Design Recommendations for an Adaptive Control System in Agricultural Tractors Based on Expert Knowledge
Authors: Marcel Racs, Andreas Kaufmann, Björn Hülle, Thomas Maier
Abstract: OBJECTIVE AND SIGNIFICANCEDue to various implements in agricultural technology, the human machine interface (HMI) in tractors is required to cover a wide range of different operating scenarios. According to the current state of the art, the wide range of operating scenarios and changing operating characteristics can be covered only suboptimally by static control elements on the operating armrest. An optimized solution with intuitive operation, high usability and the avoidance of operating errors requires an HMI that can adapt optimally to the changing scenarios. Based on the previous research project aISA, the current project aISA 2.0 (adaptive interface systems in agricultural tractors) focuses on the development of an adaptive operating system in order to provide an optimal interface for the various and changing operating scenarios in tractors. Based on a methodical categorization, a design recommendation for the interface system is developed, among others considering availability, positioning, actuation type and interface technology of the functions examined. For this purpose, expert knowledge and a method for analyzing functionalities and operating is used. The existing method  will be further developed and applied to agricultural implements.METHODThe methodological approach can be divided into the following three aspects:1.Expert interviews2.Function and operation analysis, short: FOA3.Development of design recommendations for an optimized adaptive control system in agricultural tractors.In this contribution, the structure and results of the expert interviews are presented in detail. The expert interviews were conducted with developers from six different implement manufacturers regarding eleven different implements for a duration of 1.5 - 2 hours each. The objective was to gather every relevant control function and having each function evaluated by the expert in terms of different aspects. General settings, menu navigation and indicators not related to active controls were excluded. The next step involves analyzing the HMI by applying the established FOA based on the data collected. The individual functions are examined using operating scenarios. This includes comparing the control action performed by the user with the execution of the command by the machine. The analysis results in various compatibilities for each scenario that are necessary for intuitive operation. Based on the compatibilities, the current FOA is expanded including further specifications for the design recommendation of the control functions. This involves using 15 different control types that are available via the software interface (Isobus) commonly used in agricultural engineering. These define the framework for the type of operation on the software side that later can be performed by the adaptive control elements.RESULTSThe requirements for an adaptive operating armrest in agricultural tractors are achieved by the detailed analysis of the operating scenarios, the operating characteristics, the investigation of the compatibilities, and the consideration of the control types. The results lead to specific design recommendations for a conceptual design of the adaptive HMI for the control functions of the investigated implements.
Keywords: Usability, User Interfaces, Human Machine Interaction, Adaptive Control Elements, User Experience
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