Recent technological advances have triggered the need to utilize electronics-based 3D-shape sensors to accomplish 3D geometry reconstruction, body shape change measurement and surface shape measurement. Conversely, most of these electronics based approaches are not suitable for extreme environment – high temperature, chemically unstable, and electromagnetic sensitive environments. Fortunately, the recently developed fiber optics technique has emerged as a promising candidate and highly efficient method for shape sensing. Several fiber optics techniques are viable, however, most focus chiefly on 3D curve sensing along an optical fiber or line instead of shape sensing of an object surface. Luckily, the fiber Bragg grating possessing various structures has displayed auspicious shape sensing capabilities, despite the limitations of: uni-directional curve sensing or limited resolution. To this end, there is need to develop a novel simple 3D shape sensor with higher resolution for application in biomedical works and soft robotics.
University of Georgia researchers: Li Xu, Jia Ge, Jay Patel and Mable Fok developed a compact soft 3D shape sensor utilizing a dual-layer orthogonal fiber Bragg grating mesh that could measure the complete 3D shape of an object surface. They achieved visualized 3D shape sensing which would come in handy in many potential application fields. Their work is currently published in the research journal, Optics Express.
Their experimental setup entailed the embedment of a sensor comprising of 18 standard fiber Bragg gratings inside a thin and flexible silicone film. Additionally, the 18 fiber Bragg gratings were orthogonally aligned in a dual-layer mesh structure with 9 fiber Bragg gratings in the x-direction at the top layer and 9 fiber Bragg gratings in the y-direction at the bottom layer.
The authors observed that the off-center embedding of optical fiber in the silicone film enabled the measurement of both positive and negative bending curvatures, while the orthogonal structure decomposed a curve into x- and y- axis. Moreover, the bending direction and bending curvature at each sensing point were obtained by measuring the direction and amount of Bragg wavelength shift of each fiber Bragg grating in the mesh, and the information of all the 9 sensing points could be obtained through one single spectral scan. In addition, the surface profiles of the test objects were successfully reconstructed with visual 3D plotting.
Professor Mable Fok and her colleagues has shown successful design of a soft silicone shape sensor comprising of 18 fiber Bragg gratings embedded in a flexible silicone film for 3D shape measurement. It has been seen that the proposed scheme can measure the complete 3D shape of an object surface simply by placing the sensor on top of the object. Even better, the compact and soft silicone rubber is highly compatible with human body, therefore making the demonstrated sensor a promising design for wearable monitoring devices and medical robotics.
Li Xu, Jia Ge, Jay H. Patel, and Mable P. Fok. Dual-layer orthogonal fiber Bragg grating mesh based soft sensor for 3-dimensional shape sensing. Volume. 25, No. 20 | 2 Oct 2017 | Optics Express 24727
Go To Optics Express