L10 - Automation in Precision Agriculture

AGRI4401 Precision Agriculture

Gustavo Alckmin

July 8, 2025

Manual Sugarcane Harvesting

Labour intensive, time-consuming, and hazardous

Mechanised Sugarcane Harvesting

Capital intensive, high initial investment, and requires skilled operators

Manual Coffee Harvesting

Low paid jobs, competitive advantage of countries with low labour costs.

Mechanised Coffee Harvesting

Competitive regardless of labour costs, high initial investment, requires skilled operators.

Automation in Precision Agriculture

  • Integration of GPS guidance, onboard sensors, data analytics, and variable-rate applicators
  • Transition from fixed-path task automation to adaptive, intelligence-driven machinery
  • Electronic monitoring and control origins in the 1970s with autonomy milestones in the 1990s
  • Modular scalability: calibrating hardware, software, and training investments to farm size and crop type
  • Quantifiable benefits: improved seed, water, and fertilizer efficiency; higher profitability; reduced environmental footprint
  • Current research: unifying heterogeneous systems, enhancing real-time decision support, and promoting technology adoption

Just to recap: What is Precision Agriculture?

  • Precision Agriculture Definition: A suite of geospatial, sensor, and data analytics technologies for field- and crop-specific management.
  • Integration & Adoption: Emphasis on seamless interoperability among sensors, platforms, and machinery to simplify farmer implementation.
  • Scalability & Customization: Configurable solutions for varied field sizes, crop types, soil conditions, and budget levels.
  • Investment Requirements: Upfront capital needed for GPS-enabled equipment, variable-rate applicators, IoT sensors, data management software, and training.
  • Performance Outcomes: Measurable gains in fertilizer, water, and pesticide use efficiency; yield increases; cost reductions; and minimized environmental footprint.
  • Core Technologies: GPS/GNSS guidance, remote sensing (satellite/UAV), machine learning–driven decision support, and variable-rate control systems.

Benefits of Precision Agriculture

  • Increased input efficiency (fertilizer, seed, water) via variable-rate application
  • Enhanced profitability from reduced wastage and precision resource allocation
  • Reduced environmental impacts such as nutrient runoff and soil erosion
  • Improved soil health and long-term sustainability via site-specific interventions
  • Scalability across field sizes and crop types with modular technology systems

Challenges in Precision Agriculture

  • High upfront capital investment for GPS-guided machinery, soil and crop sensors
  • Complex data integration across heterogeneous platforms and proprietary formats
  • Rigorous calibration and validation required for sensor accuracy in varied field conditions
  • Limited rural connectivity and infrastructure for real-time telemetry and remote management
  • Skills gap in data analytics, agronomic modeling, and precision-tech operation
  • Regulatory hurdles and lack of common interoperability standards among OEMs

Role of Automation

  • Integrates sensor fusion with real-time diagnostics for predictive maintenance.
  • Uses arrays of low-cost sensors and optimized fusion algorithms for noise reduction and data accuracy.
  • Continuously monitors machine health to detect and classify emerging faults.
  • Triggers condition-based alerts to operators and decision modules for timely interventions.
  • Automates self-adjustments or safe shutdowns to prevent catastrophic failures.
  • Layered approach bridges technical (data correlation, fault classification) and operational (skill gaps, operator isolation) challenges.

Example of Automation

Efficiency Gains

  • Efficiency & Profitability: Data-driven management increases yield per unit input, boosting ROI.
  • Temporal Variability: Incorporate crop rotation and seasonal cost-benefit fluctuations into models.
  • Benefit Duration: Separate one-off gains from multi-year returns and model decay rates.
  • Spatial Allocation: Allocate capital and operating costs across the entire managed area, not just sensor zones.
  • Depreciation: Use accelerated depreciation schedules to match high-tech equipment lifecycles.
  • Risk & Reliability: Quantify technology performance variability and potential operational disruptions.

