Design of a tractor guidance system using simulation trajectory results of multibody dynamic program 'DADS'.

摘要

Recent trends in agricultural industry indicate that automatic guidance of agricultural machines is indispensable for precision farming. The purpose of automatic guidance is to make the machine follow a prescribed path. A successful guidance system must be able to control the position of the machine to within a few centimeters.; This study used two of the powerful software for design and analysis of mechanical and control systems, DADS and MATLAB. Also a Fortran code was written for the purpose of PMF system identification.; First, DADS was used to model and perform tractor dynamic analysis. DADS animation feature was utilized to observe the behavior of the model under different maneuvers, lane change and semi-circular shaped maneuvers. In addition, numeric simulation results were obtained through DADS graph. Then, the PMF parameter estimation technique was used to obtain tractor linear models out of the nonlinear DADS model. The linear models were then used within MATLAB environment to design a tractor steering PID controller.; The DADS model was able to predict lane change and semi-circular shaped maneuvers on a horizontal plane trajectory. Parameter sensitivity analysis was performed for the tire-soil model within DADS. No single parameter had a significant effect on predicted trajectory.; The PID controller was designed using MATLAB. It was able to cause the tractor follow the desired path, by controlling the lateral displacement and heading angle.