On The Causes of Image Blurring in External Rear View Mirrors

2004-01-1309

03/08/2004

Event
SAE 2004 World Congress & Exhibition
Authors Abstract
Content
Effective rear view vision from external mirrors is compromised at high speed due to rotational vibration of the mirror glass. Possible causes of the mirror vibration are reviewed, including road inputs from the vehicle body and a variety of aerodynamic inputs. The latter included vibrations of the entire vehicle body, vibrations of the mirror “shell”, the turbulent flow field due to the A-pillar vortex (and to a lesser extent the approach flow) and base pressure fluctuations. Experiments are described that attempt to understand the relative influence of the causes of vibration, including road and tunnel tests with mirrors instrumented with micro accelerometers. At low frequencies, road inputs predominate, but some occur at such low frequencies that the human eye can track the moving image. At frequencies above about 20Hz the results indicate that at high speeds aerodynamics play a dominant role. When the vehicle is yawed, significantly greater aerodynamic inputs arise from the leeside vortex than from the vortex on the upwind side. However since the mounting of the mirror glass is part of a complex dynamic system the results are configuration specific.
Meta TagsDetails
DOI
https://doi.org/10.4271/2004-01-1309
Pages
12
Citation
Watkins, S., "On The Causes of Image Blurring in External Rear View Mirrors," SAE Technical Paper 2004-01-1309, 2004, https://doi.org/10.4271/2004-01-1309.
Additional Details
Publisher
Published
Mar 8, 2004
Product Code
2004-01-1309
Content Type
Technical Paper
Language
English