Abstract：Due to the limitations of structure and manufacturing process,it is difficult for the traditional pneumatic artificial muscle to meet the application requirements of high contraction ratio,high contraction force,and full flexibility.To solve these problems,a kind of flat pneumatic artificial muscle (flat muscle) is proposed based on the orthogonal hybrid weaving process of constrained layer,contraction layer,and flat balloon.The relationship among the minimum length and contraction ratio of the contraction layer,the maximum thickness of the flat muscle,the amount of flat balloon layers,and the amount of balloon fingers is analyzed by modeling,and the approximate analytical solution of the contraction force is obtained by the numerical fitting method.Main components of the flat muscle are made by the laser cutting process.The mass of the finished prototype is only 8.1 g with a thickness of 1.2 mm.The contraction experiments show that the maximum contraction force of the flat muscle can reach 280 N at a contraction ratio of 5%,which is 3527 times of its weight.Under the load of 0.5 kg,the maximum contraction ratio is 42.8%,and the maximum contraction speed is 1216.2 mm/s.Hysteresis experiments show that there exists some displacement hysteresis,but force hysteresis is not obvious.Using the closed-loop control method,the flat muscle has a good position tracking ability to the 0.25 Hz sinusoidal signal,and the maximum displacement error is 2.5 mm.When the frequency is 0.5 Hz,the flat muscle demonstrates a large displacement delay due to the deflation velocity.
 Park Y L, Chen B R, Pérez-Arancibia N O, et al. Design and control of a bio-inspired soft wearable robotic device for ankle-foot rehabilitation[J]. Bioinspiration & Biomimetics, 2014, 9(1). DOI:10.1088/1748-3182/9/1/016007.  南卓江,杨扬,铃森康一,等. 基于细径McKibben型气动人工肌肉的仿生手研发[J].机器人, 2018, 40(3):321-328. Nan Z J, Yang Y, Suzumori K, et al. Development of a bionic hand actuated by thin McKibben pneumatic artificial muscle[J]. Robot, 2018, 40(3):321-328.  Beyl P, van Damme M, van Ham R, et al. Pleated pneumatic artificial muscle-based actuator system as a torque source for compliant lower limb exoskeletons[J]. IEEE/ASME Transactions on Mechatronics, 2014, 19(3):1046-1056.  Kothera C S, Jangid M, Sirohi J, et al. Experimental characterization and static modeling of McKibben actuators[J]. Journal of Mechanical Design, 2009, 131(9). DOI:10.1115/1.3158982.  Villegas D, van Damme M, Vanderborght B, et al. Thirdgeneration pleated pneumatic artificial muscles for robotic applications:Development and comparison with McKibben muscle[J]. Advanced Robotics, 2012, 26(11-12):1205-1227.  Koizumi S, Kurumaya S, Nabae H, et al. Braiding thin McKibben muscles to enhance their contracting abilities[J]. IEEE Robotics and Automation Letters, 2018, 3(4):3240-3246.  Park Y L, Santos J, Galloway K G, et al. A soft wearable robotic device for active knee motions using flat pneumatic artificial muscles[C]//IEEE International Conference on Robotics and Automation. Piscataway, USA:IEEE, 2014:4805-4810.  Abe T, Koizumi S, Nabae H, et al. Fabrication of "18 weave" muscles and their application to soft power support suit for upper limbs using thin McKibben muscle[J]. IEEE Robotics and Automation Letters, 2019, 4(3):2532-2538.  Belding L, Baytekin B, Baytekin H T, et al. Slit tubes for semisoft pneumatic actuators[J]. Advanced Materials, 2018, 30(9). DOI:10.1002/adma.201704446.  Gorissen B, Milana E, Baeyens A, et al. Hardware sequencing of inflatable nonlinear actuators for autonomous soft robots[J]. Advanced Materials, 2019, 31(3). DOI:10.1002/adma. 201804598.  Schaffner M, Faber J A, Pianegonda L, et al. 3D printing of robotic soft actuators with programmable bioinspired architectures[J]. Nature Communications, 2018, 9. DOI:10.1038/s41467-018-03216-w.  Gupta U, Wang Y Z, Ren H L, et al. Dynamic modeling and feedforward control of jaw movements driven by viscoelastic artificial muscles[J]. IEEE/ASME Transactions on Mechatronics, 2019, 24(1):25-35.  Veale A J, Anderson I A, Xie S Q. Dielectric elastomer strain and pressure sensing enable reactive soft fluidic muscles[C]//Proceedings of SPIE, Vol.9798, Electroactive Polymer Actuators and Devices. Bellingham, USA:SPIE, 2016. DOI:10. 1117/12.2218225.  Veale A J, Xie S Q, Anderson I A. Characterizing the Peano fluidic muscle and the effects of its geometry properties on its behavior[J]. Smart Materials and Structures, 2016, 25(6). DOI:10.1088/0964-1726/25/6/065013.  Veale A J, Xie S Q, Anderson I A. Modeling the Peano fluidic muscle and the effects of its material properties on its static and dynamic behavior[J]. Smart Materials and Structures, 2016, 25(6). DOI:10.1088/0964-1726/25/6/065014.  Veale A J, Anderson I A, Xie S Q. The smart Peano fluidic muscle:A low profile flexible orthosis actuator that feels pain[C]//Proceedings of SPIE, Vol.9435, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems. Bellingham, USA:SPIE, 2015. DOI:10.1117/12.2084130.  Belforte G, Eula G, Ivanov A, et al. Bellows textile muscle[J]. The Journal of the Textile Institute, 2014, 105(3):356-364.  Lee J G, Rodrigue H. Origami-based vacuum pneumatic artificial muscles with large contraction ratios[J]. Soft Robotics, 2019, 6(1):109-117.  Li S G, Vogt D M, Rus D, et al. Fluid-driven origami-inspired artificial muscles[J]. Proceedings of the National Academy of Sciences of the United States of America, 2017, 114(50):13132-13137.  Han K, Kim N H, Shin D. A novel soft pneumatic artificial muscle with high-contraction ratio[J]. Soft Robotics, 2018, 5(5):554-566.  Yang H D, Greczek B T, Asbeck A T. Modeling and analysis of a high-displacement pneumatic artificial muscle with integrated sensing[J]. Frontiers in Robotics and AI, 2019. DOI:10.3389/frobt.2018.00136.  Kellaris N, Venkata V G, Smith G M, et al. Peano-HASEL actuators:Muscle-mimetic, electrohydraulic transducers that linearly contract on activation[J]. Science Robotics, 2018, 3(14). DOI:10.1126/scirobotics.aar3276.  Niiyama R, Rus D, Kim S. Pouch motors:Printable/inflatable soft actuators for robotics[C]//IEEE International Conference on Robotics and Automation. Piscataway, USA:IEEE, 2014. DOI:10.1109/ICRA.2014.6907793.  Hawkes E W, Christensen D L, Okamura A M. Design and implementation of a 300% strain soft artificial muscle[C]//IEEE International Conference on Robotics and Automation. Piscataway, USA:IEEE, 2016. DOI:10.1109/ICRA.2016.7487592.  Moghadam A A A, Alaie S, Nath S D, et al. Laser cutting as a rapid method for fabricating thin soft pneumatic actuators and robots[J]. Soft Robotics, 2018, 5(4):443-451.