Event and Time-Triggered Control Module Layers for Individual Robot Control Architectures of Unmanned Agricultural Ground Vehicles

Automation in the agriculture sector has increased to an extent where the accompanying methods for unmanned field management are becoming more economically viable. This manifests in the industry’s recent presentation of conceptual cab-less machines that perform all field operations under the high-level task control of a single remote operator. A dramatic change in the overall workflow for field tasks that historically assumed the presence of a human in the immediate vicinity of the work is predicted. This shift in the entire approach to farm machinery work provides producers increased control and productivity over high-level tasks and less distraction from operating individual machine actuators and implements. The final implication is decreased mechanical complexity of the cab-less field machines from their manned counter types. An Unmanned Agricultural Ground Vehicle (UAGV) electric platform received a portable control module layer (CML) which was modular and able to accept higher-level mission commands while returning system states to high-level tasks. The simplicity of this system was shown by its entire implementation running on microcontrollers networked on a Time-Triggered Controller Area Network (TTCAN) bus. A basic form of user input and output was added to the system to demonstrate a simple instance of sub-system integration. In this work, all major levels of design and implementation are examined in detail, revealing the ‘why’ and ‘how’ of each subsystem. System design philosophy is highlighted from the beginning. A state-space feedback steering controller was implemented on the machine utilizing a basic steering model found in literature. Finally, system performance is evaluated from the perspectives of a number of disciplines including: embedded systems software design, control systems, and robot control architecture. Recommendations for formalized UAGV system modeling, estimation, and control are discussed for the continuation of research in simplified low-cost machines for in-field task automation. Additional recommendations for future time-triggered CML experiments in bus robustness and redundancy are discussed. The work presented is foundational in the shift from event-triggered communications towards time-triggered CMLs for unmanned agricultural machinery and is a front-to-back demonstration of time-triggered design. Advisor: Santosh K. Pitl

Inter-row Robot Navigation using 1D Ranging Sensors

In this paper a fuzzy logic navigation controller for an inter-row agricultural robot is developed and evaluated in laboratory settings. The controller receives input from one-dimensional (1D) ranging sensors on the robotic platform, and operated on ten fuzzy rules for basic row-following behavior. The control system was implemented on basic hardware for proof of concept and operated on a commonly available microcontroller development platform and open source software libraries. The robot platform used for experimentation was a small tracked vehicle with differential steering control. Fuzzy inferencing and defuzzification, step response and cross track error were obtained from the test conducted to characterize the transient and steady state response of the controller. Controller settling times were within 4 seconds. Steady state centering errors for smooth barrier navigation were found to be within 3.5% of center for 61 cm wide solid barrier tests, and within 38% for simulated 61 cm corn row tests

Inter-row Robot Navigation using 1D Ranging Sensors

In this paper a fuzzy logic navigation controller for an inter-row agricultural robot is developed and evaluated in laboratory settings. The controller receives input from one-dimensional (1D) ranging sensors on the robotic platform, and operated on ten fuzzy rules for basic row-following behavior. The control system was implemented on basic hardware for proof of concept and operated on a commonly available microcontroller development platform and open source software libraries. The robot platform used for experimentation was a small tracked vehicle with differential steering control. Fuzzy inferencing and defuzzification, step response and cross track error were obtained from the test conducted to characterize the transient and steady state response of the controller. Controller settling times were within 4 seconds. Steady state centering errors for smooth barrier navigation were found to be within 3.5% of center for 61 cm wide solid barrier tests, and within 38% for simulated 61 cm corn row tests

Agricultural Field Robotics for Plant Data Acquisition

As the demand for food increases, we are presented with the challenge of producing food more efficiently. With the help of agricultural robots it will be possible to achieve greater yields by the application of seeds, fertilizers and chemicals in the most efficient way possible. With more advanced robotic systems accurate crop data can be obtained to improve farming products and techniques. Flex-Row is a medium sized agricultural robotic platform built for autonomously traversing through rough fields during multiple crop growing stages. This platform consisting of a flexible frame with the ability to vary both width and height will initially be implemented with sensors to monitor production plants throughout the growing season. Furthermore, the robot will perform low draft applications such as spraying. The intended goal for this project is to develop a tele-operated platform that can be automated in the future. Inter-Row is a much smaller robot designed specifically for plant data acquisition. Tall height is not needed as it individually scans each plant a few cm from the base of the plant. The robot will help eliminate the need for manual labor when counting number of plants per row, which is beneficial on a large acreage field. Advisor: Dr. Santosh K. Pitl

Agricultural Field Robotics for Plant Data Acquisition

As the demand for food increases, we are presented with the challenge of producing food more efficiently. With the help of agricultural robots it will be possible to achieve greater yields by the application of seeds, fertilizers and chemicals in the most efficient way possible. With more advanced robotic systems accurate crop data can be obtained to improve farming products and techniques. Flex-Row is a medium sized agricultural robotic platform built for autonomously traversing through rough fields during multiple crop growing stages. This platform consisting of a flexible frame with the ability to vary both width and height will initially be implemented with sensors to monitor production plants throughout the growing season. Furthermore, the robot will perform low draft applications such as spraying. The intended goal for this project is to develop a tele-operated platform that can be automated in the future. Inter-Row is a much smaller robot designed specifically for plant data acquisition. Tall height is not needed as it individually scans each plant a few cm from the base of the plant. The robot will help eliminate the need for manual labor when counting number of plants per row, which is beneficial on a large acreage field. Advisor: Dr. Santosh K. Pitl