• The Journal of Korea Robotics Society
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• v.5 no.2
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• pp.120-126
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• 2010

This paper presents to study the path tracking method of AGV(autonomous guided vehicle) which has a laser guidance system. An existing automatic guided vehicles(AGVs) which were able to drive on wired line only had a automatic guidance system. However, the automatic guidance systems that those used had the high cost of installation and maintenance, and the difficulty of system change according to variation of working environment. To solve such problems, we make the laser guidance system which is consisted of a laser navigation and gyro, encoder. That is robust against noise, and flexible according to working environment through sensor fusion. The laser guidance system can do a perfect autonomous driving. However, the commercialization of perfect autonomous driving system is difficult, because the perfect autonomous driving system must recognize the whole environment of working space. Hence, this paper studied the path tracking of AGV using laser guidance system without wired line. The path tracking method is consisted of virtual path generation method and driving control method. To experiment, we use the fork-type AGV which is made by ourselves, and do a path tracking experiments repeatedly on same experimental environment. In result, we verified that proposed system is efficient and stable for actual fork-type AGV.

• Journal of Biosystems Engineering
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• v.31 no.6 s.119
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• pp.489-499
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• 2006

Since the application of chemicals in confined spaces under the canopy of an orchard is hazardous work, it is needed to develop an autonomous guidance system for an orchard sprayer. The autonomous guidance system developed in this research could steer the vehicle by tracking an overhead guidance rail, which was installed on an existing frame structure. The autonomous guidance system consisted of an 80196 kc microprocessor, an inclinometer, two interface circuits of actuators for steering and ground speed control, and a fuzzy control algorithm. In addition, overhead guidance rails for both straight and curved paths were devised, and a trolley was designed to move smoothly along the overhead guidance rails. Evaluation tests showed that the experimental vehicle could travel along the desired path at a ground speed of 30 $\sim$ 50 cm/s with a RMS error of 5 cm and maximum deviation of less than 12 cm. Even when the vehicle started with an initial offset or a deflected heading angle, it could move quickly to track the desired path after traveling 2 $\sim$ 3 m. The vehicle could also complete turns with a curvature of 1 m. However, at a ground speed of 50 cm/s, the vehicle tended to over-steer, resulting in a zigzag motion along the straight path, and tended to turn outward from the projected line of the guidance rail.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.1
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• pp.108-114
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• 2014

This paper proposes a generation method of a navigation guidance direction and a fuzzy controller to achieve the autonomous navigation of a mobile robot using a particle swarm optimization(PSO) scheme in unknown environments. The proposed navigation guidance direction is the direction that leads a mobile robot to arrive a target point simultaneously with avoiding obstacles efficiently according to the surrounding local informations. It is generated by selecting the most suitable direction of the many directions in the surrounding environment using a particle swarm optimization scheme. Also, a robot can reach a target point with avoiding the various obstacles by controlling the robot so that it can move from its current orientation to the navigation guidance direction using the proposed fuzzy controller. Simulation results are presented to show the feasibility and validity of the proposed robot navigation scheme.

• International Journal of Ocean System Engineering
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• v.2 no.3
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• pp.139-150
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• 2012

This paper presents an improved guidance algorithm for autonomous underwater vehicles (AUV) in 3D space for generating smoother vehicle turn during the course change at the way-points. The way-point guidance by the line-of-sight (LOS) method has been modified for correcting the reference angles to achieve minimal calculation and smoother transition at the way-points. The algorithm has two phases in which the first phase brings the vehicle to converge to a distance threshold point on the line segment connecting the first two way-points and the next phase generates an angular path with smoother transition at the way-points. Then the desired angles are calculated from the reference and correction angles. The path points are regularly parameterized in the spherical coordinates and mapped to the Cartesian coordinates. The proposed algorithm is found to be simple and can be used for real time implementation. The details of the algorithm and simulation results are presented.

