Analytical study of underactuated mechanisms of anthropomorphic robotic gripper

Abstract

It is a characteristic features of anthropomorphous technology development at its current stage to be promoted from the sphere of production to the social life. The anthropomorphic robots have a particular place nowadays because they are capable of not only interacting with a human being but also fulfilling its actions in adverse conditions. The structure analogous to the human skeleton allows realizing similar kinematics and easier adapting them to the environment of the vital activity of people. As it is known the main functional steps are performed by grippers. The anthropomorphic grippers are used in most robots designs. Their creation requires the maximum coincidence of the number of degrees in mobility inherent to the same parameter of a human hand. However, the implementation of mobility with the required performance force of gripping when using contemporary drives appears to be a complicated task. The application variant of the group drive implementing the movement of members in kinematic pairs with parallel axes of rotation has been considered. Analytical research of the group drive mechanism in the two groups of executive members realizing the movements of a thumb separately in one group and simultaneous movements of other fingers in another group has been conducted. The expression of geometric relations in the vector form has been compiled for kinematic analysis, and then the system of scalar equations has been obtained. The solution for the system has been found numerically with MathCad mathematical package. As a result the graphs of angles change from the slider stroke, the position plans and trajectories of nodal points of mechanisms have been created and their angular velocities have been defined. These velocity plans allow obtaining permissible loads on the operating group of elements. The stated sequence of analytical study allows conducting kinematic and power analysis at the design stage.