• Proceedings of the KSR Conference
• /
• 2004.10a
• /
• pp.606-610
• /
• 2004

In this paper, we would like to explain about the structure analysis of wheel set as variation of contact position between wheel and rail. Measurement of interacted force between wheel and rail is necessary for running safety evaluation as important factor of derailment mechanism. It's necessary to running safety evaluation of rolling stock. Wheel unload and lateral force change as variation of contact position between wheel and rail. Interacted force between wheel and rail got as each contact position through computer simulation. This is necessary process as first research for evaluation of derailment phenomenon and running safety.

• International Journal of Control, Automation, and Systems
• /
• v.2 no.4
• /
• pp.485-493
• /
• 2004

Open-loop position estimation methods are commonly used in mobile robot applications. Their strength lies in the speed and simplicity with which an estimated position is determined. However, these methods can lead to inaccurate or unreliable estimates. Two position estimation methods are developed in this paper, one using a single optical flow sensor and a second using two optical sensors. The first method can accurately estimate position under ideal conditions and also when wheel slip perpendicular to the axis of the wheel occurs. The second method can accurately estimate position even when wheel slip parallel to the axis of the wheel occurs. Location of the sensors is investigated in order to minimize errors caused by inaccurate sensor readings. Finally, a method is implemented and tested using a potential field based navigation scheme. Estimates of position were found to be as accurate as dead-reckoning in ideal conditions and much more accurate in cases where wheel slip occurs.

• Journal of the Korean Society for Precision Engineering
• /
• v.27 no.8
• /
• pp.20-27
• /
• 2010

A precise evaluation of the contact position and the distribution of contact pressure in a wheel-rail interface analysis is one of the most important procedures to predict fatigue life and wear of wheel and rail. This paper presents the analysis result of finite element method(FEM) to investigate how the deformation of a wheelset, which is the assembly of wheel and axle of a railroad vehicle, affect the contact analysis of wheel and rail. 3D-FEM was used to analyze three contact models; a model with only wheel, a model with wheelset, and a model with simplified wheel and rail geometry. The analysis result of the contact position and the distribution of contact pressure are discussed. It is shown that the analysis results of a model with wheelset represent largest value with respect to contact pressure and contact stress. Furthermore, it is found that the distribution of contact pressure and the contact position is highly affected by the deformation of wheel and axle. It is concluded that the deformation of axle should be considered to evaluate the exact contact parameters in a wheel-rail contact analysis.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.34S no.11
• /
• pp.63-72
• /
• 1997

The design and implementation of a drive wheel position, orientation, and velocity feedback control algorithm for a differential-drive mobile robot is described here. A new concept, the most significant error, is introduced as the control design objective. Drive wheel position, orientation, and velocity feedback control directly minimize the most siginificant error by coordinating the motion of the two drive wheels. The drive wheel position, orientation, and velocity feedback control algorithm is analyzed and experiments are conducted to evaluate its performance. The experimental results are shown that drive wheel position, orientation and velocity feedback control algorithm yields substantially smaller position and orientation errors than those of conventional methods.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.22 no.3
• /
• pp.401-407
• /
• 2019

In this paper, the position estimation considering wheel slip of mecanum wheeled mobile robots is discussed. Since the mecanum wheeled mobile robot does not need a space to rotate, it is very suitable in narrow industrial fields. However, the slip caused by the roller attached to the wheel makes it difficult to estimate the position precisely. Due to these limitations, mecanum wheels are rarely applied to unmanned mobile robots in automation factories. In this paper, a method to compensate the orientation and distance error caused by the slip is proposed. The exact orientation is measured by fusing gyro and magnetometer sensor data with application of Kalman filter. In addition, the kinematic model accounting slip effects will be defined to compensate the distance error.

• Journal of the Korean Society for Precision Engineering
• /
• v.10 no.3
• /
• pp.141-151
• /
• 1993

For navigation of a mobile robot, it is one of the essential tasks to find out its current position. Dead reckonining is the most frequently used method to estimate its position. Hpwever conventional dead reckoner is prone to give us false information on the robot position especially when the wheels are slipping. This paper proposes an improved dead reckoning scheme using neural networks. The network detects the instance of wheel slopping and estimates the linear velocity of the wheel; thus it calculates current position and heading angle of a mobile robot. The structure and variables of the nerual network are chosen in consideration of slip motion characteristics. A series of experiments are performed to train the networks and to investigate the performance of the improved dead reckoning system.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.22 no.6
• /
• pp.1010-1017
• /
• 2013

Two-axial electrodynamic forces generated on a conductive plate by a partially shielded magnet wheel are strongly coupled through the rotational speed of the wheel. To control the spatial position of the plate using magnet wheels, the forces should be handled independently. Thus, three methods are proposed in this paper. First, considering that a relative ratio between two forces is independent of the length of the air-gap from the top of the wheel, it is possible to indirectly control the in-plane position of the plate using only the normal forces. In doing so, the control inputs for in-plane motion are converted into the target positions for out-of-plane motion. Second, the tangential direction of the open area of the shield plate and the rotational speed of the wheel become the new control variables. Third, the absolute magnitude of the open area is varied, instead of rotating the open area. The forces are determined simply by using a linear controller, and the relative ratio between the forces creates a unique wheel speed. The above methods were verified experimentally.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.119-122
• /
• 2004

Since a derailment of rolling stocks results in huge losses in properties and lives, the measurement of a derailment coefficient is a very important test item to estimate the running safety of rolling stocks. For a measurement of the derailment measurement of forces between the wheel and rail a measuring wheel-set should be made first. The process to make a measuring wheel-set has some stages for correct measurement. They are as follows; a finite element analysis of a wheel to find a position of holes at which vertical force shall be measured, a finite element analysis for the position of strain gauges.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2011.06a
• /
• pp.1093-1094
• /
• 2011

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.05a
• /
• pp.1465-1466
• /
• 2010