Precision Improvements

  • Geo-referenced data capture: GPS-enabled tractors, yield monitors, soil sensors collect spatially tagged field data
  • Variable-rate application: real-time adjustment of seed, fertilizer & agrochemicals via prescription maps
  • Data analysis & modeling: regression, geostatistics & interpolation in decision-support software
  • ROI & performance metrics: quantifying input costs vs. yield gains at field and sub-field scales
  • Management zone refinement: integrating multi-year datasets to optimize field-management areas
  • Validation frameworks: mathematical models (Clay et al., 2018) underpin precise input decisions

flowchart LR
  A[Geo-referenced Data Capture] --> B[Prescription Map Generation]
  B --> C[Variable-Rate Application]
  C --> D[Data Analysis & Modeling]
  D --> E[ROI & Performance Metrics]

Case Study: ROI from Automation

  • Autosteer reduces tractor size and machinery costs (Shockley et al., 2011).
  • Expands farmable acreage without larger equipment investment (Shockley et al., 2012b).
  • Automatic section control optimizes operations in irregular field shapes; autosteer is most cost-effective in large, square fields (Smith et al., 2013).
  • Precision systems integrate with existing farm electronics, though retrofit and calibration expenses may apply.
  • Operator training curve affects short-term efficiency gains and time to full adoption.
  • Field-level ROI positive when net returns exceed investment and operating costs; whole-farm and intangible costs remain under-studied.

AutoSteer

VRT Seeding Technology

  • High-precision GNSS receiver for sub-inch positioning
  • In-cab display enabling real-time guidance and variable-rate control
  • Seeder equipped with hydraulic-driven variable-rate metering units
  • Multi-hybrid dual-meter planters for simultaneous placement of two varieties or treatments
  • Wireless telemetry integration for planter, fertility, and yield data capture
  • Adjustable parameters: seeding population, hybrid selection, row-unit downforce, and planting depth

flowchart LR
  GNSS[GNSS Receiver] --> Display[In-cab Display]
  Display --> Prescription[Prescription Map]
  Prescription --> Planter[VR Metering Planter]
  Planter --> Yield[Yield & Telemetry Integration]

Implement Steering Systems

  • Real-time networked control integrates sensors, actuators, and guidance algorithm for four-wheel steering.
  • Future auto-steering embedded via Tractor–Implement Management (TIM), transferring control authority to the implement.
  • Implements autonomously assess field conditions and command tractor speed, steering angle, and power output.
  • Standardized, open communication protocol ensures interoperability across manufacturers, including SMEs.
  • Integrated safety controls continuously monitor system health, prevent faults, and support targeted maintenance.
  • Evolution from add-on modules toward fully integrated tractor–implement automation systems.

ProTrakker

  • Fine adjustment of attachments

VRT & Steering Hardware

  • Steer-assist retrofit kits: US $3,000–5,000 (bolt-on, transferable)
  • Fully integrated hydraulic kits: US $8,000–10,000 (plumbed into steering circuit)
  • Guidance modes:
    • Parallel (up-and-back)
    • Contour/“round-and-round” (select systems)
  • Electronic guidance cost spectrum:
    • Basic DGPS visual: from US $500
    • RTK autosteering systems: up to US $40,000
  • Proven benefits: improved application accuracy, reduced overlap, optimized input use
  • Operator fatigue reduction and ROI drivers underpin VRT adoption

Benefits of VRT & Steering

  • Reduced input waste through variable-rate fertilizer, pesticide, and seed application
  • Optimized input-to-yield ratio, boosting ROI on high-cost inputs
  • GPS-guided autosteer minimizes overlap, decreasing overapplication by up to 10%
  • Fewer field passes and faster coverage lower labor and fuel expenses
  • Lifecycle cost awareness: includes subscription fees, software updates, and support
  • Combined savings and efficiency gains accelerate ROI realization

