Prism Adaptation to Moving and Stationary Target Exposures

Perception ◽  
1975 ◽  
Vol 4 (3) ◽  
pp. 341-347 ◽  
Author(s):  
Benjamin Wallace
Keyword(s):  
Arm Movement ◽  
Active Movement ◽  
Moving Target ◽  
Perceptual Adaptation ◽  
Viewing Condition ◽  
Stationary Target ◽  
Prism Exposure ◽  
Prism Displacement ◽  
Availability Model ◽  
Visual Aftereffect

The magnitude of proprioceptive adaptation and visual adaptation to prism displacement was assessed for various target conditions during either observed, active or passive arm movements. Active arm movement was found superior to passive arm movement in the production of proprioceptive aftereffects and visual aftereffects. In addition, observation of a stationary target or a moving target during prism exposure produced significant proprioceptive adaptation for a passive arm viewing condition while enhancing such adaptation magnitude for an active arm movement situation. With no target present during prism exposure, significant proprioceptive adaptation was only found with active movement. The greatest visual aftereffect was produced when a moving target was observed during prism exposure. The results are interpreted in terms of an information-availability model of perceptual adaptation.

Adjustable impact-time-control guidance law against non-maneuvering target under limited field of view

2021 ◽  
pp. 095441002110129
Author(s):  
Jun-Yong Lee ◽  
Hyeong-Guen Kim ◽  
H Jin Kim
Keyword(s):  
Field Of View ◽  
Control Technique ◽  
Moving Target ◽  
Time Error ◽  
Stationary Target ◽  
Impact Time ◽  
Maneuvering Target ◽  
Time Control ◽  
Guidance Law ◽  
Intercept Point

This article proposes an impact-time-control guidance law that can keep a non-maneuvering moving target in the seeker’s field of view (FOV). For a moving target, the missile calculates a predicted intercept point (PIP), designates the PIP as a new virtual stationary target, and flies to the PIP at the desired impact time. The main contribution of the article is that the guidance law is designed to always lock onto the moving target by adjusting the guidance gain. The guidance law for the purpose is based on the backstepping control technique and designed to regulate the defined impact time error. In this procedure, the desired look angle, which is a virtual control, is designed not to violate the FOV limit, and the actual look angle of the missile is kept within the FOV by tracking the desired look angle. To validate the performance of the guidance law, numerical simulation is conducted with different impact times. The result shows that the proposed guidance law intercepts the moving target at the desired impact time maintaining the target lock-on condition.

scholarly journals Can proprioceptive training improve motor learning?

2012 ◽  
Vol 108 (12) ◽  
pp. 3313-3321 ◽  
Author(s):  
Jeremy D. Wong ◽  
Dinant A. Kistemaker ◽  
Alvin Chin ◽  
Paul L. Gribble
Keyword(s):  
Motor Learning ◽  
Visual Information ◽  
Movement Control ◽  
Arm Movement ◽  
Sensory Function ◽  
Movement Speed ◽  
Active Movement ◽  
Positional Accuracy ◽  
Control Subjects ◽  
Proprioceptive Training

Recent work has investigated the link between motor learning and sensory function in arm movement control. A number of findings are consistent with the idea that motor learning is associated with systematic changes to proprioception (Haith A, Jackson C, Mial R, Vijayakumar S. Adv Neural Inf Process Syst 21: 593–600, 2008; Ostry DJ, Darainy M, Mattar AA, Wong J, Gribble PL. J Neurosci 30: 5384–5393, 2010; Vahdat S, Darainy M, Milner TE, Ostry DJ. J Neurosci 31: 16907–16915, 2011). Here, we tested whether motor learning could be improved by providing subjects with proprioceptive training on a desired hand trajectory. Subjects were instructed to reproduce both the time-varying position and velocity of novel, complex hand trajectories. Subjects underwent 3 days of training with 90 movement trials per day. Active movement trials were interleaved with demonstration trials. For control subjects, these interleaved demonstration trials consisted of visual demonstration alone. A second group of subjects received visual and proprioceptive demonstration simultaneously; this group was presented with the same visual stimulus, but, in addition, their limb was moved through the target trajectory by a robot using servo control. Subjects who experienced the additional proprioceptive demonstration of the desired trajectory showed greater improvements during training movements than control subjects who only received visual information. This benefit of adding proprioceptive training was seen in both movement speed and position error. Interestingly, additional control subjects who received proprioceptive guidance while actively moving their arm during demonstration trials did not show the same improvement in positional accuracy. These findings support the idea that the addition of proprioceptive training can augment motor learning, and that this benefit is greatest when the subject passively experiences the goal movement.

