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The CaseCrawler is a lightweight and low-profile movable platform with a high payload capacity; it is capable of crawling around carrying a smartphone. The body of the robot resembles a phone case but it has crawling legs stored in its back. It is designed with a deployable, in-plane transmission that is capable of crawling locomotion. TheCaseCrawler’s leg structure has a knee joint that can passively bend only in one direction; this allows it to sustain a load in the other direction. This anisotropic leg allows a crank slider to be used as the main transmission for generating the crawling motion; the crank slider generates a motion only within a 2D plane. The crank slider deploys the leg when the slider is pushed and retracts it when pulled; this enables a low-profile case that can fully retract the legs flat. Furthermore, by being restricted to swinging within a plane, the hip joint is highly resistant to off-axis deformation, this results in a high payload capacity. As a result, the CaseCrawler has a body thickness of 16 mm (the transmission without the gearbox is only 1.5 mm) and a total weight of 22.7 g;
however, it can carry a load of over 300 g, which is 13 times its own weight. To show the feasibility of the robot for use in real-world 
applications, in this study, the CaseCrawler was employed as a movable platform that carries a 190 gmass, including a smartphone
and its cover. This robot can crawl around with the smartphone to enable the phone to charge itself on a wireless charging station.
In the future, if appropriate sensing and control functions are implemented, the robot will be able to collect data or return to the owner when needed.


Related papers and patents

J. Lee, G. P. Jung, S. M. Baek, S. H. Chae,  S. Yim, W. Kim, and K. J. Cho, “CaseCrawler: A Lightweight and Low-Profile Crawling Phone Case Robot," IEEE Robot. Autom. Lett., vol. 5, no. 4, pp. 5858-5865, October 2020. ​ [PDF]

Jong-Eun Lee, Gwang-Pil Jung, Kyu-Jin Cho, "Bio-inspired design of a double-sided crawling robot," Living Machines 2017, LNAI 10384, pp. 562–566, 2017. [PDF]

Jong-Eun Lee, Gwang-Pil Jung, Sang-Min Baek and Kyu-Jin Cho, "An adaptive leg structure for a meso-scale crawler," 14th International Conference on Intelligent Unmanned Systems (ICIUS 2018), 2018

Related papers and patents


· E-mail : yhjelee at
· Research Topic : Bio-inspired robots

Ph.D. Candidate

Jong-Eun Lee

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