Modeling, Design and Analysis of a Robot System for Garment Inspection

This paper presents the design and performance of a robot system that exerts a prescribed tension on fabrics to facilitate the inspection process. The robot system consists of a 3-DOF (degree-of-freedom) robotic hanger and an adaptive controller. In the hanger design, the second link is kept vertical, while that of the previous hanger has a redundant degree of freedom. In addition, this hanger has a shoulder link and a sleeve link that provide convenience for holding the garment. In the controller design, structure friction caused by joints and belt elasticity, which is non-linear in nature, are taken into consideration. Besides, the clothing stiffness also changes non-linearly with extension, which cannot be well handled by simple proportional-integral-derivative (PID) control. Due to these points, the fuzzy logic PID controller is chosen to deal with the non-linear features in this design. After establishing the system, the performance is analyzed by computer simulation, where different conditions are applied to compare fuzzy logic control with conventional PID control. The simulation results show that the fuzzy PID control method is effective in controlling the robot hanger and regulating the garment forces.