Delta RMC101 - Manual (Page 653)

Appendix A: Command Reference
A-1
Appendix A: Command Reference
A.1 General ASCII Commands
A.1.1 I-PD Position Move Command
Character: !
Decimal: 33
Hexadecimal: 0x21
Command Value: Requested Position, in position units
The I-PD Position Move command initiates a position move using the I-PD control algorithm. All
other motion commands in the RMC100 use the PID control algorithm.
The Acceleration and Deceleration fields are not used. The Speed field is the maximum velocity
allowed during the move. The Command Value is the requested position.
I-PD Explained
The I-PD control algorithm does not generate a target motion profile like the PID. Instead, the
Target Position is always the same as the Command Position. This causes a step jump in the
Target Position, which would normally cause a large step jump in the drive with the PID. The I-PD
does not cause a large jump in the drive.
I-PD moves are simpler than PID moves, but are not as precise in terms of specifying the profile
or the time it will take to reach final position.
Using I-PD to Follow Another Axis
The I-PD can be used to follow another axis. The I-PD will lag slightly behind the master during
motion, but will get to the same position as the master when stopped. The I-PD can only follow
the Actual or Target Position of the master with an offset. One suitable use for the I-PD is
following a moving axis when the initial difference between the master and slave positions is
large.
To follow an axis:
• Select the Gearing bit in the Mode word and select whether to gear to the master's Actual or
Target Position.
• The Accel, Decel, and Speed fields are not used.
• Specify the offset in the Command Value field.
• Issue the I-PD command.
Tuning I-PD Motion
The I-PD uses the Proportional, Integral and Differential gains, but not the Feed Forwards or
Accel Feed Forwards. The gains determine how quickly the I-PD gets into final position, as