When developing new active safety systems or improving existing systems, conducting performance evaluations is necessary. By performing these evaluations during early development stages, potential problems can be identified and mitigated before the system moves into the production phase.

Testing active safety systems can be difficult since the characteristic scenarios may have complex interactions. Using real vehicles for performing these types of scenarios is difficult, expensive, and potentially dangerous. Alternative methods, such as using inflatable targets, scale models, computer simulations or driving simulators, also suffer from drawbacks. Consequently, using virtual reality as an alternative to the traditional methods has been proposed. In this case, a real vehicle is driven while wearing a head-mounted display that presents the scenario to the driver.

This research aims to investigate the potential of such technology. Specifically, this work investigates how the chosen technology affects the driver. This investigation has been conducted through a literature review. A test platform was constructed, and two user studies using normal drivers were performed. The first study focused on the effects of visual time delays on driver behavior. This study revealed that lateral behavior changes with added time delays, whereas longitudinal behavior appears unaffected. The second study investigated how driver behavior is affected by different modes of virtuality. This study demonstrated that drivers perceived mixed reality as more difficult than virtual reality.

The main contribution of this work is the detailed understanding of how time delays and different modes of virtuality affect drivers. This is important knowledge for selecting which scenarios are suitable for evaluation using virtual reality.

In the last decades, there has been a substantial increase in the development of complex active safety systems for automotive vehicles. These systems need to be tested for verification and validation to ensure that the system intervenes in the correct situations using the correct measures. There are multiple methods available to perform such testing. Software-in-the-loop and hardware-in-the-loop testing offer effective driverless testing. Other methods increase the fidelity by including human drivers, such as driving simulators and experiments performed at test tracks.

This thesis examines vehicle-in-the-loop testing, an innovative method where the driver of a real vehicle wears a head-mounted display that displays virtual targets. This method combines the benefits of driving simulators with the benefits of using a real vehicle on a test track. Driving simulators offer repeatability, safety, and the possibility of complex interactions between actors. In contrast, the real vehicle provides the correct vehicle dynamics and motion feedback.

There is a need to know how the technology behind the method might influence the results from vehicle-in-the-loop testing. Two techniques for vehicle-in-the-loop systems are studied. The first involves video-see through head-mounted displays, where the focus of the research is on the effects of visual latency on driving behavior. The results show that lateral driving behavior changes with added latency, but longitudinal behavior appears unaffected. The second system uses an opaque head-mounted display in an entirely virtual world. The research shows that this solution changes speed perception and results in a significant degradation in performance of tasks dependent on visual acuity.

This research presents results that are relevant to consider when developing vehicle-in-the-loop platforms. The results are also applicable when choosing scenarios for this test method.

Dagens fordon innehåller fler och fler säkerhetssystem. Vissa av dessa system ger varningar i potentiellt kritiska trafiksituationer. Det finns också mer komplexa system som tillfälligt kan ta kontroll över fordonet för att förhindra en olycka eller åtminstone mildra effekterna. Komplexiteten hos dessa system innebär att man måste genomföra omfattande tester. Både för att se att systemen reagerar vid rätt tidpunkt, men också för att se att valet av åtgärd är korrekt.

Det finns många olika sätt att testa dessa system. Man börjar vanligtvis med simuleringar av programvara och hårdvara. Därefter kan systemet introduceras i ett fordon för att se vilka effekter systemet har när det interagerar med en riktig förare. Att utföra tester med förare ställer dock höga säkerhetskrav, och det är ofta svårt att samordna komplexa trafiksituationer på en testbana. Traditionellt har körsimulatorer varit ett naturligt alternativ eftersom de kan utföra komplexa scenarier i en säker miljö.

Denna avhandling undersöker en testmetod där man utrustar föraren med en virtual reality-display. Genom att presentera omvärlden med hjälp av virtual reality, så kan man genomföra scenarion som tidigare varit omöjliga på en testbana. Det kan dock finnas inbyggda begränsningar i virtual reality tekniken som kan påverka körbeteendet. Det är därför viktigt att hitta och kvantifiera dessa effekter för att kunna lita på resultaten från testmetoden. Att känna till dessa effekter på körbeteendet dessutom kan hjälpa till att avgöra vilka typer av scenarier som är lämpade för denna testmetod. Det är också viktig information för att avgöra var man bör fokusera den tekniska utvecklingen av testutrustningen.