Delta RMC151 - Manual (Page 109)

3 Controller Features
Non-Linear Valves
Non-linear valves have a profile where the flow of the valve is linearly proportional to the
command signal input. Common types are single-knee, and curvilinear. The RMC
motion controllers provide single-point linearization for single-knee valves.
Single-Knee Valve Curvilinear Valve
Affect on Control
The motion controller's PID control algorithm expects that the hydraulic axis will produce
a velocity that is linearly proportional to the Control Output voltage, which a linear valve
does. If the velocity is not linearly proportional—such as in a non-linear valve—the gains
will not be able to achieve optimum control. This especially affects the Velocity Feed
Forwards, which depend on a linear relationship.
3.5.10. Unidirectional Mode
Unidirectional Mode, also known as Absolute Mode, is specifically designed for systems that
require a unipolar control signal. Some common cases are:
• Two Hydraulic Valves
Some hydraulic systems have two valves, one for direction control, the other for flow
control. Unidirectional mode is for controlling the flow valve. The directional valve
must be controlled by other means, but Unidirectional Mode does provide for easy
switching of the control direction based on the directional valve setting.
• Unidirectional Belt
A belt that must always move in the same direction.
deltamotion.com 89