An Efficient Unified Method for the Combined Simulation of Multibody and Hydraulic Dynamics: Comparison with Simplified and Co-Integration Approaches

A formulation developed at the Laboratory of Mechanical Engineering allows robust and efficient simulation of large and complex multibody systems.Simulators of cars, excavators and other systems have been developed showing that real-time simulations are possible even when facing demanding manoeuvres.Hydraulic actuators are present in many industrial applications of multibody systems, like in the case of the heavy machinery field.When simulating the dynamics of this kind of problems that combine multibody dynamics and hydraulics, two different approaches are common: to resort to kinematically guide the variable length of the actuator, thus avoiding the need to consider the dynamics of the hydraulic system; or to perform a multi-rate integration of both subsystems if a more detailed description of the problem is required, for example, when the objective of the study is to optimize the pump control.This work addresses the inclusion of hydraulic actuators dynamics in the abovementioned self-developed multibody formulation, thus leading to a unified approach.An academic example serves to compare the efficiency, accuracy and ease of implementation of the simplified (kinematic guidance), multi-rate and unified approaches.Such a comparison is the main contribution of the paper, as it may serve to provide guidelines on which approach to select depending on the problem characteristics.