progress on field evaluation of aerial variable- rate systems for liquid application steven j....
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Progress on Field Evaluation of Aerial Variable-Progress on Field Evaluation of Aerial Variable-Rate Systems for Liquid ApplicationRate Systems for Liquid Application
Steven J. ThomsonSteven J. [email protected]@ars.usda.gov
Yanbo HuangYanbo [email protected]@ars.usda.gov
Research Agricultural EngineersResearch Agricultural EngineersUSDA-ARS-MSA-CPSRUUSDA-ARS-MSA-CPSRU
Stoneville, MS USA 38776Stoneville, MS USA 38776
It takes to make it all workbriansbrains
ProgressProgress Flow control testing Flow control testing
– L.A. Smith: 1997-2001L.A. Smith: 1997-2001Tested the AutoCal I and II for its ability to Tested the AutoCal I and II for its ability to
keep a constant amount/acrekeep a constant amount/acre
Variable-rate flow controlVariable-rate flow control– Smith and Thomson: 2004-2005Smith and Thomson: 2004-2005
Tested and refined the Satloc/AutoCal II Tested and refined the Satloc/AutoCal II combination for its variable-rate capabilitiescombination for its variable-rate capabilities
– Thomson, Huang, Martin: 2007 - presentThomson, Huang, Martin: 2007 - presentRefined the flow controller’s response to Refined the flow controller’s response to
changing rateschanging rates
GPS-based guidance systemsGPS-based guidance systems
Assist pilot in locating areas to apply Assist pilot in locating areas to apply for manually operated flow controlfor manually operated flow control
Are essential components of Are essential components of automatic (on-off or variable rate) automatic (on-off or variable rate) flow control systemsflow control systems
GPS-based guidance systemsGPS-based guidance systems
Ag-Nav (Guía, FireNav, FlightMasterAg-Nav (Guía, FireNav, FlightMasterTM)TM)
Hemisphere GPS Hemisphere GPS – SatlocSatloc– Del NorteDel Norte
Adapco Wingman™ GXAdapco Wingman™ GX DynaNav Dynaflight™DynaNav Dynaflight™ Trimble AgGPSTrimble AgGPS®® Trimflight 3 Trimflight 3
GPS-based guidance system
Flow Turbine Meter
Flow Controller
Flow Adjustment
consists of…
GroundSpeed
Chemical Pump on Aircraft
Pulse output
1. Electric servo on variable-pitch fan(prop) on spray pump
or
2. Electrically operated servo valve and hydraulically operated pump
or
3. Electrical in-line valve adjustment
Spray Valve
adjust
adjust
Integrated Aerial Flow Control
For VR, georeferencing
CPSRU Variable-Rate SystemCPSRU Variable-Rate System
Air Tractor 402B spray plane equipped Air Tractor 402B spray plane equipped with an engine-driven hydraulic power with an engine-driven hydraulic power package (Kawak Aviation Technologies)package (Kawak Aviation Technologies)
Satloc M3 with WAAS DGPS and 5 Hz Satloc M3 with WAAS DGPS and 5 Hz position updating. Uses AirTrac VR position updating. Uses AirTrac VR software (Hemisphere GPS)software (Hemisphere GPS)
AutoCal II automatic flow control AutoCal II automatic flow control (Houma Avionics, Houma, LA)(Houma Avionics, Houma, LA)
Hydraulically powered chemical pump Hydraulically powered chemical pump and boom valveand boom valve
Hydraulically controlled pump
Houma Avionics AutoCal IIHouma Avionics AutoCal II Compatible with most guidance systemsCompatible with most guidance systems
Interfaces with hydraulic Interfaces with hydraulic (e.g. Kawak) flow control systems(e.g. Kawak) flow control systems
Interfaces with electric valve motors and Interfaces with electric valve motors and variable-pitch pump props (with additional variable-pitch pump props (with additional servo)servo)
Has been tested by USDA-ARS-CPSRU Has been tested by USDA-ARS-CPSRU (Stoneville) for application and placement (Stoneville) for application and placement accuracy accuracy
Flow Control Evaluation Flow Control Evaluation
How does the variable-rate system perform?How does the variable-rate system perform?
