• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.1-7
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• 1996

This paper addresses the control problem of a mobile robot supporting a task robot with needs to be positioned precisely. The main difficulty residing in the precise control of a mobile robot supporting a task robot is providing an accurate and stable base for the task robot. That is, the end-plate of the mobile robot which is the base of the task robot can not be positioned accurately without external position sensors. This difficulty is resolved in this paper through the vision information obtained from the camera attached at the end of a task robot. First of all, the camera parameters were measured by using the images of a fixed object captured by the camera. The measured parameters include the rotation, the position, the scale factor, and the focal length of the camera. These parameters could be measured by using the features of each vertex point for a hexagonal object and by using the pin-hole model of a camera. Using the measured pose(position and orientation) of the camera and the given kinematics of the task robot, we calculate a pose of the end-plate of the mobile robot, which is used for the precise control of the mobile robot. Experimental results for the pose estimations are shown.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.5
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• pp.875-880
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• 2008

In this paper, a novel method to determine the optimal checkpoint interval for real-time control task is proposed considering its performance degradation according to tasks's execution time. The control task in this paper has a specific sampling period shorter than its deadline. Control performance is degraded as the control task execution time is prolonged across the sampling period and eventually zero when reached to the deadline. A new performance index is defined to represent the performance variation due to the extension of task execution time accompanying rollback fault recovery. The procedure to find the optimal checkpoint interval is addressed and several simulation examples are presented.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1362-1364
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• 2000

This paper presents the control algorithm verification process for VCB (Vacuum Circuit Breaker) of Korean High Speed Train. In order to enhance the reliability of the control algorithm, the verification process must be performed. The verification is conducted by comparing the pre-designed control algorithm with the pre-planned scenario by simulation tools such as SDL and MSC. This verification process will be applied to the other control algorithms of various control units of Korean High Speed Train.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.497-502
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• 1992

In this paper, a new design technique called Task Based Design (TBD) is proposed to design an optimal robot manipulator for a given task. Optimal design of a manipulator is difficult because it involves implicit and highly nonlinear functions of many design variables for a complex task. TBD designs an optimal manipulator which performs a given task best, by using a framework called Progressive Design which decomposes the complexity of the task into three steps: kinematic design, planning and kinematic control. An example of TBD is presented to demonstrate the efficiency and effectiveness of our framework.

• Korean Journal of Child Studies
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• v.24 no.4
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• pp.15-27
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• 2003

The subjects were individually presented with the Maxi-doll task to examine false belief and with the flower-star (Stroop-like day-night) test to examine inhibitory control skill. In the $1^{st}$ session, the subjects were tested with both the Maxi tesk and the flower-star test. Three days later, subjects were retested with the Maxi task, including an inhibitory cue. Data were analyzed by 3-way ANOVA, age(2) $\times$ inhibitory level(2) $\times$ task type(Maxi-task or Maxi-including cue). All the main effects were significant and the interaction effect between inhibitory level and task type was also significant. Thus, their understanding of the mind and inhibitory control skill both influence children's performance on a typical false belief task.

• The Journal of Korean Physical Therapy
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• v.27 no.5
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• pp.292-298
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• 2015

Purpose: The purpose of this study was to examine the effects of dual tasks on balance and postural control during standing in patients with cerebellar ataxia (CA). It was hypothesized that CA patients would exhibit different sway characteristics of the center of mass (COM) depending on the complexity of the secondary cognitive tasks compared with normal control subjects. Methods: A total of 8 patients with CA and age-matched healthy control subjects participated in this study. They were instructed to perform two balance tasks (non-dual and dual movement) with 3 different complexity of dual tasks. Range, variability, and velocity of COMs were measured. Results: According to the results CA patients showed deficits in balance and postural control with increased dual-task complexity during the static balance task in saggital sway movements. However, there was no significant difference in static balance in frontal sway. With higher difficulty in the cognitive task, CA patients took longer to stabilize their body center, while normal control subjects showed no change between conditions. In addition, CA patients had a greater COM resultant velocity during recovery in the dual-task condition compared with the single-task condition. These findings indicate that CA patients had defendable compensatory strategies in performing dual tasks. Conclusion: In conclusion, CA patients appeared to manage the priority to balance and postural control. Particularly in a situation with a postural threat such as when potential consequences of the loss of stability increase, they appeared to prioritize the control of balance and posture over the performance of the secondary task.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.1
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• pp.51-59
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• 2017

