Reduction of positional error in a path of a 2 DOF serial planar manipulator

Abstract

Tracing a path is one of the major applications of a robotic arm. In this paper, a 2 DOF serial planar manipulator which traces the desired path is discussed. Quite often the path is defined by accuracy points lying on it. To trace these points, joints of links of the manipulator are required to be given as a coordinated inputs θ 1 and θ 2 (input angles of two links). This path is traced with a desired speed indicated by the time at which the accuracy points are reached.In open-loop control, this is achieved by giving time, voltage/current input to driving motors. This path is determined based on the torque, acceleration, velocity of the linkages and individual joints. Hence the relationship between time and joint angles is necessary. When joint angles θ 1 and θ 2 are interpolated between two accuracy points, precise coordinated motion is not possible. Some deviation from the desired path will occur. This is the positional error for tracing the path. Here, analysis has been done to find the effect of degree of interpolation on the positional error.