Gaze Accuracy Differences During Single-Leg Balance Following Anterior Cruciate Ligament Reconstruction

2020 ◽  
pp. 1-7
Author(s):  
Stephan G. Bodkin ◽  
Jay Hertel ◽  
Joseph M. Hart
Keyword(s):  
Postural Stability ◽  
Ligament Reconstruction ◽  
Visual Target ◽  
Cruciate Ligament ◽  
Moving Target ◽  
Stationary Target ◽  
Target Task ◽  
Anterior Cruciate ◽  
Visual Gaze ◽  
Visual Error

Context: Individuals following anterior cruciate ligament reconstruction (ACLR) demonstrate altered postural stability and functional movement patterns. It is hypothesized that individuals following ACLR may compensate with sensory adaptations with greater reliance on visual mechanisms during activities. It is unknown if visual compensatory strategies are implemented to maintain postural stability during functional tasks. Objective: To examine visual gaze accuracy during a single-leg balance task in individuals following ACLR compared with healthy, active controls. Design: Case control. Setting: Controlled laboratory. Participants: A total of 20 individuals (10 ACLR and 10 healthy controls) participated in the study. Data Collection and Analysis: Visual gaze patterns were obtained during 20-second single-leg balance trials while participants were instructed to look at presented targets. During the Stationary Target Task, the visual target was presented in a central location for the duration of the trial. The Moving Target Task included a visual target that randomly moved to 1 of 9 target locations for a period of 2 seconds. Targets were stratified into superior, middle, and inferior levels for the Moving Target Task. Results: The Stationary Target Task demonstrated no differences in visual error between groups (P = .89). The Moving Target Task demonstrated a significant interaction between group and target level (F2,36 = 3.76, P = .033). Individuals following ACLR demonstrated greater visual error for the superior targets (ACLR = .70 [.44] m, healthy = .41 [.21] m, Cohen d = 0.83 [0.06 to 1.60]) and inferior targets (ACLR = .68 [.25] m, healthy = .33 [.16] m, Cohen d = 1.67 [0.81 to 2.52]). Conclusion: Individuals following ACLR demonstrate greater visual error during settings of high or low visual stimuli compared with healthy individuals to maintain single-limb postural stability. This population may rely on visual input to compensate for the somatosensory changes following injury.

LEARNING TO CONTROL THE THREE-LINK MUSCULOSKELETAL ARM USING ACTOR–CRITIC REINFORCEMENT LEARNING ALGORITHM DURING REACHING MOVEMENT

2014 ◽  
Vol 26 (05) ◽  
pp. 1450064
Author(s):  
Ehsan Tahami ◽  
Amir Homayoun Jafari ◽  
Ali Fallah
Keyword(s):  
Autonomous Robots ◽  
Learning Algorithm ◽  
Single Layer ◽  
Arm Movement ◽  
Learning System ◽  
Movement Direction ◽  
Average Reward ◽  
Hill Model ◽  
Stationary Target ◽  
Reaching Movement

