Sensorimotor basis of motor vehicle control

Xu, Xin (2017). Sensorimotor basis of motor vehicle control PhD Thesis, School of Human Movement and Nutrition Sciences, The University of Queensland. doi:10.14264/uql.2017.444

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Author Xu, Xin
Thesis Title Sensorimotor basis of motor vehicle control
School, Centre or Institute School of Human Movement and Nutrition Sciences
Institution The University of Queensland
DOI 10.14264/uql.2017.444
Publication date 2017-03-27
Thesis type PhD Thesis
Supervisor Guy Wallis
Steven Cloete
Total pages 148
Total colour pages 50
Total black and white pages 98
Language eng
Subjects 080602 Computer-Human Interaction
170112 Sensory Processes, Perception and Performance
110603 Motor Control
Formatted abstract
Driving represents one of the most common modes of transport world-wide. It is also one of the major causes of death and injury in developed societies prompting technological innovations through which computers share or assume control of the task of driving, through a range of Advanced Driver Assisting Systems (ADAS). Given the lengthy and substantial investment in such systems it is perhaps surprising how little we understand about how humans control motor vehicles and why, on occasion, this control fails. This is actually a problem. Driver-assist systems that do not understand human drivers well can be dangerous and promote unforeseen risks. For example, anti-lock braking systems, which are designed to prevent skidding during heavy braking, do not always have the positive impact on safety one might expect (Farmer, Lund et al. 1997, Sagberg, Fosser et al. 1997), perhaps because their operation does not mesh seamlessly with the expectations of drivers or other road users.

One route to gaining a better understanding of the control processes employed by drivers, is through the study of situations in which standard steering strategies fail. In this thesis the studies are largely inspired by reports describing what happens during a lane change manoeuvre when visual feedback is temporarily removed. A typical lane change includes two phases, but when visual feedback is withheld, drivers repeatedly omit the second phase. In this thesis, we investigated this effect in a series of experiments aimed at getting to the bottom of the causes of this error. The thesis begins by seeking to generalize the effect from the special case of a straight road which was the focus of earlier studies. This was deemed important because a typical steering wheel has a natural tendency to re-centre itself. It is possible that this behaviour reduces the active steering movements a driver must make during a lane change, since they do not have to actively return the steering-wheel to the neutral position. For that reason, we designed a circular road on which a non-zero steering wheel angle was required at all times. Through this study, we were able to conclude that the effect does generalize.

In a second set of experiments we attempted to investigate which visual cues are essential for drivers to correct their error. Apparently, a normal road with redundant information provides sufficient visual feedback for drivers to make a lane change. However, it is of interest to know to what extent the visual feedback can be reduced and still meet the minimum requirement. In our study, we chose optic flow as a starting point. Optic flow has previously been shown to suffice for the purpose of heading perception and heading control. A number of ‘steering-towards-a-target’ studies also found that optic flow is tightly related to steering performance. Hence, we asked whether optic flow was sufficient for controlling a lane change manoeuvre and, unlike much of the previous studies on flow, we posed the question in an active steering task, revealing that flow alone is not sufficient to prompt correct lane changing behaviour.

In the concluding set of experiments we took our studies out into the field. Most previous studies on lane changing have been conducted in driving simulators. Simulators are limited in that they cannot provide complete vestibular information or the lateral forces associated with physical motion. Recently, research found that primates use both visual and vestibular feedback in an optimal way to achieve precise control of self-locomotion, hence it would not be surprising if drivers incorporate motion cues in the control of steering too. To test this possibility, we tested behaviour using an instrumented vehicle. Interestingly, even though drivers could complete the manoeuvre accurately in the real car (even without visual feedback) they continued to make the systematic error in the simulator (even in a motion platform). This strongly suggests that non-visual cues play a crucial role in the control process.

Overall this thesis advances our understanding of steering control in a number of ways. It is apparent that lane-change errors apply across multiple simulators and scenarios even when the driver is required to actively steer at all times. The work also reveals that optic flow information alone is not sufficient to motivate appropriate steering responses despite the ability of observers to accurately extract their heading from the flow information. And thirdly, the work suggests that non-visual cues generated by inertial forces, form an intrinsic part of normal lane changing behaviour, allowing subjects to perform the task even in the absence of visual information. This last result, in particular, should prompt theoreticians to include somatosensory and vestibular senses into their models of control, and cautions against over-interpreting results from simulator studies in which these cues are weak or non-existent.
Keyword Optic flow
Lane change
Vestibular cues
Internal model
Inertial feedback
Real vehicle
Additional Notes 1,4,9,19,21,24-25,29,31-35,39,42,45-48,56,59-60,62-63,66,68-69,75-76,79-83,85-87,89-90,93,97-98,103-107,111-113

Document type: Thesis
Collections: UQ Theses (RHD) - Official
UQ Theses (RHD) - Open Access
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Created: Thu, 16 Mar 2017, 00:24:54 EST by Xin Xu on behalf of Learning and Research Services (UQ Library)