• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.801-805
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• 2008

Today, hydraulic systems play an important role in modern industry for the reasons that hydraulic actuator systems take many advantages over other technologies with high durability and the ability to produce large forces at high speeds. In recent years, electro-hydraulic actuator systems, which combine electric and hydraulic technology into a compact unit, have been adapted to a wide variety of force, speed and torque requirements. Moreover these systems resolve energy consumption and noise problems characteristic existed in the conventional hydraulic systems. Therefore, these systems have a wide range application fields especially in an excavator. So the purpose of this paper is to demonstrate efficiency of the energy saving and present some control algorithms which apply to electro-hydraulic actuator system in the bucket of the excavator. Experiments are carried out to verify the effectiveness of the proposed system with various external loads as in real working conditions.

• 드라이브 ㆍ 컨트롤
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• 제14권1호
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• pp.35-40
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• 2017

Whereas fuel economy of a vehicle is measured using a chassis dynamometer, that of construction machinery such as an excavator shall be presumably measured using simulated work cycle. In order to measure fuel consumption under a simulated work cycle, a measurement methodology, while excavator operates in dynamic(transient) motion, needs to be examined and developed. In this work, three methods (gravimetry, ECU CAN signal and mass flow meter) are studied and compared. This work reveals that when ECU CAN signal is properly calibrated and evaluated, compared to gravimetry or mass flowmeter, it could be used to measure fuel consumption with accuracy and thus for approval of the fuel economy of construction machinery.

• 드라이브 ㆍ 컨트롤
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• 제14권3호
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• pp.40-49
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• 2017

This study presents an online estimation of an excavator's rotational inertia by using recursive least square with forgetting. It is difficult to measure rotational inertia in real systems. Against this background, online estimation of rotational inertia is essential for improving safety and automation of construction equipment such as excavators because changes in inertial parameter impact dynamic characteristics. Regarding an excavator, rotational inertia for swing motion may change significantly according to working posture and digging conditions. Hence, rotational inertia estimation by predicting swing motion is critical for enhancing working safety and automation. Swing velocity and damping coefficient were used for rotational inertia estimation in this study. Updating rules are proposed for enhancing convergence performance by using the damping coefficient and forgetting factors. The proposed estimation algorithm uses three forgetting factors to estimate time-varying rotational inertia, damping coefficient, and torque with different variation rates. Rotational inertia in a typical working scenario was considered for reasonable performance evaluation. Three simulations were conducted by considering several digging conditions. Presented estimation results reveal the proposed estimation scheme is effective for estimating varying rotational inertia of the excavator.

• 드라이브 ㆍ 컨트롤
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• 제16권1호
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• pp.45-53
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• 2019

The objective of this study was to design and model the PEM fuel cell excavator with supercapacitor/battery hybrid power source to increase efficiency as well as eliminate greenhouse gas emission. With this configuration, the system can get rid of the internal combustion engine, which has a low efficiency and high emission. For the analysis and simulation, the governing equations of the PEM system, the supercapacitor and battery were derived. These simulations were performed in MATLAB/Simulink environment. The hydraulic modeling of the excavator was also presented, and its model implemented in AMESim and studied. The whole system model was built in a co-simulation environment, which is a combination of MATLAB/Simulink and AMESim software. The simulation results were presented to show the performance of the system.

• 드라이브 ㆍ 컨트롤
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• 제19권4호
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• pp.29-35
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• 2022

In this paper, we developed a workload index for monitoring the durability test using operation information of an excavator. First, the acceleration and cylinder pressure were selected as load factors by analyzing operation data. Through load correlation analysis according to each load factor, Root Mean Square (RMS) and Work Load Range (WLR) were respectively derived as a load feature representing mechanical load. In addition, the workload index was used to quantify load features. For applying the workload index to monitoring, a real-time monitoring system consisting of sensors and embedded controller was installed on the excavator and the system was integrated with a remote monitoring environment using a wireless network. Results of load monitoring and analysis verified that the developed workload index was effective from the viewpoint of the relative comparison of the workload.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.349-350
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• 2010

• 유공압시스템학회논문집
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• 제3권2호
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• pp.7-13
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• 2006

In this paper the noise source and the amplifying mechanism are analyzed to reduce the noise of the excavator return line using the experimental approach and the CFD simulation. The result says that the reason of noise generation is pipe vibration caused by the cavitation at the main control valve and the level of noise is proportional to the valve back pressure at the return line. The methodology to reduce this noise was proposed and verified by the vehicle test.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2010년도 추계학술대회 논문집
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• pp.421-426
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• 2010

With hydraulic noise test facility, a variety of tests were performed to investigate the pulsation pressure generation mechanism and its transmission characteristics and to derive the noise control methodology. Many experiments were carried out by changing average pressure, flow rate, pump speed, hose length and MCV spool condition. From the test results, the correlations between pulsation pressure and other design parameters, such as static pressure, flow rate and MCV spool opening area and length of hose, were found out. And also each contribution factors were evaluated from the regression analysis. By changing hose length, the pulsation pressure resonance phenomenon was investigated. In order to find out the pulsation pressure reduction measures pulsation pressure analysis, such as pulsation pressure of hydraulic pump itself and pulsation pressure of hydraulic system, by using AMESim were studied. In addition hydraulic silencer was developed based on the Helmholtz resonator. And its performance was evaluated by installing the silencer at the excavator.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.132.5-132
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• 2001

In teleoperation field robotic system such as hydraulically actuated robotic excavator, the maneuverability and convenience is the most important part in the operation of robotic excavator. Particularly the force information is important in dealing with digging and leveling operation in the teleoperated excavator. Excavators are also subject to a wide variation of soil-tool interaction forces. This paper presents a new force reflecting joystick in a velocity-force type bilateral teleoperation system. The master system is electrical joystick and the slave system is hydraulically actuated cylinder with linear position sensor. Particularly Pneumatic motor is used newly in the master joystick for force reflection and the information of the pressure of salve cylinder is measured and utilized as the force feedback signal. Also force-reflection gain greatly affects the ...

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.65.6-65
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• 2002

In teleoperation robotic system such as hydraulically actuated robotic excavator for dangerous area, the maneuverability and convenience is the most important part. Particularly the force information is important in dealing with digging and leveling operation in the tole-operated excavator. Excavators are also subject to a wide variation of soil-tool interaction forces. This paper proposes a new force reflecting joystick using pneumatic motor and a new algorithm for selecting force-reflecting gain in a velocity-force type bi lateral teleoperation system. The master system is electrical joystick with the same structure of that of real excavator. Particularly Pneumatic motor is used newly in...