[SystemSafety] COTS display certification

[Dave Banham]

Haim,

if the problem that you are concerned with is whether or not a display symbol is 
placed in the correct location on the display then looking at display technology 
failure modes is not going to help you because all a display does is, well, 
display the image data given to it. You'd have to consider where in the data 
path the transformation from world coordinates to display coordinates is made 
and then where the image of the display symbol is rendered into the raster 
memory before the raster image data is transfer to the display. And then 
consider the ways in which this could go wrong.


A failure modes analysis of a modern computer display might at least start of by 
considering the following symptoms, then their operational impact, possible 
route courses, and then the mitigations:

* Blank display

* Stuck pizel(s)

* Dead pixel(s)

* Stuck row(s) or column(s)

* Dead/failed row(s) or column(s)

* Flickering

I would have thought that display panel manufactures would have reliability data 
for at least display panel faults and that OEM display manufacturs could add the 
reliability figures of their electronics to that.

You might also want to consider some "soft" display /failure/ symptoms too, e.g.:

* On screen display menu/status originating from the display obscures actual 
display information for some amount of time.

* Light glare obscures (makes hard to clearly see) the displayed image

* Poor colour contrast leads to unreliable colour identification


Hope that gives you some ideas.

Regards,

Dave Banham


On 25/07/2016 17:04, Haim Kuper wrote:
> Dear System Safety List Members,
>
> We need to develop and certify a Ground Control Station (GCS) that controls
> an avionic platform.
> The GCS contains an In-house-developed Control Computer (CC) and a COTS
> Display.
> Hazard's analyses of the GCS showed that we need to develop and certify to
> DAL-B.
> Regarding the display:
>   1 - It's usually a problem to verify World-coordinates to
> Display-coordinates conversion results-on-screen so that the operator will
> be 100% sure that the symbol is exactly on the correct spot (on the world
> map/screen).
>   2 - I've asked some famous companies (Acer, Samsung, HP, LG) for any
> supporting data, such as service history (as shown in DO-178C section 12.3.4
> "Product Service History" )  of failure data, any measured or designed-to
> reliability figures: IMHO, I'll not get any assistance from them.
>   3 - We are checking some safety design mechanisms such as
>      a. monitoring using another display
>      b. develop some hardware/software/humanware based Built In Tests, and
>      c. still looking for a creative idea to tackle this subject
>
> Per your experience, please advise how to certify the COTS display within
> the GCS development.
>
> Thanks and Regards,
> Haim kuper
>
>
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