Hydraulic Linear Actuators with High Dynamic Load Stiffness

The simple, compact design and the high power and force density of linear-motion hydraulic actuators make them suitable for a wide range of applications in the machine building and systems engineering sectors. Linear hydraulic actuators do, however, demonstrate more elasticity with respect to the desired position than their electric counterparts by dynamically changing loads. The time response for maintenance of the desired position when subjected to dynamic load changes is referred to below as dynamic load stiffness.

This article begins by considering the elementary principles of a cylinder's stiffness. Afterwards it then goes on to describe various approaches in an attempt to increase dynamic load stiffness and to present the simulation results for the different systems. Then it concludes by discussing these results and using them as the basis for an assessment of the potential of each approach. Based on this assessment this article presents approaches for design of actuators with high dynamic load stiffness.