Task space control of a welding robot using a fuzzy coordinator

Abstract

This paper introduces a fuzzy coordinator as a novel application of fuzzy controller. A control transformation from the task space to the joint space is required to control a robot manipulator in the task space. Because the actuators operate in the joint space while the manipulator is controlled in the task space. A conflict between two spaces is produced due to using an imprecise transformation. Fuzzy coordinator coordinates two spaces by modifying the control transformation affected by uncertainties. The fuzzy coordinator is designed simply and operates as a robust controller. The role of fuzzy coordinator is analyzed and illustrated in the robust control of a welding robot in the task space. A circular trajectory is planned for a welding task performed by a SCARA robot. The fuzzy coordinator is then used to improve the performance of control system affected by imprecise transformations including the imprecise path transformation and the approximated feedback linearization.

Real-Time Robust and Optimized Control of a 3D Overhead Crane System

“…Despite the underactuated nature of overhead crane, the developed independent joint model provides a set of decoupled multi–input multi–output (MIMO) linear equations as derived in (7)–(9), and simplified swing dynamics in (10) and (11), where control inputs are now the actual applied voltages to the motors rather than driving forces [55]. The first set of equations can be used for tracking control purposes, and swing dynamics can be used for load swing suppression.…”

A new approach to overhead cranes parameter estimation and friction modeling

“…The remaining questions here are firstly what happens to the effects of swing dynamics in (7), and secondly, the nonlinear terms in disturbances f dx and f dl in (5)-(6) which depend on swing angle as can be seen in (9) and (10). The answer to the above questions lies in how the proposed parameter identification procedure is performed.…”

“…It should be noted that the input voltage limit of the motors and the maximum admissible motor torque restrict the range of the applied control input. Therefore, it seems beneficial to include both the coulomb friction and actuator dynamics as part the overall overhead crane model to be able to improve the performance of the overhead crane operation [10].…”