarities And Differences ◽  
Maximum Grip

While reaching and grasping are highly prevalent manual actions, neuroimaging studies provide evidence that their neural representations may be shared between different body parts, i.e. effectors. If these actions are guided by effector-independent mechanisms, similar kinematics should be observed when the action is performed by the hand or by a cortically remote and less experienced effector, such as the foot. We tested this hypothesis with two characteristic components of action: the initial ballistic stage of reaching, and the preshaping of the digits during grasping based on object size. We examined if these kinematic features reflect effector-independent mechanisms by asking participants to reach toward and to grasp objects of different widths with their hand and foot. First, during both reaching and grasping, the velocity profile up to peak velocity matched between the hand and the foot, indicating a shared ballistic acceleration phase. Secondly, maximum grip aperture and time of maximum grip aperture of grasping increased with object size for both effectors, indicating encoding of object size during transport. Differences between the hand and foot were found in the deceleration phase and time of maximum grip aperture, likely due to biomechanical differences and the participants' inexperience with foot actions. These findings provide evidence for effector-independent visuomotor mechanisms of reaching and grasping that generalize across body parts.

Effects of Competitive Activation on Precision Movement Control

1996 ◽  
Vol 83 (3_suppl) ◽  
pp. 1203-1208 ◽  
Author(s):  
F. de Melo ◽  
M. Laurent
Keyword(s):  
Emotional State ◽  
Peak Velocity ◽  
Movement Control ◽  
Peak Acceleration ◽  
Movement Kinematics ◽  
Acceleration Phase ◽  
Movement Sequence ◽  
Movement Parameters ◽  
Competitive Activation

Models of emotional activity consider that the emotional state can have general effects on movement control. This control depends on programmed movement invariants (movement sequence, duration of the relative phases, etc.) and on the setting of the movement parameters (amplitude, velocity, etc.). This study of 14 adults shows an influence of the emotional state upon movement kinematics, namely, the peak velocity and the peak acceleration, the amplitude, and the duration of the acceleration phase.

scholarly journals A Wind-Storage Combined Frequency Regulation Control Strategy Based on Improved Torque Limit Control

2021 ◽  
Vol 13 (7) ◽  
pp. 3765
Author(s):  
Benxi Hu ◽  
Fei Tang ◽  
Dichen Liu ◽  
Yu Li ◽  
Xiaoqing Wei
Keyword(s):  
Control Strategy ◽  
Storage System ◽  
Energy Storage System ◽  
Frequency Regulation ◽  
Small Scale ◽  
Acceleration Phase ◽  
Deceleration Phase ◽  
Combined Control ◽  
Inertial Response ◽  
Battery Energy

The doubly-fed induction generator (DFIG) uses the rotor’s kinetic energy to provide inertial response for the power system. On this basis, this paper proposes an improved torque limit control (ITLC) strategy for the purpose of exploiting the potential of DFIGs’ inertial response. It includes the deceleration phase and acceleration phase. To shorten the recovery time of the rotor speed and avoid the second frequency drop (SFD), a small-scale battery energy storage system (BESS) is utilized by the wind-storage combined control strategy. During the acceleration phase of DFIG, the BESS adaptively adjusts its output according to its state of charge (SOC) and the real-time output of the DFIG. The simulation results prove that the system frequency response can be significantly improved through ITLC and the wind-storage combined control under different wind speeds and different wind power penetration rates.

scholarly journals A conceptual model of cyclical glacier flow in overdeepenings

2014 ◽  
Vol 8 (4) ◽  
pp. 4463-4495 ◽  
Author(s):  
J. B. Turrin ◽  
R. R. Forster
Keyword(s):  
Conceptual Model ◽  
The Other ◽  
Acceleration Phase ◽  
Alaska Range ◽  
Deceleration Phase ◽  
Surface Slopes ◽  
Glacier Dynamics ◽  
Major Tributary ◽  
Cyclical Behavior ◽  
Glacier Flow

Abstract. A nearly four-decade, satellite-based velocity survey of the largest glaciers in the Alaska Range, Chugach Mountains, and the Wrangell Mountains of southern Alaska, spanning the early- to mid-1970s through the 2000s, reveals nine pulsing glaciers: Capps, Copper, Eldridge, Kahiltna, Matanuska, Nabesna, Nizina, Ruth, and Sanford glaciers. The pulses increase velocity by up to 2449% (Capps Glacier) or as little as 77% (Nabesna Glacier), with velocity increases for the other glaciers in the range of 100–250%. The pulses may last from between six years (Copper Glacier) to 12 years (Nizina Glacier) and consist of a multi-year acceleration phase followed by a multi-year deceleration phase during which significant portions of each glacier move en masse. The segments of each glacier affected by the pulses may be anywhere from 14 km (Sanford Glacier) to 36 km (Nabesna Glacier) in length and occur where the glaciers are either laterally constricted or joined by a major tributary, and the surface slopes at these locations are very shallow, 1–2°, suggesting the pulses occur where the glaciers are overdeepened. A conceptual model to explain the cyclical behavior of these pulsing glaciers is presented that incorporates the effects of glaciohydraulic supercooling, glacier dynamics, surface ablation, and subglacial sediment erosion, deposition, and deformation in overdeepenings.

