Trajectory tracking of a single flexible-link robot using a modal cascaded-type control

• Published in: Applied Mathematical Modelling Vol. 104; pp. 531 - 547
• Main Authors: Peza-Solis, J.F., Silva-Navarro, G., Garcia-Perez, O.A., Trujillo-Franco, L.G.
• Format: Journal Article
• Language: English
• Published: New York Elsevier Inc 01-04-2022; Elsevier BV
• Subjects: Actuators; Cascaded control; Euler–Bernoulli beam; Mechanical systems; Modal analysis; Robots; Servocontrol; Servomotors; Sliding mode control; Tracking control; Trajectory control; Cascaded control; Euler–Bernoulli beam; Sliding-mode control; Modal analysis
• ISSN: 0307-904X; 1088-8691; 0307-904X
• DOI: 10.1016/j.apm.2021.12.002

•A cascaded-type model of a flexible-link robot is obtained for a simple representation of tip position in robot workspace.•Controller easy to implement using only joint angle and tip position measurements.•Asymptotic trajectory tracking of the robot tip is achieved.
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The control problem of a single flexible-link robot is addressed for tip position and trajectory tracking control, with no other actuators into the mechanical system than a servomotor installed at the rigid joint. A multi-modal cascaded-type model of the robot is obtained, where the angle of the rigid joint is considered as the control input for the flexible-link rather than the torque provided by the servomotor. A Sliding-Mode Control approach is used to overcome the rigid mode dynamics and ensure a precise tracking of a flexible-state dependent trajectory at the joint level. The proposed control scheme is simple, easy to implement and yet robust against parametric uncertainties. The main results show that, trajectory tracking at the tip of the flexible-link is achieved, with guaranteed closed-loop stability, since the problem is reduced to the tracking of an adequate trajectory at the joint level. The proposed results are validated with several experimental results. Finally, the control scheme is quantitatively compared with two different controllers for flexible robots.