In recent years, automation within agriculture became more and more important with GPS-based automatic guidance systems. These systems are covering different tasks like highly precise alignment of lanes and are therefore able to bring economical and ecological advantages. Already today, several manufacturers offer proprietary solutions of such systems which are permanently increasing in accuracy, performance and comfort. Therefore, innovations often lead to an expensive exchange of the overall system. Because of this, there is a great need for the development of well structured subsystems with standardised interfaces. The standard ISO 11783 is on the way of being the main standard for agricultural machines, whereas leading manufacturers already offer ISOBUS interfaces as standard equipment on their tractors.
The aim of this work was the development of an ISOBUS based electronic steering control system. The main task of this system is to control the steering angle of a wheel based tractor as quick, smooth and exact as possible. For this purpose, a FENDT VARIO 818 with an integrated ISOBUS system was available. To allow electronic steering control, several modifications on the tractor needed to be done. A suitable hydraulic valve and a steering angle sensor had to be chosen and integrated into the standard steering system. After that, the steering control software has been developed. Because of its remarkable abilities, a PID control algorithm was chosen as the core part of the software. After defining a detailed list of requirements, a general model of the system was set up. Additionally to a comfortable steering behaviour, a safety concept was designed and realised. After developing the main software, it was adapted to the physical steering system of the tractor. Optimal system settings were finally determined by a wide series of experiments and verified accordingly. Whilst runtime, real time data was recorded and accurately analysed. By using the optimal controller setup, the steering system was able to reach each possible steering angle in less than three seconds with a remaining difference to the set point of less than 0.1 degrees. A temperature influence on the steering behaviour could not be found.
The automation on the agricultural sector is far away of coming to an end - quite the contrary - the efforts in developing autonomous vehicles will increase furthermore because of economical reasons. Considering an environmental friendly cultivation, it must be the target to remain competitive against low-wage countries beside the production of high quality food. Supporting this competitiveness, powerful and future-oriented interfaces like ISOBUS are already usable.
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In recent years, automation within agriculture became more and more important with GPS-based automatic guidance systems. These systems are covering different tasks like highly precise alignment of lanes and are therefore able to bring economical and ecological advantages. Already today, several manufacturers offer proprietary solutions of such systems which are permanently increasing in accuracy, performance and comfort. Therefore, innovations often lead to an expensive exchange of the overall s...
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