Analysis of ABS Plastic and Concentric Cylindrical Shells’ Chemical Detonation Scatter Process

2014 ◽  
Vol 574 ◽  
pp. 421-424
Author(s):  
Yue Guo Shen ◽  
Nai Juan Du ◽  
Jun Hai Zhang
Keyword(s):  
Mathematical Model ◽  
Water Molecules ◽  
Initial Moment ◽  
Acceleration Phase ◽  
Phase Form ◽  
Scatter Process ◽  
Deceleration Phase ◽  
Liquid Ring ◽  
Scatter Experiment ◽  
Phase Motion

In this paper, basing on the FAE theory, simulating the process of scatter from chemical detonation about ABS plastic and concentric cylindrical shell according to experiment, on the basis of the assumption that the initial moment of the explosion being at the source ,we analyzed the gaseous phase motion equation and liquid ring controlling equation, and build the liquid ring movement mathematical model, then analyze the scatter process according to the chemical detonation scatter experiment, and classify the chemical detonation scatter into acceleration phase and deceleration phase, form the initial fog group, then we can reveal the mechanism of changing the chemical detonation into the fog. After the initial fog being formed, the effect of the chemical detonation disappeared, and the water molecules are uniformly dispersed into the air.

scholarly journals Perception of combined translation and rotation in the horizontal plane in humans

2016 ◽  
Vol 116 (3) ◽  
pp. 1275-1285 ◽  
Author(s):  
Benjamin T. Crane
Keyword(s):  
Motion Perception ◽  
Horizontal Plane ◽  
Peak Velocity ◽  
Human Subjects ◽  
Human Motion ◽  
Subjective Equality ◽  
The Right ◽  
Biased Perception

Thresholds and biases of human motion perception were determined for yaw rotation and sway (left-right) and surge (fore-aft) translation, independently and in combination. Stimuli were 1 Hz sinusoid in acceleration with a peak velocity of 14°/s or cm/s. Test stimuli were adjusted based on prior responses, whereas the distracting stimulus was constant. Seventeen human subjects between the ages of 20 and 83 completed the experiments and were divided into 2 groups: younger and older than 50. Both sway and surge translation thresholds significantly increased when combined with yaw rotation. Rotation thresholds were not significantly increased by the presence of translation. The presence of a yaw distractor significantly biased perception of sway translation, such that during 14°/s leftward rotation, the point of subjective equality (PSE) occurred with sway of 3.2 ± 0.7 (mean ± SE) cm/s to the right. Likewise, during 14°/s rightward motion, the PSE was with sway of 2.9 ± 0.7 cm/s to the left. A sway distractor did not bias rotation perception. When subjects were asked to report the direction of translation while varying the axis of yaw rotation, the PSE at which translation was equally likely to be perceived in either direction was 29 ± 11 cm anterior to the midline. These results demonstrated that rotation biased translation perception, such that it is minimized when rotating about an axis anterior to the head. Since the combination of translation and rotation during ambulation is consistent with an axis anterior to the head, this may reflect a mechanism by which movements outside the pattern that occurs during ambulation are perceived.

Factors Affecting Navigation of the S.S.T.

1965 ◽  
Vol 18 (4) ◽  
pp. 498-504 ◽  
Author(s):  
B.O.A.C
Keyword(s):  
Noise Reduction ◽  
Vertical Plane ◽  
Acceleration Phase ◽  
Factors Affecting ◽  
Deceleration Phase ◽  
Aircraft Navigation ◽  
Special Factors ◽  
Performance Variations ◽  
Subsonic Region ◽  
Made In

This note provides some qualitative impressions of the need for precise navigation in the S.S.T. operation having due regard to performance and noise. It highlights the increased signific ance of the vertical plane, but quantitative conclusions as to horizontal ability cannot be made in the absence of knowledge of traffic amounts. It suggests that any tactical ‘chasing’ of noise reduction through performance variations not planned before flight is impracticable.In common with other aircraft types, the S.S.T. has three distinct phases of flight apart from take-off and landing: climb to cruise altitude, cruise and descent. The S.S.T. climb is characterized by an acceleration phase dividing the subsonic portion of flight from the supersonic. Similarly, the descent profile includes a deceleration phase which restores flight to the subsonic region. Contained in these three phases of flight unique to the S.S.T.—acceleration, supersonic flight and deceleration—are some of the special factors affecting aircraft navigation.

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