Hybrid PID-feedforward control for trajectory tracking in 2-DOF robotic systems

Abstract

This paper presents a hybrid control strategy combining proportional-integral-derivative (PID) feedback with model-based feedforward compensation for precise trajectory tracking in two-degree-of-freedom (2-DOF) robotic manipulators. The approach addresses nonlinear dynamics, including inertial coupling, Coriolis effects, and gravity, by deriving the Euler-Lagrange equations for a planar arm and implementing a computed torque feedforward term augmented by PID correction. Theoretical stability is analyzed using Lyapunov methods, ensuring asymptotic convergence of tracking errors. Simulations demonstrate superior performance compared to standalone PID, with root-mean-square errors reduced to 0.5751° for the first joint and 1.4416° for the second under sinusoidal references. Results include phase portraits, torque decompositions, and sensitivity analysis to parameter variations, validating the method's robustness for industrial applications.