Patent ID: 7403846

Claim:
A method of activating an optimal sieve control action, the method comprising: registration of a deviance from a threshold value for crop material load on the upper sieve of a grain cleaning system, wherein the sieve control action comprises a open-close sieve control action which is determined by the parameter t 0 (s), representing the activation time of a special sieve setting, and the parameter t 1 (s), representing the time at which the nominal sieve setting is restored, wherein the parameters t 0 ,(s) and t 1 (s) are optimized according to the cost function V(t 0 , t 1 ), following V ⁡ ( t 0 , t 1 ) = ∑ k = τ 0 T sim ⁢ y ⁡ ( k ) + γ ⁢ ⁢ ∑ k = τ 0 T sim ⁢ ( x ⁡ ( k ) - x c ) + 2 + ρ ⁡ ( t 1 - t 0 ) wherein u(k) represents the flow of crop material that is transported to the front end of the pre-sieve in a grain cleaning system, y(k) represents the flow of material that leaves the back side of the upper sieve, and x(k) represents the return flow fraction of crop material, wherein - ∑ k = τ 0 T sim ⁢ y ⁡ ( k ) calculates the total amount of sieve losses that are simulated in the [τ 0 , T sim ] interval wherein γ ⁢ ∑ k - τ 0 T sim ⁢ ( x ⁡ ( k ) - x C ) + 2 introduces a soft constraint on the instantaneous return flow x(k)<x c to avoid overload in the return flow system, and wherein time interval ρ(t 1 -t 0 ) penalizes long activation intervals of the special settings.