Adaptive Control of Auto-Steer Farm Tractors




The GPS and Vehicle Dynamics Lab at Auburn University is currently working with John Deere & Company to improve the performance of AutoTrac GPS guided tractors. A picture of a John Deere tractor equipped with the AutoTrac system is shown in Figure 2. The AutoTrac system currently steers the tractor on a straight line determined by the operator. The technology is still in the refinement stages because the system has to be manually adjusted to compensate for changes in parameters of the tractor which occur when implements are changed or implement depths are altered. If the AutoTrac controller gain is too high or too low, performance of the system will be compromised.

The purpose of this research is to develop a direct adaptive control algorithm that will automatically adjust the AutoTrac controller gain on-line to compensate for changes to the tractor’s parameters. Figure 1 shows a block diagram of a model reference adaptive steering controller. This algorthm has been shown to adjust the AutoTrac controller gain on-line in order to compenstate for varying hitch loading. Once completed, the direct adaptive control algorithm will provide better AutoTrac performance while increasing the ease of use for the operator.

Figure 1:


Adaptive Control Block Diagram

Figure 2:


John Deere 8420 AutoTrac