Learning to control the planar three-link musculoskeletal arm by using an Actor–Critic learning algorithm during reaching movements to stationary target is presented. The arm model used in this study includes three skeletal links (hand, forearm and upper arm), three joints (wrist, elbow and shoulder without redundancy) and six nonlinear monoarticular muscles with redundancy which are modeled based on Hill model. The learning system is composed of Actor and Critic parts. For each part, a single layer neural network is used. This learning system applies six activation commands to six muscles at each instant of time. It also uses a reinforcement (reward) feedback for learning process and controlling the arm movement direction. The results showed that with a learning rate α = 0.9 and after 20 episodes, Mean square error (MSE), average reward and average time of reaching the target are gradually converged to the values: 0.0056, 0.02262 and 187 s, respectively. After the 20th episode, the learning will be completed. The research suggests a new direction for designation of learning-based controllers for functional electrical stimulation (FES) applications and for arm movement of autonomous robots.

scholarly journals Using smooth pursuit calibration for difficult-to-calibrate participants

2017 ◽  
Vol 10 (4) ◽  
Author(s):  
Pieter Blignaut
Keyword(s):  
Young Children ◽  
Standard Method ◽  
Smooth Pursuit ◽  
Good Accuracy ◽  
Random Order ◽  
Mental Effort ◽  
Moving Target ◽  
Autistic Children ◽  
Stationary Target ◽  
Horizontal Path

Although the 45-dots calibration routine of a previous study (Blignaut, 2016) provided very good accuracy, it requires intense mental effort and the routine proved to be unsuccessful for young children who struggle to maintain concentration. The calibration procedures that are normally used for difficult-to-calibrate participants, such as autistic children and infants, do not suffice since they are not accurate enough and the reliability of research results might be jeopardised.Smooth pursuit has been used before for calibration and is applied in this paper as an alternative routine for participants who are difficult to calibrate with conventional routines.  Gaze data is captured at regular intervals and many calibration targets are generated while the eyes are following a moving target. The procedure could take anything between 30 s and 60 s to complete, but since an interesting target and/or a conscious task may be used, participants are assisted to maintain concentration.It was proven that the accuracy that can be attained through calibration with a moving target along an even horizontal path is not significantly worse than the accuracy that can be attained with a standard method of watching dots appearing in random order. The routine was applied successfully for a group of children with ADD, ADHD and learning abilities.This result is important as it provides for easier calibration – especially in the case of participants who struggle to keep their gaze focused and stable on a stationary target for long enough.

scholarly journals Simulation of Moving Target Indication Radar System Based on VisSim/Comm Application

2021 ◽  
Vol 5 (2) ◽  
pp. 38-45
Author(s):  
Ghassan A. QasMarrogy ◽  
Husham J. Ahmad
Keyword(s):  
Mechanical Properties ◽  
Delay Line ◽  
Radar System ◽  
Moving Target ◽  
Moving Targets ◽  
Simulation Design ◽  
Stationary Target ◽  
Know How ◽  
Radar Signals

Moving target indication (MTI) is mainly designed to detect moving targets and while unmoving targets are filtered out. It focuses on the technique of the modern stationary target indication (STI), by using directly the signal details to determine the reflecting object’s mechanical properties, after that it becomes easier to find moving or non-moving targets. This paper presents the simulation design of the MTI radar system. The main purpose of this design is to help students in understanding the radar system subject and help teachers to explain this subject in a simpler approach. Both students and teachers need to know how the signals inside the MTI radar processor are working and how they are generated and related to each other. This paper introduces a method of simulation of MTI radar signals including, A-scope radar display, transmitted and returned radar pulses with constant and multiple PRF, n-delay line cancellers.

scholarly journals Prediction and final temporal errors are used for trial-to-trial motor corrections

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Joan López-Moliner ◽  
Cécile Vullings ◽  
Laurent Madelain ◽  
Robert J. van Beers
Keyword(s):  
Prediction Error ◽  
Movement Time ◽  
Onset Time ◽  
Arm Movements ◽  
Arm Movement ◽  
Saccadic Eye Movements ◽  
Fixed Time ◽  
Button Press ◽  
Moving Target ◽  
Internal Error

