Detection Of Movement Direction Research Articles

Detection of Human Movement Direction Using Optical Flow Analisys on Multiple Camera Angles

The active movement of children poses a safety risk in the absence of adult supervision. To reduce the risk of accidents in children, an automatic detection system for the direction of children's movements is crucially needed. In this study, detection of the direction of human movement based on image processing was carried out with the input of videos produce from 4 CCTV installed in each corner of the room. The system will detect the direction of object movement with classification of orientation, namely front, back, right and left. The detection method used in this research is Optical Flow. Optical Flow will calculate the value of the direction or orientation of the movement of an object. The orientation obtained is then accumulated with HOOF (Histogram Orientation of Optical Flow), where HOOF will collect the orientation of objects on the whole frame according to a 8-part Cartesian angle. The results of the orientation with Optical Flow will be compared with the direction of detection measured manually to determine whether the detection of movement direction using Optical Flow is running well. According to the results, it is known that the Optical Flow method has succeeded in detecting the direction of movement accurately based on different camera angles. Keywords : Image Processing, CCTV, Optical Flow, HOOF

QGesture

Many HCI applications, such as volume adjustment in a gaming system, require quantitative gesture measurement for metrics such as movement distance and direction. In this paper, we propose QGesture, a gesture recognition system that uses CSI values provided by COTS WiFi devices to measure the movement distance and direction of human hands. To achieve high accuracy in measurements, we first use phase correction algorithm to remove the phase noise in CSI measurements. We then propose a robust estimation algorithm, called LEVD, to estimate and remove the impact of environmental dynamics. To separate gesture movements from daily activities, we design simple gestures with unique characteristics as preambles to determine the start of the gesture. Our experimental results show that QGesture achieves an average accuracy of 3 cm in the measurement of movement distance and more than 95% accuracy in the movement direction detection in the one-dimensional case. Furthermore, it achieves an average absolute direction error of 15 degrees and an average accuracy of 3.7 cm in the measurement of movement distance in the two-dimensional case.

The effect of experimentally-induced subacromial pain on proprioception

Shoulder injuries may be associated with proprioceptive deficits, however, it is unknown whether these changes are due to the experience of pain, tissue damage, or a combination of these. The aim of this study was to investigate the effect of experimentally-induced sub-acromial pain on proprioceptive variables. Sub-acromial pain was induced via hypertonic saline injection in 20 healthy participants. Passive joint replication (PJR) and threshold to detection of movement direction (TTDMD) were assessed with a Biodex System 3 Pro isokinetic dynamometer for baseline control, experimental pain and recovery control conditions with a starting position of 60° shoulder abduction. The target angle for PJR was 60° external rotation, starting from 40°. TTDMD was tested from a position of 20° external rotation. Repeated measures ANOVAs were used to determine differences between PJR absolute and variable errors and TTDMD for the control and experimental conditions. Pain was elicited with a median 7 on the Numeric Pain Rating Scale. TTDMD was significantly decreased for the experimental pain condition compared to baseline and recovery conditions (≈30%, P = 0.003). No significant differences were found for absolute (P = 0.152) and variable (P = 0.514) error for PJR. Movement sense was enhanced for the experimental sub-acromial pain condition, which may reflect protective effects of the central nervous system in response to the pain. Where decreased passive proprioception is observed in shoulders with injuries, these may be due to a combination of peripheral tissue injury and neural adaptations that differ from those due to acute pain.

The Synaptic Mechanism of Direction Selectivity in Distal Processes of Starburst Amacrine Cells

Patch-clamp recordings revealed that distal processes of starburst amacrine cells (SACs) received largely excitatory synaptic input from the receptive field center and nearly purely inhibitory inputs from the surround during both stationary and moving light stimulations. The direct surround inhibition was mediated mainly by reciprocal GABA(A) synapses between opposing SACs, which provided leading and prolonged inhibition during centripetal stimulus motion. Simultaneous Ca(2+) imaging and current-clamp recording during apparent-motion stimulation further demonstrated the contributions of both centrifugal excitation and GABA(A/C)-receptor-mediated centripetal inhibition to the direction-selective Ca(2+) responses in SAC distal processes. Thus, by placing GABA release sites in electrotonically semi-isolated distal processes and endowing these sites with reciprocal GABA(A) synapses, SACs use a radial-symmetric center-surround receptive field structure to build a polar-asymmetric circuitry. This circuitry may integrate at least three levels of interactions--center excitation, surround inhibition, and reciprocal inhibitions that amplify the center--surround antagonism-to generate robust direction selectivity in the distal processes.

