Position Controller (Position Control Function) - Festo CiA 402 Manual

4 Setting parameters
4.6

Position controller (Position Control Function)

Overview
This chapter describes all parameters required for the position controller. The position setpoint value
(position_demand_value) of the curve generator is applied to the input of the position controller. In
addition, the actual position value (position_actual_value) is added from the angle encoder (EnDat,
incremental encoder, etc.). The actions of the position controller can be influenced by parameters. It is
possible to limit the output variable (control_effort) to keep the position control loop stable. The out-
put variable is supplied to the speed regulator as the speed setpoint value. All input and output vari-
ables of the position controller are converted in the Factor Group from the application-specific units
into the respective internal units of the regulator.
The following subfunctions are defined in this chapter:
1. Following error (Following_Error)
The deviation of the actual position value (position_actual_value) from the position setpoint value
(position_demand_value) is designated as a following error. If this following error is greater than
specified in the following error window (following_error_window) for a specific time period (follow-
ing_error_time_out), then bit 13 following_error is set in the object statusword. The permissible
time period can be specified via the object following_error_time_out.
Following_error_window (6065
Following_error_window (6065
Following_error_time_out (6066
Statusword, bit 13 (6041
Fig. 4.6 Following error – functional overview
Fig. 4.7 below shows how the window function is defined for the "following error" message. The
tolerance range (following_error_window) is defined symmetrically around the setpoint position
reference value (position_demand_value) If the drive leaves this window and does not return to the
68
)
h
0
)
h
)
h
)
h
Festo – GDCP-CMMS/D-C-CO-EN – 1404NH – English