No abstract

Accurate path scouting control of an autonomous agricultural robot is substantially influenced by terrain variability, field patterns, and uncertainties in sensed information. Based on conventional farming techniques, the targeted test crop of strawberries grows in semi-structured environments. Thus in this study, the proposed scouting control architecture comprises of three distinct portions and in each portion different sensors are used. Based on range finder (RF) information, the first region uses a proportional-integral-derivative (PID) controller with logic steps to account for undesirable pop-up events. In the other two portions, vision-based robust controllers are developed, in which a new bound is derived for the focal length uncertainty in vision. Stabilities of the controllers are proven and the reachabilities are analyzed to guarantee that the final state of each portion is within a desired initial region of the next portion controller. The proposed multiphase scouting control is successfully validated for our custom-designed robot in a commercial strawberry farm.

In recent years, the interests of introducing autonomous robots by growers into agriculture fields are rejuvenated due to the ever-increasing labor cost and the recent declining numbers of seasonal agricultural workers. Among all the enabling technologies used in robot operations for agricultural products with shallow structures, controlling a robot to traverse throughout a field is challenging. In this study the motion control of a robot, custom-designed for strawberry fields, is separated into multiple phases to deal with the over-bed and cross-bed operation needs. Different sensors are used for different control phases. In particular, nonlinear robust controllers are designed for the cross-bed motion, purely relying on vision feedback. The proposed sensing and control methods are successfully validated in a commercial farm.

Development of an ultra-high temperature sensor advocates numerous applications in a variety of diverse fields. Combustion turbine engine advancements are predominately the benefactors of high temperature measurement capabilities; founded upon the principle of higher combustion reaction efficiency. The interior combustion chamber of a gas turbine is an extremely hostile environment for any typical material, especially a measurement component. Implementing the conductive properties and high temperature stability of a polymer derived ceramic (PDC) offers a solution to this predicament. Complementing the virtuous mechanical properties of the unique ceramic is micro-machinability and tunable electric characteristics established from the precursor compounds. The thermo-electric qualities of the PDC prepare formulation of a relationship between the changing temperatures of the research environment with respect to the internal resistance of the ceramic. An elected measurement system will actively monitor a PDC sensory circuit as well as reference thermocouple temperature. Series of response experiments were performed to characterize the functionality of the sensor within the high temperature environment.