Improvement of Kinaesthetic Deficits by Subthalamic Nucleus Stimulation in Parkinson's Disease

Recent studies have revealed that patients with Parkinson's disease (PD) exhibit kinaesthesic deficits. For example, they have higher perceptual thresholds in detecting passive elbow movements. Deep brain stimulation (DBS) of the subthalamic nucleus (STN) improves motor deficits in PD, but its effect on kinaesthesia is unknown. We have now examined how STN DBS affects the perception of limb position. 9 PD patients with bilateral chronic STN DBS and 7 controls were tested. The subject's forearm was moved passively (˜ 0.5 deg/s) while resting on a splint. A torque motor was mechanically connected to the splint, moving it at a constant speed causing either forearm flexion or extension. For each condition (ON or OFF stimulation), 40 flexion and 40 extension movements were recorded with elbow joint angular displacements of 0.2, 0.6, 1 up to 8. To account for order effects, a subset of the PD patients (n=5) was tested in the ON-stimulation state first, while the remaining patients were first examined during the OFF-stimulation state (n=4). A 1° displacement was detected in 78% of the trials and a 2° displacement in over 91% of the trials by the control subjects. In contrast, PD patients were clearly impaired in the correct detection of movement direction. During ON-stimulation they showed correct responses in 74% for 2° displacements. Deficits worsened when the DBS device was OFF with PD patients correctly detecting 2° displacements in only 60% of the trials. Thresholds for 75% correct responses were 0.9° for controls, 2.5° for PD patients when stimulation was OFF and 2.0° when stimulation was ON. We conclude that STN DBS may improve kinaesthesic deficits in PD, but does not lead to a full recovery of proprioceptive function. (Work supported by a grant from the DFG (MA 2209/3–1.)

Quais são as funções dos mecanoreceptores da articulação do ombro?: uma revisão da literatura

Nontraumatic glenohumeral instability is the most common shoulder pathology among young people causing pain and impingement syndrome symptoms. This instability usually affects athletes who perform overhand activities such as throwing and swimming. The glenohumeral stability is usually provided by rotator cuff musculature and capsule-ligament structures (glenoid labrum, glenohumeral ligaments and capsule). In order to control the synergistic relationship between muscles and capsuloligamentous structures, the somatosensory system located in the glenohumeral joint plays an essential function. These mechanoreceptors, Pacini, Ruffini and Golgi tendon organs are functionally distributed in the shoulder joints, and they have a complex relationship with the shoulder's musculature. According to the latencies obtained between stimuli in shoulder joints and muscular responses, suggests the consideration that mechanoreceptors not only contribute to detection of movement direction and joint position sense, but are also implicated in the control of movements and coordination. Rehabilitation programs for altered movement patterns using proprioceptive techniques appear to be justifiable. Also, to enhance proprioceptive techniques, more attention should be focused on shoulder exercises that use sequences and coordination in their execution.

The detection of movement direction and effects of contrast reversal in the cat's striate cortex

Single cell responses to moving visual stimuli have been recorded in the striate cortex of anaesthetized and immobilized cats, and the effects of the reversal of stimulus contrast have been tested. The detection of the direction of movement of a light stimulus in the cat's striate cortex depends to a certain extent on the receptive field type and—in cells having simple receptive fields—also somewhat on the eccentricity in receptive field location. In a high proportion of striate cells a reversal in stimulus contrast either changes the degree of the direction sensitivity or even reverses the preferred direction. The effects of the contrast reversal are much stronger in simple than in complex cells. Susceptibility to contrast reversal is observed mainly in directional asymmetric and bidirectional cells; the responses of the majority of unidirectional cells remain stable under contrast reversals. These latter cells are therefore the directional selective cells and they comprise about 25% of the total striate cell population.