Passive systems have the beneficial property that their interconnections with other passive systems result in necessarily stable systems. This vmue of passive systems can be exploited with hydraulic systems to build owerful machines that are safe and human friendly. A digculty in a plying the passivity concept to electrohydraulic systems is i a t they are not intnnsically passive. In a previous...

In the general framework of hydraulic servo systems, this paper addresses the problem of position control in the presence of important friction nonlinearities. The accent falls on the variable structure methodology, as we try to use its intrinsic robustness properties. Several friction observers, including the one based on a variable structure approach, were incorporated and tested in an accele...

Hydraulic machines used in mining and excavation applications are non-linear systems. Besides the nonlinearity due to the dynamic coupling between the different links there are significant actuator non-linearities due to the inherent properties of the hydraulic system. Optimal motion planning for these machines, i.e. planning motions that optimize a user-selectable combination of criteria such ...