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

Abstract

In this paper, we investigate the accuracy and the computational efficiency of an IMU-based approach for solving the direct kinematics problem of parallel mechanisms with length-variable linear actuators under dynamic conditions. By avoiding to measure the linear actuators’ lengths and by using orientations instead, a comprehensive, low-cost sensor structure can be obtained that provides a unique solution for the direct kinematics problem. As a representative example, we apply our approach to the planar 3-RPR parallel mechanism, where P denotes active prismatic joints and R denotes passive revolute joints, and investigate the achievable accuracy and robustness on a specially designed experimental device. In this context, we also investigate the effect of sensor fusion on the achievable accuracy and compare our results with those obtained from linear actuators’ lengths when the Newton-Raphson algorithm is used to compute the manipulator platform’s pose iteratively. Finally, we discuss the applicability of inertial measurement units (IMUs) for solving the direct kinematics problem of parallel mechanisms.

Vision-Based Rigid-Body and Deformation Motion Extraction of High-Speed and Flexible Mechanisms with Multiple Connected Components

“…In general, this motion consists of a large rigid-body translation and rotation in combination with smaller component deformations, and the motion is constraint by the inter-component connections. In the past, accelerometers [3,4], linear and rotational joint encoders [3,4,5], gyroscopes [4] and inertial measurement units (IMUs) [5,6] are all been used for the motion measurement of these mechanisms. However, as these sensors provide spatially discrete measurements, they are not suited for full-field motion measurements of flexible component systems.…”