Structured Variable Description

i_stPGC

The following table describes the parameter structure of the data type i_stPGC

wDrvAcc

Acceleration ramp used for hold and close axes. The value is used by the FB in position synchroni­zation and load sharing as a base for output acceleration values q_wDrvAccHold and q_wDrvAccClose.

wDrvDec

Deceleration ramp used for hold and close axes. The value is used by the FB in position synchroni­zation and load sharing as a base for output deceleration values q_wDrvDecHold and q_wDrvDecClose.

wDrvSpdHsp

High speed value used for hold and close axes. Defines the maximum speed reference that the FB is allowed to use for both axes.

wEncPulsPerRevo

Number of encoder pulses per motor revolution. Must be identical for both axes.

wDrvSpdNom

Nominal (synchronous, without slip) speed of the motor. Must be identical for both axes.

50 Hz:

o1pole pair: 3000 RPM

o2pole pairs: 1500 RPM

o3pole pairs: 1000 RPM

o4pole pairs: 750 RPM

60 Hz:

o1pole pair: 3600 RPM

o2pole pairs: 1800 RPM

o3pole pairs: 1200 RPM

o4pole pairs: 900 RPM

rKpPosSync

Proportional gain of position controller used during position synchronization. It defines the difference of speed references of hold and close axes based on their actual position deviation. The default value is 0.01. It is internally normalized by encoder pulses per motor revolution i_stPGC.wEncPulsPerRevo and does not need to be changed when encoder type changes.

Decrease the value if motor speeds or torques are oscillating during position synchronization. Increase the value if the correction is not sufficient to reduce the position deviation to an acceptable value.

rKpTrqShr

Proportional gain of torque controller used during load sharing. It defines the difference of speed references of hold and close axes based on the actual difference of torques of both motors. Default value is 0.1. Decrease the value if motor speeds or torques are oscillating during load sharing. Increase the value if the correction is not sufficient to keep the motor torques at similar values.

wTrqAddOnClose

A torque offset for close axis. The FB allows for a torque difference between close and hold axes during load sharing when the grab is closed. This difference with higher torque on the close axis helps to keep the filled grab closed and prevent spillage of material. The default value is 50 [0.1%]. This parameter does not have any influence in hook mode.

wLowTrqDecRamp

An alternative short deceleration ramp used in downwards direction when a grab is on the ground. The ramp reduces the rope slack. It is used when the difference of torques of hold and close is below i_stPGC.wLowTrqDecRampThsh.

wLowTrqDecRampThsh

Torque threshold for switching between normal and alternative short deceleration ramp. [0.1%]. The function block switches the deceleration ramp to a short ramp defined in i_stPGC.wLowTrqDecRamp when the difference between hold and close motor torques gets below the value defined by i_stPGC.wLowTrqDecRampThsh. You can disable the function by setting i_stPGC.wLowTrqDecRampThsh to zero. The function is active when hold and close are moving synchronously. It is not active when the grab is opening or closing during downwards movement.

wClsHoldTrqLim

Torque limitation of hold motor during closing on stack. The value must be high enough to keep hold cables straight, but low enough to allow sinking of the grab into material during closing on stack. The usual value is between 10 and 15% of nominal torque. Default value: 100 [0.1%]

wClsHoldSpdRef

Speed reference for hold drive during closing on stack. The speed reference should be approximately 10% of nominal motor speed.

wClsTrqCloseThsh

Torque threshold of close motor for considering the grab closed. The threshold is an alternative to detecting closed state of the grab by relative position of hold and close axes. It is used when a full grab does not close completely because of bulky material. Typical example is a cactus (spider) grab used in scrap metal or waste handling. The right value of torque must be found during commissioning, ideally using a trace in EcoStruxure Machine Expert.

wClsTrqCloseTimeFltr

Time filter used for detection of closed state of the grab based on torque. It defines for how long must the torque of close motor stay above i_stPGC.wClsTrqCloseThsh to consider the grab closed. [ms]

wClsClosedPosOfst

Offset of closed position for closing on stack. This parameter allows exceeding the closed position during closing on stack. When controlling clamshell grabs, it is usually required to exceed the closed position during closing on stack to prevent spillage of material during lifting. Start with a zero value and increase it if the grab spills during lifting. Spider (orange peel) grabs do not close fully when they are filled with material and therefore it is not necessary to use this parameter. Set this value to zero when controlling a spider grab.

wScrapHoldTrqLim

Torque limitation of hold motor during scraping. The value is slightly higher than i_stPGC.wClsHoldTrqLim. The torque must be low enough for the jaws to stay in contact with the surface, but high enough to prevent the grab from scraping too hard. [0.1%]

wBrakTimeDelay

Estimation of the time brakes of hold and close axes need to open. This parameter is used to prevent one of the axes moving while the other one is opening its brake. [ms]

xTrqScopeScale

When TRUE, the values of actual torque are divided by 4.096 internally by the FB for scaling of the “Motor torque scope” object (SOTR). Logic address 3226, CANopen index 2002:1B to the standard -3000 to 3000 range with 0.1% resolution. If it is FALSE, input torque values must be scaled to this range outside of the FB.