Spray Boom & Nozzle Controllers

  • Traditional section control: 3–6 m wide on/off valves
  • Individual-nozzle actuation via CAN bus at 0.5 m spacing
  • Lateral resolution improved to nozzle-spacing scale (~0.5 m)
  • Longitudinal resolution: ~1 s solenoid (~4 m at 4 m/s) vs. <10 ms fast solenoids (<0.04 m)
  • Overlapping spray patterns yield diffuse cut-off edges despite finer control
  • Dose regulation alters both concentration and total spray volume

flowchart LR
  A[Section Valves 3 to 6 m] --> B[Nozzle CAN Control 0.5 m]
  B --> C[Lateral Res: 0.5 m]
  B --> D[Longitudinal Res: <10 ms]
  C --> E[Sharper Modulation]
  D --> F[Sub-decimeter Accuracy]

PWM Technology

  • Hardware timers count from BOTTOM to TOP, resetting each cycle
  • COMPARE register sets duty cycle: ON while counter < COMPARE, OFF otherwise
  • Key parameters: duty cycle, period, frequency, resolution
  • Agronomy uses PWM to pulse valves for precise flow control
  • Nozzle PWM runs at lower frequencies to ensure full valve opening
  • Individual valve control maintains boom pressure and supports variable-rate mapping

Example PWM Diagram

Multiple Nozzle Control

  • Multiple-nozzle holders support up to four nozzles per unit for variable forward speeds and spatial targeting
  • Individual or simultaneous switching delivers turn-down ratios exceeding 10:1 for precise flow modulation
  • Pneumatically actuated clusters (Miller et al., 1997) achieved a 5:1 turn-down ratio and eliminated delivery gaps via on/off sequencing
  • On-the-fly droplet size adjustment enables larger droplets at field boundaries to reduce drift risk
  • Four-nozzle setup: two standard flat-fan nozzles for bulk spraying and two air-induction nozzles for boundary zones
  • GPS-referenced automatic switching ensures precise dose delivery, optimized efficacy, and minimal off-target movement

Case Study: Precision Spraying

  • Boom pressure regulation vs. injection-metering for map-based “look-ahead” dosing
  • Consistent response times enable precise rate changes along the boom
  • Lab tests with 1.0 mm stainless-steel rods reveal deposit pattern variances
  • All nozzles at 0.8 L/min and 300 kPa produced different droplet spectra
  • Nozzle design must align droplet size distribution with crop geometry
  • Optimized coverage reduces off-target loss and enhances efficacy

PWM Spraying Systems

Australian Autonomous Farm Machinery

Citrus Orchard Autonomous Sprayer

Evaluating Automation Equipment

  • Setup, calibration, and data management demands
  • Integration with yield monitors, VRT, and management software
  • ROI assessment: farm- and field-level economic variability
  • Environmental benefits: precise input targeting reduces runoff and emissions
  • Automated guidance: operator fatigue reduction and error minimization
  • Attachment compatibility & overall application accuracy

Telematics & Data Transfer

  • Real-time telemetry via radio and cellular networks for location, orientation, engine status, fuel use
  • ISOBUS-compliant messaging over vehicle data buses for standardized data integration
  • Remote monitoring of farm machinery, UAVs and logistics fleets
  • Environmental input digitization from distributed weather stations (wind, temperature, humidity)
  • Rule-based alerting (e.g., fire-danger warnings) driven by real-time sensors
  • Smart-control linkage to automate machine shutdowns upon threshold breaches

RTK Guidance

  • Utilizes GNSS differential corrections via base stations and rovers
  • Real-Time Kinematic (RTK) delivers ±1 inch positional accuracy
  • Operator aligns initial pass (A–B wayline), then engages automated steering
  • Leverages WAAS, subscription networks or local RTK services for corrections
  • Key components: implement steering, marker arms and robust communication links
  • Benefits include higher field efficiency, reduced overlap and decreased operator fatigue

Auto-Steering Technologies

  • Control Shift: Implements perform sensing (soil, crop) and command tractors for precision maneuvers.
  • Open Communication Standards: Manufacturer-neutral protocols ensure interoperability across brands and scales.
  • Safety & Maintenance: Embedded safety interlocks prevent unintended movements; diagnostics enable targeted servicing.
  • Aftermarket Hardware: Steer-assist modules (~USD 3,000–5,000) vs. fully integrated hydraulic kits (~USD 8,000–10,000).
  • Guidance Modes: Supports straight “up-and-back” and circular “round-and-round” patterns; parallel passes dominate.
  • Cost Spectrum: Basic DGPS visual aids (~USD 500) to advanced RTK-GPS autosteer solutions (> USD 40,000).

