Design of Pressure Control for Optimal Damping in Individual Metering Systems
Date Issued
2021-06
Author(s)
Rath, Gerhard
Stojanoski, Goran
Abstract
Modern oil-hydraulic systems for moving heavy payloads are designed for optimised
motion, but also for minimal energy loss. Individual metering technique, using separate
control of the two actuator chambers, offers some advantages. A common strategy
when moving the load is to control the incoming oil flow to obtain a desired speed,
and the pressure at the downstream side for good efficiency. In this work analysis and
design of PI (proportional-integral) pressure control is done. The adjustment of the
control parameters of this loop is usually uncritical. In the worst case, the damping
of the mechanical system is the only contribution. It is shown in this work, that pressure
control can increase the damping of load oscillations. The influence of the P and
I parameters to the system properties is investigated using the poles of the transfer
function of the system. It is shown, that there is a point, where the damping factor
of the system has its maximum value, and a design method for this optimisation is
given. The problem ends up in a system of two equations of fourth order. A method is
shown how to reduce the problem to solving one third-order equation, which is done
numerically. Finally, the results are verified using simulation.
motion, but also for minimal energy loss. Individual metering technique, using separate
control of the two actuator chambers, offers some advantages. A common strategy
when moving the load is to control the incoming oil flow to obtain a desired speed,
and the pressure at the downstream side for good efficiency. In this work analysis and
design of PI (proportional-integral) pressure control is done. The adjustment of the
control parameters of this loop is usually uncritical. In the worst case, the damping
of the mechanical system is the only contribution. It is shown in this work, that pressure
control can increase the damping of load oscillations. The influence of the P and
I parameters to the system properties is investigated using the poles of the transfer
function of the system. It is shown, that there is a point, where the damping factor
of the system has its maximum value, and a design method for this optimisation is
given. The problem ends up in a system of two equations of fourth order. A method is
shown how to reduce the problem to solving one third-order equation, which is done
numerically. Finally, the results are verified using simulation.
Subjects