• Journal of Institute of Control, Robotics and Systems
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• v.8 no.11
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• pp.916-921
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• 2002

We presents a new method of constructing an equivalent T-S fuzzy model by using the sum of products of linearly independent scalar functions from nonlinear dynamics. This method exactly expresses nonlinear systems and automatically determines the number of rules. We design a stabilizing controller f3r ul inverted pendulum system by using the concep of parallel distributed compensation (PDC) and linear matrix inequalities (LMIs) based on the proposed T-S fuzzy modeling method. We show effectiveness of a systematically designed fuzzy controller based on the proposed T-S fuzzy modeling method through the simulation and experiment of an inverted pendulum system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.9
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• pp.1147-1153
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• 1999

The attitude control of a double inverted pendulum with a periodical disturbance at link top is dealt in this paper. The proposed system is consisted of the double inverted pendulum and a disturbing link; a triple inverted pendulum with two motors. The lower link is hinged on the plate to free for rotation in the vertical plane. The upper link is connected to the lower link through a DC motor. The DC motor is used to control the posture of the pendulum by adjusting the position of the upper link. The periodical disturbance can be generated by the additional like attached at the end of link 2 through another DC motor, which is the modeling of a posture for a biped supporting with one leg. The motor for the joint simulates the knee joint(or hip joint) and the disturbance for the legs moving in air. The algorithm for controlling the proposed inverted pendulum which is regarded as a virtual double inverted pendulum with a periodic disturbance, is consisted of a state feedback control and a fuzzy logic controller connected in parallel. The fuzzy controller keeps the center of gravity of the biped within the specified range through the nonlinear feedback compensator. The state feedback control takes over the role to maintain a desired posture regardless the disturbance at the link top. Simulations with a mathematical model and experiments are conducted to show the validity of the proposed controller.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.11
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• pp.483-490
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• 2006

When the nonlinearities, such as friction and backlash, are not considered in the controller design, undesirable oscillations can occur in the steady-state response of a control system. This paper deals with a method to reduce oscillations that often appear in the steady-state response of a pendulum system, which is controlled by a state feedback controller based on the linearized system model. With an assumption that the oscillations shown in the steady-state are caused by the Coulomb friction, we improve the performance of stabilization and tracking by estimating and compensating for the Coulomb friction in the pendulum system. Experimental results show that the control performance can be improved sufficiently by the proposed method, when it is applied to an inverted cart pendulum which is a multi-variable unstable system. Furthermore, we could see that the Coulomb friction model used in the estimation of the friction is valid in applying the suggested method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.311-314
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• 1995

Biped locomotion can be simply modeled as a linear inverted pendulum mode. This model considers only the CG (center of gravity) of the entire system. But in real biped robot systems, the free-leg motion dynamics is not negligible. So if its dynamics is not considered in designing the reference CG motion, it is badly influence to the ZMP(zero moment point) position of the biped robot walking in the sagittal plane. Therefore, we modeled the biped locomotion similar to the linear inverted pendulum mode but considered the predetermined free-leg dynamics. To verify that the proposed biped locomotion is more stable than the linear inverted pendulum mode, we constructed a biped robot simulator and designed a serco controller to track both the reference motion of the free leg and the reference motion of CG of the biped robot using the computed torque control low. And through simulations, we verified that the proposed walking is better in stability than the one based on the linear inverted pendulum mode.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.7
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• pp.656-663
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• 2007

A new dynamic balancing algorithm has been proposed to minimize the number of sensors necessary for the horizontal balancing of the mobile inverted pendulum while maintaining the same level of the commercial performance. The inverted pendulum technique is getting attention and there have been many researches on the Segway since the US inventor Dean Kamen commercialized. One of the major problems of the Segway is that many sensors are required for the control of the Segway, which results in the high price. In this research, a single gyro and a tilt sensor are fused to obtain the absolute tilt information, which is applied for the control of the mobile inverted pendulum. A dynamic balancing technique has been developed and applied for a robust control system against disturbances. The intelligent handling and stable curving of the Segway as a next generation mobile tool are verified with a human loading.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.79-81
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• 2004

LQ-Servo controller inherits the stability-robustness from rational LQR structure and also, satisfies performance-robustness that is lacking in LQR structure by importing partial output feedback. In this paper, LQ-Servo controller is suggested for strengthening the performance-robustness. For this, Several executings are effectively performed by implementing to the rotational inverted pendulum system.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2006.11a
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• pp.323-326
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• 2006

Rotational inverted pendulum is a typical under-actuated system. For its highly nonlinear characteristic, a sliding mode controller is chosen for its robustness against the system uncertainties. Tow fuzzy inference mechanisms are applied in this paper to reduce the chattering phenomenon. One is proposed to construct a time-varying sliding surface. Another one is used to obtain the minimum upper bound of the uncertainties. A comparison between the conventional sliding mode and the fuzzy sliding mode is shown by simulations.

• The Journal of Korea Robotics Society
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• v.4 no.4
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• pp.289-297
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• 2009

This paper presents the development and control of a two wheeled car-like mobile robot using balancing mechanism whose heading control is done by turning the handle. The mobile inverted pendulum is a combined system of a mobile robot and an inverted pendulum system. A sensor fusion technique of low cost sensors such as a gyro sensor and a tilt sensor to measure the balancing angle of the inverted pendulum robot system accurately is implemented. Experimental studies of the trajectory following control task has been conducted by command of steering wheel while balancing.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.643-645
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• 1999

In experiment, a real inverted pendulum system has state constraints and limited amplitude of input. These problems make it difficult to design a swing-up controller. To overcome these problems, we design a sliding mode controller considering physical behaviour of the inverted pendulum system. This sliding mode controller uses a switching control action to converge along a specified path derived from energy equation from a state around the path to desired states(standing position). And optimal control method is used to guarantee stability at unstable equilibrium position. The designed controller can be applied to all inverted pendulum systems regardless of the values of their parameters. Compared with previous existing controllers, it is simple and easy to tune. Experimental results are given to show the effectiveness of this controller.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.6
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• pp.746-752
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• 2006

This paper presents a scheme for the parameter estimation and stabilization of unstable systems, such as inverted pendulum systems. First a stable feedback loop is constructed for an inverted pendulum system and then its parameters are estimated based on input-output data, a real-coded genetic algorithm(RCGA) and the model adjustment technique. Then, a PI-type LQ control scheme is designed based on the estimated model. The performance of the proposed algorithm is demonstrated through a set of simulation and experiment.