• Journal of the Institute of Convergence Signal Processing
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• v.12 no.4
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• pp.348-354
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• 2011

Mobile robots performed various missions in various environments. In order to move to target precisely, the mobile robots need a precise position sensing system In this paper, a new high precision docking sensor is proposed. Proposed docking sensor consists of linear CCD(charge coupled device) sensor and ultrasonic sensors. The docking sensor system can measure lateral position(X), longitudinal position(Y) and angle(${\theta}$) between the sensor and flat target with simple mark. Two ultrasonic sensors measure two distances which can be converted to longitudinal position and angle. Linear CCD sensor measures lateral position using center mark of the target. To verify performance of the sensor, the sensor is applied to an omnidirectional mobile robot. Several experimental results show highly precise performance of the sensor. Repeatability of the docking sensor is less than 1mm and $0.2^{\circ}$. Proposed docking sensor can be applied for precise docking of mobile robot.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.4
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• pp.470-477
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• 2009

Modular reconfigurable robots with physical docking capability easily adapt to a new environment and many studies are necessary for the modular robots. In this paper, we propose a vision-based fuzzy autonomous docking controller for the modular docking robots. A modular docking robot platform which performs real-time image processing is designed and color-based object recognition method is implemented on the embedded system. The docking robot can navigate to a subgoal near a target robot while avoiding obstacles. Both a fuzzy obstacle avoidance controller and a fuzzy navigation controller for subgoal tracking are designed. We propose an autonomous docking controller using the fuzzy obstacle avoidance and navigation controllers, absolute distance information and direction informations of robots from PSD sensors and a compass sensor. We verify the proposed docking control method by docking experiments of the developed modular robots in the various environments with different distances and directions between robots.

• Journal of Advanced Navigation Technology
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• v.23 no.2
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• pp.125-133
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• 2019

In this paper, a new study was performed on the docking of AUV to docking station using light and light sensor system under the water. For this, a guiding system for AUV loading sensor system composed of lense, light sensor, signal processor, and processor and docking system with LED are proposed. An analysis on light sensor system and light-collecting lense to obtain accurate relative angle and measurement accuracy was performed. To prove this, the system was built and a basic experiment was performed. Finally, the feasibility of the developed docking system was verified the test in the water tank.

• Journal of Ocean Engineering and Technology
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• v.30 no.3
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• pp.208-213
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• 2016

This paper proposes a potential field-based guidance law for docking a USV (unmanned surface vehicle). In most cases, a USV without side thrusters is an under-actuated system. Thus, there are undockable regions near docking stations where a USV cannot dock to a docking station without causing a collision or backward motion. This paper suggest a guidance law that prevents a USV from enter such a region by decreasing the lateral error to the docking station at the initial stage of the docking process. A Monte-carlo simulation was performed to validate the performance of the proposed method. The proposed method was compared to conventional guidance laws such as pure pursuit guidance and pure/lead pursuit guidance. As a result, the collision angle and lateral distance error of proposed method tended to have lower values compared to conventional methods.

• Journal of the Korea Safety Management & Science
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• v.15 no.2
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• pp.167-184
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• 2013

A cross docking operation involves multiple inbound trucks that deliver items from suppliers to a distribution center and multiple outbound trucks that ship items from the distribution center to customers. Based on customer demands, an inbound truck may have its items transferred to multiple outbound trucks. Similarly, an outbound truck can receive its consignments from multiple inbound trucks. The objective of this study is to find the best truck spotting sequence for both inbound and outbound trucks in order to minimize total operation time of the cross docking system under the condition that multiple visits to the dock by a truck to unload or load its consignments is allowed. The allocations of the items from inbound trucks to outbound trucks are determined simultaneously with the spotting sequences of both the inbound and outbound trucks.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.10
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• pp.930-935
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• 2015

An unmanned forklift requires precise positioning and pallet detection. Therefore, conventional unmanned forklifts use high-cost sensors to find the exact position of the pallet. In this study, a docking algorithm with two cameras is proposed. The proposed method uses vision data to extract the angle difference between the pallet and the forklift. Then the control law is derived from the extracted angle for successful docking. The extracted angle is compared with the actual angle in the real environment. The control law is tested with the Lyapunov stability test and Routh-Hurwitz stability criterion. Through various experiments, the proposed docking algorithm showed the success rate high enough for real-life applications.

