SBW Feedback : Design of feedback system for increased usability in monostable SBW shifters

Abstract: Electromechanical shift-by-wire car transmission systems make way for new innovative shifter designs such as monostable shifters that spring back to a starting position after a gear has been chosen. Unfortunately the radical change in the communication between the user and shifter has resulted in accidents due to incorrect gear selection. The inadequate usability of the monostable shifters can be attributed to the feedback it provided to users.   The aim of the thesis project was to develop a feedback concept that would improve the usability of a monostable shifter and to study if auditory feedback could be introduced to vehicle systems. By implementing design theory, benchmarking and various creativity methods five concepts with feedbacks in different modalities were developed. The concepts were evaluated in a usability study that involved 25 test participants. A review of the observations from the usability study along with an analysis of the interviews and collected data resulted in the final VRA concept. VRA was a multimodal concept with permanent visual feedback and optional auditory feedback. The shifting pattern was shown on the instrument cluster where the active gear was highlighted through light intensity, color and shape contrasts. The solid blue block, within which the abbreviation for the active gear was displayed, could be seen in the peripheral view. It was perceived as calm and helped the users navigate the shifter. A female machine voice that had a Swedish pronunciation was chosen as the auditory feedback to accompany the “P”, “R” and “D” gear selections. None of the users were indifferent towards the auditory feedback, some perceived it as caring while others found it annoying. Since the analysis did not indicate that auditory feedback was crucial, the VRA concept included an option to turn on or off the sound.   Monostable shifters behave differently compared to traditional polystable shifters, therefore with the changes in the physical movement the communication must also be reviewed. It is recommended to include the shifting pattern on the instrument cluster together with monostable shifters, as it makes up for the loss of the visual and haptic information from the physical shifter. Although the usability study showed that auditory feedback was not necessary, improvements were observed among people who favored it. The auditory information would most likely be better received if earcons were implemented instead of speech.