Elmo HARmonica, HARSFEN0602 software manual 130, Dual feedback mode UM=4

HARSFEN0602ElmoHARmonicaSoftwareManual PRELIMINARYDRAFT

The commutation accuracy will be limited by backlash and gear compliance

•The motor speed can be measured with better resolution and less delay because the

motor rotates much faster than the load. In addition, the speed sensor is not subject to dead zones caused by backlash.

The block diagram the dual feedback mode UM=4 is depicted below:

130

	Enable if
	RM==1	d/dt
Auxiliary position	Stop
command	manager
		-
		DV[3]
Software
position	Smoother
com m and	Σ
Stop and limit
switches
Auxiliary
feedback
encoder
main feedback	Speed
encoder	Estimator

d/dt

FF[2]

Position

Controller

Position

correction

Acceleration

feed forward

FF[1]

Speed

Error

-

DV[2]

Figure 22: Dual feedback mode (UM=4)

The position and the speed commands are generated by:

The position software command generator

The position auxiliary command generator

•The position Stop Manager

The generation of the position and speed commands is similar to the position and speed commands generation in UM=4, and will be described later the chapter on "The position reference generator".

The speed command, multiplied by the gain FF[2], is fed as reference to the speed controller in addition to the position correction. When FF[2] is set exactly to the gear ratio between the position sensor and the speed sensor, there will be no steady state constant-speed tracking error.

The acceleration of the position command, multiplied by FF[1], can be injected directly as torque command. By default, FF[1]=0.

The reference values to the position, speed, and torque controllers can be inquired by DV[3],DV[2], and DV[1] respectively.