Progress 09/01/03 to 08/31/05
Outputs
A system and method of remote monitoring of individual spray nozzles was developed and implemented on agricultural sprayers. The technique was based on measurement of the characteristic vibration produced by conventional agricultural, flat-fan nozzles. A theoretical analysis of the sheet break-up of aqueous solutions emitted from fan nozzles at typical operating flow rates and liquid pressures suggested that predominant frequencies would be in the 4 to 7 kHz band. Experimental data confirmed that the predicted wavebands were indeed the predominant frequencies and were of sufficient magnitude for detection, even in noisy industrial environments. A prototype nozzle vibration detector was developed using low-cost MEMS technology. The detector was embedded into commercial nozzle mounting hardware to allow simple retrofit onto existing spray systems and to facilitate introduction into the market. A microprocessor was coupled to the MEMS-based detector and sampled the
vibration measured by the detector. Gated sampling and sample-averaging algorithms were developed to aid in rejection of spurious signals, false detection of clogged or inoperative nozzles and failure of components. Nozzle-specific algorithms were developed for air induction and conventional atomizers as typically found on agricultural sprayers. The microprocessor was coupled to a network controller, allowing each nozzle sensor and microprocessor to operate as a distinct system but also be networked. A plurality of the microcontrollers were incorporated into a CAN bus network along the spray boom of an agricultural vehicle. The network allowed a cab-mounted operator interface to communicate with each nozzle-based unit. Configuration, calibration, communication and control algorithms for the system and the alert and annunciator functions were embedded in the operator interface. The network design allowed the number and location of nozzle sensors to be easily adapted for the range of
spray systems in the marketplace. Additionally, the system was designed to operate with pulsed flow nozzles, as are commonly used in pulse-width modulation systems for flow control. When monitoring pulsing flow, the sensor system was synchronized to sample flow only during periods when flow was discharged. Field-testing of the prototype system on mobile, agricultural vehicles evaluated the performance of the technique. Partially clogged nozzles were successfully detected and the operator was alerted to malfunctions. Monitoring techniques were developed for other spray system components such as pumps and filters. The network system also allowed not only monitoring but also individual control of pulsed-flow valves at each spray nozzle.
Impacts
Misapplication of agrochemicals and fertilizers cause economic losses to agricultural growers due to loss of chemical performance and/or the need for re-spraying fields. Additionally, the chemicals that are wasted or need to be reapplied create additional environmental loading in the air, soil and water of rural areas. Often, the misapplication is due to malfunction of the spraying system, often as simple as a clogged nozzle. The low-cost, robust system being developed will immediately alert a spray operator as to malfunctions of individual nozzles on the sprayer. The operator can easily correct the problem before significant land areas have been mistreated. Financial losses and needlessly applied chemical can be reduced. Additionally, the system under development may provide for individual nozzle flow control. This will allow greater precision in variable rate applications and provide new features, such as correction for turning radius and prevention of overlap
spraying.
Publications
- No publications reported this period
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Progress 10/01/03 to 09/30/04
Outputs
The feasibility of monitoring spray nozzles for proper operation by detecting the vibrations created by the atomization of the liquid sheet has been confirmed. Low-cost, commercial-grade sensors have been selected and tested. The sensors provide the necessary sensitivity and frequency bandwidth to provide suitable performance for typical agricultural spray nozzles. Characteristic frequencies for nozzle operation have been found in the 4 to 6 kHz range, well outside the characteristic frequencies for vehicle vibration. Novel signal processing algorithms have been developed and implemented on localized microprocessors at each nozzle. The algorithms use discrete Fourier transforms and relative spectral density signatures to detect changes in nozzle performance. Proprietary techniques have been developed to reduce false-positive and false-negative indications of proper nozzle performance. Data have indicated that various types of nozzles, such as flat fan, air-inclusion
and pre-orifice designs produce unique spectral signatures; however, properly designed algorithms appear to be robust across a range of nozzle configurations. Positioning of the sensor, relative to the liquid sheet being atomized, is critical and new data have guided the optimal positioning. A field-prototype is being designed; the sensor will be externally mounted for the prototype but work is underway to determine feasibility of internal mounting. A pre-prototype test system has been mounted on a 3-point hitch sprayer and partially-clogged spray nozzles were successfully detected during normal spraying operations. Local microprocessors are networked to an in-cab operator interface for programming, monitoring of operation and annunciation of improper operation. The network, designed to current industrial standards for networks on mobile agricultural equipment, also facilitates individual nozzle flow control through pulse-width-modulation of local solenoid valves. Operation of the
flow control and the nozzle monitoring have been coordinated such that nozzle and/or valve malfunction can be determined.
Impacts
Misapplication of agrochemicals and fertilizers cause economic losses to agricultural growers due to loss of chemical performance and/or the need for re-spraying fields. Additionally, the chemicals that are wasted or need to be reapplied create additional environmental loading in the air, soil and water of rural areas. Often, the misapplication is due to malfunction of the spraying system, often as simple as a clogged nozzle. The low-cost, robust system being developed will immediately alert a spray operator as to malfunctions of individual nozzles on the sprayer. The operator can easily correct the problem before significant land areas have been mistreated. Financial losses and needlessly applied chemical can be reduced. Additionally, the system under development may provide for individual nozzle flow control. This will allow greater precision in variable rate applications and provide new features, such as correction for turning radius and prevention of overlap
spraying.
Publications
- No publications reported this period
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