Method for controlling the applied volume per unit area on a cultivated field

Method for controlling the applied volume per unit area on a cultivated field of an agriculture spraying vehicle moving over said cultivated field for selective spot spraying application, the agriculture spraying vehicle comprising a spot spraying equipment, said equipment comprising an imaging system, a trailing spray bar aligned perpendicularly to the movement of the equipment, said spray bar comprising a plurality of electromechanical nozzles being spaced apart from each other by a constant pitch distance, including each a nozzle and an electromechanical valve, the spraying equipment further comprising a tank and pressure system with pressure sensor, a control unit to process images and control the electromechanical valve of each electromechanical nozzle, and a spray bar height control unit to place the nozzles at a desired distance from the objects to be sprayed, the method comprising:

• acquiring, by the at least one imaging system, an image of an area of the cultivated field and differentiating on the image, by the processing unit, a plant to be sprayed from a plant which shall not be sprayed to obtain a segmented image with masks to be sprayed and masks not to be sprayed,
• based on the desired volume per unit area to be applied, on the vehicle speed and on the liquid pressure, determining a density of active nozzle per unit length, and determining a vertical distance from nozzle to the target to guarantee constant jet overlap,
• modulating the flow of opened nozzles with a PWM ratio to obtain the desired volume per unit area to be applied,
• selecting the highest distance between a spray bar minimal height defined by the user and said determined vertical distance from nozzle to the target,
• moving the spray bar with the spray bar height control unit so as to position the nozzles at said determined vertical distance from nozzle to the target,
• computing a lateral jet shift distance corresponding to half the spray spot width at the ground and based on the divergence angle of the nozzle, on said liquid pressure and on said highest vertical distance previously selected,
• from an input segmented plant image containing masks of plants to be sprayed and masks of plants not to be sprayed, extending the masks of plants to be sprayed by a distance to obtain an extended mask to be sprayed.
• reducing laterally the size of said extended masks to be sprayed with said computed lateral jet shift distance to obtain reduced masks to spray,
• defining a nozzle activation map by the intersection of the spray bar nozzles trajectories with the masks to spray, further taking into account said opened nozzles and said PWM ratio, and
• transforming said nozzle activation map into time varying electromechanical valve state vectors, and applying signals to the electromechanical valves based on said time varying electromechanical valve state vectors.