• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.8
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• pp.855-861
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• 2007

Haptic rendering is a process providing force feedback during interactions between a user and a virtual object. This paper presents a real-time haptic rendering technique for deformable objects based on visual information of intervention between a tool and a real object in a remote place. A user can feel the artificial reaction force through a haptic device in real-time when a slave system exerts manipulation tasks on a deformable object. The models of the deformable object and the manipulator are created from the captured image obtained with a CCD camera and the recognition of objects is achieved using image processing techniques. The force at a rate of 1 kHz for stable haptic interaction is deduced using extrapolation of forces at a low update rate. The rendering algorithm developed was tested and validated on a test platform consisting of a one-dimensional indentation device and an off-the shelf force feedback device. This software system can be used in a cellular manipulation system providing artificial force feedback to enhance a success rate of operations.

• Journal of the Korean Society of Physical Medicine
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• v.16 no.3
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• pp.107-113
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• 2021

PURPOSE: Selective strengthening of the transverse abdominis muscle (TrA) during abdominal hollowing makes an important contribution to the stability and control of the spine. This study examined the effects of abdominal hollowing exercise (AHE) according to the visual feedback method on the external oblique, internal oblique, and transverse abdominis muscles. METHODS: Twenty healthy subjects were assigned randomly to an AHE with visual feedback from real-time ultrasound image (group A, n = 10), AHE with visual feedback with pressure biofeedback unit (group B, n = 10). Both groups underwent 20 min of AHE with visual feedback once daily, five days/week for two weeks. The changes in the muscle thickness of the TrA, internal oblique abdominal muscle (IO), and external oblique abdominal muscle (EO) were measured by ultrasonography. RESULTS: The thickness of TrA was changed significantly in both groups (p < .05). However, the lowest minimal detectable changes were achieved in Group A. The thickness of the IO and EO muscles in group A was changed significantly, but there were no significant changes in group B. CONCLUSION: Both visual feedback methods were effective for strengthening the TrA muscles selectively. Nevertheless, AHE with visual feedback using real-time ultrasound images may be more useful in trA muscle contraction.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.4
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• pp.428-434
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• 2012

Missiles suffer from flight instability problems at high angles of attack, since vortex flow over a fuselage cause lateral force to the body. To overcome this problem at a high angle of attack, the development of a real time vortex controller is needed. In this paper, Proper Orthogonal Decomposition (POD) and feedback controllers are developed for real time vortex control. The POD method is one of the most well known techniques for modeling low order models that represent the original full-order model. An adaptive control algorithm is used for real time control.

• Journal of the Korea Convergence Society
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• v.1 no.1
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• pp.17-21
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• 2010

This paper proposes a mechanism for managing overload in real-time web service system. The many previous mechanisms manage overload with controlling web request. These mechanisms can control only new web request. They don't have any control existing tasks, especially periodic tasks. We design a controller that able to meet real-time performance with controlling even periodic tasks. A feedback control system is implemented applying the proposed mechanism. And we verified the stable operation of system.

• Physical Therapy Rehabilitation Science
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• v.9 no.4
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• pp.287-294
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• 2020

Objective: This study aimed to investigate the effects of an ultrasound-based bar graph proportional to the quadriceps muscle thickness as a real-time visual feedback training tool in the elderly. Design: Cross-sectional study. Methods: Twenty-four elderly persons participated in this study and were randomly divided into three groups: oral training group (n=8, group 1), ultrasound imaging group (n=8, group 2), and graph group (n=8, group 3). In the pre condition, all participants performed maximal voluntary isometric contraction (MVIC) of the quadriceps with knee extension three times with oral training. In the post condition, group 1 performed MVIC of the quadriceps with oral training, group 2 performed MVIC of the quadriceps with real-time visual feedback using ultrasound imaging, and group 3 performed MVIC of the quadriceps with real-time visual feedback using a bar graph proportional to the quadriceps muscle thickness, three times for all groups. Muscle thickness, activity (mean, peak), tone, stiffness, logarithmic decrement, relaxation, and creep were measured in both conditions in all participants. Results: Visual feedback with a bar graph showed significant effects on muscle thickness, mean muscle activity, and peak muscle activity compared with oral training and visual feedback with ultrasound imaging (p<0.05). Conclusions: Isometric training of the quadriceps with real-time visual feedback using a bar graph proportional to the quadriceps muscle thickness may be more effective than other methods in improving muscle thickness and muscle activity. This study presented a tool that can help increase muscle thickness in the elderly.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.5
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• pp.120-129
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• 2001

