Bosch driverless e-Shuttle is fault tolerant

April 20, 2020 //By Murray Slovick, Electronic Design
Bosch driverless e-Shuttle is fault tolerant
Thanks to redundant systems and fault tolerance to boost safety, the continued operation of shuttle buses is possible. Driverless shuttle buses have to meet different requirements than ADAS vehicle systems, in which ultimately a driver can still intervene. By using it on "familiar" terrain, which is on pre-programmed routes, safety and performance requirements can be reduced to a certain degree. But what if the power supply for steering the vehicle or a camera fails during passenger transport at 20 or 30 km/h ?

In such a situation, the systems used must be fault-tolerant and robust, so that the safety of passengers and other road users is guaranteed in all cases. How the corresponding vehicle components have to be designed in the face of such challenges is the question being addressed by Bosch with its 3F project that focuses on fail-safe operation.

“The aim was to develop solutions to ensure that automated shuttles can move around safely, even if a technical malfunction occurs or obstacles suddenly appear,” says Steffen Knoop, project leader in research and advance engineering at Robert Bosch GmbH.

To operate without drivers, shuttles must be able to monitor their system autonomously—i.e., perform diagnostic tasks—and cope with any technical faults detected so that they can continue driving. At the same time, they must be able to secure the system in the event of critical faults, for example by bringing the shuttle to a stop.

One approach is to build in redundancy; in other words, to duplicate safety-relevant functions. For example, Bosch researchers developed redundant systems for the power supply so that the electrical powertrain and vehicle electrical system are reliably protected. They also adapted and improved sensor technology to suit the vehicle design.

To reliably detect obstacles, they installed several LiDAR and radar sensors at various points around the vehicle, giving it the ability to observe its surroundings from different positions. By delivering a 360-degree birds-eye view and avoiding blind spots, this created a kind of 3D protection zone. The setup not only detects obstacles on the road, such as barriers, it also spots things like hanging branches.

Fault Tolerance

Another solution employed by Bosch is to build in fault tolerance, whereby the failure of a subsystem is at least partly compensated for by other functions. This isn’t unlike how people behave—if the lights suddenly go out in a room, we use our other senses and feel our way around instead of becoming paralyzed. The shuttle behaves similarly: If it’s blind in a certain area, say because leaves are stuck to the sensor or a large object such as a dumpster is completely blocking the view in one direction, it slows down or omits the parts of the route that can no longer be detected.

next: it is all down to sensors


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