Application of GPS Guidance to a Steering Control System for Self-Propelled Agricultural Machines
Date Issued
2015
Date
2015
Author(s)
Hsu, Han-Chao
Abstract
In the age of automated industry, agricultural machines are also becoming more automated. This paper implements a GPS-guidance system that allows Taiwanese agricultural machinery to be steered automatically. The study is in two parts. Firstly, a single-track vehicle model is used to understand the characteristics of auto-steering and path-tracking. A GPS guidance system is then implemented in a field test. An Ez-Guide 250 monitor with a GPS receiver and a bulkhead antenna are used as the guidance system. The Ez-Steer 500 system includes a control unit and a driving motor that imitates a human’s actions in turning a steering wheel to allow auto-steering. The system is then installed on a self-propelled field boom sprayer, named SYL-800, which is manufactured in Taiwan, to execute the field tests. A computer program is then written using Matlab, to analyze the data recorded from this system. The experiments initially test the GPS signal using an APP program named GPS test, to ensure that the signal is sufficiently strong for the system during the field test. Experiments are performed in seven rounds, as follows. During the first three rounds, the speed of the sprayer is fixed at 2.3 km/h and the system tracks a straight line, a cornering line and a continuous turning path, respectively. During the next four rounds, the system tracks straight line, cornering line and U-turn line trajectories and the speed of the sprayer is fixed at 3.6 km/h. During these four experiments, the straight-line path is run at two different factor settings: the sprayer’s speed is set to 2.3 km/h and 3.6 km/h. This method is used to prove the characteristics of mathematical model that is established. The experiment results show that the system works well as an auto-steering system for path tracking when there are proper factor settings. The system tracks a straight line with negligible deviation regardless of whether the speed of sprayer is 2.3 km/h or 3.6 km/h. The deviation in the cornering line is within 0.5 -1.6 m. However, the system shuts down when the path is a continuous turning line or a U-turn line, because the control signals are not continuous. Care should be exercised when running the system in this mode.
Subjects
Agricultural Machines
Self-Propelled
GPS
Type
thesis
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