Controlled Traffic Farming

  • Identify and standardize tramline width based on widest implement
  • Align all machinery to permanent wheel-tracks using RTK-GNSS for sub-decimetre accuracy
  • Configure tyres/tracks and ballast for uniform soil contact and compaction control
  • Limit wheel traffic to less than 15% of field area to preserve crop-zone bulk density
  • Monitor compaction depth with penetrometer and bulk-density sampling
  • Stage CTF adoption from seeding through spraying, fertilizing, and harvesting

flowchart LR
  A[Tramline Grid Layout] --> B[Machinery Alignment]
  B --> C[RTK-GNSS Guidance]
  A --> D[Soil Compaction Reduction]
  D --> E[Enhanced Water Infiltration & Root Growth]

Data Integration for Management

  • Multi-year profitability analyses identify underperforming zones, enabling targeted practice changes to increase ROI.
  • Production cost calculations follow Fausti and Wang (2017) methodologies for standardized economic assessments.
  • Systematic archiving of yield monitor data with yearly, data-type folders ensures consistent backup and retrieval.
  • Basic legacy software used by smaller operations contrasts with integrated databases in advanced PA systems (Daberkow & McBride, 2003).
  • OEM-developed platforms enable seamless mobile-to-farm data transfers and in-field analytics.
  • Cloud adoption remains limited due to data ownership, security, and financial sensitivity concerns.

flowchart LR
  A[Yield Monitor Data] --> B[Archive & Backup]
  B --> C[Cloud/Local Storage]
  C --> D[Centralized Database]
  D --> E[Analytics Platform]
  E --> F[Decision Support]

Precision Planting Equipment

  • Excessive row spacing requiring multiple passes for uniform coverage
  • Lack of in-furrow or split-band fertilizer application modules
  • Small seed hopper volumes leading to frequent refilling
  • Corn/soy seed discs incompatible with winter grain seed size/flow characteristics
  • Metering control systems struggle with smaller seeds, affecting target plant populations
  • Disc opener clogging in sticky, high-moisture soils reduces placement consistency

Downforce Management

  • Load cells on each planter row continuously measure force on opener, gauge, and closing assemblies
  • Control unit analyzes real-time load data to determine required downforce adjustments
  • Hydraulic or pneumatic actuators modulate pressure independently for each row
  • Automatically compensates for soil moisture, texture, residue cover, and terrain variability
  • Increases downforce in high-strength soils to maintain target seeding depth
  • Reduces downforce in soft or wet soils to prevent over-penetration and seed damage

flowchart LR
  A[Soil Variability] --> B[Load Cell Sensors]
  B --> C[Control Unit]
  C --> D[Hydraulic/Pneumatic Actuators]
  D --> E[Row-by-Row Downforce Adjustment]
  E --> F[Uniform Seeding Depth]

Singulation Accuracy

  • GNSS pass-to-pass accuracy (15-minute relative measure)
  • Long-term accuracy typically ~3× worse over days/weeks
  • Static accuracy assessed on known benchmarks; dynamic filters may introduce motion bias
  • Relative accuracy: consistency of position changes within a single pass
  • Absolute accuracy: deviation from fixed reference frame for multi-vehicle or historical overlays
  • Trade-offs in filter design impact static vs. dynamic performance

Air Drill

  • Think about the metrics (e.g., seeding)

