Structure Parameter - AntiSwayOpenLoop

Structure Parameter - AntiSwayOpenLoop_2

i_stPAS

A structure of the data type PAS containing configuration parameters.

For example, a declaration of structure variable with initial values:

VAR

struct_instance: data_type := (element1 := XX, ement2 := YY);

END_VAR

Parameter	Data Type	Description
wDrvSpdRefMax	WORD	Maximum speed reference for the drive. Range: 1...6000 (default is 1500) Scaling/Unit: RPM (alternatively 0.1 Hz, the unit must be the same as i_wDrvSpdRef)
rSpdLinMax	REAL	Maximum linear speed corresponding to maximum speed reference. Range: 0.0001...5 (default is 1) Scaling/Unit: m/s (accuracy 0.001 m/s)
wAswAccDsbl	WORD	Acceleration ramp time between zero and i_stPAS.wDrvSpdRefMax for operation without Anti-sway. When the Anti-sway is disabled, the system accelerates using a linear ramp. Range: 5...300 (default is 50) Scaling/Unit: 0.1 s
wAswDecDsbl	WORD	Deceleration ramp time between i_stPAS.wDrvSpdRefMax and zero for operation without Anti-sway. When the Anti-sway is disabled, the system accelerates using a linear ramp. Range: 5...300 (default is 50) Scaling/Unit: 0.1 s
wAswAccStrt	WORD	Acceleration ramp time between zero and i_stPAS.wDrvSpdRefMax for operation with Anti-sway enabled, before the Anti-sway action starts (while the speed reference is under i_stPAS.rAswSpdStrt). The FB uses this parameter to calculate a ramp for smooth transfer between pre-Anti-sway and Anti-sway speed profile. Range: wAswRampLim...300 (default is 100) Scaling/Unit: 0.1 s
wAswDecStrt	WORD	Deceleration ramp time between i_stPAS.wDrvSpdRefMax and zero for operation with Anti-sway enabled, before the Anti-sway action starts (while the speed reference is under i_stPAS.rAswSpdStrt). The FB uses this parameter to calculate a deceleration ramp analogic to pre-Anti-sway acceleration ramp. Range: wAswRampLim...300 (default is 100) Scaling/Unit: 0.1 s
wAswRampLim	WORD	Maximum allowed acceleration for Anti-sway. Range: 5...300 (default is 20) Scaling/Unit: 0.1 s Refer to detailed description below this table.
wDrvDecEmgy	WORD	Emergency deceleration ramp time. This sets a short emergency ramp, used in case of an emergency stop without the Anti-sway function. This ramp is based on the stop limit switch and in the case that the feedback signal from a brake goes to FALSE during a movement. Range: 1...100 (default is 5) Scaling/Unit: 0.1 s
wBrakDly	WORD	Brake open delay. Range: 0...5000 (default is 0) Scaling/Unit: ms NOTE: This function is active in both, enabled and disabled state of the FB. Refer to detailed description below this table.
rCoefFrct	REAL	Friction coefficient. Range: 0...1 (default is 0.2) Refer to detailed description below this table.
rAswSpdStrt	REAL	Speed threshold for activation of Anti-sway function. Range: 0...100 (default is 25% of maximum speed) Scaling/Unit: 1% Refer to detailed description below this table.
rAswSpdEnd	REAL	Speed threshold for stopping the movement with active Anti-sway function. Anti-sway movement is finished when the output speed reference is below i_stPAS.rAswSpdEnd for longer than i_stPAS.wAswTimeEnd. Range: 0...20 (default is 1% of maximum linear speed) Scaling/Unit: 1%
wAswTimeEnd	WORD	Time of speed below rAswSpdEnd before deactivation of Anti-sway. This defines how long the output speed reference must remain below i_stPAS.rAswSpdEnd before finishing the movement. Range: 0...5000 (default is 200) Scaling/Unit: 1 ms
wSmplRate	WORD	Controller cycle time. This is the period of execution of the Anti-sway FB. Too short a cycle time results in loss of information, because of over-sampling. Too long a cycle time results in loss of information due to under-sampling. Both cases degrade the Anti-sway performance. NOTE: A sampling rate between 40 and 100 ms is recommended. NOTE: AntiSwayOpenLoop_2 FB must run with a fixed execution period to work correctly. Range: 30...200 (default is 50, corresponding task must be periodic) Scaling/Unit: 1 ms
wCalcDistTime	WORD	Time reserved for stop distance calculation. Range: 0...wSmplRate (default is 0) Scaling/Unit: 1 ms Refer to detailed description below this table.
xOptimRampDecEn	BOOL	Enables additional stop ramp optimization. Refer to detailed description below this table.