AbstractMany daily life situations (e.g. dodging an approaching object or hitting a moving target) require people to correct planning of future movements based on previous temporal errors. However, the actual temporal error can be difficult to perceive: imagine a baseball batter that swings and misses a fastball. Here we show that in such situations people can use an internal error signal to make corrections in the next trial. This signal is based on the discrepancy between the actual and the planned action onset time: the prediction error. In this study, we used three interception tasks: reaching movements, saccadic eye movements and a button press that released a cursor moving ballistically for a fixed time. We found that action onset depended on the previous temporal error in the arm movement experiment only and not in the saccadic and button press experiments. However, this dependency was modulated by the movement time: faster arm movements depended less on the previous actual temporal error. An analysis using a Kalman filter confirmed that people used the prediction error rather than the previous temporal error for trial-by-trial corrections in fast arm movements, saccades and button press.

Initial tracking conditions modulate the gain of visuo-motor transmission for smooth pursuit eye movements in monkeys

1994 ◽  
Vol 11 (3) ◽  
pp. 411-424 ◽  
Author(s):  
Joshua D. Schwartz ◽  
Stephen G. Lisberger
Keyword(s):  
Eye Movements ◽  
Smooth Pursuit ◽  
Visual Motion ◽  
Initial Conditions ◽  
Target Motion ◽  
Moving Target ◽  
Smooth Pursuit Eye Movements ◽  
Stationary Target ◽  
Motor Processing ◽  
Pursuit Eye Movements

AbstractSmooth pursuit eye movements allow primates to keep gaze pointed at small objects moving across stationary surroundings. In monkeys trained to track a small moving target, we have injected brief perturbations of target motion under different initial conditions as probes to read out the state of the visuo-motor pathways that guide pursuit. A large eye movement response was evoked if the perturbation was applied to a moving target the monkey was tracking. A small response was evoked if the same perturbation was applied to a stationary target the monkey was fixating. The gain of the response to the perturbation increased as a function of the initial speed of target motion and as a function of the interval from the onset of target motion to the time of the perturbation. The response to the perturbation also was direction selective. Gain was largest if the perturbation was along the axis of ongoing target motion and smallest if the perturbation was orthogonal to the axis of target motion. We suggest that two parallel sets of visual motion pathways through the extrastriate visual cortex may mediate, respectively, the visuo-motor processing for pursuit and the modulation of the gain of transmission through those pathways.

Functional contribution of T1 to the brachial plexus in infants

2011 ◽  
Vol 37 (3) ◽  
pp. 237-243 ◽  
Author(s):  
A. Fattah ◽  
C. G. Curtis ◽  
A. M. R. Agur ◽  
H. M. Clarke
Keyword(s):  
Brachial Plexus ◽  
Upper Limb ◽  
External Rotation ◽  
Physiological Activity ◽  
Arm Movement ◽  
Elbow Flexion ◽  
Early Postoperative Period ◽  
Active Movement ◽  
Anatomical Dissection ◽  
Obstetrical Brachial Plexus Palsy

To determine the contribution of the T1 root to movements of the upper limb in infancy, 40 infants presenting with obstetrical brachial plexus palsy who underwent resection and reconstruction of all brachial plexus roots with the exception of the T1 root were assessed in the early postoperative period. The movements of the limb were recorded using the Hospital for Sick Children active movement scale and demonstrated considerable variability. All movements of the upper limb were observed in this group with the exception of external rotation of the shoulder and elbow flexion. Classical accounts of the function of T1 have limited its activity to the small muscles of the hand and were based on anatomical dissection, brachial plexus injuries and electrical stimulation. By contrast, this study isolated the physiological activity of T1 and analysed the functional contribution of this root to arm movement. We show a greater than generally recognized contribution of T1 to the function of the upper limb in infants.

scholarly journals Pilots’ Attention Distributions Between Chasing a Moving Target and a Stationary Target

2016 ◽  
Vol 87 (12) ◽  
pp. 989-995 ◽  
Author(s):  
Wen-Chin Li ◽  
Chung-San Yu ◽  
Graham Braithwaite ◽  
Matthew Greaves
Keyword(s):  
Moving Target ◽  
Stationary Target
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