Comparison of performance between PID and LADRC algorithm in linear motion platform

The traditional linear motion platform in engineering applications is a typical large-inertia and nonlinear system. The lag and overshoot of response caused by the large inertial characteristics of the platform is a crucial point of control. The non-linear factors, such as the friction characteristics of the linear guide, the insensitivity zone and the saturation output characteristic of the amplifier, constitute uncertainty factors of the platform. The "error"-based Proportion, integral, derivative (PID) control algorithm can guarantee the accuracy within the same working condition, but cannot realize the self-tuning of parameters under the conditions of internal and external disturbances, which will directly lead to the decline of positioning accuracy. In this paper, the linear active disturbance rejection control (LADRC) algorithm based on "information" is applied to the control system. The total disturbance of the system is estimated by extended state observer (ESO) as much as possible and compensated in the controller. The experimental results show that the settling time of LADRC algorithm can be effectively decreased by more than 72% compared with the PID algorithm under the same working conditions. In the active disturbance rejection and sine tracking experiments, LADRC shows stronger robustness and better dynamic tracking capabilities.