Sensing and control of liquid application using an agricultural machine

An agricultural machine, comprising:

• a liquid reservoir that stores liquid to be applied to a field over which the agricultural machine is traveling;
• a supply line that defines a supply conduit;
• a plurality of valves disposed along the supply line, each valve having an inlet end and an outlet end and being controlled to pulse between an open position and a closed position by a pulsed control signal;
• a pump system that pumps the liquid from the liquid reservoir along the supply line to the inlet ends of the plurality of valves;
• a plurality of nozzles, at least one nozzle corresponding to each valve so that when the corresponding valve is open, the liquid flows through the valve to the corresponding nozzle;
• a plurality of row pressure sensors each sensing pressure at the outlet end of one of the plurality of valves and generating a corresponding row pressure signal indicative of the sensed pressure;
• pulse characteristic sensing logic that receives the row pressure signal from each row pressure sensor and identifies a pulse characteristic indicative of a liquid pulse provided by the corresponding valve in the open position, based on the row pressure signal, and generates a valve pulse characteristic signal indicative of the pulse characteristic;
• a pulsed valve control signal generator that generates the pulsed control signal based on the valve pulse characteristic signal;
• time delay logic configured to:
• receive the pulsed control signal and the valve pulse characteristic signal;
• identify an open time delay between the pulsed control signal generating a valve open signal controlling the valve to open and the valve pulse characteristic signal indicating that the valve is in the open position;
• and
• identify a close time delay between the pulsed control signal generating a valve close signal controlling the valve to close and the valve pulse characteristic signal indicating that the valve is in the closed position;
• and
• seed/chemical correlation logic configured to identify plant locations in die field and control timing of the pulsed control signal based on the identified plant locations, the seed/chemical correlation logic comprising:
• a pulse frequency controller configured to generate a pulse frequency control signal to control a frequency of the pulsed control signal based on the plant locations in the field the open time delay and the close time delay.