CANopen Programmer's Manual - Maccon.de

4: Control Loop Configuration CANopen Programmer’s Manual
The Velocity Loop
Overview of the Velocity Loop
As shown below, the velocity loop limiting stage accepts a velocity command, applies limits, and
passes a limited velocity command to the input filter. The filter then passes a velocity command to
the summing junction. The summing junction subtracts the actual velocity, represented by the
feedback signal, and produces an error signal. (The velocity loop feedback signal is always from
the motor feedback device even when an additional encoder is attached to the load.) The error
signal is then processed using the integral and proportional gains to produce a current command.
Programmable digital filters are provided on both the input and output command signals.
Velocity
Command
Velocity Limiter
Filter
Limited
Velocity
Velocity Loop
Velocity Integral Gain (Vi)
Velocity Proportional Gain (Vp)
Limits:
Velocity
Acceleration*
Feedback (Derived Velocity)
Deceleration*
Emergency Stop Deceleration*
*Not used w hen velocity loop is controlled by position loop. See "Velocity Loop Limits" for details.
+
-
Current
Command
Velocity Loop Limits
The velocity loop starts with a command limiter. This is useful because the position loop may
produce large spikes in its output velocity command value that are beyond the safe operating
range of the motor. During normal operation, with the velocity loop driven by the position loop, the
limiter requires and accepts only a maximum velocity value.
Optionally, the velocity loop can be driven by an alternate source of control (such as such as the
device’s serial port, digital I/O channels, analog reference, or internal generator), without input
from the position loop. (See Alternative Control Sources Overview, p. 225.) In these cases, the
velocity loop limiter also requires and accepts maximum acceleration and deceleration values.
Velocity limiter parameters are accessed through the following objects:
Limiter Object Name/ID Page #
Velocity Loop – Maximum Velocity / 0x2103 (used in all control modes) 145
*Velocity Loop Maximum Acceleration / 0x2100 (used only without position loop) 144
*Velocity Loop Maximum Deceleration / 0x2101 (used only without position loop) 145
Velocity Loop Emergency Stop Deceleration / 0x2102 (used only without position loop) 145
*Not used when velocity loop is controlled by position loop.
Velocity Loop Input
The output of the velocity loop limiter is the input of the velocity loop. It is accessed through the
object Limited Velocity (index 0x2230, p. 146).
Velocity Loop Gains
The velocity loop uses the following gains. See Error! Reference source not found. (index
0x2381, p. 146).
Gain Description
Vp - Velocity loop
proportional
The velocity error (the difference between the actual and the limited commanded velocity) is
multiplied by this gain. The primary effect of this gain is to increase bandwidth (or decrease the
step-response time) as the gain is increased.
132 Copley Controls
+
+
Filter