Free-model fractional-order absolutely continuous sliding mode control for euler-lagrange systems

Euler-Lagrange systems, such as robots, exhibit benign structural properties, including passivity, which allow us to design robust and efficient energy-shaping controllers. A great variety of passivity-based control schemes are available and recently model-based fractional order discontinuous sliding mode control has been proposed. In this paper, a fractional order absolutely continuous control scheme for Euler-Lagrange systems is proposed, without depending on the dynamic model, which enforces in finite-time a commensurable rational fractional order regime. Additionally, a frequency domain analysis is addressed, which is very useful for some applications. A numerical simulation assessment is presented, including the frequency domain response based on Bode plots. Final concluding remarks are discussed in view of the state of the art in fractional order controllers.