Displays in a vibrating environment: How NASA addressed a blurry problem


vibratingDisplay2

The effect of synchronized strobed display to reduce motion blurring readibility issues in a high vibration environment. Or more specifically, Turning a mess into less of a mess.

The stereotypes are true: the boost into space from sea level is a shaky, G-infested carnival ride with every Fourier component you care to name. NASA had a similar problem as part of its problematic Ares 1 project. Some rockets have a dominant resonance frequency in long axis that is termed ‘pogo’ (like the stick) and in human rated vehicles this means a dominant mode vibration passes to the passengers. In the case of the Ares I, this was on the order of 0.7G’s at about 12 Hertz, working out to around 5mm motion. If the computer displays the passenger is looking at do not have the same damping and resonance characteristics as their own eyes and head, motion blur in the displays will make them unreadable as simulated above.

A solution tested was to strobe the display in the same way LED-based displays are dimmed – a square wave duty cycle is applied so that the display is actually off some of time. The duty cycle is synchronized to the main vibrational component of the the pogo motion, removing the worst of the motion blur at the expense of some brightness (This simulated view assumes that brightness can be boosted somewhat to compensate).

 

Trading Brightness for clarity: effect of strobing a display in sync with a sinusoidal vibration mode

Trading Brightness for clarity: effect of strobing a display in sync with a sinusoidal vibration mode

When compensating for a single, sinusoidal mode, the loss in brightness is not that great if the duty cycle of the strobing is phase matched to a displacement peak of the motion as shown. A vibration reduction of 90% is possible with a 20% duty cycle, or 80% loss in brightness.

Read the article and see the demo video here:

http://gizmodo.com/5880850/how-nasa-solved-a-100-million-problem-for-five-bucks

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s