ADELANTO, Calif. — The following is the first of a three-part series produced by Carlos Lujan Tutusaus, Senior Manager Homologation, Commercial Vehicles, Automated Driving & Vehicle Dynamics in Applus IDIADA and Oriol Flix Viñas, Homologation Engineer, Commercial Vehicles, Automated Driving & Vehicle Dynamics in Applus IDIADA
In the context of a deep transformation in the automotive technology, especially with the wide introduction of ADAS functions and the first commercially available vehicles with automated functions, the classic type-approval procedures have been challenged and new methodologies are required.
This article describes the actions being carried out at different levels in order to tackle such challenge, as well as the main future trends with regards to the new assessment and testing methodologies for the type-approval of vehicles and their systems.
Technological innovations in the field of Connected and Automated Driving have a strong impact in different areas in the automotive industry. Among those areas, the effect on vehicle homologation procedures is game changing, in a way that requires a brand-new approach. Traditionally, the homologation process based on the UNECE Regulatory framework has been a single step at the end of the development phase, where regulations normally defined a series of repeatable scenarios to be evaluated, where the effect of the driver is typically suppressed by means of the measurement of the inputs on the vehicle commands or by means of the use of driving robots.
In such context, the evaluation process could be scenario oriented: A limited number of repeatable scenarios were reproduced under controlled conditions, and the performance of the vehicle/system alone was evaluated, in equal conditions.
This approach was initially challenged by the introduction of assisted systems, such as Advance Emergency Brake. Those systems are commanded by Electronic Control Systems which, in some circumstances, may control certain vehicle functions, such as braking or steering. The introduction of those functions required a different approach to the vehicle type approval, in order to evaluate possible failures associated to the Electronic Control Systems.
In such context, concepts such as Functional Safety (FuSa) or Safety of The Intended Functionality (SOTIF) were introduced as part of the type approval process. This new approach turned the technical evaluation of the compliance from a testing activity in selected scenarios into a combination of testing and assessment of the manufacturer safety concept.
The vehicle is still under control of the human driver at all times, but the reaction of the vehicle may depend on the interventions of complex electronic systems. It is then necessary to guarantee that manufacturers have designed and built the vehicle to take safe decisions both in normal operation and failure conditions.
This methodology was already introduced in Regulation such as UN Regulation N. 13 and UN Regulation N. 13H, where systems like EBS or ESP may activate the braking system without intentional action from the human driver.
2. The Challenge of Automated Vehicles Type-Approval
The introduction of the first SAE L3 functions into the market add a new layer of complexity into the type approval methodology. Such technologies replace the human driver during certain dynamic driving tasks, within an unlimited number of scenarios. This circumstance does not allow the classic strategy of removing the human effect from the test scenarios and requires a second loop in the modification of the type approval processes, so as to move from an evaluation of the performance to an evaluation of the behavior of the vehicle.
In this case, there are two main aspects that the traditional approach could not solve efficiently:
a) The driving strategy: In vehicles operating in automated mode, the dynamic driving tasks are responsibility of the vehicle itself, without any human intervention. That means that the vehicle is not only responsible for the performance but also for the decisions on how to react to the inputs, assuming the role of the driver. In such circumstances, a classic type-0 braking test is not representative to evaluate the safety of a vehicle, because a vehicle with a lower mechanical braking performance may follow a more conservative driving strategy, so that will avoid the need for emergency braking in most of the possible scenarios, while a vehicle with a more performant braking system, but with a much more aggressive driving strategy may not be as safe.
b) The number of scenarios: In vehicles corresponding to SAE Level 2 or lower, a reduced number of scenarios is tested to evaluate the safety of its systems. As the human driver influence in the safe operation of the vehicle has a majority weight on the overall safety, over the system performance itself, it is possible to evaluate the safety of the system by excluding the human effect, by means of a limited number of test cases under repeatable and controlled conditions. However, if the driver effect cannot be excluded, as in the case of automated driving vehicles, it cannot be guaranteed that vehicles which are similar from the mechanical point of view will have similar performance under different scenarios, as the driving strategy may be variable depending on the scenario, affecting the behavior of the vehicle and, as a consequence, the performance.
About Applus IDIADA
With more than 25 years’ experience and 2,450 engineers specializing in vehicle development, Applus IDIADA is a leading engineering company providing design, testing, engineering, and homologation services to the automotive industry worldwide.
Applus IDIADA is in California and Michigan, with further presence in 25 other countries, primarily in Europe and Asia.