Method and apparatus for automatically steering a vehicle in an agricultural field using a plurality of fuzzy logic membership functions

A method of guiding an agricultural vehicle having at least one steerable wheel in an agricultural field having a plurality of rows of crops, the method comprising:

• taking a picture of the rows of crops with an electronic camera;
• successively processing a plurality of lines of the picture;
• extracting from the plurality of processed lines at least one value indicative of a crop line;
• extracting another value from the at least one value that is indicative of the lateral displacement of the crop line with respect to the vehicle;
• processing the another value in a fuzzy logic input membership function, then a fuzzy logic inference engine and then a fuzzy logic output membership function to develop a signal indicative of the degree the at least one steerable wheel should be turned;
• providing the signal indicative of the degree to which the steerable wheel should be turned to a feedback control circuit configured to steer the at least one steerable wheel in a direction that minimizes a difference between the signal indicative of the degree the at least one steerable wheel should be turned and another signal indicative of the degree to which the at least one steerable wheel is actually turned;
• generating a valve control signal calculated to reduce the difference;
• applying the valve control signal to an electro-hydraulic control valve configured to steer the at least one steerable wheel;
• and
• steering the wheel accordingly, wherein the step of extracting another value includes the step of extracting values sufficient to define a line indicative of a row of crops, a gap between a row of crops, or a cut/uncut boundary in a field,
• wherein the step of processing the another value includes the step of processing the another value in the input membership function to produce at least a first input value indicative of a degree of membership in a first input membership function domain and a second input value indicative of a degree of membership in a second input membership domain,
• wherein the step of processing the another value includes the step of processing the first and second input values in the fuzzy logic inference engine, and
• wherein the output membership function includes at least three domains symmetric with respect to a steering angle of zero, and further wherein the at least three domains include a center domain wherein a 100% membership causes the at least one steerable wheel to move toward or to remain in a mode of straight line travel.

A method of guiding an agricultural vehicle having at least one steerable wheel in an agricultural field having a plurality of crop rows, the method comprising:

• taking a picture of the crop rows with an electronic camera;
• extracting from the pictures row location values indicative of a location of at least one crop row;
• determining, based upon at least one previous row location value, whether the row location values are valid;
• and for each such row location values that are determined valid:
• deriving therefrom a value indicative of a desired direction of travel;
• processing the value indicative of a desired direction of travel in a fuzzy logic inference engine to produce a control signal;
• providing the control signal to an automatic control loop that uses feedback control based upon the position of the at least one steerable wheel to generate a valve command signal;
• applying the valve command signal to an electro-hydraulic steering control valve;
• and for each such row location values that is determined invalid:
• not using such invalid row location value in the automatic control loop.