• 제어로봇시스템학회논문지
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• 제21권4호
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• pp.336-341
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• 2015

This paper proposes a balancing and driving control system for a Mecanum wheel ball robot which has a two axis structure and four motors. The inverted pendulum control method is adopted to maintain the balance of the ball robot while it is driving. For the balancing control, an anon-model-based controller has been designed to control the device simply without the need of a complex formula. All the gains of the controller are heuristically adjusted during the experiments. The tilt angle is measured by IMU sensors, which is used to generate the control input of the roll and pitch controller to make the tilt angle zero. For the driving control, the PID control algorithm has been adopted with angles of the wheels and the encoder data. The performance of the designed control system has been verified through the real experiments with the suggested ball robot.

• Wind and Structures
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• 제28권3호
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• pp.155-170
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• 2019

This paper presents a novel test method for the galloping of iced conductor using wind generated by a moving vehicle which can produce relative wind field. The theoretical formula of transiting test is developed based on theoretical derivation and field test. The test devices of transiting test method for aerodynamic coefficient and galloping of an iced conductor are designed and assembled, respectively. The test method is then used to measure the aerodynamic coefficient and galloping of iced conductor which has been performed in the relevant literatures. Experimental results reveal that the theoretical formula of transiting test method for aerodynamic coefficient of iced conductor is accurate. Moreover, the driving wind speed measured by Pitot tube pressure sensors, as well as the lift and drag forces measured by dynamometer in the transiting test are stable and accurate. Vehicle vibration slightly influences the aerodynamic coefficients of the transiting test during driving in ideal conditions. Results of transiting test show that the tendencies of the aerodynamic coefficient curve are generally consistent with those of the wind tunnel tests in related studies. Meanwhile, the galloping is fairly consistent with that obtained through the wind tunnel test in the related literature. These studies validate the feasibility and effectiveness of the transiting test method. The present study on the transiting test method provides a novel testing method for research on the wind-resistance of iced conductor.

• 대한기계학회논문집A
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• 제26권8호
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• pp.1565-1576
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• 2002

By way of driving a 2-way on/off solenoid hydraulic valve with a pulse width modulation (PWM) signal, control of the pressure in a certain volume is frequently used in various applications. However, the pressure built-up according to the duty ratio and carrier frequency of the PWM signal is not so well understood. In order to clarify the characteristics of 2-way valve hydraulic pressure control systems, in this paper two formula fur the mean and ripple of the load pressure were derived through theoretical analysis. And the accuracy of the derived formula were verified by comparison with the experimental test result. Generally 2-way valve systems are constructed as a bleed-off circuit, while 3-way valves are used as a control element in a meter-in circuit pressure control system. In a bleed-off circuit, the system supply pressure from a hydraulic power pack does not remain constant, but changes according to their external load. In turn, the relief valve in the hydraulic power pack reacts accordingly showing complicated dynamic behavior, which makes an analytical study difficult. In order to resolve the problem, simple but accurate empirical dynamic models fer a bleed-off system were used in the course of formula derivation. As the result, selection criteria for two major control parameters of the driving signal is established and the basic strategy to suppress the unnecessary pressure fluctuation can be provided for a hydraulic pressure control system using a 2-way on/off solenoid valve.

• 한국지반공학회논문집
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• 제15권1호
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• pp.5-13
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• 1999

말뚝은 타입될 때 가장 큰 응력이 발생하며 이 응력이 말뚝의 허용응력보다 크면 말뚝이 손상 되어 위험을 초래할 수 있다. 따라서 사전에 이를 정확히 예측하여 과도한 항타를 미연에 방지해야 한다. 콘크리트말뚝 타입 시 말뚝에 발생하는 압축응력의 예측방법은 여러 가지가 있으며 현재는 파동이론의 전산해석으로 만족스러운 결과를 얻을 수 있다. 그러나 경우에 따라서는 이 방법의 적용이 곤란할 수 있으며, 이 때에는 간단한 산정식을 적용하는 것이 실용적이다. 본 연구에서는 이 산정식들 중 비교적 합리적이라고 평가되는 산정식들 만을 선정하고 현장에서 실측한 항타응력과 선정된 산정식들로부터 구한 값을 비교, 분석하였다. 그 결과 Uto와 Huyuki의 식이 비교적 정확한 값을 제공하며 지반 및 시공조건에 따라 이 값에 감소계수를 곱하여 수정하면 보다 더 정확한 값을 얻을 수 있음을 알 수 있었다.

