Friction-resilient position control for machine tools—Adaptive and sliding-mode methods compared

Adaptive and sliding mode friction-resilient machine tool positioning – Cascaded control revisited

“…This paper extends the study done in [42] by revisiting the position-velocity cascaded architecture for machine tool axis positioning. The proposed designs comprise a P controller for the position loop, followed by a nonlinear controller for the motor velocity.…”

“…Although the powerful robustness properties of these controller families have been extensively analysed, their performance and applicability to machine tool control had not been adequately assessed, especially in comparison to the conventional P-PI cascades. Such a comparative study was carried out in [42], in which the performance of three nonlinear controllers, namely of an Adaptive Backstepping Controller (ABSC), an Output Super-twisting Sliding Mode Controller (OSTSMC) and an Adaptive Super-twisting Sliding Mode Controller (ASTSMC), was experimentally assessed with respect to high-accuracy and robustness against unknown and increasing friction. All three controllers shared the same direct-position architecture, i.e.…”

“…The motivation for this approach was to utilize the friction-resilience of the nonlinear controllers and at the same time reduce the design complexity that direct positioning methods introduce. Similarly to [42], the designs are based on sliding-mode and nonlinear-adaptive control principles. Specifically, a Super-twisting Sliding Mode Controller (STSMC), a certainty-equivalence Nonlinear Adaptive Controller (NAC) and a Immersion and Invariance Adaptive Controller (I&I-AC) are proposed for the motor velocity.…”

“…The theoretical properties of each solution are elaborated and the controller's performance is assessed through experiments conducted on state-of-the-art machine tool equipment. The proposed nonlinear methods are systematically compared to the standard P-PI cascade and to the controllers from [42], based on criteria for robust positioning accuracy, efficiency and overall complexity of each method.…”

“…Section 4 presents the design of the proposed control schemes used for axis positioning, along with the stability and convergence properties of the closed-loop system. Experimental results on the performance of the control schemes are presented in Section 5, while Section 6 offers an overall comparison of the controllers to the methods proposed in [42]. Finally, conclusions and future work are discussed in Section 7. where ω m , ω l are the motor and load angular velocities, respectively.…”