Head mounted displays (HMDs) is an emerging technology and the availability of affordable systems is growing fast. Replacing projector and large screen solutions with head mounted displays may appear as an appealing solution. However, inherent properties and technical limitations of these systems need to be understood and considered before making the leap to virtual reality.

This paper outlines some of the most fundamental limitations of head mounted displays relevant to this context, both from a technical and human factors perspective. Desirable properties of scenarios and types of studies are deduced, based on these limitations. Finally, a meta analysis is performed on the feasibility of transferring simulator studies found in the literature to platforms with head mounted displays. The results suggest that a noticeable amount (40%) of the investigated simulator studies could likely have been performed with head mounted displays. This number could be increased further with technical advances in display resolution, display technology, reduction in latency, etc.

Real-time information about the friction coefficient between the tyre and the road can be used to improve active safety systems and is an enabler for autonomous vehicles. Large tyre force excitation is normally required to obtain an accurate friction estimate. This paper quantifies this requirement for four different tyre models on wet salted asphalt at water freezing temperatures. Cost functions and different tyre models are evaluated and the results are compared to a previous study performed for snow conditions. The suitability of commonly used tyre models for friction estimation on snow and wet asphalt has thus been investigated.

Many traffic accidents are due to winter conditions like slippery roads and limited visibility. The road administrators put a lot of effort into snow removal and de-icing the roads, and the vehicle manufacturers have been working with functionality to support drivers in winter conditions for decades.

Many issues of driving in winter conditions originate in drivers’ behaviours such as risk taking and lack of awareness. Studying drivers’ behaviour in winter conditions in general, and the effect of various countermeasures of the vehicle, would increase the understanding of the underlying mechanisms and could possibly be used to reduce the accident risks. Motion-base driving simulators are tools frequently used for driving behaviour research. However, the validity of the results of such studies depends to a large extent on the realism of the simulation. The purpose of this project was to study winter simulation with the aim to improve the realism of simulator driving in winter conditions.

Driving in winter is in many ways different from driving in summer. The difference can to a considerable extent be explained by the tire-to-road interaction. Winter driving is typically characterized by softer motion and slower development of tire forces. In the present project two aspects of the motion have been studied, the motion feedback in the simulator and models for tire-to-snow behaviour.

Vehicle motion during winter driving is characterized by large vehicle body slip angles and the associated yaw motions. Thus, understanding the importance of yaw motion feedback is essential to simulate winter conditions. A study was designed to investigate the impact that lack of yaw motion will have on the driver, and if it alters his driving behaviour. It was found that the yaw motion alters the driving behaviour, implying that it contains vital information for a wide range of driving situations. A second study was carried out to investigate if the rotation centre, which is a consequence of the yaw and lateral motions, can be used to present valuable information about the vehicle state to the driver. Indicative results suggest that the rotation centre of the motion is valuable to the driver, but further studies are needed. The softer and slower motions of winter driving suggest that pre-positioning of the simulator’s motion platform could be performed to improve the motion envelope. A third implementation study performed in the project suggests this.  

This work presents a comprehensive study of the performance of winter tires on snow, ice, and asphalt. A set of 77 different winter tires were carefully selected for the study. Of these, 27 were new and 50 were worn from real traffic use. All three tire types for winter conditions (Nordic, European, and studded) were represented. All tires have been tested using a mobile tire-testing device for snow and asphalt and using a stationary tire-testing facility for ice. Both devices recorded the tire forces and motions, enabling a close to complete stationary characterization of the tires. In addition, 42 of the tires were tested on a passenger car, where brake performance was evaluated for the three different road conditions. This enables a comparative study of performance between tire types and wear for various winter road conditions. The results suggest that the recorded data represent real vehicle performance. Some conclusions from the measurements are that the effect of wear is consistent between the tire groups and that the performance degradation is most noticeable on studded tires on ice and on European tires on snow.

This paper presents a comparative study of driving behavior when using different virtual reality modes. Test subjects were exposed to mixed, virtual, and real reality using a head mounted display capable of video see-through, while performing a simple driving task. The driving behavior was quantified in steering and acceleration/deceleration activities, divided into local and global components. There was a distinct effect of wearing a head mounted display, which affected all measured variables. Results show that average speed was the most significant difference between mixed and virtual reality, while the steering behavior was consistent between modes. All subjects but one were able to successfully complete the driving task, suggesting that virtual driving could be a potential complement to driving simulators.

