Delta RMC151 - Manual (Page 100)

RMC70/150 and RMCTools User Manual
Force Pressure/Force Control, Pressure/Force Limit
High-Order Control
The RMC also supports Acceleration Control and Active Damping, for difficult-to-control
systems such as pneumatic cylinders.
Other
Cascaded Loops
Gain Scheduling
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.
For more details, see the Unidirectional Mode axis parameter.
Velocity and Torque Drives
Most actuators, together with their power source and/or drive electronics, can be
classified as velocity mode or torque mode. Which type it is affects the tuning procedure
and how the actuator handles certain RMC commands.
A velocity mode actuator produces a speed proportional to the Control Output. A torque
mode actuator produces a torque or force proportional to the Control Output.
For details, see the Velocity and Torque Drives topic.
3.5.2. Closed Loop Control
Closed Loop control uses feedback from the system being controlled. First, the RMC generates
a target (position, velocity, pressure, or force) which specifies where the axis should be at
each moment in order to move to the requested position. Then, the RMC compares the
feedback to the target and calculates how much Control Output should be given to make the
feedback match the target. The RMC repeats this for every control loop time. All closed-loop
commands specify the target to be generated. The tuning parameters specify how to calculate
the Control Output, which makes the axis follow the target.
Closed Loop Control Algorithms
The RMC offers several different algorithms for closed-loop control, depending on the feedback
type:
Feedback Type Closed-Loop Control Algorithms
Position
Position PID
Advanced:
Position I-PD
Velocity PID
Velocity I-PD
Velocity Velocity PID
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