Human Factors Issues of Advanced Rider Assistance Systems (ARAS)
Authors: Coelho Chason , Garets Stephen , Bailey Jordan , Frank Todd , Scully Iiona , Cades David 
Published: June 2023

Advanced driver assistance systems (ADAS), such as adaptive cruise control (ACC), automatic emergency braking (AEB), and blind-spot monitoring (BSM) for passenger vehicles are becoming ubiquitous, with some features being standard on vehicles. The same is not true for motorcycles. However, limited analogous advanced rider assistance systems (ARAS) have been introduced, and the ARAS market is expected to grow significantly in the coming years. Some reasons for the development and implementation lags of ARAS include functional differences between passenger vehicles and motorcycles, such as lack of passenger restraints, more pronounced vehicle dynamics, greater operator physical involvement in achieving vehicle control, and more constrained means of presenting information for motorcycles. In turn, these differences highlight notable human factors issues, especially because ARAS may produce unique or unexpected riding situations that may impact the performance of the motorcycle operator. For example, abrupt, unexpected changes in the orientation and/or dynamics of the motorcycle, such as through application of AEB, could result in control problems, operator or passenger separation from the motorcycle, or both, even while still mitigating collision involvement. In this paper, we review relevant scientific and technical literature and discuss how unique demands of ARAS applications can shape the ways research can be translated into practical innovation, development, and implementation of ARAS features. Relevant scientific topics include feedback modalities, perceptual-motor behavior and control, perception-reaction time, user acceptance and trust, learning, and attention, with a focus on safety-critical issues spanning multiple scientific topics. For example, operator visual behavior, and in particular, operator sight distance (i.e., how far the operator is looking down the road at a given time), have been identified as critical variables that can affect rider safety. An operator can be said to override the sight distance when they travel above a speed that would allow them to safely stop the motorcycle after detecting a hazard. In this situation, ARAS may be able to alert the operator via forward collision warnings and/or intervene more directly via AEB. Important questions exist about whether and how to present warning information through vision, audition, or touch modalities, and with what physical features (e.g., frequency, duration, and intensity). Regarding the latter possibility, using more direct ARAS intervention with assistive control inputs to the motorcycle raises safety-critical questions about the degrees to which the ARAS technology can predict and/or detect the state of the operator and the degrees to which the operator can predict and/or detect and respond to the assistive actions on the motorcycle. We discuss these topics in the context of relevant literature with the overarching goal of informing future research, development, and adoption of ARAS, in addition to the development of evaluative test criteria and standards.