• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2146-2148
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• 2002

In this paper, PID control method using genetic algorithm to control the nonlinear multivariable system is presented. Genetic algorithms are global search techniques for nonlinear optimization. For experiment, the x-y rod balancing system with driver circuit board is fabricated. Experiments such as angle and position control for system are performed. The validity and control performance of the GA-based PID controller are confirmed by experimental results.

• PNF and Movement
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• v.15 no.1
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• pp.57-65
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• 2017

Purpose: The purpose of this study was to examine the effects of resistant gait training with proprioceptive neuromuscular facilitation (PNF) on the walking and balancing abilities of chronic stroke patients. Methods: Twelve chronic stroke patients were randomly assigned to either a control group (n = 6) that underwent treadmill gait training or an experimental group (n = 6) that underwent resistant gait training using PNF. The interventions were performed five times per week for four weeks. Gait variables were measured using a GAITRite system (CIR System Inc, Clifton, NJ, USA) to examine changes in walking ability; the Berg balance scale (BBS) was used to measure changes in balance; and the activity-specific balance confidence scale (ABC) was measured to examine changes in confidence about balance. A Wilcoxon signed-rank test was used to examine intragroup differences before and after the interventions, and a Mann-Whitney U-test was used for intergroup comparisons of the effects of the interventions. All statistical significance levels were set to ${\alpha}=0.05$. Results: Both the experimental group and the control group showed significant intragroup improvement in walking speed, the number of steps per minute, stride length, double support time, balance, and confidence about balance after the interventions (p < 0.05). In intergroup comparisons after the interventions, the experimental group showed significant improvements over the control group in walking speed, the number of steps per minute, stride length, balance, and confidence about balance (p < 0.05). No significant difference in double support time was seen in the intergroup comparison after training (p > 0.05). Conclusion: This study applied resistant gait training using PNF to chronic stroke patients, and the results showed significant improvements in the patients' walking and balancing abilities. Therefore, resistant gait training using PNF is thought to be applicable as an intervention method for chronic stroke patients.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.8
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• pp.758-765
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• 2015

This paper proposes an attitude control system to keep the balance for a two-wheeled mobile manipulator which consists of a mobile platform and a three D.O.F. manipulator. In the conventional control scheme, complicated dynamics of the manipulator need to be derived for balancing control of a mobile manipulator. The method proposed in this paper, however, three links are considered as one body of mass and the dynamics are derived easily by using an inverted pendulum model. One of the best advantage of a sliding mode controller is low sensitivity to plant parameter variations and disturbances, which eliminates the necessity of exact modeling to control the system. Therefore the sliding mode control algorithm has been adopted in this research for the attitude control of mobile platform along the pitch axis. The center of gravity for the whole mobile manipulator is changing depending on the motion of the manipulator. And the orientation variation of center of gravity is used as reference input for the sliding mode controller of the pitch axis to maintain the center of gravity in the middle of robot to keep the balance for the robot. To confirm the performance of controller, MATLAB Simulink has been used and the resulting algorithms are applied to a real robot to demonstrate the superiority of the proposed attitude control.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.73-78
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• 1999

This paper presents an effective construction method of adaptive multiple control systems utilizing some knowledge upon the plants. The adaptive multiple control system operates plants un-der widely changing environmental conditions. The adaptive multiple control system is composed of a family of candidate controllers together with a supervisor. The system does not require any identification schemes of environmental conditions. Monitoring outputs of the plant, the supervisor switches from one candidate controller to another, The basic ideas of adaptation are as follows: (1)each candidate controller is prepared for each environmental condition in advance; (2)the supervise. applies a sequence of speculative controls to the plant with candidate controllers just after the start of control or just after the detection of a change in the environmental condition. Each candidate controller can keep the system stable during one-step period of the speculative control and the most appropriate candidate controller for the environmental condition to which the system is exposed can be selected before the last trial of speculative control step comes to an end. We proposed a construction method of adaptive multiple control system without any knowledge of plant dynamics and applied the method to a cart-pole balancing problem and a vehicle anti skid braking system. In real applications, as we can often easily obtain a piece of knowledge upon plant dynamics beforehand, we intend to extend the method such that multiple control systems can be efficiently designed using the knowledge. We apply the new idea to the cart-pole balancing problem with variable length of the pole. The simulation experiments lead us to the conclusion that the new attempt can reduce the manpower to design the candidate controllers for adaptive multiple control systems.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.2
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• pp.162-172
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• 2011

This paper proposes embedded System of two wheeled inverted pendulum robot designed by model based design method, using MATLAB/SIMULINK and LEGO NXT Mindstorms. At first, stability and performance of controller is verified through modeling and simulation. After that direct conversion from simulation model to C code is carried and effectiveness of controller is experimentally verified. Two wheeled inverted pendulum robot has basic function about autonomous balancing control using principle of inverted pedulum and it is also possible to arrive at destination. In this paper, state feedback controller designed by quadratic optimal control method is used. And quadratic optimal control uses state feedback control gain K to minimize performance index function J. Because it is easy to find gain, this control method can be used in the controller of two wheeled inverted pendulum robot. This proposed robot system is experimentally verified with following performances - balancing control, disturbance rejection, remote control, line following and obstacle avoidance.

