Ergonomics of intelligent vehicle braking systems

The present thesis examines the quantitative characteristics of driver braking and pedal operation and discusses the implications for the design of braking support systems for vehicles. After the current status of the relevant research is presented through a literature review, three different methods are employed to examine driver braking microscopically, supplemented by a fourth method challenging the potential to apply the results in an adaptive brake assist system. First, thirty drivers drove an instrumented vehicle for a day each. Pedal inputs were constantly monitored through force, position sensors and a video camera. Results suggested a range of normal braking inputs in terms of brake-pedal force, initial brake-pedal displacement and throttle-release (throttle-off) rate. The inter-personal and intra-personal variability on the main variables was also prominent. [Continues.

Impact of conversational demand on driver distraction

This article concisely describes three experiments testing the effects of auditory/cognitive distraction deriving from levels of conversational demand. In the pilot study, 8 participants drove three simulated routes with and without the task of holding a conversation with the experimenter. In the pilot experiment, 8 participants drove three different virtual routes with and without conversing with the experimenter. In experiment 1, 24 participants drove one virtual route under three conditions: no interaction with the experimenter, holding an informal conversation and holding a conversation concerning issues at work. The same design was repeated in the second experiment, with the difference that the 12 participants were tested on the Lane Change Task (Mattes, 2003). The results suggest a significant effect for conversation on driver ability to control the vehicle laterally, as well as a differentiation between conversation topics

Reset to zero and specify active safety systems according to real world needs

Emergency Brake Assist (EBA), Adaptive Cruise Control (ACC) and alternative instantiations of intelligent vehicle control systems aspire to support the driver in controlling the vehicle and alleviate the incidents that would lead to collisions and injury. This paper resets to zero and based on data from the On-The-Spot (OTS) accident study challenges the capability of active safety systems to aim at the sources of longitudinal control failures. The road user interactions file from 3024 road accidents in Thames Valley and Nottinghamshire in UK was analysed. Interactions where “failure to stop” or “sudden braking” is the precipitating factor are analysed and the main contributory factors are identified. Some of those factors are addressed by current and coming technologies – like low road friction, excessive speed and close following, but other common ones are significantly neglected – like distraction, failure to judge other person’s path, failure to look, and “look but did not see” instances

Getting back to basics: using road accident investigation to identify the desirable functionality of longitudinal control systems

ABS (antilock brake system), EBA (emergency brake assist), ACC (adaptive cruise control) and alternative examples of intelligent vehicle control systems aspire to support the driver in controlling the vehicle and alleviate the incidents that would lead to collisions and injuries. This paper considers some requirements for such systems based on a study of accidents occurring in the real-world. While systems are rationally developed in the engineering laboratory, on the test track and through use of simulations, the need for a through understanding of the design needs as observed in the real-world of current day accidents is increasingly recognized. This paper overviews the range of data available on the causes of accidents in the UK. A fresh look is taken at some issues relating to braking by specific reference to data from the On-The-Spot (OTS) accident research study in an attempt to consider the necessary functionality of active safety systems pertinent to longitudinal control failures. The road user interactions file from 3024 road accidents in Thames Valley and South Nottinghamshire regions of the UK, as covered by OTS study, were analysed. Significant contributory factors where “failure to stop the vehicle” was identified as the accident precipitating factor were seen to be “following too close”, “disobeyed automatic traffic signal”, “careless/reckless/in a hurry”, “failure to look” and “failure to judge other person’s path or speed”. On the other hand, where “sudden braking” is identified as the accident precipitating factor, contributory factors included “sudden braking” (as a contributor), distraction, aggressive driving, failure to judge other person’s path, “masked road markings”, “excessive speed”, “following too close”, and “road layout”. Current systems address some of these issues, while possibly overlooking others; recommendations for future safety engineering designs are made accordingly

Towards a driver-centred brake assist system

Active safety systems relevant to longitudinal control like Emergency Brake Assist (EBA) have been developed and specified based on assumptions about the differentiation of driver’s input between “normal” and emergency events. The consequence of these assumptions is a system that does not accommodate for driver variability and can be engaged when it is not intended to and not engaged when it is necessary. The present paper presents data from an empirical study that examined differences in driver braking response in normal and “emergency” situations. 24 participants drove an instrumented vehicle on open roads and on a closed track. Participants were first asked to drive 10km on public roads as an indication of their “normal” braking responses. When they arrived at the closed track they were instructed to follow “at their preferred distance” another car towing a trailer at 48kmph/30mph. After 322m (0.2 mile) the trailer was released and automatically braked. Throttle pedal angle and brake pedal pressure were measured and foot/pedal movements were videorecorded. Results indicate patterns in driver responses that an intelligent brake system could “learn” from, in order to accommodate driver variability and achieve effective augmented braking

