Modelling and simulation of mechanical transmission in roller-screw electromechanical actuators
Résumé
Purpose – To develop accurate model and simulation of mechanical power transmission within roller-screw electromechanical actuators with special attention to friction, compliance and inertia effects. To propose non intrusive experiments for the identification of model parameters with an integrator or system oriented view. Design/methodology/approach – At system design level, the actuation models need to reproduce with confidence the energy losses and the main dynamic effects. The adopted modelling methodology is based on non intrusive measurements taken on a standard actuator test-bench. The actuator model is firstly structured with respect to the Bond-Graph formalism that allows a clear identification of the considered effects and associated causalities for model implementation. Various approaches are then combined, mixing blocked or moving load, position or torque control and time or frequency domains analysis. The friction representation model is suggested using a step-by-step approach that covers a wide domain of operation. The model is validated under varying torque and speed conditions. Findings – A structured model is introduced with support of the Bond-Graph formalism. Combining blocked/moving load and time/frequency domain experiments allows the development of progressive model identification. An advanced friction representation model is proposed including the effects of speed, transmitted force, quadrant of operation and roller-screw preload. Originality/value – Mechanical transmission energy losses and dynamics are modelled in a system oriented view without massive need to confidential design parameters. Not only speed but also load and operation quadrant effects are reproduced by the proposed friction model. The non intrusive experimental procedure is made consistent with use of a standard actuator test-bench.