• Journal of The Korean Society of Integrative Medicine
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• v.3 no.2
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• pp.55-61
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• 2015

Purpose: The purpose of this study was to investigate the effect of regularly strength exercise of spine in teenagers with tutor. Method: Study subjects were 24 middle school students. They were arranged to 2 groups(n=12, respectively). Then experimental group did regularly strength exercise of spine as the handout maneuver during 50min/day and 1day/week in 8 weeks with tutor, but control group did regularly exercise of spine as same maneuver without tutor. For muscle strength of both extensor and flexor of lumbar, the balancing ability and weight distribution index were measured before and after the intervention. Results: For muscle strength of both extensor and flexor of lumbar, there was not significant differences after the intervention, but both flexor and extensor increase mean value of muscle strength than control group. For balancing ability and weight distribution index, there were not significant difference after intervention(p>.05), but experimental group show a tendency to decrease in a few position than control group. Conclusion: When teenagers regularly exercise for spine strengthening for a long time with tutor, it may be increased muscle strength of lumbar and trunk balance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.2
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• pp.228-236
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• 2012

In this paper, a controller for two wheeled inverted pendulum robot is designed to have more stable balancing capability than conventional controller. Fuzzy control structure is chosen for the two wheeled inverted pendulum robot, and fuzzy membership function factors for the controller are obtained for specified 3 users' weights using trial-and-error method. Next a neural network is employed to generate fuzzy membership function factors for more stable control performance when the user's weight is arbitrarily selected. Through the simulation study we find that the designed fuzzy controller using the neural network is superior to the conventional fuzzy controller.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.2 no.2 s.3
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• pp.13-22
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• 2003

It is recognized that one of the problems for the current 'Traffic Adaptive Control System in Seoul' is the performance at the oversaturated condition. Instead of 'Degree of Saturation' adopted in the current system, the methodology of balancing the queue length was developed and evaluated in this study. This method keeps the balance of queue lengths on the intersections and reduces the overall queue lengths. In addition a traffic signal control model was developed based on the method. This model can reduce not only the queue lengths but also the average delay of vehicles according to the macroscopic and microscopic evaluations.

• Journal of Power Electronics
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• v.12 no.2
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• pp.344-356
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• 2012

In recent years, multilevel technology has become an effective and practical solution in the field of moderate and high voltage applications. This paper discusses an APF with a three-level NPC inverter. Obviously, the application of such converter to APFs is hindered by the problem of the voltage unbalance of DC capacitors, which leads to system instability. This paper comprehensively analyzes the theoretical limitations of the neutral-point voltage balancing problem for tracking different harmonic currents utilizing current switching functions from the space vector PWM (SVPWM) point of view. The fluctuation of the neutral point caused by the load currents of certain order harmonic frequency is reported and quantified. Furthermore, this paper presents a close-loop digital control algorithm of the DC voltage for this APF. A PI controller regulates the DC voltage in the outer-loop controller. In the current-loop controller, this paper proposes a simple neutral-point voltage control method. The neutral-point voltage imbalance is restrained by selecting small vectors that will move the neutral-point voltage in the direction opposite the direction of the unbalance. The experiment results illustrate that the performance of the proposed approach is satisfactory.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1500-1511
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• 2017

The purpose of this paper is to study a high-performance control scheme for neutral-point-clamping three-level (NPC-3L) inverter fed dual three-phase permanent magnet synchronous motor (PMSM) drives by considering some asymmetric factors such as the non-identical parameters in phase windings. To implement this, the system model is analyzed for dual three-phase PMSM drives with asymmetric factors based on the vector space decomposition (VSD) principle. Based on the equivalent circuits, PI controllers with feedforward compensation are used in the d-q subspace for regulating torque, where the cut-off frequency of the PI controllers are set at the twice the fundamental frequency for compensating both the additional DC component and the second order component caused by asymmetry. Meanwhile, proportional resonant (PR) controllers are proposed in the x-y subspace for suppressing the possible unbalanced currents in the phase windings. A dual three-phase space vector modulation (DT-SVM) is designed for the drive, and the balancing factor is designed based on the numerical fitting surface for balancing the DC link capacitor voltages. Experimental results are given to demonstrate the validity of the theoretical analysis and the proposed control scheme.