• The Journal of Korea Robotics Society
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• v.11 no.1
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• pp.1-8
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• 2016

In this paper, we propose a new algorithm of the guidance line extraction for autonomous agricultural robot based on vision camera in paddy field. It is the important process for guidance line extraction which finds the central point or area of rice row. We are trying to use the central region data of crop that the direction of rice leaves have convergence to central area of rice row in order to improve accuracy of the guidance line. The guidance line is extracted from the intersection points of extended virtual lines using the modified robust regression. The extended virtual lines are represented as the extended line from each segmented straight line created on the edges of the rice plants in the image using the Hough transform. We also have verified an accuracy of the proposed algorithm by experiments in the real wet paddy.

• Agricultural and Biosystems Engineering
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• v.4 no.1
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• pp.22-27
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• 2003

An autonomous tractor requires not only automatic steering (automatic guidance) but also automated control of tractor functions and implement operations. Examples of tractor functions include engine throttle, transmission speed, and 3-point hitch position. Implement operations include tillage, planting, and cultivating. This article provides an overview of a map-based methodology used for the implementation of autonomous field operations of agricultural tractors. The procedure for developing autonomous field operation maps were presented, and several important issues in the implementation of map-based autonomous operations were discussed. These issues included combining field operation maps, position offset, and real-time sensing and update of field operation maps.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.11
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• pp.1417-1423
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• 2020

This paper proposes a waypoint guidance algorithm for the Autonomous Underwater Vehicle(AUV). The proposed simplified guidance algorithm is presented, which is combined LOS guidance and cross-track guidance for path following. Cross-track error is calculated using the position of the AUV and reference path. LOS guidance and cross-track guidance are appropriately changed according to cross-track error. And the stability of the system has been improved using variable cross-track control gain by cross-track error. Also, in this paper, navigation hardware in-the loop simulation(HILS) is implemented to verify navigation algorithm of AUV that performs combined navigation using inertial navigation device and doppler velocity log(DVL). Finally, we design integrated system HILS (including navigation HILS) for performance verification of guidance algorithm of the autonomous underwater vehicle. By comparing the sea test result with HILS result, the proposed guidance algorithm and HILS configuration were confirmed be correct.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.2
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• pp.214-219
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• 2007

In this paper, a new magnetic position sensing mettled for autonomous vehicle and robot guidance is presented. In autonomous vehicle and robot control, position sensing is an important task for the identification of their locations, such as the current position within a trajectory. The magnet based autonomous vehicle and robot was identified position via magnetic materials. In the magnetic sensing system, the Earth field is one of the largest disturbance. To removal of the Earth field, this paper proposes 1-dimensional magnetic field sensors array and develops precise petition sensing system using linear operating region of the magnetic field sensor. This proposal is verified a feasible magnetic position sensing system for autonomous vehicle and robot guidance by the experimental results.

• Agricultural and Biosystems Engineering
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• v.2 no.2
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• pp.50-58
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• 2001

Chemical application is very hazardous in confined spaces under the canopy ceiling in Korean vineyard. For a small orchard sprayer adaptable to such a working condition, a low-cost autonomous steering control system was developed using two ultrasonic sensors, two electrically-operated cylinders and 80196kc microprocessor. A distance ranging system timed the round-trip for each ultrasonic wave to travel against parallel targets, placed every 1.5m spacing along both sides of a desired path. A steering control algorithm of the autonomous operation began with ranging left and right targets and the heading was decided using difference between the distances. Electrically-operated cylinders actuated steering clutches to guide the sprayer. Evaluation tests showed that the orchard sprayer could travel within RMS value of 5cm along the desired path. Ground speed did not affect the performance of the autonomous guidance system at the speed ranges of 0.29~0.52m/sec.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.2
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• pp.239-246
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• 2004

In this paper, we develop and implement a high integrity GNC(Guidance, Navigation, and Control) system, based on the combined use of the Global Positioning System (GPS) and an Inertial Measurement Unit (IMU), for autonomous land vehicle applications. This paper highlights guidance for the predetermined trajectory and navigation with detection of possible faults during the fusion process in order to enhance the integrity of the navigation loop. The implementation of the GNC system to the autonomous land vehicle presented with fault detection methodology considers high frequency faults from the GPS receiver caused by shadowing and multipath error The implementation, based on a low-cost, strapdown INS aided by standard GPS technology, is described. The results of the field test in the urban environment are presented and showed effectiveness of the GNC system.