As many sensors and actuators are used in many automated systems, various industrial networks are adopted for real-time distributed control. In order to take advantages of the networking, however, the network implementation should be carefully designed to satisfy real-time requirements considering network delays. This paper presents the implementation of a remote feedback control system via Profibus-DP net work for real-time distributed control More specifically, the effect of the network delay on the control performance evaluated on Profibus-DP testbed. Also, the traditional PID gain tuning methods are used to demonstrate the feasibility of the remote feedback control.

• Journal of the Korean Institute of Intelligent Systems
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• v.10 no.5
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• pp.423-431
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• 2000

In this paper, the effect of computing time-delay in the real-time digital fuzzy control systems is investigated and the design methodology of a real-time digital fuzzy controller(DFC) to overcome the problems caused by it is presented. We propose the fuzzy feedback controller whose output is delayed with unit sampling period. The analysis and the design problem considering computing time-delay is very easy because the proposed controller is syncronized with the sampling time. The stabilization problem of the digital fuzzy control system is solved by the linear matrix inequality(LMI) theory. Convex optimization techniques are utilized to find the stable feedback gains and a common positive definite matrix P for the designed fuzzy control system Furthermore, we develop a real-time fuzzy control system for backing up a computer-simulated truck-trailer with the consideration of the computing time-delay. By using the proposed method, we design a DFC which guarantees the stability of the real time digital fuzzy control system in the presence of computing time-delay.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.2
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• pp.157-162
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• 1998

This paper provides some properties of positive real systems in time domain. It is well-known that a positive real system and a bounded real system are closely related by bilinear transform in a frequency domain. By using supply rate and storage function, we show that a positive real system can be transformed into a bounded real system, and that a positive real system can be transformed into another positive real system with in a time domain. Also, we show that an ESPR(extended strictly positive real) system can be decomposed into a feedback system of lossless positive real system and another ESPR system. These results may be used to design an output feedback controller for mixed H$H_2$ESPR problem.

• Journal of Korea Multimedia Society
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• v.2 no.3
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• pp.339-346
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• 1999

When a multicast video conference system utilizes RTP (Real Time Protocol) and RTCP (Real Time Control Protocol), the loss rate and the synchronization of transfer in RTCP affect the scalability of the system. The random delay technique introduced to resolve the problems is so simple that leads the network to meet some congestion in synchronizing feedback information when lots of people transfer the feedback information simultaneously, which reduces the scalability of system. In this paper, we propose a new feedback control algorithm that provides priority levels with the RTCP packet, which cuts down the feedback delay and increases the scalability. The criteria of providing priority Based on the decided priority level, Agent forced the session participants to provide much more RTCP packets, positively controlled, and the possible bandwidth can be measured. The simulation on this technique decreases the delay, and the feedback messages are equally distributed on a given time period.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.2
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• pp.130-135
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• 2009

In recent years, researches on rotary inverted pendulum control systems have been significantly focused due their highly nonlinear dynamics and complicated geometric structures. This paper presents a novel control approach for such systems by means of similarity transformation theory. At first, we represent nonlinear system dynamics to the controllability-formed state space model including a time-varying parameter vector. We establish the state-feedback control configuration based on the transformed model and derive an adaptive control law for adjusting desired characteristic equation. Numerical analysis is achieved to evaluate our control method and demonstrate its superiority by comparing it to the traditional control strategy. Furthermore, real-time control experiment is carried out to test its practical reliability.