Delta RMC151 - Manual (Page 99)

3 Controller Features
• Via Auto Stops.
After a Halt has Occurred
If the halt was caused by an Auto Stop, you should first make sure the error condition
that caused it has been resolved before continuing. Once it has been fixed, you can clear
the Halted status bit by issuing the Clear Faults (4) command. Issuing a valid motion
command will also clear the Halted status bit.
Why Bother?
This halt is useful when you want to set the Control Output to zero and turn off the
Enable Output because of a potentially dangerous error. The Open Loop Halt Ramp
parameter is used to avoid an abrupt (and potentially damaging) stop. If you wish to halt
the axis but still have closed loop control over it, use the Closed Loop Halt.
The Auto Stops can be set up to cause this halt when an error bit turns on.
3.5. Control Modes
3.5.1. Control Modes Overview
This topic describes various modes of control. For details on motion types, see the Controller
Features Overview.
Open Loop Control
Open Loop Control is the simplest form of control. A control output is given to a system,
for example 2 volts, causing the motion system to move at some approximate speed.
Open loop control does not use the feedback to determine how much Control Output
should be given. Therefore, in open loop control, there is no way of commanding the
system to go exactly at a specific speed or go to an exact position. See the Open Loop
Control topic for more details.
Closed Loop Control
Closed Loop control uses feedback from the system being controlled. For example, a
command is issued to go to 20 inches. The RMC computes a target (a motion path) to get
to 20 inches. For each control loop, the controller (the RMC) uses the feedback and the
gains to compute the amount of Control Output that should be given to the system so
that it follows the profile. The system will automatically go to 20 inches. See the Closed
Loop Control topic for more details.
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
Advanced:
Velocity I-PD
Pressure Pressure/Force Control, Pressure/Force Limit
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