F2008-02-053
Design and Validation of Safer Multifunctional Gearshift for Vehicle Settings Control through Cognitive Ergonomics Techniques
An innovative concept of HMI has been developed to enhance the control of vehicle settings (gear, driving mode, cruise control, car height, suspension hardness and HMI graphic features) through a single device integrated in the gearshift, and a head-up display. Prototype variations of this HMI concept have been evaluated in a driving simulator, in order to assess their influence on driving performance, mental workload and user´s emotional response. These aspects have been previously proved to be related with risk situations and driving safety, and are used to validate the conformance of the design with current initiatives of intelligent transport. The concept of a multifunctional single control responds to the ergonomic principle of reducing complexity of user interfaces. The two dimensional movement allowed by the gearshift may be combined with a small number of buttons to provide rapid access to a high amount of functions and options, using a established navigation model for users of new technologies. Other principles from the field of Cognitive Ergonomics have been considered in the design of the head-up display and the navigation procedure through menu options, in order to reduce time consumption in the HMI operations, minimize error risk and keep a safe mental workload level. Anthropometric and biomechanical characteristics of users population have been likewise considered in the design of the gearshift and its navigation buttons, in order to assure a quick access and comfortable handling, and to prevent accidental operations by involuntary push of buttons or incorrect manipulation. Driving performance is evaluated in simulator trials by measuring longitudinal and lateral control of the vehicle, comparing the results in the HMI manipulation context with the baseline of driving in different workload contexts. Mental workload has been assessed objectively through HMI operation performance, and subjectively by the Driving Activity Load Index (DALI), a driving-oriented version of the NASA-TLX procedure. Emotional response has been also evaluated with multivariate measurements, through psychophysiological variables and subjective questionnaires. These tests provide a holistic view of the impact of this HMI concept on safety, and scientifically validated criteria to determine the best design options between the variant elements in the prototypes.