VRA for Fertilizers

  • Utilizes spatial soil nutrient variability data (grid and zone sampling) to generate prescription maps
  • Integrates real-time sensor fusion (optical NDVI, electromagnetic induction) for in-season nutrient status assessment
  • Employs GPS-guided variable flow controllers for precise granular and liquid fertilizer application
  • Adapts application rates via advanced algorithms that incorporate soil, crop, and environmental data layers
  • Validated through calibration trials (Whelan & Taylor, 2013; Grisso et al., 2018) ensuring ±15% delivery accuracy
  • Continuous refinement via machine learning and autonomous systems showcased at ISPA conference proceedings

VRA for Pesticides

  • Environmental gains from precise pesticide placement: reduced off-target drift and lower chemical inputs
  • Real-time, sensor-driven VRA integrates multispectral or proximal sensors with decision-support software
  • Closed-loop control hardware adjusts nozzle-level dosage dynamically based on field variability
  • Most efficacy studies infer benefits from rate models; true field-scale measurements are costly and complex (Bongiovanni & Lowenberg-DeBoer, 2004)
  • Simulations in vineyards and orchards show mixed economic outcomes depending on scenario parameters (Tona et al., 2018)
  • Stricter environmental regulations (Karkee et al., 2014) increasingly favor VRA systems to meet pesticide use limits

flowchart LR
  A[Multispectral Sensors] --> B[Data Processing]
  B --> C[Decision-Support Software]
  C --> D[Control Unit]
  D --> E[Variable-Rate Nozzles]
  E --> F[Field Application]
  F --> A

Green-on-Green (GoG)

  • AI-driven real-time weed identification and spot spraying
  • Extends selective application from fallow (green-on-brown) to in-crop scenarios
  • Technical challenges: boom stability, stubble/crop shading, dust interference, operating speed
  • Environmental and economic benefits via reduced herbicide volumes and improved control
  • Risk factors: off-label applications, residue limit breaches, regulatory uncertainty
  • Necessity for coordinated Australian image datasets and structured risk-assessment framework

Green-on-Brown (GoB)

  • Definition: Green-on-Brown (GoB) isolates green vegetation reflectance by subtracting brown soil background signal.
  • Spectral computation: GoB = G – (R + B)/2 using bands at 550 nm (green), 650 nm (red), 470 nm (blue).
  • Enhanced discrimination: Accentuates sparse canopy and crop vigor distinctions versus bare soil.
  • Visualization: Positive GoB values indicate live foliage; values near zero denote soil or senescent residue.
  • Applications: Delineate nutrient stress zones, monitor weed patches, assess early insect or disease damage.
  • Caveats: Sensitive to soil moisture, surface residues; requires calibration and ground truthing.

Examples: WeedIT & Bilbery

  • WeedIT: Open-source image database and machine-learning pipeline for automated weed species recognition
  • Curated annotated masks (ryegrass vs. turnip) to train object-detection architectures
  • Open Weed Location (OWL) University of Sydney post-2021 project completion
  • Demonstrates integration of big data, sensor networks, and real-time decision support

WeedIT

Soil Moisture Sensing

  • Remote sensing offers soil moisture estimates over multi-kilometer footprints but is limited to the top ~5 cm and affected by crop canopy (Jackson & Schmugge, 1989).
  • Elevated surface reflectance signatures can indicate high-salinity soils, enabling spatial mapping of salt-affected areas.
  • Soil organic matter is estimated via multispectral and proximal sensors, integrating reflectance indices with ground-truth calibration (Bhatti et al., 1991; Roberts et al., 2010).
  • The Crop Water Stress Index (CWSI) uses canopy temperature and meteorological data to quantify plant water stress levels (Idso et al., 1981).
  • Proximal surface-moisture sensors inform field operations, preventing compaction and puddling by timing machinery traffic according to surface wetness.
  • In-field moisture probes provide representative readings of deeper soil horizons, complementing in-situ crop sensors that detect instantaneous stress and nutrient deficits (Cosh et al., 2012).

