Phileas project - driving simulator investigation

The Phileas is a new public road transport system which can be operated in the traditional mode of steering by hand but is also fully automatic. In a driving simulator study at the Centre for High Performance Computing and Visualisation, the ergonomic and safety aspects of this vehicle were investigated. A group of experienced bus drivers drove a number of simulated regular route trips to investigate the control concept with respect to ergonomic and safety aspects, especially in critical situations such as unexpected cross traffic while driving in automatic mode.

Phileas

Phileas is the name of a new public transport system which was developed and built in the Netherlands by APTS: Advanced Public Transport Systems. It is an electrically driven road vehicle with the properties of a bus, tram or metro system. It allows several driving modes:

• Manual control with the use of accelerator, brake and steering wheel as in a normal bus.
• Semi-automatic control with computer-controlled lateral tracking as in a tram or metro. The Phileas’s electronic navigation system is guided here by a chain of magnetic bars hidden in the road surface.
• Fully automatic control which additionally controls speed and smooth parking and departure at bus stops. In this mode the driver's main task is the supervision of the system and to take over control when necessary.

A fuel-burning engine loads energy into batteries which power the electric motors driving the wheels. In crowded areas the Phileas can switch off the fuel engine and drive electrically for a while, thus minimizing noise and pollution. Braking energy is stored back in the batteries. Each wheel is driven separately and can also be steered individually, which allows accurate tracking in narrow winding lanes and the spectacular lateral crabbing for parallel parking at bus stops.

The scientific investigation concerning the ergonomic and safety aspects of driving this vehicle is summarized below.

Research questions

The Phileas will operate automatically or semi-automatically in specially prepared lanes and controlled by hand at other locations. This triple modality is new in the area of public transport. APTS consulted specialists about aspects of human ergonomic design, particularly in safety issues related to the behavioural reactions of drivers in critical situations when the automatic driving mode must be switched to hand-controlled mode for emergency handling. The main research topics of this study therefore were:

- Investigation of the ergonomic aspects of driving this vehicle, especially the alternation between automatic and controlled driving.

- Investigation of safety aspects related to this system, i.e. the question whether the driver is able to take over control and act appropriately in critical situations.

Experimental study

The project was carried out by the Department of Experimental and Work Psychology (E&A) at the University of Groningen (project leader Dr K.A. Brookhuis). The driving simulator experiment was performed at the VR laboratory of the Centre for High Performance Computing at this university.

The driver's cabin consisted of a wooden mockup (see photo) equipped with a real production-type dashboard and all relevant controls such as accelerator and brake pedals. The steering wheel axis was extended by the E&A technical staff with a force feedback servo system for a realistic feel. The dynamic road behaviour of the cabin was simulated by a computational model running on a PC. The model enabled all three driving modes, while acceleration and braking parameters were derived from data tables provided by APTS.

Simulation software was provided and configured by ST-Software, a company specialized in software for driving simulators for research and training.

The experimental bus route in the simulation was designed from schematic track plans provided by APTS. The route included all intersections and bus stops at realistic locations in the route (see figure). Simulated environmental traffic (cars and bicyclists) was controlled by scenario scripts which contained, in addition to normal traffic, some critical situations which precipitated specific danger. For example, a bicyclist crossing the bus lane unexpectedly while the Phileas is driving in automatic control mode. Then the driver had to take over control quickly to prevent an accident.

Participants in the experiment were all regular bus drivers from public transport bus companies in Groningen (Arriva) and Eindhoven (Hermes). The drivers completed a number of 20-minute rides up and down the simulated route and encountered regular and critical situations.

The behaviour and reactions of the drivers were analyzed in terms of response time, critical distance to other traffic participants and driving velocity control. Additional questionnaires provided insight into the subjective experiences of the drivers.

Outcomes

Generally, drivers responded positively to the new automatic system of driving. Drivers who were reluctant initially were more positive after participating in the experiment. They liked the automatic guidance and looked forward to the chance to drive these vehicles in reality.