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DynamicFluid4 locks onto the target rate

6 February 2013

A powerful, pre-emptive pressure-based application rate control system meets the demands of modern precision farming and sets new standards in precise immediate-response rate control.

DynamicFluid4 locks on to the target rate through ever-changing spraying speeds, when turning in or out of headlands and with auto boom section control active. Also DynamicFluid4 can lock onto the target rate even when that rate is continually changing based on a variable rate application (VRA) map.

Traditional fluid systems start regulating after the nozzles are turned on then ‘chase the rate’. That system was characterised by lag in which the regulation valve failed to keep up with the changes.

Four sensors in the fluid system monitor nozzle pressure, pump speed, regulation valve disc angle and flow input data. The flow rate is controlled by processing the input data including forward speed, target rate and active boom sections with advanced computer algorithms.


The DynamicFluid4 regulation valve comprises of two ceramic discs, one fixed and the other able to rotate through 84 degrees with zero leakage.  An angle sensor monitors the valve position and the system pressure is varied by changing the disc angle. 


The ceramic disc rotates with pin-point precision and the regulation speed is controlled using pulse-width modulation (power switching frequency). The valves incremental movement is smooth, incredibly fast and holds the target rate through changing speeds, sections switching and VRA.  

When all the nozzles are off on the headland DynamicFluid4 looks ahead to pre-empt the correct valve disc angle for when the nozzles are switched back achieving the target rate without any lag.

The COMMANDER II pump flow characteristic is known in the DynamicFluid4 software algorithm and therefore any change in pump speed is also used to determine the precise valve position.

The flow meter is used to calibrate the fluid system, to verify the flow and work as back up for the pressure transducer. DynamicFluid4 also detects the nozzle size by running a calibration routine using both the pressure and flow sensors.

If the flow meter fails DynamicFluid4 will continue to control the application rate based on pressure alone. If the pressure transducer fails then the system will switch to a flow based system.  In the event pressure, flow and pump rpm are all lost then rate control can be operated manually through DynamicFluid4 regulation valve and pressure gauge.

DynamicFluid4 has a custom set SoftStart maximum start up pressure to avoid starting spraying with too high a nozzle pressure which is the effect of the regulation valve trying to maintain the correct application rate as the tank empties.

There is wide spread interest from broadacre farmers. HARDI is demonstrating the system at every opportunity.

DynamicFluid4 summary

1. DynamicFluid4 is a pressure based fluid system (not flow based).
2. Advanced algorithms are used to compute the pressure needed to deliver the programmed application rate.
3. Pressure at the boom is kept accurate by managing the DynamicFluid4 regulator valve disc angle.
4. Pressure based regulation is running at 20Hz, which is up to 20 times faster than conventional flow meter based regulation systems.
5. The DynamicFluid4 regulator allows for precise incremental pressure change.
6. Pressure, flow, tank content, valve angle position, pump rpm, forward speed and active boom sections are all monitored.
7. The on-board computer processes input data in order to pre-empt the valve disc angle
8. Acting on the known valve angle the ceramic disc rotates with pin-point precision providing fast pressure changes to keep the target rate accurate.
9. The flow meter is used to calibrate the fluid system, to verify the flow and work as back up for the pressure transducer.
10. The fluid system detects the nozzle size by running a calibration routine using pressure and flow.
11. The pressure transducer controls the nozzle pressure and corrects the flow rate at very low flows (potentially 1 nozzle) not possible for a flow meter which stops working at 5 lpm. The signal rate is 250Hz (up to 250 times faster than the flow meter at 1Hz).
12. DynamicFluid4 will control the rate with pressure transducer alone in the event the flow meter fails.
13. The DynamicFluid4 regulator holds the target rate whether sections are switched on or off, changing speed, pump rpm, application rate or turning in or out of headlands.
14. DynamicFluid4 is highly accurate, smooth and incredibly fast.


DynamicFluid4 application control

A. Flow

B. Pressure

C. Pump rpm

D. DynamicFluid4 regulator

E. Valve disc angle sensor


F. Speed ring with speed sensor or GPS speed input

G. Boom width

H. Number of sections

I. Nozzles per section

J. Nozzle size

K. Tank volume

L. EFC section valves

M. Pump 


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