System was evaluated with respect to:System was evaluated with respect to:
– Position error of spray deposits relative Position error of spray deposits relative to management zone boundariesto management zone boundaries
– System response timeSystem response time
– Application accuracyApplication accuracy
Test AreaTest Area
32 acre field (1660 x 900 ft) land 32 acre field (1660 x 900 ft) land formed and seeded to Bermuda formed and seeded to Bermuda grassgrass
Management zone boundaries were Management zone boundaries were located using an RTK GPS system located using an RTK GPS system with centimeter level accuracywith centimeter level accuracy
0 gpa
4 gpa
3 gpa
5 gpa
6 gpa
265 ft
265 ft
265 ft
265 ft
531 ft
531 ft
354 ft
354 ft
354 ft
Boundaries georeferenced with RTK GPS receiver
Used west lane of prescription test Used west lane of prescription test areaarea
Captured data stream generated by Captured data stream generated by AutoCal IIAutoCal II
Captured flow meter data with a 0.1s Captured flow meter data with a 0.1s monitor designed to read the flow monitor designed to read the flow meter at regular intervalsmeter at regular intervals
First Tests for Variable-Rate (2005): First Tests for Variable-Rate (2005):
Evaluate AutoCal II response to Evaluate AutoCal II response to changing rates changing rates
First needed to initiate flow 0.5 s earlyFirst needed to initiate flow 0.5 s early
L. A Smith - “Steve, your estimate is 0.05 seconds from optimal ! ”
Pass 1 FM11-30-05c
0
20
40
60
80
100
120
-0.90 0.30 1.50 2.70 3.90 5.10 6.30
Time (s)
Flo
w R
ate
(g
pm
)Speed: 132 Knots, 152 mph, 67.9 mps
Pass 2 11-30-05c
0
20
40
60
80
100
120
-0.96 0.30 1.56 2.82 4.08 5.34 6.60
Time (s)
Flo
w R
ate
(g
pm
)Speed: 125 Knots, 144 Mile/h, 64.31 m/s
Results – Flow Control ErrorResults – Flow Control Error
PassActual (gal)
Required (gal)
Average Error (%)
1 6.63 6.57 0.83
2 6.01 5.90 1.87
3 6.39 6.23 2.57
4 6.14 6.19 -0.84
5 6.49 6.42 1.10
6 6.48 6.45 0.40
|Average| 1.08
-- Spray Deposit
-- No Spray
W10
W9
W8
W7
W6
W5
W4
W3
W2
W1
RCB
E1
E2
E3
E4
E5
E6
E7
E8
E9
E 10
Results - Spray DepositsResults - Spray Deposits
6 gpa 0 gpa
Flow controller response to rate changes Flow controller response to rate changes resulted in average application volume resulted in average application volume error (not including sign) of 1.08%error (not including sign) of 1.08%
Spray deposit position error from ten Spray deposit position error from ten runs over water sensitive cards, ranged runs over water sensitive cards, ranged from -6 m to 16 m and 80% of the error from -6 m to 16 m and 80% of the error magnitudes were 6 m or less.magnitudes were 6 m or less.
Summary of 2005 results:
• For research purposes (2005), a high resolution (0.1s) flow monitor was used to read the flowmeter directly.
• Although it can be constructed, flow monitor is not readily available to users.
•So, we can look at response without flow monitor
Thoughts on Further Testing: (2008-2009)
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0 1 2 3 4 5 6
Time (s)
Flo
wra
te (
L/m
in)
Required
Actual
2005 response with flow monitor to increase data resolution
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0 1 2 3 4 5 6
Time (s)
Flo
wra
te (
L/m
in)
Required
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2005 response (raw)
In 2008, experiments were conducted and In 2008, experiments were conducted and system was modified to further improve system was modified to further improve response to changing ratesresponse to changing rates
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0 1 2 3 4 5 6 7 8
Time (s)
Flo
wra
te (
L/m
in)
Actual
Required
2008 response – before program modification
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0 1 2 3 4 5 6 7
Time (s)
Flo
wra
te (
L/m
in)
Actual
Required
2008 response – after program modification
New setup to test multiple guidance New setup to test multiple guidance systems/flow controllerssystems/flow controllers
Old Setup
Installed by Air Repair – Cleveland, MS
Autocal II flow controlreadoutSatloc
Ag-Nav Guia
Observation – what is necessary Observation – what is necessary for aerial VR to be successfulfor aerial VR to be successful::
Droplet spectra must maintain consistency at Droplet spectra must maintain consistency at different flowrates and pressuresdifferent flowrates and pressures
still
Can use mixed nozzle tip sizes to Can use mixed nozzle tip sizes to extend operating range (CP)extend operating range (CP)
Rotary atomizers – Do they maintain Rotary atomizers – Do they maintain similar spectra at different working similar spectra at different working pressures?pressures?
Fixed nozzles – New designs are neededFixed nozzles – New designs are needed
Thank you!Thank you!