| Article Info |
제24권 2호 강원 농업생명환경연구 Vol.24, No.2, pp.18-23, 2012
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| Title |
DGPS를 이용한 트랙터의 직선추종 조향시스템 개발
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| Author |
김기덕, 신범수
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| Institutions |
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| Abstract |
The purpose of this research was to construct the hardware to control tractors’ steering autonomously using an electro hydraulic direction/flow control valve and steering angle sensors attached to king pins on both front wheels for the automatic driving as well as a DGPS for the navigation. A steering control algorithm is developed to drive the tractor straightforward from a position to the destination position for the parallel tracking farm-work operation. Contrary to previous steering control systems which use dead zones for starting point and finishing point, in this research, the dead zone for only finishing points was used in order to make it converged and proceed faster. The preliminary experimental results showed that P-control was sufficient as long as the control time of a loop maintained less than 50 ms. Since GPS provides data on every 200 ms, however, the same control of 50 ms interval was replicated 4 times, for a single period of position data acquisition. Through experiments conducted by changing the amount of steering angle at given ground speed, it was concluded that the desired RMS error should be less than 20 cm of GPS measurement error. The steering angle per control cycle should be within 2.65 ° when the ground speed of tractor is 0.836 m/s. If the tractor speed gets slow upto 0.491 m/s, the amount of steering angle should be less than 11.25 °.
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| Keyword |
DGPS, Electro hydraulic valve, P-control, Steering control, Tractor.
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 3LeeSS.pdf
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