تصميم نظام تحكم لا خطي لتحسين الأداء الديناميكي لذراع روبوتية تسلسلية 4dof

Abstract

Robotic systems exhibit nonlinear characteristics, making linear control methods ineffective in mitigating vibrations and nonlinear parameters that unpredictably affect their responsiveness, ultimately reducing their overall performance.

In this study, we designed a Fuzzy PID (FLC-PID) controller for an open-source model of a serial robotic arm with four degrees of freedom (4-DOF) powered by servo motors. The performance of this controller was compared with the conventional P-PI controller in a MATLAB environment to enhance dynamic control over the angular position of joints and minimize end-effector deviation along the x, y, and z axes.

The proposed fuzzy control unit was tested at the joint level, considering the forces and torques affecting the joints and causing movement, as well as the variants that induce disturbances, such as gravitational acceleration, which jointly impact the performance of robotic systems.

Simulation and modeling results showed that the fuzzy control unit outperforms the conventional proportional-integral (P-PI) controller. It demonstrated high resistance to noise and disturbances that could affect the studied robotic system, leading to a reduction in maximum overshoot and static error in determining the angular position of the joints—ensuring better and more accurate tracking of angular position values. Additionally, it proved its ability to minimize the deviation of the end-effector position from the coordinate axes (x, y, z) to 0% when a constant input was applied while maintaining an error rate close to zero during the system’s time response to variable input. It also achieved an angular rotation close to the reference values of the input trajectory within a short time, with a small maximum overshoot of 11% and positioning errors of 0.04%, 0.02%, and 0.05% on the coordinate axes.