Optimized fuzzy sliding mode control to enhance chattering reduction for nonlinear electro-hydraulic servo system

Variable structure control with sliding mode can provide fine control performance and robustness. However, chattering phenomenon introduced due to discontinuous switching gain limits their applications. To achieve precise tracking performance with reduced chattering effect, fuzzy sliding mode control is introduced and evolutionary simultaneous tuning of control parameters is employed. Novel evolutionary algorithm (NEA) is applied for simultaneous optimization process due to its computational efficiency and reliability. Chattering reduction issue is further improved by introducing the weighting factors estimation technique. In this technique, weighting factors for each control term are estimated with the objective to provide control action according to desired response. The integrated weighted control action not only reduces the chattering amplitude but also improves the tracking performance. The proposed techniques are applied to nonlinear electro-hydraulic servo system. Extensive simulation and experiment results indicate that proposed schemes not only improve the tracking performance but also ensure chattering reduction. Further, controller developed based on proposed schemes sustains the performance under parametric uncertainties and disturbances.