Graduate Studies, UNL

 

Dissertations and Doctoral Documents from University of Nebraska-Lincoln, 2023–

First Advisor

Santosh Pitla

Degree Name

Doctor of Philosophy (Ph.D.)

Committee Members

Joe Luck, Roger Hoy, Terry Howell

Department

Agricultural & Biological Systems Engineering

Date of this Version

2025

Document Type

Dissertation

Citation

A dissertation presented to the faculty of the Graduate College of the University of Nebraska in partial fulfillment of requirements for the degree Doctor of Philosophy (Ph.D.)

Major: Agricultural and Biological Systems Engineering

Under the supervision of Professor

Lincoln, Nebraska, December 2025

Comments

Copyright 2025, the author. Used by permission

Abstract

This dissertation addresses the need to better characterize real-world tractor power requirements across drawbar, power take-off (PTO), and hydraulic modes to support more representative tractor testing. Conventional testing protocols, such as OECD Code 2, emphasize steady-state performance under controlled high-load conditions, which do not reflect the mixed and dynamic demands of modern field operations. To address this gap, a Tractor Instrumentation System (TIS) was developed, validated, and deployed to collect high-resolution, mixed-mode power data during planting, anhydrous ammonia application, and grain cart operations. The TIS integrates physical sensors, including custom load pins, hydraulic pressure/flow sensors, and a redesigned PTO torque transducer, with ISOBUS and J1939 CAN-bus signals via a modular SCANGate data acquisition system. This architecture enables synchronized monitoring of drawbar, PTO, and hydraulic loads in real time while maintaining compatibility with standard implement interfaces.

Over two growing seasons, ISOBUS/CAN data and physical sensor measurements were collected from a John Deere 7250R tractor during commercial corn production in Nebraska. The results demonstrate wide variation in power demands: anhydrous application produced sustained drawbar loads averaging 47; planting operations combined draft (80%) with hydraulic (20%) demand averaging 36 kW; and grain cart hauling introduced diverse drawbar and PTO cycles, including 48 kW during unloading and 6−12 kW drawbar loads during empty and full cart movement.

Using these datasets, mixed-mode load profiles were developed for each operation and then combined into a single proposed duty cycle. This cycle captures idle, operating, turning, unloading, and transport phases with time and load fractions derived directly from measured field behavior. The proposed cycle aligns more closely with real tractor power use than steady-state tests and supports efforts to develop advanced testing. This work establishes a methodology for capturing and applying real-world mixed-mode load profiles and provides a foundation for future tractor testing, design, and energy optimization.

Advisor: Santosh Pitla

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