Integrated robust optimal design (IROD) of header height control system for combine harvester

This paper presents an integrated control-structure design methodology that is robust to parametric variations and its application to the design of combine header height control. Traditional design process of controlled multibody systems is sequential wherein the structural design is accomplished first followed by the control design. Such sequential process can only provide suboptimal overall design and yield a suboptimal performance. In this paper, a sensitivity based integrated robust optimal design (IROD) methodology is used to determine optimal structural parameters concurrently with a controller with an objective of improving header height control performance for a combine harvester. The problem is to control the height of the heavy header assembly at a constant distance above the rough terrain to maximize the yield and efficiency during harvesting. The design methodology is demonstrated by choosing the pivot location of the hydraulic actuator on the header as a structural design parameter concurrently with controller parameters. The design obtained with this methodology was compared with the sequential design for tracking performance and robustness. It is shown that the integrated design obtained from IROD yields better performance, lower control power, and improved robustness than the sequential method. It also allows for higher vehicle speed and lower operational cost.