Back
Back

How the city bus will become autonomous.

  • 22. September 2016
  • Autonomous Driving
  • Illustration: Coen Pohl
  • Text: Ernesto Singer

Safely and autonomously through city traffic: The Mercedes-Benz Future Bus recognises pedestrians and traffic-lights. This is made possible by highly precise technology.

At first sight, people who sit behind the steering wheel of a moving vehicle without their hands on the wheel give rise to distrust or amazed looks on the part of others. The same applied to the bus driver who took his seat in the Future Bus for its debut journey: he did not need to intervene even once on the approx. 20-kilometre long route from Schalkwijk Centrum to Schiphol Handelskade. Everything proceeded fully automatically, with the Future Bus passing through the outskirts of Amsterdam completely autonomously at speeds of up to 70 km/h. The so-called CityPilot took over command on the separate bus lane of the regular 300 line.

The bus recognises traffic lights and pedestrians

The Future Bus operates at semi-automated level two of the five levels on the way to autonomous driving: it stays on course and is capable of linear guidance as well as acceleration and braking manoeuvres on the basis of networked assistance systems.

In technical terms, the CityPilot is closely related to the Highway Pilot of the Mercedes-Benz Actros. However, the city bus has greater capabilities than the truck. New onboard features include immensely important functions for city traffic, such as traffic-light recognition, pedestrian recognition, centimetric precision when approaching bus stops and semi-automated driving through tunnels.

10 cameras monitor the traffic

All this is made possible by a sheer wealth of precise high-tech sensors. No less than ten high-resolution cameras in different systems share the task of comprehensively monitoring the area ahead of the city bus. The signals of the short and long-range radar systems are fused to provide precise data which are in turn constantly compared with the stored values.

There is also Vehicle2Infrastructure communication by WLAN: the Mercedes-Benz Future Bus is networked with the ultra-modern traffic-light system on Amsterdam’s BRT system (BRT = Bus Rapid Transit). In this way the city bus of the future becomes at one with its environment, not only because of its future-oriented interior and exterior design, but also thanks to the technology it uses to travel in its lane and communicate with its surroundings in real time.

The Future Bus drives completely autonomously at speeds of up to 70 km/h.

10 cameras monitor the traffic

All this is made possible by a sheer wealth of precise high-tech sensors. No less than ten high-resolution cameras in different systems share the task of comprehensively monitoring the area ahead of the city bus. The signals of the short and long-range radar systems are fused to provide precise data which are in turn constantly compared with the stored values.

There is also Vehicle2Infrastructure communication by WLAN: the Mercedes-Benz Future Bus is networked with the ultra-modern traffic-light system on Amsterdam’s BRT system (BRT = Bus Rapid Transit). In this way the city bus of the future becomes at one with its environment, not only because of its future-oriented interior and exterior design, but also thanks to the technology it uses to travel in its lane and communicate with its surroundings in real time.

Precise positioning

Thanks to the CityPilot, the Future Bus knows where it is at all times. It determines its position using a GPS location system (GPS = Global Positioning System), a lane camera with a range of 80 metres and side-mounted cameras for global visual location. These four cameras are mounted on the flanks above the front axle, and monitor the surroundings in a range of between eight centimetres and 200 metres.

They compare the live image with previously stored graphic material, also in illuminated tunnels. Thanks to recognition of so-called waypoints on the route, the bus can determine its position even more precisely. Two further short-range cameras arranged vertically downwards at the front sides recognise the pattern of the road surface like a fingerprint.

The interaction between the different optical sensors produces a highly precise picture of the surroundings – and the exact position of the city bus. No human driver could match the centimetric accuracy with which the CityPilot keeps the Future Bus on track.

Cameras recognise the pattern of the road surface - like a fingerprint.

Networked and efficient

Gentle acceleration and braking manoeuvres are among the key skills of any bus driver. The CityPilot not only uses its extensive camera systems, but also WLAN to communicate with the surrounding traffic infrastructure. As a result it obtains information about the status of traffic lights and the duration of their phases far sooner than a human bus driver could.

The adaptations in speed resulting from the Vehicle2Infrastructure data mean an even more flowing driving style for the passengers, at the same time lowering fuel consumption and wear-and-tear. To provide additional safety, a stereo camera with a range of approx. 30 metres monitors the status of traffic lights.

Precise approach to bus stops

Thanks to the highly precise CityPilot systems, the city bus of the future follows an imaginary line to an accuracy of two centimetres at slower speed. To ensure that passengers are able to enter and exit conveniently, the Mercedes-Benz Future Bus fully automatically stops very close to the kerbside at bus stops. This makes bus travel much simpler for passengers with restricted mobility or parents with pushchairs. The doors open and close automatically, and above them a green or red LED light band marks them as entry or exit doors.

In unclear traffic situations, e.g. directly near a busy bus stop, four short-range sensors with a range of 10 metres enhance the safety of all road users – including pedestrians with their not always predictable walking directions. Should the road ahead not be completely free when a stop has been completed – or if a pedestrian suddenly steps out onto the road – the Future Bus patiently waits.

The driver is always able to intervene

The long-range radar keeps an eye on vehicles travelling ahead. It is located just below the Mercedes star on the front of the vehicle, and covers a range of up to 200 metres. A stereo camera monitors the area up to 60 metres in front of the Future Bus, and reliably recognises crossing pedestrians. In such cases the city bus of the future automatically initiates gentle braking with a maximum deceleration of 2 m/sec2. Out of consideration for standing passengers and those not wearing seat belts, only the driver is able to initiate emergency braking. The driver at the wheel is able to take control of the bus at any time.

The Future Bus reliably recognises crossing pedestrians.

Related topics.

Popular
Recommended