A practical method for parameter identification of optical tweezers in a flow field with control

In this paper, we propose a practical method for identifying the dynamic parameters of an active optical tweezers (OT) system operating in a flow field. It enables rapid and low-cost estimation of three key dynamic parameters: OT trap stiffness, trapping range, and flow field velocity, using only a single circular trajectory. By relying on a single circular trajectory, the proposed method reduces both the number of required measurements and computational steps. Fractional-order control is introduced into the automatic optical tweezers (AOT) system to enhance its precision and robustness, leveraging the superior dynamic tuning capabilities of the fractional-order Proportional–Integral–Derivative (FOPID) controller. The FOPID control strategy, incorporating Anti-Windup integrator and feedforward compensator, serves primarily to validate the parameter identification results and improve operational accuracy under uniform flow conditions. Numerical simulations and experimental analyses demonstrate that the proposed method reduces overshoot by 0.5μm and improves tracking accuracy by 15%, showing significant improvement over conventional methods.