• 전자공학회논문지A
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• 제31A권7호
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• pp.110-116
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• 1994

In this paper a Duty Effective Overlap Scanning method (DEOS) for the improvement of driving efficiency of LC displays which have the RMS voltage responding characteristics is proposed and new processing method of data signals for optimum application of this method is also proposed. Proposed method has a few advantages such as the increment of duty ratio the increment of driving power loaded on LC cell and the decrement of RMS voltage error rate caused by signal attenuation on electrodes composing of display when compared with the conventional method which is called as optimum voltage amplitude selection method. And also by adopting new data signal processing method which has 3 kinds of voltage levels additional advantage much improving crosstalk phenomenon which is the most serious problems of simple matrix structured display is obtained. For the characteristic estimation new mathematical representation for new overlap scanning method and data signal processing method are induced and defined. And by the defined formula and simulation the characteristics of the proposed method and the conventional method are compared and analyzed. As a result of estimation this new method being able to optimize the overlap rate of scan signal and using 3 levels of data signals has the characteristic which can improve the driving efficiency of LC displays.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.42-45
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• 2002

In the two-mass motor drive system driving a load through a flexible shaft or transmission system, a shaft torsional vibration is often generated. The overshoot of the motor drive system easily causes vibration. In this case I-PD controller has been generally used in speed control, because of the simplicity of structure. This paper using an analytical pole assignment design, proposes the overshoot formulas, and the settling time formula. The objective of this paper is to provide a design method of I-PD controller by using overshoot formulas, and settling time formula. The simulation results show that we can design the controller with desired overshoot and settling time.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.686-689
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• 2005

A numerical simulation method is developed to analyze the dynamic response of a cantilever switch, which is driven by electrostatic force and a basic component of electro-mechanical coupled system. First, point-charges model on conductor is proposed as a lumped parameter of electrical part. Then, this model is easily incorporated into a multi-body dynamics analysis algorithm, the generalized recursive dynamics formula previously developed by our research group. The resulting motion of a coupled overall system is formulated as a differential algebraic equation form including electrical and mechanical variables together. The equation is simultaneously solved in every time step. To implement this approach into the useful dynamics analysis tool, we used multibody dynamics software (RecurDyn) based on the generalized recursive formula using relative coordinate. The developed numerical simulation tool is evaluated by applying to many different driving condition and switch configuration. The final analysis model will be added to RecurDyn as a basic module for dynamics analysis of electro-mechanical coupled system.

• 한국지반환경공학회 논문집
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• 제4권1호
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• pp.59-66
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• 2003

건설공사에서 발생하는 환경문제에 대한 관심이 고조되는 가운데 기성 말뚝을 항타하는 과정에서 유발되는 소음, 진동문제를 해결하기 위해 저소음, 저진동 공법인 매입말뚝공법이 많이 적용되고 있다. 국내에서는 매입말뚝공법으로 SIP공법이 주로 사용되고 있다. 그러나 아직까지 SIP공법에 관한 합리적인 지지력 산정식이 제시되어있지 못한 실정이다. 이에 대해 본 연구에서는 SIP 말뚝의 주면저항력 특성을 고찰하여 이러한 문제점들을 개선, 보완하기 위하여 다양한 조건에서 SIP말뚝 주면과 지반사이의 경계면에 대하여 직접전단 시험을 실시하였다. 시험 결과를 토대로 통일분류상 SM, SC 지반에서의 SIP말뚝 주면저항력 특성을 고찰하고 해당 지반에서 주면저항력 산정식을 제시하였다. 또한, 말뚝 경계요소의 저항력에 대한 새로운 비선형 수치 모델식과 계수산정식을 제안하였다.

• 드라이브 ㆍ 컨트롤
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• 제19권3호
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• pp.39-46
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• 2022

In South Korea, to evaluate the rollover safety of domestic vehicles, the maximum slope angle of the vehicle is specified, which is verified by the rollover safety test of driving vehicles. However, the domestic rollover safety test is not suitable for buses, because the small amount of static stability factor (SSF) will invalidate the rollover experimental equation due to the high center of mass position of buses. To solve the above problems, a dynamic model of the bus is prepared with assumptions of mass and suspension spring properties. Subsequently, the maximum slope angle of the model was computed by using the simulation of multi-body dynamics, and the result was compared with actual test results to validate the dynamics model. Also, the rollover Fishhook (roll stability) test was conducted in the simulation for driving model. During the simulation, roll angle and roll rate were calculated to check if a rollover occurred. Through the rollover simulation of buses, the domestically regulated formula for rollover safety and the procedure of rollover test for driving vehicles are evaluated. The conclusion is that the present regulation of rollover test should be reconsidered for buses to ensure to get the valid results for rollover safety.

• 자동차안전학회지
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• 제10권4호
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• pp.33-39
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• 2018

Recently, the automobile industry has developed ADAS (Advanced Driver Assistance System) to prevent traffic accidents and reduce driver's driving burden. Among the ADAS, the LKAS (Lane Keeping Assistance System) is a support system for the convenience and safety of the driver, and the main function is to maintain the driving lane of the vehicle. LKAS is a system that uses radar sensor and camera sensor to collect information about the position of the vehicle in the lane and to support keeping the lane through control if necessary. In many countries, LKAS has already been commercialized and the convenience and safety of drivers have been improved. The international LKAS evaluation test procedure is being developed and discussed by standardization committees such as the ISO (International Organization for Standardization) and the Euro NCAP (New Car Assessment Program). In Korean, the LKAS test method is specified in the KNCAP (Korean New Car Assessment Program), but the evaluation method is not defined. Therefore, the LKAS test procedure that meets international standards and is suitable for domestic road environment is necessary. In this paper, development of LKAS test evaluation scenarios that meets international standards and considering domestic road environment, and the formula that can evaluate the result value after control as the relative distance of lane and the front wheel are suggested. And a comparative analysis was conducted to verify the validity of the suggested scenario and formula. The test evaluation was conducted using the vehicle equipped with the LKAS.