• Journal of Drive and Control
• /
• v.13 no.4
• /
• pp.14-22
• /
• 2016

This paper presents a stochastic and predictive working-risk-assessment algorithm for excavators based on a one-layer laser scanner. The one-layer laser scanner is employed to detect objects and to estimate an object's dynamic behaviors such as the position, velocity, heading angle, and heading rate. To estimate the state variables, extended and linear Kalman filters are applied in consideration of laser-scanner information as the measurements. The excavator's working area is derived based on a kinematic analysis of the excavator's working parts. With the estimated dynamic behaviors and the kinematic analysis of the excavator's working parts, an object's behavior and the excavator's working area such as the maximum, actual, and predicted areas are computed for a working risk assessment. The four working-risk levels are defined using the predicted behavior and the working area, and the intersection-area-based quantitative-risk level has been computed. An actual test-data-based performance evaluation of the designed stochastic and predictive risk-assessment algorithm is conducted using a typical working scenario. The results show that the algorithm can evaluate the working-risk levels of the excavator during its operation.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.6
• /
• pp.136-144
• /
• 1996

We developed a part of stroke sensing cylinder for position control of automatic excavator and its measurement system. In this paper, for development of stroke sensing cylinder, we consist of 2-axis control instrument system with Hall sensor. A performance of piston rod with magnetic scales is evaluated by the developed measurement system. Furthermore, the position control for good performance of instrument system is achieved by a sliding mode control which is a new method diminishing the chattering in that control by setting 2-dead band along the swtching line. The unknown parameters for sliding mode control are estimated by the signal compression method.

• Tunnel and Underground Space
• /
• v.20 no.5
• /
• pp.325-331
• /
• 2010

In the present research paper large scale blasting was conducted on two different firing patterns, namely, straight V type and skewed V type pattern on the same sandstone overburden bench with similar explosives. The post-blast fragmentation assessments were made by use of digital imaging technique. The total cycle time of 10 $m^3$ rope shovels was also recorded in the field. The results reveal improvements in the fragmentation and excavator performance results for the blasts fired on skewed V type pattern. The paper discusses the skewed V firing pattern and the reasons for its superior performance vis-$\grave{a}$-vis the straight V type pattern.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.21 no.1
• /
• pp.18-23
• /
• 2011

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.

• International Journal of Fluid Machinery and Systems
• /
• v.9 no.1
• /
• pp.39-46
• /
• 2016

A high frequency hydraulic rock drill drifter with sleeve valve is developed to use on arm of excavator. In order to ensure optimal working parameters of impact system for the new hydraulic rock drill drifter controlled by sleeve valve, the performance test system is built using the arm and the hydraulic source of excavator. The evaluation indexes are gained through measurement of working pressure, supply oil flow and stress wave. The relations of working parameters to impact system performance are analyzed. The result demonstrates that the maximum impact energy of the drill drifter is 98.34J with impact frequency of 71HZ. Optimal pressure of YZ45 rock drill is 12.8 MPa-13.6MPa, in which the energy efficiency reaches above 58.6%, and feature moment of energy distribution is more than 0.650.

• Journal of Institute of Control, Robotics and Systems
• /
• v.8 no.9
• /
• pp.728-735
• /
• 2002

The Field robot means the machinery applied for outdoor tasks in construction, agriculture and undersea etc. In this study, to field-robotize a hydraulic excavator that is mostly used in construction working, we have developed an automatic excavation system and an adaptive control system. A model-reference adaptive controller has been designed based on the model that is obtained through off-line system identification. It is illustrated by computer simulations that the proposed control system gives good performance in the trajectory tracking control and the adaptation to parameter variation.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.496-499
• /
• 1997

Field robot represented by excavator can be applied for various kinds of working in manufacturing, construction, agriculture etc. because of the flexibility of its multi-joint mechanism and the high power of hydraulic actuators. In general, the dynamics of field robot have strong coupling, various kinds of non-linearity, and time-varying parameters according to working conditions. Therefore, it is very difficult to describe the system well, and design controller systematically based on its model. This paper established the mathematical model of field robot driven by electro-hydraulic servomechanism and constructed the adaptive control system robust to external load variations. The proposed control system for the field robot was evaluated by the computer simulation and the performance results of trajectory tracking were compared with that of PID control system.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.8 no.1
• /
• pp.1-7
• /
• 2012

In this paper Vehicle driving simulator have been used in the development and modification of models. A real-time simulation system and washout algorithm for an excavator have been developed for a driving simulator with six degrees of freedom. An interesting question, "how the 6 DOF Driving Simulator can be controlled optimally for the various tasks?" is not easy to be answered. This paper presents the hardware and software developed for a driving simulator of construction vehicle. A simulator can reduce cost and time a variety of driving simulations in the laboratory. Using its 6 DOF Simulator can move in various modes, and perform dexterous tasks. Driving simulators have begun to proliferate in the automotive industry and the associated research community. This effort involves the real-time dynamic of wheel-type excavator the design and manufacturing of the Stewart platform an integrated control system of the platform and three-dimensional graphic modeling of the driving environments.

• Journal of Drive and Control
• /
• v.16 no.2
• /
• pp.30-35
• /
• 2019

EPPR (Electro-hydraulic Proportional Pressure Reducing) valves are pressure control valves. In this study, an independent metering valve (IMV), which is a combination of a spool valve opened and closed with the help of an EPPR valve, was discussed. The overall performance of the valve (IMV) was obtained by the respective modeling and simulation of the system. The valve investigated in this study is to be used for independent metering of hydraulic excavator actuator e.g. boom, arm, bucket etc. To design the model, continuity equations and force balance equations were used. The set of differential equations were then simulated in Simulink using ODE45 option in the configuration toolbox. The valve has to be able to control the flow rate going in and out of the cylinder separately, which is why the particular configuration was needed and selected.

• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.708-713
• /
• 2004

This research develops a sensorless hydraulic servo system of Parallel-Typed robot for harbour construction. Purpose of the robot is to mechanize the construction, which is accomplished through a joystick's operating by a stoneworker (or diver). The robot is attached on the end of an excavator as its attachment or transported by a crane to reach the desired place. The embedded compact controller is installed on the robot body and controlled by wireless telecommunication. For underwater work, it is necessary to waterproof the robot and its sensors. Especially, a sensor waterproof is a main drawback for the underwater robot. This leads us to develop a hydraulic robot position controller using an observer which gives the position information without any position sensor. We design a neural network to identify the displacement change according to the command voltage to servo valve. To verify the sensorless controller, this paper presents the performance of the sensorless control for which the position is given by the observer comparing with that of the sensor control for which the position is measured by LVDT sensors.