• 대한인간공학회지
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• 제31권4호
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• pp.551-556
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• 2012

Objective: This study presents the effect of visual feedback on one-hand gesture performance in vision-based gesture recognition system when people use gestures to control a screen device remotely. Backgroud: gesture interaction receives growing attention because it uses advanced sensor technology and it allows users natural interaction using their own body motion. In generating motion, visual feedback has been to considered critical factor affect speed and accuracy. Method: three types of visual feedback(arrow, star, and animation) were selected and 20 gestures were listed. 12 participants perform each 20 gestures while given 3 types of visual feedback in turn. Results: People made longer hand trace and take longer time to make a gesture when they were given arrow shape feedback than star-shape feedback. The animation type feedback was most preferred. Conclusion: The type of visual feedback showed statistically significant effect on the length of hand trace, elapsed time, and speed of motion in performing a gesture. Application: This study could be applied to any device that needs visual feedback for device control. A big feedback generate shorter length of motion trace, less time, faster than smaller one when people performs gestures to control a device. So the big size of visual feedback would be recommended for a situation requiring fast actions. On the other hand, the smaller visual feedback would be recommended for a situation requiring elaborated actions.

• 대한인간공학회지
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• 제31권6호
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• pp.725-731
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• 2012

Objective: The aim of this study is to investigate visual feedback effects and human performance in the foot mouse control. Background: Generally, computer mouse tasks are controlled by visual feedback. In order to understand the characteristics of a foot mouse control, it is important to investigate the patterns of visual feedback involved in foot-mouse control tasks. Human performance of foot mouse control is also an important factor to understand the foot mouse control. Method: Three types of mouse control were determined to investigate visual feedback effects and human performance in the foot mouse control. Visual feedback effects in the foot mouse control were compared with those of a typical hand mouse. The cursor movement speed and mental workload were measured in the three types of tasks and two types of mouses. Results: Mouse control tasks with an element of homing-in to the target were more quickly performed by the hand mouse than the foot mouse. Mental workload was also higher in the foot mouse than the hand mouse. However, in the steering movement, human performance of the foot mouse control was not lower than that of the hand mouse control. Visual feedback in the foot mouse control was less required than in the hand mouse control. Conclusion: The foot mouse was not efficient in the most mouse control tasks, compared to the hand mouse. However, the foot mouse was efficient in the steering movement, moving a cursor within a path with lateral constraints. Application: The results of this study might help to develop the foot mouse.

• The Journal of Korean Physical Therapy
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• 제31권3호
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• pp.151-156
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• 2019

Purpose: This study aimed to investigate the immediate effects of posture correction and real-time visual feedback using a video display on muscle activity and change of head position during overhead arm lift test in individuals with forward head posture. Methods: Fifteen subjects with forward head posture and fifteen normal subjects who volunteered were included in this study. During both groups performed the overhead arm lift test, the muscle activity of the upper trapezius, serratus anterior, sternocleidomastoid, and lower trapezius muscle were measured using electromyography, and head position change was measured using photographs. Then, forward head posture group was asked to perform overhead arm lift test again after posture correction and real-time visual feedback using a video display respectively. One-way analysis of variance (ANOVA) was used to analyze four conditions: pre-test, posture correction, real-time visual feedback, and the control group. Results: The upper trapezius and lower trapezius muscle activity significantly decreased posture correction, real-time visual feedback, and control group than pre-test of forward head posture group (p<0.05). The sternocleidomastoid muscle significantly decreased real-time visual feedback and control group than pre-test of forward head posture group. Head position change significantly decreased three conditions than pre-test of forward head posture group and real-time visual feedback and control group significantly decreased than posture correction. Conclusion: This study recommend for maintaining cervical stability during the overhead arm lift test, postural control using real-time visual feedback is more effective in subjects with forward head posture.

• 한국기계가공학회지
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• 제12권1호
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• pp.35-42
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• 2013

This paper proposes a new approach to the designed of visual feedback control system based on visual servoing method. The main focus of this paper is presented how it is effective to use many features for improving the accuracy of the visual feedback control of industrial articulated robot for assembling and inspection of parts. Some rank conditions, which relate the image Jacobian, and the control performance are derived. It is also proven that the accuracy is improved by increasing the number of features. The effectiveness of redundant features is verified by the real time experiments on a SCARA type robot(FARA) made in samsung electronics company.

• The Journal of Korean Physical Therapy
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• 제19권6호
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• pp.37-41
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• 2007

Purpose: Hemiplegic patients usually present with difficulties in maintaining their balance. Balance retraining is a major component of a rehabilitation program for patients with neurological impairments. This study compared the effects of prorpioceptive exercise and visual feedback program on the limits of stability (LOS) in chronic hemiplegia patients. Methods: Thirty subjects (mean age $57.0{\pm}9.8$) were recruited. The subjects were divided into a proprioceptive group and a visual group. The subjects for the proprioceptive group participated in the proprioceptive exercise program for 4 weeks, and the visual group were treated with visual feedback training using a Balance Master. Results: At the 4 week follow-up test, the LOS in the proprioceptive group improved significantly in all directions (p<0.05). However, improvement was only observed in the forward direction in the visual feedback group. Therefore, the proprioceptive control approach improves the LOS in chronic hemiplegia patients. Conclusion: These results suggest that compared with physical therapy alone using a proprioceptive control approach to hemiplegia, there was no additional benefit of visual feedback training, such as Balance Master, when administrated in combination with other physical therapy interventions.