• Journal of Advanced Research in Ocean Engineering
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• v.2 no.3
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• pp.150-157
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• 2016

When blocks are supported on a dock, huge reaction forces concentrated at the supports cause structural damage owing to local stress concentrations. Thus, the supports should be arranged to avoid local failure from the reaction forces by redistributing those forces. Docking analyses to determine the proper blocks and their support arrangements are introduced so that the local stresses are minimized to warrant the safety of the docking supports. Local stresses enforced by the support arrangement should be evaluated by finite element analysis (FEA). However, it is difficult to consider an accurate 3D geometry of the blocks in the finite element model because the structural design information is too complicated to determine within several days using the FEA model. This paper presents a simplified FE model to evaluate the safety of the arrangement of supports using a simplified grillage element. The grillage element can be efficiently used to obrain the reaction forces in docking analysis becasuse the reaction forces at the supports are enough to assess the safety of block. Since a simplified grillage model of the entire ship cannot accurately calculate the local stresses, an optimized modeling method based on the grillage element was introduced. The local reaction forces obtained by the proposed approach and three-dimensional FEA were discussed for typical types of ships. It is shown that the reaction forces obtained by the present grillage model are in reasonably good agreement with the FEA model.

• Journal of the Korea Safety Management & Science
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• v.19 no.3
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• pp.129-135
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• 2017

The respective delivering vehicle loaded with the own cargo moves into the respective delivery area. At the base, the delivery points D1 and D2, for example, have the same starting point but the destination is different. The average delivering time of the delivery vehicle is mostly more than 8 hours a day. Therefore, the efficiency of delivery is generally low. In this study, the deliveries will be forwarded from a base station to a delivery point where cross docking will be applied to a single vehicle, and will be distributed from the cross docking point through cross docking. If the distribution is implemented, one vehicle will not have to be operated from the base to the cross docking point. In that case, logistics cost will be reasonably saved by the reduction of transportation cost and labor time. If one vehicle only runs from the base to the cross docking point, each vehicle will be operated in two shifts, and the vehicle operation can be efficiently implemented. This research model is based on the assumption that the 3 types of ratios between the traffic volume of the vehicles starting at the base and the vehicles waiting at the cross docking point are set to the first ratio of 30% to 70%, the second ratio of 50% to 50% and the final ratio of 70% to 30%. As a result of the study, The delivery time in the cross docking point is much higher than that in present on the condition that the cargo volume in the D2 area is more than 50%. Likewise, the delivery time is slightly higher on the condition that the cargo volume is less than 50%. Time is reduced in terms of 50% model like AS-IS model.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.12
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• pp.137-144
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• 2001

The major movement blocks of the container are the range between the apron and the designation points on yard in container terminals. The yard tractor drived by operator takes charge of it's movement in conventional container terminals. In automated container terminal, AGV(automatic guided vehicle) takes charge of a yard tractor's role and information of navigation path are ordered from upper control system. The automated container terminal facilities must have the docking system that guides landing zinc to execute high speed travelling and precision positioning. This paper describes the new docking method with the rotating LSB(laser slit beam) generator and two pair of photo receiver. The LSB generator is installed on the fixed ground and the photo receiver is implemented on the moving vehicle such as AGV. The proposed docking system is implemented to confirm it's function and accuracy. The accuracy of measured moving position is represented in ±5mm at 1 data sampling.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.3
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• pp.311-317
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• 2010

In the paper, we propose an improved mobility method of modular robots by physical docking in the uneven environments. The modular robot system consists of autonomous docking device, 3 DOF robotic arm, motion controller, and main controller. Real-time location and direction of the robot are estimated using inner GPS and they are used to control direction and path of each robot for physical docking between modular robots. We design a navigation algorithm of modular robot using physical docking and cooperative navigation in the environment with broken road and low stair. The proposed method is verified by navigation experiments of three developed modular robots in the uneven environments.