Dynamic modeling and impedance control of a shield-type flexible support device

To address the problems that complex and variable surrounding rock conditions during coal mine roadway support can cause stress concentration and rock strata damage when traditional rigid support systems are used, this study investigated the dynamic modeling and impedance control of a shield-type flexible support device. A dynamic model of the shield-type flexible support device was established using the Lagrange method. To meet the support force requirements of the heading face, a dual-loop sliding-mode impedance control strategy comprising outer-loop impedance control and inner-loop sliding-mode control was proposed. The outer-loop impedance controller generated pose correction commands according to the support force error, while the inner-loop sliding-mode controller achieved accurate pose tracking based on the dynamic model. A hyperbolic tangent function was introduced to eliminate the inherent chattering of the sliding-mode controller, and the stability of the control system was ensured using Lyapunov stability theory. Simulation experiments were conducted on the MATLAB/Simulink platform under three types of operating conditions: constant reference support force, varying reference support force, and varying environmental stiffness. The results showed that under constant reference support forces of 300, 600, and 900 kN; step, multiple, and continuous changes in the reference support force; and abrupt, continuous, and random variations in surrounding rock stiffness, the proposed method achieved rapid and stable tracking of the support force. The response time was less than 1 s, the steady-state error did not exceed 1%, and the overshoot was less than 5%. The proposed method exhibits good adaptability and disturbance rejection capability.