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March, 2021
Improving Image Stabilization Tests with
Hexapod Motion Simulators By Doris Knauer, Project Manager Global Campaigns — Industrial Automation, Physik Instrumente (PI) GmbH
H
igh-quality still images and video are critical for a wide range of industrial applications. The cameras that produce these images are analyzed for performance, based on properties that include
image stabilization, contrast, color, texture, zoom, and many others. Independent benchmark firm DXOMARK specializes in com-
plete laboratory solutions for the analysis, comparison and optimiza- tion of image quality. Its Analyzer systems combine hardware, soft- ware and extensive testing protocols, bundled within serval modules designed to ensure repeatable, operator-independent results.
Modular Image Analyzer Depending on the image quality attributes being evaluated, dif-
ferent modules can be used. A special capability of Analyzer is its vi- sual noise measurement. It produces visual noise metrics, which di- rectly correlate with visual perception. The video analysis encom- passes exposure, white balance, definition and texture for changing lighting conditions. Automated lighting scenarios can also be pro- grammed for user-specific test requirements. The latest version of Analyzer includes the Selfie module to enable accurate and repeat- able smartphone front-camera testing. The image stabilization test assesses how well the optical and elec-
tronic image stabilization systems built into cameras work. These sys- tems are designed to compensate movements and avoid blurred images. Sensors measure linear and angular motion acceleration so that the image stabilization system can automatically offset these influences.
Image Stabilization Test For all image stabilization test methods, it is important that the
shaking camera or the vibrations in vehicles and aircrafts are repro- ducible. “We must ensure that the simulated frequencies and move- ments, for example, around pitch, yaw and roll, are identical for each test,” says Nicolas Touchard, vice president of marketing at DXO- MARK. “We are currently using hexapods in the latest version of Ana- lyzer because they allow precisely reproducible motions up to frequen- cies of 30 Hz, increasing the number of potential test scenarios.” Camera and smartphone tests typically require up to 12 Hz,
however, the image stabilization function of driver assistance sys- tems offset much higher frequencies. The hexapod’s parallel kine- matic design suits it well for the precise simulation of motions and vi- brations. Compared with serial (stacked) systems, they show much better path accuracy, repeatability and flatness. Also, the moved mass is lower, offering greater dynamic performance that is the same for all motion axes.
Hexapods The hexapods used in the latest Analyzer are made by PI
(Physik Instrumente). PI’s H-840 hexapod is designed for the testing of image stabilization systems and certified to CIPA Standard DC- 011-2015. This standard defines rotational axes, test frequencies and vibration amplitudes. Since mid-2019, another hexapod is being used by the Analyzer.
The H-860 hexapod is designed for the testing of image stabilization systems. It offers simulation frequencies up to 30 Hz, and travels pre- defined trajectories (sinusoids) and freely definable paths with a high degree of trajectory control. Due to the friction-free voice coil drives and the lightweight design consisting of extremely stiff carbon fiber parts with low-moving masses, it is possible to achieve fast and smooth motion, as well as high acceleration. The hexapod used for testing is fixed to a baseplate. The brackets
for the test items are installed on the baseplate. They keep the test de- vice safely in place on the hexapod during vibration simulation. The system is controlled by PI’s C-887 and easy-to-use software.
Positions are specified in Cartesian coordinates and the controller calculates the transformations for each individual drive. With high accuracy and great flexibility in use, six-axis parallel kinematics are quickly becoming frontrunners in many motion simu-
lation applications. Contact: PI (Physik Instrumente) L.P., 16 Albert St., Auburn, MA 01501 %508-832-3456 E-mail:
info@pi-usa.us Web:
www.pi-usa.us r
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