• 한국산업융합학회 논문집
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• 제17권1호
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• pp.27-34
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• 2014

This paper proposes a new approach to the designed of visual feedback control system based on visual servoing method. The main focus of this paper is presented how it is effective to use many features for improving the accuracy of the visual feedback control of industrial articulated robot for assembling and inspection of parts. Some rank conditions, which relate the image Jacobian, and the control performance are derived. It is also proven that the accuracy is improved by increasing the number of features. The effectiveness of redundant features is verified by the real time experiments on a SCARA type robot(FARA) made in samsung electronics company.

• 한국산업융합학회 논문집
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• 제18권2호
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• pp.90-98
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• 2015

This research propose with image-based visual a new approach to design a feedback control of mobile robot. because mobile robot must be recharged periodically, it is necessary to detect and move to docking station. Generally, laser scanner is used for detect of position of docking station. CCD Camera is also used for this purpose. In case of using camera, the position-based visual servoing method is widely used. But position-based visual servoing method requires the accurate calibration and it is hard and complex work. Another method using cameras is inmage-based visual feedback. Recently, image based visual feedback is widely used for robotic application. But it has a problem that cannot have linear trajectory in the 3-dimensional space. Because of this weak point, image-based visual servoing has a limit for real application. in case of 2-dimensional movement on the plane, it has also similar problem. In order to solve this problem, we point out the main reason of the problem of the resolved rate control method that has been generally used in the image-based visual servoing and we propose an image-based visual feedback method that can reduce the curved trajectory of mobile robot in th cartesian space.

• 한방재활의학과학회지
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• 제21권1호
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• pp.137-148
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• 2011

Objectives : This study was to investigate the visual bio-feedback training for 5 weeks on balance and postural control for patients with stroke. Methods : The 26 subjects were randomly selected from the patients of the E hospital in the S city who met the study conditions. They were divided into a visual bio-feedback training group of 13 patients and a self-resistance exercise group of 13 patients. The visual bio-feedback training group received visual bio-feedback and general physiotherapy for five weeks and the self-resistance exercise group received cycling and general physiotherapy for the same period. The subjects were measured and compared for stability index, weight distribution index, fall down index, functional reach test and timed up and go test before and after the program. Results : The visual bio-feedback training group showed significant changes after the experiment in stability index, weight distribution index, functional reach test and timed up and go test(p<0.05), and the self-resistance exercise group also showed significant differences(p<0.05). The changes between prior to and after the experiment show that the visual bio-feedback training group had more significant effects than the self-resistance exercise group(p<0.05). Conclusions : The visual bio-feedback training for five weeks had effects in the improvement of the balance and posture control of stroke patients. Based on these results, more effective training programs should be developed and propagated.

• The Journal of Korean Physical Therapy
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• 제34권2호
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• pp.57-62
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• 2022

Purpose: The purpose of this study was to determine the effects of bilateral visual feedback training with visual targets on the postural balance and fall efficacy of stroke patients with hemiparesis. Methods: A total of 24 stroke patients with hemiparesis were randomly assigned to either a bilateral visual feedback training (BVFT, n=8) group, unilateral visual feedback training (UVFT, n=8) group, or a control group (n=8). The BVFT and UVFT groups performed weight-bearing training on the bilateral (less-affected and affected side) or unilateral side (affected side) with visual feedback using visual targets. The control group performed squat training without visual feedback using visual targets. The training program was conducted in the form of 3 sets a day, 3 times a week, for 4 weeks. The participants were evaluated using the Berg balance scale (BBS), lateral reaching test (LRT), timed up and go test (TUG), and the activities-specific balance confidence scale (ABC). Results: In the intra-group comparison after the intervention, the BVFT group showed a significant difference in the BBS, TUG, affected and less-affected side LRT, and ABC (p<0.05). The UVFT group showed a significant difference in the BBS and ABC (p<0.05). In the inter-group comparison after the intervention, the BVFT group showed significant improvements in their BBS, affected side LRT, and TUG, when compared to the control group (p<0.05). Conclusion: These findings show that bilateral visual feedback training with visual targets during bilateral weight-bearing exercises can improve the postural balance function in stroke patients.

• 한국전문물리치료학회지
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• 제19권3호
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• pp.40-50
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• 2012

The purpose of this study was to investigate the effect of visual feedback on the postural control of stroke patients, by systematically varying conditions of visual feedback [eye-open condition (EO) vs. eye-closed condition (EC)], and base-support (both-side support, affected-side support, and unaffected-side support). In this study, we allocated 41 stroke patients with no damage in the cerebellum and visual cortex who can walk at least 10 meters independently, and 35 normal adults who have no experience of stroke to the control group. Both groups were asked to perform a "sit-to-stand" task three to five times, and their postural control ability was measured and compared in terms of asymmetric dependence (AD) instead of the traditional symmetric index (SI) in the literature. The results showed that although both subject groups maintained better postural control in the EO condition than in the EC condition, the patient group appeared to be more stable in EC than in EO when they were required to perform the task of the support condition given on the affected side. These results implied that visual feedback can impair stroke patients' postural control when it is combined with a specific support condition.