Precise End-Position Control of Flexible Manipulators

Flexible manipulators, owing to their lightweight structure, high degrees of freedom, and environmental adaptability, hold great promise for applications in medical surgery, aerospace, industrial inspection, and other fields. However, challenges such as rigid-flexible coupling, strong nonlinear dynamics, and vibration sensitivity make precise end-effector positioning a core difficulty. This study constructs a system model for a flexible manipulator and implements end-position control using Proportional-Integral-Derivative (PID), Linear Quadratic Regulator (LQR), Sliding Mode Control (SMC), and an improved Fast Terminal Sliding Mode Control (FTSMC) method. Results show that PID control yields an overshoot of 4.6% with a settling time of 1.374 seconds, making it suitable for scenarios with highly accurate models. LQR control results in an overshoot of 5.7% and a settling time of 3.426 seconds; while energy-optimal under precise modeling conditions, its dynamic performance (in terms of overshoot and settling time) is inferior. The SMC controller demonstrates strong robustness with zero overshoot, but it has a slower rise time and requires attention to chattering suppression. FTSMC also shows strong robustness and eliminates overshoot, while achieving faster rise times, albeit with chattering issues that need to be addressed. This study identifies new application scenarios for the four representative control strategies and analyzes their respective strengths and limitations. Future work may focus on adaptive optimization by integrating fuzzy logic and neural networks, as well as improving practical applicability through robust control, model order reduction, and nonlinear control techniques.