Thermally Actuating Multi-layered Tunable Aperture for Robot Distance Sensing

A Thermally Actuating multi-layered tunable aperture for distance sensing is proposed to measure distance to the obstacle. This tunable aperture uses metal of high thermal expansion to make different aperture size by Joule’s heating which operates when the voltage is applied to two copper metal structure. This aperture consists of eight thermal actuators that can obtain 3D image and distance information in a single camera simultaneously. The distance data can be obtained by Depth from Defocus method which compares blurriness of two images from each aperture size. The proposed thermal actuator is chevron type that has two beams that are slightly bent from each other to amplify the displacement of aperture perpendicularly. To find the exact displacement, COMSOL MULTIPHYSICS simulation tool was used. The device was fabricated with MEMS technology with two masks, and aperture was formed by bonding four identical layers with 45 degrees to each other to create octagonal shape. The dimension of thermally actuating part is 10mm by 100um by 40um and overall dimension is 10mm by 10mm by 2.2mm. The measurement result shows that the average displacement of 462um was obtained when 7.2V was applied which makes the aperture size from 546um to 1008um.