Copley Controls Xenus Plus Series - Page 26

Xenus Plus User Guide 16-01344 Rev 06
Copley Controls 26
Trajectory Limits
In position mode, the trajectory generator applies the following user-set limits to generate the motion
profile.
Limiter
Description
Maximum Velocity
Limits the maximum speed of the profile.
Maximum Acceleration
Limits the maximum acceleration rate of the profile.
Maximum Deceleration
Limits the maximum deceleration rate of the profile.
Abort Deceleration
Specifies the deceleration rate used by the trajectory generator when motion is aborted.
Position Loop Inputs From the Trajectory Generator
The position loop receives the following inputs from the trajectory generator.
Input
Description
Profile Velocity
The instantaneous velocity value of the profile. Used to calculate the velocity feed forward
value.
Profile Acceleration
The instantaneous acceleration/deceleration value of the profile. Used to calculate the
acceleration feed forward value.
Limited Position
The instantaneous commanded position of the profile. Used with the actual position feedback
to generate a position error.
Position Loop Gains
The following gains are used by the position loop to calculate the velocity command:
Gain
Description
Pp - Position loop proportional
The loop calculates the position error as the difference between the actual and
limited position values. This error in turn is multiplied by the proportional gain
value. The primary effect of this gain is to reduce the following error.
Vff - Velocity feed forward
The value of the profile velocity is multiplied by this value. The primary effect of
this gain is to decrease following error during constant velocity.
Aff - Acceleration feed forward
The value of the profile acceleration is multiplied by this value. The primary effect
of this gain is to decrease following error during acceleration and deceleration.
Gain Multiplier
The output of the position loop is multiplied by this value before being passed to
the velocity loop.
Position Loop Feedback
Xenus Plus supports two position feedback configurations
• Single sensor. Position loop feedback comes from the encoder or resolver on the motor.
• Dual sensor. Position loop feedback comes from the encoder attached to the load.
(Note that in either case, velocity loop feedback comes from the motor encoder or resolver.) For
more information, see Position Feedback (p. 17).
Position Loop Output
The output of the position loop is a velocity command used as the input to the velocity loop.