Assurance Pitfalls When Using COTS Components

Assurance Pitfalls When Using COTS Components:
Using a name-brand, familiar component doesn't automatically ensure safety.

It is common to repurpose Commercial Off-The-Shelf (COTS) software or components for use in critical autonomous vehicle applications. These include components originally developed for other domains such as mine safety, low volume research components such as LIDAR units, and automotive components such as radars previously used in non-critical or less critical ADAS applications.

Generally such COTS components are being used in a somewhat different way than the original non-critical commercial purpose, and are often modified for use as well. Moreover, even field proven automotive components are typically customized for each vehicle manufacturer to conform to customer-specific design requirements. When arguing that a COTS item is proven in use, it is important to account for at least whether there is in fact sufficient field experience, whether the field experience is for a previous or modified version of the component, and other factors such as potential supply-chain changes, manufacturing quality fade, and the possibility of counterfeit goods.

In some cases we have seen proven in use arguments attempted for which the primary evidence relied upon is the reputation of a manufacturer based on historical performance on other components. While purchasing from a reputable manufacturer is often a good start, a brand name label by itself does not necessarily demonstrate that a particular component is fit for purpose, especially if a complex supply chain is involved.

COTS components can be problematic if they don't come with the information needed for safety assessment. (Hint: source code is only a starting point. But often even that isn't provided.) While third party certification certainly is not a panacea, looking for independent evaluation that relevant technical, development process, and assurance process activities have been performed is a good start to making sure COTS components are fit for purpose.

(This is an excerpt of our SSS 2019 paper:  Koopman, P., Kane, A. & Black, J., "Credible Autonomy Safety Argumentation," Safety-Critical Systems Symposium, Bristol UK, Feb. 2019.  Read the full text here)