An Active Zero-Stiffness Eddy Current Damper for Low-Friction Pneumatic Cylinder Optimization

Pneumatic cylinders often face challenges in high-precision motion control due to their low damping characteristics. This study develops an actively controllable zero-stiffness hybrid excitation eddy current damper (ECD) with adaptive damping adjustment, tailored to meet the diverse application needs of low-friction cylinders. The proposed active ECD combines the advantages of passive and electric excitation ECDs, offering a compact design with a minimal air gap, thereby providing substantial damping within confined cylinder spaces. Finite element analysis (FEA) validates the reliability of the theoretical modeling of the ECD. An impact test rig, equipped with air bearings, is developed to assess its behavior under variable excitation currents. The active ECD is integrated into a low-friction cylinder, and a cascade control strategy for pneumatic system control is employed. Experimental results, including step response and position tracking tests at various frequencies, demonstrate that the active ECD effectively reduces overshoot, settling time, and steady-state error, thereby significantly improving the position control accuracy of low-friction pneumatic systems.