Design and Analysis of the Flat Pneumatic Artificial Muscle

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.