Steven Cloete

Limitations of Feedforward Control in Multiple-Phase Steering Movements

When attempting to perform bi-phasic steering movements (such as a lane change) in the absence of visual and inertial feedback, drivers produce a systematic heading error in the direction of the lane change (Wallis et al., Curr Biol 12(4):295–299, 2002; J Exp Psychol Hum Percept Perform 33(55):1127–1144, 2007). Theories of steering control which employ exclusively open-loop control mechanisms cannot accommodate this finding. In this article we show that a similar steering error occurs with obstacle avoidance, and offer compelling evidence that it stems from a seemingly general failure of human operators to correctly internalise the dynamics of the steering wheel. With respect to lateral position, the steering wheel is an acceleration control device, but we present data indicating that drivers treat it as a rate control device. Previous findings from Wallis et al. can be explained the same way. Since an open-loop control mechanism will never succeed when the dynamics of the controller are internalised improperly, we go on to conclude that regular, appropriately timed sensory feedback—predominantly from vision—is necessary for regulating heading, even during well-practiced, everyday manoeuvres such as lane changing and obstacle avoidance.

Evaluating driver behavior toward innovative warning devices at railway level crossings using a driving simulator

Control at railway level crossings, using either road rumble strips or in-vehicle auditory warning devices, has the potential to improve safety. This article evaluates driver behavior of these two devices and two conventional crossing devices (flashing lights and a stop sign) using a driving simulator. Rumble strips have been seen to encourage drivers to reduce speed earlier on approach to a level crossing but did not affect stopping compliance. In-vehicle auditory warnings have produced high compliance and, overall, have produced behavior comparable to that seen for conventional flashing lights. However, the detailed design features of such devices require further development before more concrete conclusions can be drawn. Contributing factors of age, gender, speed, and types of warning devices were all found to significantly affect driver behavior at crossings. Overall, the results indicate that drivers behave differently and demonstrate higher signal compliance at actively protected crossings than at passively protected crossings for alternative and conventional warning devices.

Modelling driver behaviour towards innovative warning devices at railway level crossings

Improving safety at railway level crossings is costly and as funds are often limited, it is important to search for cost-effective, evidence-based solutions. The effect that the many existing alternative systems have on driver behaviour is not always known. This paper compares driver behaviour towards two novel warning devices (rumble strips and in-vehicle audio warning) at railway level crossings with two conventional warning devices (flashing light and stop sign). Regression models were developed to reflect drivers responses towards the four different types of devices based on data collected from a driving simulation experiment. The regression models include a binary choice model for predicting the probability of a driver stopping or driving through a railway crossing, as well as mixed regression models for predicting the moment at which a driver will produce specific behavioural responses before stopping at a crossing (e.g. initiation of accelerator release and application of foot-pedal brake). Violation results indicated the active systems produced much higher levels of driver compliance than passive devices. Contributing factors, such as age, gender, speed and types of warning devices were found significant at different approach stages to the level crossings. With the application of such behavioural models and traffic conflict techniques in microscopic simulation tools, traffic safety indicators, such as collision likelihood and time-to-collision can be estimated. From these, relative safety comparisons for the different traffic devices are derived.

Control Order and Visuomotor Strategy Development for Joystick-Steered Underground Shuttle Cars

Objective: In this simulator-based study, we aimed to quantify performance differences between joystick steering systems using first-order and second-order control, which are used in underground coal mining shuttle cars. In addition, we conducted an exploratory analysis of how users of the more difficult, second-order system changed their behavior over time. Background: Evidence from the visuomotor control literature suggests that higher-order control devices are not intuitive, which could pose a significant risk to underground mine personnel, equipment, and infrastructure. Method: Thirty-six naive participants were randomly assigned to first- and second-order conditions and completed three experimental trials comprising sequences of 90° turns in a virtual underground mine environment, with velocity held constant at 9 km/h−1. Performance measures were lateral deviation, steering angle variability, high-frequency steering content, joystick activity, and cumulative time in collision with the virtual mine wall. Results: The second-order control group exhibited significantly poorer performance for all outcome measures. In addition, a series of correlation analyses revealed that changes in strategy were evident in the second-order group but not the first-order group. Conclusion: Results were consistent with previous literature indicating poorer performance with higher-order control devices and caution against the adoption of the second-order joystick system for underground shuttle cars. Application: Low-cost, portable simulation platforms may provide an effective basis for operator training and recruitment.

Steering Performance and Dynamic Complexity in a Simulated Underground Mining Vehicle

Research concerning the visuomotor control of steering suggests that some steering systems used in underground shuttle cars are not optimal. This research compared the performance of two groups of participants steering with a joystick interface through a simulated underground mine environment. The joystick employed either first-order or second-order control of heading. Results indicated poorer performance with second-order steering dynamics in the early stages of the experiment, which generally did not improve to levels observed in the first-order group. Poorer overall performance suggests that equipment manufacturers should reconsider the use of second-order steering dynamics in their vehicle designs. Alternately, simulation-based training technologies may have the potential to safely accelerate individual attainment of competence in the use of second-order steering systems.

Highway traffic incident management: an operator-centred investigation

Effective traffic incident management is a fundamental factor in road safety and congestion control, decreasing the occurrence of secondary incidents at scenes and minimising the impact of resultant traffic congestion and emissions. Emergency and traffic officers working within traffic incident inner and outer cordons are highly trained; however, it is still a dangerous work environment and fatalities and injuries regularly occur. In 2007, the Australian association of road transport and traffic authorities (Austroads) adapted the US Federal Highways Association traffic incident management self-assessment tool and tested it in five Australian capital cities. Results from the Austroads study indicated that the city of Brisbane had the lowest ranking for perceived safety of responders and motorists at traffic incidents. As such, the present study investigated issues with the physical environment of the outer cordon at traffic incidents in Brisbane and surrounding areas. Interviews with the operators involved in incident management highlighted issues regarding the safety of responders at traffic incidents, lighting and other warning devices at traffic incidents, and driver perceptions and behaviours. These findings were supported and extended by a survey of traffic response officers. As part of an ongoing programme of research, the benefits of taking an operator-centred approach and the subsequent research to be undertaken are discussed.

Searching for Faces is Easiest when they are Cross(es)

It has been suggested that certain facial expressions are subject to enhanced processing to maximize the speed and accuracy with which humans locate individuals posing an imminant threat. Evidence supporting this proposal comes largely from visual search tasks which have demonstrated that threatening expressions are more rapidly detected than nonthreatening ones. An open criticism of this effect is that it may be due to low-level visual artifacts, rather than biological preparedness. One successful approach for controlling low-level, image-based differences has been to use schematic faces (simplified line drawings). We report experiments aimed at discovering whether the enhanced processing of threatening schematic faces, might also be due to low-level features. The first study replicated the standard threat search advantage, but also measured an effect using similar stimuli comprised of obliquely oriented lines. The effect was also present with these stimuli rotated, a manipulation which served to remove any residual resemblance the abstract images had to a face. The results suggest that low-level features underlie the search advantage for angry, schematic faces, thereby undermining a key source of evidence of a search advantage for specific facial expressions.