Muscle Activity Estimation Based on Inverse Dynamics, Muscle Stress Analysis by Finite Element Method
This paper proposes a method to estimate muscle activity with taking account the volumetric effects of muscles. We analyze muscles as elastic bodies by using finite element method combined with computation technique in robotics. We describe the way to est
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Moscow State Textile University ’A.N. Kosygin’, Moscow, Russia Mechanical Engineering Research Institute of RAS, Moscow, Russia
Abstract A translational parallel manipulator with three degrees of freedom and three kinematic chains is considered. Each kinematic chain contains five revolute joints. Kinematics, workspace, singularities and dynamics of the proposed mechanism are discussed.
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Introduction
Since the moment when famous Clavels Delta robot was presented (Clavel, 1987), parallel manipulators with three translational degrees of freedom have attracted much attention from researchers (Ceccarelli, 2004, Gogu, 2009) and manufacturers, as it was discovered that such manipulators are very useful in many areas (Merlet, 2006). Usually, this kind of spatial mechanisms consists of base plate, moving platform (end-effector) and three symmetric kinematic chains, also called legs or limbs (Kong and Gosselin, 2007). For instance, Delta robot has three R-R-Pa-R legs and provides pure translational motion to its moving platform in three dimensions. This mechanism is widely used in packaging and pick-and-place operations because of its phenomenal speed capability and low inertia. Another variation of Delta mechanism was proposed by Tsai (Tsai and Stamper, 1996). The inverse variation of Delta was also studied by Briot (Briot et al., 2008). Another conceptual approach was presented by Wenger and Chablat (Wenger and Chablat, 2000). Their Orthoglide mechanism has three P-R-Pa-R identical kinematic chains. The moving plate of this mechanism is capable to achieve various complicated trajectories and the workspace of this robot is very close to a cube shape. All these manipulators are constructed using parallelograms, which are widely used in 3-DOF translational parallel manipulators, as a parallelogram directly constrains rotation about a certain axis. Carricato (Carricato and Parenti-Castelli, 2004) has discussed 3 R-UR-R mechanism that could be treated as 3 R-R-R-R-R mechanism. Each V. Padois, P. Bidaud, O. Khatib (Eds.), Romansy 19 – Robot Design, Dynamics and Control, CISM International Centre for Mechanical Sciences, DOI 10.1007/978-3-7091-1379-0_2, © CISM, Udine 2013
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P. Laryushkin and V. Glazunov
leg prevents the moving platform from rotating around a certain axis and, as all three axes are linearly independent, this mechanism does not exhibit constraint singularities. Lee (Lee and Herv´e, 2006) has presented a concept of the 3-R-R-R-R-R mechanism that is similar to one which presented in this paper. In this paper, we present a 3-DOF translational parallel mechanism with three legs consisting of five revolute joints. We analyze its kinematics, workspace, singularities and dynamics. Singularity analysis is based on both Jacobian matrix (Gosselin and Angeles, 1990) and screw theory (Dimentberg, 1965, Glazunov, 2010) and dynamics is analyzed by LagrangeD’Alembert principle. All obtained theoretical results are tested on a virtual model of the mechanism within MATLAB/Simulink environment. The main contribution of th
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