The main scope of the project was to initiate a technical framework for studying manual and automated high-speed driving of long vehicle combinations (LVCs) in a driving simulator environment.
The included parts are:
- Implementation and validation of a rigid truck solo 6x2 (reference vehicle) and an A-double LVC model, which together with the motion queuing system emulates the vehicle dynamics to the driver. This in order to accomplish satisfactory realism in regards to truck vehicle dynamics.
- Evaluation of the road environment developed in the ViP project Known Roads (Nåbo, Andhill et al., 2015). The road description includes profiles of the road curvature, elevation, lateral inclination, and the surface roughness. Detailed vertical road input per wheel was accounted for as input to the vehicle dynamic models. This in order to accomplish satisfactory realism in regards to road environment.
- Evaluation and comparison of manual and automated driving of an LVC using a driving simulator study including professional truck drivers.
The project included implementation and evaluation of vehicle models representing a rigid truck solo (reference vehicle) and an A-double LVC in VTI driving simulator IV.
The A-double combination consisted of a 6x4 tractor unit followed by a three-axle semi-trailer, two-axle converter dolly and a second three-axle semi-trailer unit. The total vehicle length of the A-double was 32 metres and the total weight was set to 80 tonnes.
The implementation of the vehicle models was evaluated by drivers from Volvo product development. The evaluation was carried out during normal driving conditions, with speeds ranging from 0 to 90 km/h. Besides the implementation and evaluation of vehicle models, the project also included a driving simulator study in which manual and automated driving of the A-double have been studied.
The participants in the study were 12 professional truck drivers from a haulage contractor and 8 drivers from Volvo product development. The driving scenario consisted of a relatively curvy and hilly single-lane Swedish county road (Road 180), without additional road users and safety critical events. Two automated driving strategies for steering, propulsion and braking were formulated, whereof one of the steering strategies included results from an optimal control based receding horizon approach. The drivers’ manual lane keeping and speed profiles were recorded for post-analysis. In addition, the drivers’ subjective acceptance of automated driving trajectories was also collected.
The main conclusion from the assessment questionnaires was that the realism of the road environment, vehicle suspension, steering wheel feeling and the manoeuvrability/drivability during steering was adequate but would benefit from more tuning. More urgent are adjustments of braking, acceleration, level of engine sound and improved view in the right-hand side mirror.