Robust, Fast and Accurate Solution of the Direct Position Analysis of Parallel Manipulators by Using Extra-Sensors

Forward kinematic model improvement of a spherical parallel manipulator using an extra sensor

“…A theoretical study of this approach is presented in the work of Vertechy and ParentiCastelli [8]. According to [8], the extra sensors are added for at least one of the following reasons: 1) to render the FKM an explicit problem with a closed form solutions; 2) to render the FKM a linear problem, which makes it possible to find the actual orientation of the mobile platform; 3) to speed-up the computation of the FKM solution; 4) to make the method robust against SPM singular configurations; and 5) to improve the accuracy of the solution by reducing the influence of the joint sensor sensibility. In this work, the extra sensor is added, first, to make the FKM robust against the singular configuration, second, to speed-up the computation time of the FKM and finally, to improve the accuracy of the FKM.…”

Performance Evaluation of a Sensor Concept for Solving the Direct Kinematics Problem of General Planar 3-RPR Parallel Mechanisms by Using Solely the Linear Actuators’ Orientations

“…In fact, the pose the algorithm converges to is neither necessarily the actual pose due to the quality of the initial pose estimation nor the closest possible pose next to the initial estimate [28]. The iterative algorithm might also fail to converge in case of singularities [28,51].…”

“…Merlet [28] extensively discussed possible additional sensor concepts and Vertechy et al [51] presented a very detailed, chronological review. Usually, length sensors and rotary sensors are used as additional sensors to derive the orientations of the linear actuators or passive legs in addition to the linear actuators' lengths, see, for example, References [16][17][18][19][20][21][22][23]51,[53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68]. However, several other sensor types were proposed as additional sensors for solving the direct kinematics problem.…”

On Using Inertial Measurement Units for Solving the Direct Kinematics Problem of Parallel Mechanisms

“…In these references, the authors use additional length sensors, rotary sensors, or orientation sensors such as inertial measurement units (IMUs) to derive the orientations of the linear actuators or passive legs in addition to the linear actuators' lengths. In this context, Merlet [59] extensively discussed possible additional sensor concepts, and Vertechy et al [58] presented a very detailed, chronological review. However, none of the concepts presented so far can guarantee to find the actual pose of the manipulator platform unambiguously, fast, and universally valid.…”

“…However, none of the concepts presented so far can guarantee to find the actual pose of the manipulator platform unambiguously, fast, and universally valid. Most of the concepts using additional sensors fail in terms of applicability [37,38,49,55,59], while the concepts using additional numerical methods fail in terms of computational speed and the fact that they cannot guarantee to converge to the correct solution, see, for example, [58,59].…”