Abstract—Deployment of pneumatic muscles in various industrial applications is still in its early days, considering the relative newness of these components. The field of robotics holds particular future potential for pneumatic muscles, especially in view of their specific behaviour known as compliance. The paper presents and discusses an innovative constructive solution for a gripper system mountable on an industrial robot, based on actuation by a linear pneumatic muscle and transmission of motion by gear and rack mechanism. The structural, operational and constructive models of the new gripper are presented, along with some of the experimental results obtained subsequently to the testing of a prototype. Further presented are two control variants of the gripper system, one by means of a 3/2-way fast-switching solenoid valve, the other by means of a proportional pressure regulator. Advantages and disadvantages are discussed for both variants. Keywords—Gripper system, pneumatic muscle, structural modeling. I. INTRODUCTION REHENSION, as a general action, includes grabbing and seizing with fingers, claws or tweezers of objects, in view of repositioning. While, as suggested by this assertion, this action is characteristic primarily to living natural systems, biomimetics helped conceive artificial gripper systems, also known as “mechanical hands”. Mechanical hands are meant to replace human ones, their required abilities being dictated by the large variety of applications. Thus, studies have revealed that related to the 100% gripping ability of a five-finger mechanical hand, this decreases to 99% in a four-finger one, to about 90% in a three- finger and to mere 40% in a two-finger hand [1]. Gripper systems represent the final elements in robotic structures and are often not included by their “anatomy”. Their role is to facilitate temporary contact with the manipulated object, ensuring its position and orientation during transport and specific activities [2], [3]. The characteristic motions of prehension are generated by means of motors that have to fulfil the mean tasks of such a system, like ensuring a sufficient clamping force, precision, reliability, flexibility, compliance etc. By the type of energy used by the motors, these can be electrical, hydraulic, pneumatic or non- conventional [4]. Pneumatic actuation is the one most frequently encountered Prof. Dr. Eng. Tudor Deaconescu and Prof. Dr. Eng. Andrea Deaconescu are with the Transilvania University of Brasov, Faculty of Technological Engineering and Industrial Management, Department of Industrial Engineering and Management, Bd. Eroilor 29, Romania, RO-500036 (phone: 0040-268-477113; fax: 0040-268-477113; e-mail: tdeacon@ unitbv.ro, deacon@ unitbv.ro). in the construction of gripper systems, due to certain advantages like using a non-polluting working environment, the possibility of overloading the system, easy adjusting of forces, torques, speeds, compliant behaviour etc. [5]. Linear or rotating pneumatic motors combined with mechanical systems for the transmission of motion ensure the mobility of the fingers by straight or curved trajectories, as demanded by any concrete application. Over the last years membrane type pneumatic motors (pneumatic muscles) have benefitted from continued development for the generation of both linear and circular motion. Pneumatic muscles stand out by valuable properties like their shock-absorbing capacity, low weight, small size, reduced mass-to-power unity ratio and elasticity (springlike behaviour) due to air compressibility on one hand, and variation of force with displacement on the other. Such characteristics render pneumatic muscles optimum constructive elements for the construction of gripper systems. Linear pneumatic muscles have been commercialised by the Bridgestone Rubber Company of Japan starting 1980 and more recently, by the American Shadow Robot Company and the Festo Corporation of Germany [6]-[8]. A rotating chamber type pneumatic muscle has been developed at Bremen University in Germany in order to generate rotation by a circular arc of limited angle. Its construction is based on series-connecting several chambers made from welded plastic foils communicating via a channel through that compressed air is fed to the system. A higher compressed air pressure will generate a greater rotation angle of the system [9], [10]. At present construction of gripper systems driven by pneumatic muscles is limited, because of insufficient knowledge of these actuators. One of the gripper systems whose actuation deploys a linear pneumatic muscle is called Power Gripper and is manufactured by Festo. Its working principle mimics the seizing of objects by birds using their beaks, and its construction is based on Watt linkages. Fig. 1 shows a view of such a gripper system [11]. Fig. 1 Power Gripper Tudor Deaconescu, Andrea Deaconescu Design and Evaluation of a Pneumatic Muscle Actuated Gripper P World Academy of Science, Engineering and Technology International Journal of Mechanical and Materials Engineering Vol:8, No:9, 2014 1600 International Scholarly and Scientific Research & Innovation 8(9) 2014 ISNI:0000000091950263 Open Science Index, Mechanical and Materials Engineering Vol:8, No:9, 2014 publications.waset.org/9999368/pdf