Abstract: Combine harvesters are complex agricultural machines to harvest different kinds of grain
crops. There are now indications that a further increase in machine size may no longer be possible for
reasons of soil compaction by the heavy loads and also because of access to public roads. It is expected
that further increase in efficiency and productivity of the harvesting process can be obtained by
controlling the whole harvesting process as well as all sub-processes online and, desirably,
optimally..However, this makes it necessary to estimate certain machine efficiency indicators such as
grain losses online.Model-based estimation techniques are suitable for this task. However,the method
requires a mathematical model of the process as well as system-relevant measurements.