The necessity of the soft gripping devices is increasing day-by-day in medical robotics especially when safe, gentle motions and soft touch are necessary. In this paper, a novel asymmetric bellow flexible pneumatic actuator (AFPA) has been designed and fabricated to construct a miniaturised soft gripper that could be used to grip small objects. The model of AFPA is designed using solid works and its bending motion is simulated in Abaqus software for optimisation and compared with experimental results. The actuator is fabricated using compression molding process that includes micromachining of the molds. Experiments conducted show the bending characteristics of the actuator at different pressures. The actuator shows excellent bending performance and the eccentricity in its design supports increased bending or curling motion up to a certain extent compared to normal bellows without eccentricity. The effects of profile shape and eccentricity on the actuator performance are analysed and the results are presented. 1. Introduction Different types of soft actuators are developed that could generate the bending motion by themselves or by the mechanism that bends, due to their actuation [1, 2]. But most of these actuators are not single chamber or the actuator as a single cannot bend, but a combination of them with appropriate mechanism does the necessary bending motion [3–5]. Flexible pneumatic actuator (FPA) was designed by Joseph L. McKibben in the 1950s known as pneumatic muscle actuator. Toshiba Corp. (Japan) developed a three-degree-of-freedom actuator known as flexible microactuator (FMA) . Even though the FMAs with two or more chambers with fiber reinforcement provide multiple DOF, they require multiple pressure supplies, valves, and sensors as well as complicated manufacturing. Asymmetric flexible pneumatic actuators (AFPAs) have been developed for the first time during the 1990s using asymmetric polymer/rubber tube and rubber bellow actuators with proper reinforcement to overcome the disadvantages of FMA and FPAs and proposed as an innovative method of fabricating a dexterous human hand [7, 8]. It has also been applied to fabricate a four fingered robot gripper [7–9] and microwalking robot . The design and analysis for application to robotic hand using asymmetric nitrile rubber actuators have been studied [11–13]. Later symmetric thickness bellow actuators for miniature gripper fabricated by moulding technique and rubber bonding process with excimer light [14, 15] and asymmetric bellow actuator of about 10？mm diameter and 120？mm length that was
L. Zhang, Z. Wang, Q. Yang, G. Bao, and S. Qian, “Development and simulation of ZJUT hand based on flexible pneumatic actuator FPA,” in Proceedings of the IEEE International Conference on Mechatronics and Automation (ICMA '09), pp. 1634–1639, IEEE, Changchun, China, August 2009.
I. Gaiser, S. Schulz, H. Breitwieser, and G. Bretthauer, “Enhanced flexible fluidic actuators for biologically inspired lightweight robots with inherent compliance,” in Proceedings of the IEEE International Conference on Robotics and Biomimetics (ROBIO '10), pp. 1423–1428, Tianjin, China, December 2010.
K. Suzumori, S. Endo, T. Kanda, N. Kato, and H. Suzuki, “A bending pneumatic rubber actuator realizing soft-bodied manta swimming robot,” in Proceedings of the IEEE International Conference on Robotics and Automation (ICRA '07), pp. 4975–4980, Roma, Italy, April 2007.
K. Suzumori, S. Iikura, and H. Tanaka, “Development of flexible microactuator and its applications to robotic mechanisms,” in Proceedings of the IEEE International Conference on Robotics and Automation, pp. 1622–1627, Sacramento, Calif, USA, April 1991.
G. Udupa, Study and development of an unconventional device for industrial applications including robots and instrumentation [M.S. thesis], University B.D.T College of Engineering, Davangere, India, 1992.
G. Udupa and R. Krishna Murthy, “A new flexing technique for soft Gripper design,” in Proceedings of the 16th All India Manufacturing Technology Design and Research Conference, pp. 353–358, Bangalore, India, December 1994.
G. Udupa, P. Sreedharan, and K. Aditya, “Robotic gripper driven by flexible microactuator based on an innovative technique,” in Proceedings of the 6th IEEE Workshop on Advanced Robotics and Its Social Impacts, pp. 1–6, Korean Institute of Science and Technology, Seoul, Korea, October 2010.
S. Dinesh, R. Raveendran, K. Aditya, P. Sreedharan, and G. Udupa, “Innovative micro walking robot using flexible microactuator,” in Proceedings of the 28th International Symposium on Automation and Robotics in Construction, Seoul, Republic of Korea, June 2011.
C. P. S. Menon, P. Sredharan, and G. Udupa, “Design and analysis of multi-fingered dexterous hand based on an innovative asymmetric flexible pneumatic actuator,” in Proceedings of the 2nd International Conference on Simulation, Modeling, and Analysis, pp. 246–253, Vishwa Vidyapeetham, Coimbatore, India, 2011.
K. B. S. Pavan Kumar, S. K. Srinath, C. P. Sankar Menon, S. Pramod, and G. Udupa, “A novel technique for the development of an artificial human hand for prosthetic application,” in Proceedings of the National Conference on Application of Data Mining in Management of Metabolic and Degenerative Disorders, India, pp. 1–7, April 2012.
S. Wakimoto, K. Ogura, K. Suzumori, and Y. Nishioka, “Miniature soft hand with curling rubber pneumatic actuators,” in Proceedings of the IEEE International Conference on Robotics and Automation (ICRA '09), pp. 556–561, Kobe, Japan, May 2009.
S. Wakimoto, K. Suzumori, and K. Ogura, “Miniature pneumatic curling rubber actuator generating bidirectional motion with one air-supply tube,” Advanced Robotics, vol. 25, no. 9-10, pp. 1311–1330, 2011.
S. Hirai, T. Masui, and S. Kawamura, “Prototyping pneumatic group actuators composed of multiple single-motion elastic tubes,” in Proceedings of the IEEE International Conference on Robotics and Automation (ICRA '01), vol. 4, pp. 3807–3812, Seoul, Republic of Korea, May 2001.