Reset to zero and specify safety systems according to real world needs

Emergency Brake Assist (EBA), Adaptive Cruise Control (ACC) and alternative instantiations of intelligent vehicle control systems aspire to support the driver in controlling the vehicle and alleviate the incidents that would lead to collisions and injury. This paper resets to zero and based on data from the On-The-Spot (OTS) accident study challenges the capability of active safety systems to aim at the sources of longitudinal control failures. The road user interactions file from 3024 road accidents in Thames Valley and Nottinghamshire in UK was analysed. Interactions where “failure to stop” or “sudden braking” is the precipitating factor are analysed and the main contributory factors are identified. Some of those factors are addressed by current and coming technologies – like low road friction, excessive speed and close following, but significantly neglect to address other common ones – like distraction, failure to judge other person’s path, failure to look, and “look but did not see” instances

Exploitable characteristics of driver braking

Previous work (Perron et al., 2001) on emergency brake application concluded that driver population diversity and “the overlap of braking parameter distributions between normal conditions and emergency situations” is such, that triggering criteria cannot both detect all emergency braking actions and never activate the assistance in situations where it is not necessary. The objective of this study was to investigate driver-braking characteristics, in order that future systems might achieve greater effectiveness. 48 drivers drove an instrumented vehicle on a public road section before arriving at a test track, where they were instructed to follow at their preferred distance another vehicle towing a trailer. They were told the aim was to measure their preferred car-following distance. They were naïve to the fact that 0.2 miles down the track the trailer would be released and rapidly decelerate to a stop. The main variables analysed included “throttle-off” rate, brake pedal pressure/force, and clutch pedal pressure/operation. The results indicate a series of relationships exploitable by an intelligent brake assist system. An intelligent brake assist system could take advantage of those characteristics and adapt its performance to individuals’ braking style. Limitations of the study include resource constraints (use of a single instrumented vehicle, time-limited access to the test track)and the contrived nature of the emergency braking scenario (need for surprise element, practically a one-off study, limitation of speed to 30mph/48kmph). The study provides evidence of a background for a customisable brake assist system that learns from the driver and adjusts its full-brake trigger accordingly

The impact of verbal interaction on driver lateral control: an experimental assessment

Driver distraction is acknowledged as one of the key contributors to driver accidents (Treat, J.R., et al., 197747. Treat, J. R. 1977. Tri-level study of the causes of traffic accidents (No. DOT-HS-034-535-77-TAC(1)), Bloomington, IN: Institute for Research in Public Safety – Indiana University. View all references. Tri-level study of the causes of traffic accidents (No. DOT-HS-034‐535‐77-TAC(1)). Bloomington, IN: Institute for Research in Public Safety – Indiana University; Knipling, R.R., et al., 199328. Knipling, R. R. 1993. Assessment of IVHS countermeasures for collision avoidance: Rear-end crashes (No. DOT HS 807 995), Washington, DC: National Highway Traffic Safety Administration. View all references. Assessment of IVHS countermeasures for collision avoidance: Rear-end crashes (No. DOT HS 807 995). Washington, DC: National Highway Traffic Safety Administration). As driving is mainly considered a visual task (Wierwille, W.W., 199353. Wierwille, W. W. 1993. “Visual and manual demands of in-car controls and displays”. In Automotive ergonomics, Edited by: Peakock, B. and Karwowski, W. 229–320. London: Taylor and Francis. View all references. Visual and manual demands of in-car controls and displays. In: B. Peakock and W. Karwowski, eds. Automotive ergonomics. London: Taylor and Francis, 229–320) the use of auditory channels for interacting with intelligent vehicle systems has been suggested as a solution to possible visual overload. This article presents two studies which assess the potential impact of distraction caused by verbal interaction on the driving task. The first study used a low-cost, game-based, simulation and the second study used the same experimental design with a generic driving simulation, the Lane Change Task (Mattes, S., 2003. The lane change task as a tool for driver distraction evaluation. In: H. Strasser, H. Rascher, and H. Bubb, eds. Quality of work and products in enterprises of the future. Stuttgart: Ergonomia Verlag, 57–60). Twenty-four young adults, 12 males and 12 females, participated in the first study and 12 young adults, 6 males and 6 females, in the second study. Road departures, time/speed and subjective workload were the measures in the first study, while the second study used mean course-departure and subjective workload as dependent variables. The results indicated that game-based simulation can be a solution when realism is needed but resources are limited, and suggested that concurrent verbal interaction may impair lateral vehicle control

The 50-driver naturalistic braking study: overview and first results

Considering the importance of vehicle brake systems, it is surprising how little is known about the way that people operate them. Previous ergonomic studies have attempted to define the maximum acceptable resistance to depression in the pedal (Diffrient, Tilley, & Harman, 1993; Eaton & Dittmeier, 1970). Accordingly, they focussed on the responses of weak (5 percentile muscle strength) female drivers and little is known about the full range of braking response. A re-examination of this basic control mechanism is necessitated by the evolution of vehicle systems. The present paper offers an overview of a study measuring driver “pedipulation” in a naturalistic environment. Fifty-eight fully-licensed drivers drove a car for a day. The types of trip analysed included commuting to work, shopping, and picking up children from school. Measures taken included throttle pedal angle, brake pedal pressure, and clutch pedal pressure. The foot well was constantly video recorded during each trip. Main results are presented and comparisons with earlier studies are discussed