0000000000210210
AUTHOR
Petter H. Gøytil
A Novel Solution for the Elimination of Mode Switching in Pump-Controlled Single-Rod Cylinders
This paper concerns the stability issue of pump-controlled single-rod cylinders, known as mode switching. First, a review of the topic is provided. Thereafter, the most recently proposed solution for the elimination of mode switching is investigated and shown to result in unstable behavior under certain operating conditions. A theoretical analysis is provided demonstrating the underlying mechanisms of this behavior. Based on the analysis, a novel control strategy is proposed and investigated numerically. Proper operation and stability are demonstrated for a wide range of operating conditions, including situations under which the most recently proposed solution results in unstable behavior a…
On the Energy Efficiency of Dual Prime Mover Pump-Controlled Hydraulic Cylinders
Abstract This paper concerns the energy efficiency of a special class of pump-controlled hydraulic cylinders utilizing two prime movers. The performance of such circuits has been studied previously motivated by their capability of providing an actuator stiffness similar to that of servo valve-controlled systems. This characteristic may improve performance and robustness in applications requiring feedback control. In this paper, the presence of losses similar to that of fluid throttling, in the sense that they occur even in the absence of component inefficiencies, are demonstrated for such circuits and shown to degrade the overall energy efficiency of the system. The conditions under which s…
Iterative Learning Applied to Hydraulic Pressure Control
This paper addresses a performance limiting phenomenon that may occur in the pressure control of hydraulic actuators subjected to external velocity disturbances. It is demonstrated that under certain conditions a severe peaking of the control error may be observed that significantly degrades the performance of the system due to the presence of nonlinearities. The phenomenon is investigated numerically and experimentally using a system that requires pressure control of two hydraulic cylinders. It is demonstrated that the common solution of feed forwarding the velocity disturbance is not effective in reducing the peaking that occurs as a result of this phenomenon. To improve the system perfor…
Motion Control of Large Inertia Loads Using Electrohydrostatic Actuation
Electrohydrostatic actuation is an emerging technology combining the advantages of hydraulic and electric actuation, resulting in energy efficient solutions that appear electric from the outside while hydraulic on the inside. Conventional solutions, however, significantly reduce the natural frequency of the system compared to traditional hydraulic actuators. This may result in considerable loss of performance under feedback control. In this paper, a simple modification for increasing the natural frequency of the system involving a high-pressure accumulator is proposed and investigated. Theoretical analysis demonstrates the potential for considerable improvements using the proposed solution,…