NOTE: Unlike the acceleration and deceleration time parameters on the Altivar that are between zero and nominal speed, the ramp time values of Anti-sway FB are calculated between zero and maximum speed. Therefore the ramp times need to be set accordingly when the maximum speed does not equal the nominal speed of the drive to maintain the required ramp slope.

wAswRampLim

This parameter defines the steepest ramp the Anti-sway function is allowed to use in order to correct the sway. Lower values of this parameter makes the correction more aggressive and allow shortening of the acceleration and deceleration phase which improves load handling for the operator (it is easier to estimate a 2 m stop distance than a 4 m and therefore it is possible to arrive to a target position with much higher precision).

The disadvantage is that the stress of the crane structure is increased.

It is essential to find the right compromise during commissioning.

q_wStat bit 6 indicates whether an additional stop distance optimization is possible with the current combination of i_stPAS.wAswRampLim and i_rCbleLenActl. If it is not possible, the i_stPAS.wAswRampLim value can be lowered in order to allow for the optimization.

Stop distance optimization is beneficial mainly with longer cable lengths that approach or exceed 10 m. For shorter cable lengths, the effect is not that significant and the normal stopping distances are acceptable without optimization.

wBrakDly

This is an alternative to the feedback signal from a brake (i_xBrakFbck). If the brake feedback signal is not available and the i_stPAS.wBrakDly value is not zero, an internal timer is used to enable the speed profile generation instead.

If there is a command to run present (i_xDrvFwd or i_xDrvRev) and other conditions to start the movement are fulfilled, the corresponding direction output command (q_xDrvFwd or q_xDrvRev) is set to TRUE immediately. (in order to switch the drive to RUN state) Ramp generation starts after the time specified by i_stPAS.wBrakDly has elapsed.

rCoefFrct

This is the friction coefficient during the movement which is used to adjust the mathematical model to be closer to the behavior of the real crane. A high value for the friction coefficient results in higher damping of the calculated sway in the mathematical model. Use a low value for a hoist with a simple pulley block and a higher value for complex pulley blocks.

Example: set 0.1 for a single rope hoist without much friction, 0.9 for a hoist with a very complex pulley block, 12 thick ropes and a high friction.

rAswSpdStrt

This is the speed threshold for activation of the Anti-sway function (given in % of maximum speed).

When set to zero, Anti-sway is active from the beginning of a movement. As it corrects the sway continuously, this results in a less predictable behavior during short movements.

An alternative is to set this threshold higher than the lowest speed of the crane. This allows for short, accurate movements without Anti-sway.

wCalcDistTime

This defines how much time the FB is allowed to spend on recursive calculation of the required stop distance for one cycle. A zero value disables the calculation completely.

The calculation can run over several controller cycles. A low value for i_stPAS.wCalcDistTime saves processing time, but increases the number of controller cycles needed to finish the calculation. This decreases accuracy in the result especially during acceleration and deceleration.

A high value of i_stPAS.wCalcDistTime speeds up the calculation but requires more processing time. This must be taken in account especially when more than one AntiSwayOpenLoop_2 function blocks are executed simultaneously on a slow controller.

NOTE: The function is designed for use with automatic cranes. On manually controlled cranes it can be left disabled to save processing time.

xOptimRampDecEn

This parameter enables additional stop distance optimization. It allows a considerable shortening of a stop distance. Performance of this function depends on the maximum allowed steepness of acceleration and deceleration ramp (see description of i_stPAS.wAswRampLim. Sharper acceleration and deceleration ramps results in shorter stop distances and less time but at the cost of possibly higher mechanical stress to the crane structure.