Project “Performance Based Standards for High Capacity Transports in Sweden” started at the end of 2013 to investigate applicability of PBS in Sweden, and ended in Autumn 2017. The purpose of the project was to propose a performance based regulation of HCT vehicles and their access to the road network; under a PBS approach to regulation, standards would specify the performance required from the vehicle, rather than mandating prescriptive length and weight limits. In this project, all the three domains of safety, infrastructure and environment were addressed, but the focus has been on safety for which extensive testing, simulations and analysis were performed. This report gathers the outcomes of the project.

Projektet “Performance Based Standards for High Capacity Transports in Sweden” startade i slutet av 2013 för att undersöka möjligheterna att applicera prestandabaserade kriterier, eller Performance Based Standards (PBS), i Sverige. Projektet avslutades hösten 2017. Vid prestandabaserade föreskrifter så specificeras kriterier eller standarder för en prestandanivå som ett fordon måste uppfylla, istället för att bestämma hur samma prestandanivå skulle uppnås genom att sätta gränser för fordonets längd eller vikt. I PBS-projektet har de tre domänerna säkerhet, infrastruktur och miljö beaktas, men fokus var på säkerhet och därför har omfattande testning, simulering och analys genomförts. Denna rapport beskriver resultatet från projektet.

The aim of the present paper was to develop and validate a heavy vehicle dynamics model for driving simulators. The model was thought to be open, with a high level of readability and flexibility for future understanding, modification and use. A stepwise increment of the model complexity was utilized to understand the most contributing factors and to obtain a model capable of running in real-time. The model has been validated objectively using a previously validated model and through subjective evaluation in a driving simulator.

This paper presents a comparative study of driving behavior when using different virtual reality modes. Test subjects were exposed to mixed, virtual, and real reality using a head mounted display capable of video see-through, while performing a simple driving task. The driving behavior was quantified in steering and acceleration/deceleration activities, divided into local and global components. There was a distinct effect of wearing a head mounted display, which affected all measured variables. Results show that average speed was the most significant difference between mixed and virtual reality, while the steering behavior was consistent between modes. All subjects but one were able to successfully complete the driving task, suggesting that virtual driving could be a potential complement to driving simulators.

Using mixed reality in vehicles provides a potential alternative to using driving simulators when studying driver-vehicle inter- action. However, virtual reality systems introduce latency in the visual system that may alter driving behavior, which, in turn, results in questionable validity. Previous studies have mainly focused on visual latency as a separate phenomenon. In this work, latency is studied from a task-dependent viewpoint to investigate how participants’ driving behavior changed with increased latency. In this study, the investigation was performed through experiments in which regular drivers were subjected to different levels of visual latency while performing a simple slalom driving task. The drivers’ performances were recorded and evaluated in both lateral and longitudinal directions along with self-assessment questionnaires regarding task performance and difficulty. All participants managed to complete the driving tasks successfully, even under high latency conditions, but were clearly affected by the increased visual latency. The results suggest that drivers compensate for longer latencies by steering more and increasing the safety margins but without reducing their speed.

Performance-based standards (PBS) is a regulation policy to address the complexity of variations in vehicle combinations. It enables a direct way of addressing certain requirements associated with the safety, environment and road network and their implications to the vehicle specific quantities without stipulating vehicle properties.

Computer-based simulations may be an efficient tool to assess the performance measures. However, using simulations through models in a legislation raise questions of model accuracy and model complexity. What is a required level of modelling details to be used to assess a PBS measure?

We investigate three level of complexity of models and the impact this have on three longitudinal performance measures; Startability, Gradeablity and Acceleration Capability. Simulations for 10 vehicle combinations are compared with two different engine alternatives. For Nordic countries, slippery road conditions are common during winter conditions. Hence, low friction is included in the comparison.

The comparison suggested that the complexity could potentially be kept really low, without major loss of accuracy. However, for slippery conditions, a higher levels of complexity might be required.