PURPOSE: This study compared cognitive task-directed functional motor control ability for reaching and kicking movements in younger and older adults. METHODS: Subjects were divided into two groups of younger and older adults, with 13 subjects in each group. Subjects were required to perform a dual task combining a functional movement and cognitive component. The task consisted of reaching and kicking movements. Participants performed indicated movements when a target appeared on a monitor. The target randomly appeared on the monitor every 10 seconds. The total performance time (TPT), joint angular velocity (JAV), and muscle activation time were used to evaluate motor control ability. RESULTS: There were significant differences in all evaluation factors in a comparison of younger and older adults (p<.05). TPT was significantly shorter in older adults, and JAV and muscle activation time were significantly slower than that in the younger adult group. Although the results for older adults were within the normal range for functional assessment, their motor control abilities were significantly worse for cognitive tasks compared with those of younger adults. CONCLUSION: The results of this study indicated that a motor control assessment tool using a cognitive task would be helpful in assessment of motor control ability in healthy older adults.

• Physical Therapy Korea
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• v.19 no.1
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• pp.86-93
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• 2012

The purpose of this study was to assess the feasibility of task-oriented arm training for chronic hemiparetic stroke patients. The experimental design in this study was the pre-test and post-test with control group for 4-week intervention. Thirty patients with chronic hemiparetic stroke were recruited from 2 rehabilitation units. The subjects were divided randomly into experimental and control groups. The experimental group conducted task-oriented approach, involving 3 subparts of upper extremity activities, and the control group involved in the general upper extremity exercises. Functional movements of the upper extremities were assessed using clinical measures, including the Fugl-Meyer Assessment-Upper Extremity Section, Box and Block Test, and Action Research Arm Test. The score of Fugl-Meyer Assessment showed greater increases in the experimental group than in the control group after training. The improvement in Box and Block Test between pre-test and post-test measurements was significantly greater after task-oriented arm training compared to general upper extremity exercises. Action Research Arm Test scores also improved after task-oriented arm training compared to exercises in the control group. The task-oriented arm training improves the gross and fine motor activities and encouraging the use of the paretic arm through activity dependent intervention expedites the recovery of functional activities in the upper extremities for chronic hemiparetic stroke.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.410-410
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• 2000

Impedance control is recognised as one of the most proper control scheme to carry out the assembly tasks, since it can control the dynamic relationship between the manipulator and environment directly. However, it is well known that the contact force cannot be controlled directly using the impedance control. Also impedance parameters should be properly defined depending on the task to be performed. We propose a new position based impedance control, which has self-adjusted impedance parameters and can control the contact force explicitly, Impedance parameters, as time-varying parameters, are adjusted automatically based on the measured contact force and the position error during the task. A proposed algorithm was implemented on the peg-in-hole task with the industrial manipulator. We shows the effectiveness of proposed control method experimentally.

• Journal of Mechanical Science and Technology
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• v.16 no.8
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• pp.1053-1063
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• 2002

This paper presents a robust nonlinear controller for a f degree of freedom (DOF) parallel manipulator in the task space coordinates. The proposed control strategy requires information on orientations and translations in the task space unlike the joint space or link space control scheme. Although a 6 DOF sensor may provide such information in a straightforward manner, its cost calls for a more economical alternative. A novel indirect method based on the readily available length information engages as a potential candidate to replace a 6 DOF sensor. The indirect approach generates the necessary information by solving the forward kinematics and subsequently applying alpha-beta-gamma tracker With the 6 DOF signals available, a robust nonlinear task space control (RNTC) scheme is proposed based on the Lyapunov redesign method, whose stability is rigorously proved. The performance of the proposed RNTC with the new estimation scheme is evaluated via experiments. First, the results of the estimator are compared with the rate-gyro signals, which indicates excellent agreement. Then, the RNTC with on-line estimated 6 DOF data is shown to achieve excellent control performance to sinusoidal inputs, which is superior to those of a commonly used proportional-plus-integral-plus-derivative controller with a feedforward friction compensation under joint space coordinates and the nonlinear controller under task space coordinates.