We have generated a large number of pose vectors by assigning values within the workspace required for gait rehabilitation. For this, a set of motion has been designed by our physiotherapist to consist all the six parameters of motion for gait rehabilitation purpose. The prescribed movement consist of three position coordinates of the center of mass of mobile platform in the base frame (X, Y, Z) and three Roll-Pitch-Yaw rotation angles of mobile platform with respect to the base frame (three rotation angles of mobile platform in space consist of , and angles, see Fig. 3). It is noted that regularly spaced intervals within the range of pose components will not produce uniform link space coverage due to the nonlinear forward kinematics mapping. Moreover, some combinations of the pose vector components may result in infeasible link values. There can be two types of such infeasible values. The first type occurs when substituting a generated pose vector in Eq. 5 which produces link lengths that are outside their physical range. The second type is due to mechanical constraints, e.g. limitation on the joints connecting the links to the base or platform, links crossing each other, etc. A complete analysis of Stewart workspace presented in 24, 25. In both cases, the infeasible link data and their corresponding pose are removed from the data set and will not be used.
Any solution for the FKP of Stewart robot—either mathematical or soft computing methods—involve applying the length data of the robot’s limb as inputs and obtain the position and rotation angle as output; as shown in Fig. 3. Accordingly, in the present study to model the forward kinematic of a Stewart robot, the lengths of the robot’s limbs from the generated data set will be used as inputs for modeling, and then the obtained outputs from models will be compared with their counterparts in the generated data set.