Introduction

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.[1] The same has not been true for motorcycles. However, analogous advanced rider assistance systems (ARAS) have been introduced, and the ARAS market is expected to grow significantly in the coming years. Why might there be a lag in ARAS implementation, and what implications might the answers have for incident examinations and claims?

Passenger Vehicles and Motorcycles

To address these questions, it helps to first acknowledge pertinent differences between passenger vehicles and motorcycles. Passenger vehicles are typically manufactured with passenger restraint systems, whereas most motorcycles are not. Most passenger vehicles are steered by a driver using a steering wheel, whereas motorcycles achieve maneuvering through a combination of counter-steering and a rider and motorcycle leaning in intended directions of travel, especially at higher speeds. Motorcycles tend to have more pronounced movements of pitch (forward/backward), roll (lean left/right), and yaw (clockwise/counterclockwise) than passenger vehicles.[2] The body of a rider is also typically more involved in achieving these vehicle dynamics.[3] Though not exhaustive, these observations highlight some engineering and human factors differences that may present challenges for the implementation of ARAS.

Engineering and Human Factors Challenges

A notable engineering challenge concerns radar-based detection of objects on the road. Greater dynamic pitch, roll, and yaw movements can constrain radar projections, and the effectiveness of radar can be reduced when the motorcycle is leaned and during other riding phases due to vibrations.[4]^,[5] For these reasons and others, ARAS implementation by motorcycle manufacturers, at this point, has been limited mainly to ACC and BSM.[6] It should be noted, however, that development of helmet-based ARAS technologies has made significant progress; the main goals of these “smart helmet” features are to provide riders with blind spot, rear, and front collision indications via head-up visual displays and/or auditory alerts.

From a human factors perspective, ARAS may produce unique or unexpected riding situations that may impact rider performance.[7] Riders keep themselves aboard, at least in part, by grasping the handlebars, bracing the motorcycle with their legs, and keeping their center of mass in the appropriate position. Combined with the fact that there are usually no passenger restraints, these observations mean that abrupt unexpected changes in the orientation and/or dynamics of the motorcycle, such as through application of AEB, could result in control problems, rider separation from the motorcycle, or both. Thus, pertinent issues include the degrees to which the ARAS technology can predict and/or detect the state of the rider and the degrees to which the rider can predict and/or detect and respond to the assistive actions on the motorcycle.

Implications for Examinations and Claims

With the increase in ADAS there has been an increase in claims and lawsuits alleging either that unequipped vehicles should have been or that vehicles equipped with ADAS should have performed differently. There have also been allegations that aspects of the human interaction with ADAS technology may have contributed to the incident. Allegations can center on false or unintentional activation of ADAS features and on allegations of problems with a driver responding to signals from the technology. Areas of inquiry in these examinations are often whether and how the system provided assistance when the driver did not intend or expect it to and whether and how the system became engaged or disengaged with or without the driver noticing. Other questions involve whether a manufacturer should have provided ADAS that functioned in a specific way or with a specific timing or how ADAS indications are presented in terms of sensory modality, such as through vision, audition, or touch, and in terms of physical characteristics, such as frequency, duration, and intensity.

There is no reason to believe that this will be any different in ARAS-related incidents. And there may well be important nuances of assistive technologies for motorcycle operators that render the above complaints unique. For instance, more pronounced vehicle dynamics of motorcycles combined with more extensive involvement of the rider in those dynamics may have implications for allegations that an ARAS system presented a challenging transition from a situation where the assistive system was operating to one where a rider may have needed to respond. Addressing this issue will undoubtedly require additional complex analyses of human performance and vehicle dynamics issues, such as rider attention to the state of the motorcycle and perceptual-motor controllability, as well as whether and how the ARAS is capable of monitoring or predicting the state of the rider and of the vehicle at the same time.

The relatively small number of ARAS-equipped motorcycles may make allegations related to standards of care unlikely in the short term, but it is reasonable to expect the frequency of these questions to increase rapidly as research, development, and adoption of ARAS become more widespread, and as evaluative test criteria and standards are further developed. Similarly, the available ARAS features are currently limited, but as the number of features grows and the levels of rider assistance from those features increase, allegations pertaining to human performance capabilities and limitations could be expected to increase commensurately. The same should apply to the indications and feedback the ARAS present to the rider, which may be made more complex due to issues such as limited dash and instrumentation real estate to present visual feedback and challenges of rendering auditory and tactile information to a rider who is more exposed to other environmental stimuli than the driver of a typical passenger car.[8]

Closing Remarks

In conclusion, there seems to be an emerging consensus that widespread implementation and adoption of ARAS is not a matter of “if” but a matter of “when.” Moreover, the engineering and scientific questions will likely be similar to some of the ADAS-related questions that have arisen, but will also likely be somewhat novel due to unique characteristics of motorcycling. The unique issues of ARAS incident examination will certainly call for thorough understandings of human-machine interaction and motorcycle vehicle dynamics.

References

Akamatsu, M., Green, P., & Bengler, K. (2013). Automotive technology and human factors research: Past, present, and future. International Journal of Vehicular Technology, 1-28.
Diederichs, J. P., Fontana, M., Bencini, G., Nikolaou, S., Montanari, R., Spadoni, A., Widlroither, H., & Baldanzini, N. (2009). New HMI concept for motorcycles–the Saferider approach. Engineering Psychology and Cognitive Ergonomics, 358–366. https://doi.org/10.1007/978-3-642-02728-4_38
Diederichs, F., Knauss, A., Wilbrink, M., Lilis, Y., Chrysochoou, E., Anund, A., Bekiaris, E., Nikolaou, S., Finér, S., Zanovello, L., Maroudis, P., Krupenia, S., Absér, A., Dimokas, N., Apoy, C., Karlsson, J., Larsson, A., Zidianakis, E., Efa, A., … Bischoff, S. (2020). Adaptive transitions for automation in cars, trucks, buses and motorcycles. IET Intelligent Transport Systems, 14(8), 889–899. https://doi.org/10.1049/iet-its.2018.5342