Weather Condition Sensors

  • On-site weather stations measure wind speed, rainfall, temperature, humidity and solar radiation
  • Standardized sensors (ultrasonic anemometers, tipping-bucket rain gauges) ensure cross-platform compatibility
  • Signal-processing algorithms calibrate raw data, filter noise and adapt to varied topographies
  • Remote surface-moisture sensors provide rapid readings but lack deeper horizon insights
  • Buried moisture probes capture representative subsurface moisture profiles across soil layers
  • In-situ optical/multispectral sensors detect real-time crop water stress, nutrient deficiencies and early pest/disease symptoms

Automated Harvesting Machinery

  • System-level analyses demonstrate economic feasibility and technical frameworks for agricultural robots (Pedersen et al., 2006)
  • Demeter automated harvester integrates real-time grain mass flow sensors with adaptive harvesting control (Pilarski et al., 2002)
  • Autonomous self-propelled units incorporate path planning, obstacle detection, and environment mapping (Posselius & Foster, 2012)
  • Closed-loop feedback regulates forward speed to modulate feeding rate based on engine load and grain flow signals
  • Adaptive control algorithms compensate for biological variability from soil type, moisture, and crop heterogeneity
  • Streamlined operator interfaces unify sensor outputs, control commands, and diagnostics for peak throughput

Yield Monitoring & Mapping

  • Real-time yield measurement via onboard mass flow and moisture sensors
  • Calibration routines adjusted for crop type, flow rate, and moisture content
  • GPS integration for spatially explicit yield data and map generation
  • Yield curves relating nutrient application rates to measured crop output
  • Identification of yield-limiting factors: soil properties, topography, plant health
  • Multi-year and extreme-weather overlays to isolate persistent low-yield zones

Data Integration & Analytics

  • Proprietary formats and lack of interoperability impede cross-vendor equipment data exchange
  • Transition from siloed farm-management software to unified systems with centralized databases
  • Secure data pipelines: ingestion, ETL processes, and real-time telemetry from sensors and machinery
  • Big Data frameworks (Hadoop, Spark) enable spatial-temporal analysis and large-scale crop modeling
  • Prescriptive analytics translate raw field data into variable-rate application prescriptions
  • Robust data governance ensures ownership, security, and compliance in cloud or on-premises deployments

Small Automated Machinery

Case Study: FarmBot

  • Field-proven architectures: CARMEN, Agroamara, Mobotware, SAFAR
  • Task modularization into reusable process pipelines
  • Standardized messaging and inter-process communication protocols
  • Distributed module orchestration for synchronized operations
  • Open-source scarcity; Mobotware remains actively maintained
  • Autonomous retrofits (Noguchi 2013) for tillage, seeding, spraying, harvesting

graph TD
  FM[Field Map Input] --> TP[Autonomous Task Planner]
  TP --> MB[Standardized Messaging Bus]
  MB --> S[Sensor Module]
  MB --> N[Navigation Module]
  MB --> A[Actuation Module]
  MB --> V[Vehicle Control Interface]
  V --> O[Tillage/Seeding/Spraying/Harvesting]

Case Study: Solinftec & Other UGVs

  • Solinftec’s autonomous UGV integrates RTK-GPS, LiDAR and multispectral cameras for precision row-based operations
  • Real-time CNN-based weed detection at 20 FPS with multi-spectral fusion, achieving ≥95 % precision
  • A* path planning on occupancy grids with dynamic obstacle avoidance; end-to-end latency ≤50 ms on NVIDIA Jetson TX2
  • ROS-based modular control architecture combining PID and MPC controllers to maintain ≤5 cm positional error
  • Cloud-augmented fleet management over 4G/LTE for telemetry, OTA updates, and remote task scheduling, yielding 30 % labor savings
  • Comparative platforms (e.g., FarmWise mechanical weeder, AgXeed) benchmarked on ROI, throughput and crop yield impact

DIY Robotics

  • Early development (Ardupilot - Follow-me mode)

Conclusion & Q&A

  • Automation is one of the trends in agriculture
  • Requires specialised knowledge
  • Niche markets and competitive advantage
  • Sensor are cheap and the trend is that will become cheaper (Moore’s law)