Optimisation

Ansys Speos and optiSLang for light guide optimization design

Ansys Speos and optiSLang for light guide optimization design

In this example, we will use Ansys Speos and optiSLang for light guide optimization design of light guides for automotive daytime running lights, interior ambient lights, etc., and improve the uniformity of light guide brightness to achieve a better lighting appearance by automatically optimizing the design.

Ansys Speos and optiSLang for light guide optimization design

Overview

In automotive lighting applications, daytime running lights are a unique lighting signature. These light guides are almost always illuminated, so the design of the light guides needs to meet the standards for lighting uniformity and government regulations. To achieve light guide design and optimization, we use Ansys Speos optical part design to create the light guides and Ansys optiSLang to drive the light guide design parameter changes to find the best design.

Ansys Speos and optiSLang for light guide optimization design

Optimize workflow

Data transmission between Speos and optiSLang
There are three ways to transfer data between Speos and optiSLang: the first is to link Speos and optiSLang in Workbench to optimize data transmission; the second is to link workbench in optiSLang, which contains Speos data, to complete data transmission; the third is to directly use scripts to complete the data link between Speos and optiSLang.
 

Ansys Speos and optiSLang for light guide optimization design

The light guide is designed in Speos software and the brightness and intensity of the light guide are simulated and checked for regulations.

In the Speos simulation, there are several key simulation parameter settings:

Lightguide Meshing: Accurate meshing is very important for light guide design. Users who use Speos know the importance of meshing. If the parameters of meshing are not considered, the light output effect in the light guide design will be affected. Local meshing is usually used to set the meshing division of special geometry.

Maximum number of Surface interaction: Light guides rely on total internal reflection to guide the light, which results in more interactions between light and surfaces, especially between light and the light guide prism. The default value of 100 is usually too low, so this value can be increased. Light guides rely on total internal reflection to guide the light, which results in more interactions between light and surfaces, especially between light and the light guide prism. The default value of 100 is usually too low, so this value can be increased.

XML Template: The XML file contains the definition and value verification of key values ​​​​in the Sensor. Using the XML file, you can directly get the numerical situation of the simulation results, and make each reference value available as an output result in optiSLang . You can get the XML standard template on the official website of Ansys customer portal.

Ansys Speos and optiSLang for light guide optimization design

After setting the above parameters of Speos, the simulation results of intensity graph and brightness graph are obtained, and the optical performance is measured from the aspects of regulations and uniformity. The grid view of the intensity graph emphasizes regulatory compliance. Each table represents an intensity measurement point, and the value of the measurement point is subject to regulations. The middle value represents the simulation result, the lower left value represents the minimum limit of the regulation, the upper left value represents the maximum limit of the regulation, and the right side represents the safety limit set by the individual. If the regulation is not passed, it is marked in red, if the safety limit is not reached, it is marked in yellow, and if it is passed, it is marked in green.

Ansys Speos and optiSLang for light guide optimization design

Ansys Speos and optiSLang for light guide optimization design

The measurement of uniformity performance is defined in the luminance diagram. The measurement is based on an 18-point line, or even more points, along which the luminance uniformity can be evaluated, measuring the average and RMS contrast. The luminance result will also be used as the output of the optimization, the optimization goal is to obtain uniform appearance lighting, reduce RMS contrast and maximize the average of the line while keeping the requirements of ECE regulations.

 optiSLang Sensitivity Analysis, which demonstrates parameter analysis capabilities by performing sensitivity studies to identify important light guide input parameters and by creating a meta-model showing the relationship between input and output parameters.

After the parameterized system is established, parameter sensitivity analysis is performed. In the sensitivity analysis, the output change is predicted through the COP matrix. The COP value tells us the quality of the model. In addition, we can see the impact of the parameters on the output. Therefore, we will know which design parameters in the light guide design parameters are the key to affecting the brightness uniformity, root mean square, and light intensity of the design target light guide, and we can directly understand the optical behavior.

Ansys Speos and optiSLang for light guide optimization design

optiSLang Optimizer optimization capabilities by performing model-based multi-objective optimization followed by local and single-objective direct optimization demonstrate to achieve the best possible design.

The optimization algorithm samples 10,000 designs on the MOP to find the best combination of input parameter values ​​​​that achieves the best design. The results of the multi-objective optimization are displayed on the “Pareto surface” (see the figure below). figure shows the trade-off between the two objectives, with the set of best designs marked with red dots (defined as the Pareto front). The workflow automatically verifies the 20 best designs through a real solver call (as shown by the green dots) . Due to the good COP values, the difference between the predicted and verified values ​​​​is small. By selecting one of the designs, the corresponding parameter values ​​​​and responses are displayed in the post-processing other figures of optiSLang. The picture shows the verified 7574 design. To further improve the design, local and single-objective optimization can be performed by converting one of the objectives into a constraint.

Ansys Speos and optiSLang for light guide optimization design

Single-objective optimization using sensitivity studies (black) and response surface-based iterative addition of samples to the optimal design region (colored).

Ansys Speos and optiSLang for light guide optimization design

Optimize results

Thanks to sensitivity analysis and optimization, the best data between RMS contrast and average brightness can be found, so that the appearance of uniform lighting can be significantly improved while achieving all photometric regulations and customer specifications.

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