Technical Insight
Safety - The Comprehensive View
The influence of vehicle dynamics on the functional safety of ADAS/AD. MICHAEL PEPERHOWE
dSPACE
T
he integration of ADAS/AD functions in vehicles serves one goal: To ensure and, where possible, increase the safety of all road users. But what needs to be considered in the validation of intelligent systems? Is the consideration of regulations, test scenarios, sensors, and functions sufficient, or does the dynamic behavior of
the vehicle also play a decisive role?
Vehicle Dynamics A driving dynamics insight: Physically, vehicles are more than a point mass and their dynamic driving behavior has a particular influence on critical driving situations. A simple example might be braking on surfaces with different friction
coefficients: The vehicle starts skidding as torque is generated around its vertical axis. Even if stability systems intervene to prevent rotation, safety aspects must always be evaluated from a sensor perspective. But what information do these provide when dynamic driving effects influence the imaging sensor technology? And how do functions for ADAS/AD (advanced driver assistance systems/autonomous driving) use this information?
Testing via Simulation Fortunately, we do not have to perform any elaborate and dangerous maneuvers on the proving grounds to investigate the vehicle’s dynamic behavior. With just a few clicks, simulations deliver revealing insights. We want to look at selected relevant situations using the dSPACE tool suite Automotive Simulation Models (ASM) in combination with the sensor-realistic simulation software AURELION. Figure 1 Full braking at ideal friction value: The truck comes to a stop well before the stationary obstacle (bus). The truck and trailer remain in their own lane.
Figure 2 Full braking with a lower coefficient of friction: A much more critical situation arises, as the lower coefficient of friction lengthens the braking distance and completely changes the movement behavior of the truck-trailer combination. The truck protrudes into the oncoming lane.
50 | Telematics Wire | April 2022
1) Vehicle Dynamics Testing: Emergency Braking at the Limit A truck is used to perform emergency braking at the limit on roads with different friction coefficients, for example, due to leaves, wetness, or snow, and with the electronic brake system (EBS) switched off, in order to separately highlight the influence of the vehicle dynamics on the overall system behavior. The braking process is triggered in each case by the automatic emergency braking (AEB) system as part of an ADAS on the basis of the detected collision risk. The examples show that emergency braking can be realistically represented in the simulation only if all physical aspects of driving are taken into account (friction values, torques between the truck and trailer). And the function of the ADAS can only be fully evaluated and validated
