This paper examines important challenges in the mechanics of bionic prostheses, focusing on improving their functionality, reliability, and accessibility against increasing global amputation rates. This research aims to identify key mechanical components requiring development and to substantiate the advantages of implementing compliant mechanism technology in bionic finger designs. The methodology is based on functional-cost analysis using the FAST diagram approach, which systematically breaks down the functional hierarchy of finger prostheses and reveals critical relationships between various components. This analysis is complemented by a comprehensive review of recent innovations in flexible joint mechanisms for robotic and prosthetic applications. Three main functional nodes with the highest interconnectivity were identified as subjects of research: phalanges material, drive mechanism with joints, and additive manufacturing technologies. Compliant mechanisms provide significant advantages over traditional designs, replacing multiple hinged joints with integrated flexible structures. Quantitative analysis from reviewed studies shows that optimized compliant designs can provide up to 68% greater force (5.86 N compared to 3.48 N in conventional designs), absorb 11% more impact energy, and withstand static loads up to 26 kg while maintaining natural movement patterns with deflection angles of 45-90°. The originality of this research lies in the systematic identification of functional relationships in bionic finger mechanics and the substantiation of compliant mechanism technology as an integrative solution that simultaneously satisfies multiple functional requirements. The practical value includes the potential for significantly reducing manufacturing complexity, eliminating maintenance needs, improving durability, and enhancing adaptive gripping capabilities, which directly contribute to better user experience and prosthetic acceptance.
[1] B. Yuan, H. Dong, S. Gu, S. Xiao, and F. Song, "The global burden of traumatic amputation in 204 countries and territories," Frontiers in Public Health, vol. 11, 2023.
https://doi.org/10.3389/fpubh.2023.1258853
[2] B. Van Hooreweder, D. Moens, R. Boonen, J.-P. Kruth, and P. Sas, "On the difference in material structure and fatigue properties of nylon specimens produced by injection molding and selective laser sintering," Polymer Testing, vol. 32, no. 5, pp. 972-981, 2013.
https://doi.org/10.1016/j.polymertesting.2013.04.014
[3] J. Rauter, "Transtibial Prosthetic Care: Digital Preparation, Optimized Design & Additive Manufacturing," M.S. thesis, University of Applied Sciences Technikum Wien, Vienna, Austria, 2023.
[4] M. R. Cutkosky and R. D. Howe, "Human grasp choice and robotic grasp analysis," in Dextrous Robot Hands, New York, NY: Springer, 1990, pp. 5-31.
https://doi.org/10.1007/978-1-4613-8974-3_1
[5] S. M. Engdahl, B. P. Christie, B. Kelly, A. Davis, C. A. Chestek, and D. H. Gates, "Surveying the interest of individuals with upper limb loss in novel prosthetic control techniques," Journal of NeuroEngineering and Rehabilitation, vol. 12, no. 53, 2015.
https://doi.org/10.1186/s12984-015-0044-2
[6] A. M. Dollar and R. D. Howe, "The highly adaptive SDM hand: Design and performance evaluation," The International Journal of Robotics Research, vol. 29, no. 5, pp. 585-597, 2010.
https://doi.org/10.1177/0278364909360852
[7] S. Kim, C. Laschi, and B. Trimmer, "Soft robotics: A bioinspired evolution in robotics," Trends in Biotechnology, vol. 31, no. 5, pp. 287-294, 2013.
https://doi.org/10.1016/j.tibtech.2013.03.002
[8] J. T. Belter, J. L. Segil, A. M. Dollar, and R. F. Weir, "Mechanical design and performance specifications of anthropomorphic prosthetic hands: A review," Journal of Rehabilitation Research & Development, vol. 50, no. 5, pp. 599-618, 2013.
https://doi.org/10.1682/JRRD.2011.10.0188
[9] L. L. Howell, Compliant Mechanisms. New York, USA: John Wiley & Sons, Inc., 2001.
[10] F. Lotti and G. Vassura, "A novel approach to mechanical design of articulated fingers for robotic hands," in Proc. IEEE/RSJ International Conference on Intelligent Robots and Systems, Lausanne, Switzerland, 2002, vol. 2, pp. 1687-1692.
https://doi.org/10.1109/IRDS.2002.1043998
[11] M. Manti, T. Hassan, G. Passetti, N. D'Elia, C. Laschi, and M. Cianchetti, "A bioinspired soft robotic gripper for adaptable and effective grasping," Soft Robotics, vol. 2, no. 3, pp. 107-116, 2015.
https://doi.org/10.1089/soro.2015.0009
[12] F. Alkhatib, E. Mahdi, and J. J. Cabibihan, "Design and analysis of flexible joints for a robust 3D printed prosthetic hand," in Proc. IEEE 16th International Conference on Rehabilitation Robotics (ICORR), 2019, pp. 784-789.
https://doi.org/10.1109/ICORR.2019.8779372
[13] L. Garcia, M. Naves, and D. M. Brouwer, "3D-printed flexure-based finger joints for anthropomorphic hands," in Proc. IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2018, pp. 1437-1442.
https://doi.org/10.1109/IROS.2018.8594102
[14] K. Y. Choi, A. Akhtar, and T. Bretl, "A compliant four-bar linkage mechanism that makes the fingers of a prosthetic hand more impact resistant," in Proc. IEEE International Conference on Robotics and Automation (ICRA), 2017, pp. 6694-6699.
https://doi.org/10.1109/ICRA.2017.7989791
[15] D. M. Brouwer, J. P. Meijaard, and J. B. Jonker, "Stiffness analysis of parallel leaf-spring flexures," in Proc. 25th Annual Meeting of the American Society of Precision Engineering, 2010, pp. 226-229.
[16] M. Naves, "Design and optimization of large stroke flexure mechanisms," Ph.D. dissertation, University of Twente, 2021.
[17] G. Hao, X. He, and S. Awtar, "Design and analytical model of a compact flexure mechanism for translational motion," Mechanism and Machine Theory, vol. 142, article 103593, 2019.
https://doi.org/10.1016/j.mechmachtheory.2019.103593