Crane and control system for crane
A crane that controls an actuator on the basis of a target speed signal Vd of cargo W includes: a control device having a feedback control unit that calculates a target path signal Pdα of the cargo from the target speed signal Vd by integration to correct the target path signal Pdα on the basis of the differential of current position coordinates p(n) of the cargo W corresponding to the target path signal Pdα; and a feedforward control unit that adjusts a weight coefficient of a transfer function G(s) expressing the characteristics of the crane on the basis of a target path signal Pd 1 α that has been corrected. The target path signal Pd 1 α corrected by the feedback control unit is corrected using the transfer function G(s) for which the weight coefficient has been adjusted by the feedforward control unit.
1. A crane in which an actuator is controlled based on a target speed signal relating to a moving direction and a speed of a load suspended by a wire rope supported by a boom, the crane comprising:
a manipulation tool with which the speed and the moving direction of the load for the target speed signal are input; and
control circuitry including a feedback control section that is configured to compute a target course signal for the load by integrating the target speed signal and generates a first correction target course signal by subtracting a signal relating to the current position of the load from the target course signal, and a feedforward control section that is configured to adjust a weight coefficient of a transfer function representing a characteristic of the crane based on the first correction target course signal,
wherein the control circuitry is configured to
generate a second correction target course signal by correcting the first correction target course signal with the output of the feedforward control section,
compute a current position of a tip of the boom relative to the reference position based on a swivel angle of the boom, a luffing angle of the boom and an extension/retraction length of the boom,
compute a let-out amount of the wire rope based on the current position of the load and the current position of the tip of the boom,
compute a direction vector of the wire rope based on the current position of the load and a target position of the load computed based on the second correction target course signal,
compute a target position of the tip of the boom for the target position of the load based on the let-out amount of the wire rope and the direction vector of the wire rope, and
generate an operation signal for the actuator based on the target position of the tip of the boom.
2. The crane according to claim 1 , wherein:
the control apparatus includes a plurality of the feedforward control sections; and
the transfer function is decomposed into one or more first-order models, the weight coefficient is provided for each of the one or more models, and the weight coefficient that is adjusted is assigned for each of the feedforward control sections.
3. The crane according to claim 1 or 2 , wherein the transfer function is expressed by Expression 1 including a low-pass filter that curbs a predetermined frequency component:
[1]
(
Expression
1
)
G
(
s
)
=
W
α
1
s
+
W
α
2
(
A
s
+
1
)
+
W
α
3
(
B
s
+
1
)
+
W
α
4
(
Cs
+
1
)
(
1
)
where each of A, B and C is a coefficient, each of wα1, wα2, wα3 and wα4 is a weight coefficient and s is a differentiation element.
4. A control system for a crane in which an actuator is controlled based on a target speed signal relating to a moving direction and a speed of a load, the control system comprising:
a feedback control section configured to compute a target course signal for the load by integrating the target speed generate a first correction target course signal by subtracting a signal relating to the current position of the load from the target course signal, and compute a target position of the load based on the first correction target course signal; and
a feedforward control section configured to adjust a weight coefficient of a transfer function representing a characteristic of the crane based on the first correction target course signal and correct the first correction target course signal by an output generated based on the target speed signal and the transfer function with the weight coefficient adjusted,
wherein each time the target course signal is corrected in the feedback control section, the weight coefficient of the transfer function is adjusted by the feedforward control section.
5. The control system for a crane according to claim 4 , wherein:
the control system includes a plurality of the feedforward control sections; and
the transfer function is decomposed into one or more first-order models, the weight coefficient is provided for each of the one or more models, and the weight coefficient that is adjusted is assigned for each of the feedforward control sections.
6. The control system for a crane according to claim 4 , wherein the transfer function is expressed by Expression 1 including a low-pass filter that curbs a predetermined frequency component:
[1]
(
Expression
1
)
G
(
s
)
=
W
α
1
s
+
W
α
2
(
A
s
+
1
)
+
W
α
3
(
B
s
+
1
)
+
W
α
4
(
C
s
+
1
)
(
1
)
where each of A, B and C is a coefficient, each of wα1, wα2, wα3 and wα4 is a weight coefficient and s is a differentiation element.