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Table 1 Summary of observed vehicle behaviours, possible reasons, applied solutions and occurrences
From: Digibus©: results from the first self-driving shuttle trial on a public road in Austria
Observed behaviour | Possible reason | Applied solution | Occurrence |
|---|---|---|---|
Shuttle stopped for obstacle | • Parking vehicles on the roadside or at bus stops | • Bypassing the obstacle manually • Setting the shuttle to automatic mode after the obstacle | • Frequent |
Shuttle stopped for no apparent reason | • Branches of trees or shrubs on the roadside • Wrongly detected obstacle • Unreliable positioning • Sensor reflections due to water lacquers, heavy rain or snowfall | • Setting the shuttle to automatic mode again for continuing the test drive • If this was not successful, driving back manually to a safe parking position (e.g. bus stop) | • Frequent |
Detection of other road users failed | • Velocities > 30 km/h of approaching or passing vehicles at left turns or exits from bus stops or side roads • Dead angles of 360° LIDAR sensors due to vehicle’s own shading • Low spatial resolution of the Velodyne VLP-16 LIDAR sensors | • Stopping the shuttle and taking over manual control | • Frequent |
Unclear interaction with other road users | • Planned safety stops • Stopping without any reason • Is overtaking safe? • Abandoned priority • Missing trust by other road users | • Variable messages on the back screen of the vehicle • Using hand signs if possible | • Frequent |
Shuttle could not be set to automatic mode after a stop | • Vehicle being out of driving path • Software problem | • Driving manually to the next safe parking position (e.g. bus stop) • Applying one or several restarts • Contacting the Navya supervision team for solving the problem via remote control | • Several test drives |