EP0626337A1 - Procedure for controlling a crane - Google Patents
Procedure for controlling a crane Download PDFInfo
- Publication number
- EP0626337A1 EP0626337A1 EP94108141A EP94108141A EP0626337A1 EP 0626337 A1 EP0626337 A1 EP 0626337A1 EP 94108141 A EP94108141 A EP 94108141A EP 94108141 A EP94108141 A EP 94108141A EP 0626337 A1 EP0626337 A1 EP 0626337A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- oscillation
- hoisting
- procedure
- load
- length
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
- B66C13/00—Other constructional features or details
- B66C13/04—Auxiliary devices for controlling movements of suspended loads, or preventing cable slack
- B66C13/06—Auxiliary devices for controlling movements of suspended loads, or preventing cable slack for minimising or preventing longitudinal or transverse swinging of loads
- B66C13/063—Auxiliary devices for controlling movements of suspended loads, or preventing cable slack for minimising or preventing longitudinal or transverse swinging of loads electrical
Definitions
- the invention relates to a procedure according to the preamble of claim 1 for controlling the traversing motion of a crane.
- traversing motion means both the traversing motion of the trolley and the motion of a carriage supporting the trolley or other essentially horizontal motion used to move an element which has a suspension point for a hoisting cable or on which a hoisting drum or equivalent for winding up the hoisting cable is installed.
- patent application FI 920751 presents a procedure in which the control commands for the travesing motor of the crane are so modified that, when the commands are being issued, acceleration periods are formed which both implement the control commands and compensate the oscillation of the load at the end of the traversing motion.
- the object of the present invention is to achieve a procedure for controlling a crane whereby the oscillation of the load can be compensated even when the oscillation length of the hoisting cable changes during traversal. This is implemented via the actions defined in the characterization part of claim 1.
- the changes in the hoisting cable length, which has an effect on the oscillation are taken into account in the control procedure. Therefore, the control substantially follows the actual oscillation of the load and changes the motor acceleration periods accordingly. Even in the case of high hoisting speeds, the oscillations can be compensated.
- the load can be moved without oscillation when the hoisting height changes even without speed feedback by using acceleration periods determined in the control procedure. Deceleration periods are to be understood as corresponding to acceleration periods, only the direction of the change of velocity is reversed.
- the trolley 1 of the crane is moved by its traversing motor along the supporting rails 2 in direction x at a speed v determined by the control.
- a hanging load 4 is supported by a hoisting cable 3 fixed to the trolley 1.
- oscillations of the hoisting cable and the load supported by it are generated as a result of control actions, these oscillations being determined by the oscillation equation of the system.
- the length of the hoisting cable is calculated here as the distance between the cable suspension point in the trolley 1 to the centre of gravity of the load 4.
- the hoisting cable 3 forms an angle ⁇ with respect to the vertical direction y.
- the solution of equation (3) is a periodic function whose cycle duration, i.e. the oscillation cycle, is T.
- deceleration periods 23 and 24 are started at instants t4 and t6 and ended at instants t5 and t7, respectively.
- the broken line represents the variation of velocity v during the traversal.
- Fig. 2b illustrates the variation of the oscillation angle ⁇ with respect to time resulting from the acceleration periods in Fig. 2a).
- the broken lines represent the oscillations caused by individual changes in acceleration while the solid lines represent the oscillation angle of the total load oscillation.
- the motor acceleration period is modified by including in it a correction term which takes the effect of the hoisting speed into account.
- a correction term which takes the effect of the hoisting speed into account.
- the change in the length of the hoisting cable as well as the hoisting speed of the load are determined.
- equation (1) will be reduced to the form of equation (3), where u has the value of u1. Since the correction term u k is a function of time depending on the time derivative of the oscillation angle and the hoisting cable length, the value of u k changes as a function of time.
- FIG. 3 illustrates the generation of the control period according to the invention.
- Fig. 3a shows an additional control period 31 according to the correction term at the beginning of the traversal and a corresponding additional control period 31' at the end of it.
- the hoisting speed is assumed to be constant during the control period.
- the corrections made in connection with acceleration and deceleration are depicted as having equal magnitudes and beginning at an instant when the oscillation angle and the oscillation velocity are zero.
- Fig. 3c depicts the total control periods 34 and 35 in solid lines and the acceleration periods 21-24 generated on the basis of the control in broken lines.
- Fig. 4 presents a diagram of the control principle for implementing the procedure of the invention.
- the control periods are generated in unit 41, whose output is taken into a correction unit 42, where the control is modified by a correction term u k .
- the input quantities of unit 41 are the cable length L, the oscillation angle ⁇ .
- the input quantities of unit 42 are, in addition to the correction term u k , the output quantity u1 of unit 41 and the duration T of the oscillation cycle.
- the correction term u k is generated by unit 43, whose input quantities are the angular velocity ⁇ ' of the oscillation and the rate of change L' of the cable length.
- the output quantity obtained from unit 42 is the motor control period U as a function of time.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Control And Safety Of Cranes (AREA)
Abstract
The invention relates to a procedure for controlling the traversing motion of a crane when the length (L) of its hoisting cable changes. In the procedure, the traversing motion of the crane is controlled by using motor acceleration periods (u₁) determined on the basis of control commands and the length (L) of the hoisting cable is measured. According to the invention, when the length (L) of the hoisting cable changes, at least one motor acceleration period (uk) proportional at least to the hoisting speed (L') of the load and to the angular velocity (Θ') of the load oscillation is generated.
Description
- The invention relates to a procedure according to the preamble of claim 1 for controlling the traversing motion of a crane. In this context, traversing motion means both the traversing motion of the trolley and the motion of a carriage supporting the trolley or other essentially horizontal motion used to move an element which has a suspension point for a hoisting cable or on which a hoisting drum or equivalent for winding up the hoisting cable is installed.
- A problem in the control of the traversing motion of a load suspended from the hoisting cable of a crane is how to damp the load oscillation to a minimum. In relevant industry, several solutions are known which aim at stopping the load without oscillation at its point of destination. For example, patent application FI 920751 presents a procedure in which the control commands for the travesing motor of the crane are so modified that, when the commands are being issued, acceleration periods are formed which both implement the control commands and compensate the oscillation of the load at the end of the traversing motion.
- This previously known solution makes use of a differential equation representing the oscillation of the load is utilized. However, for easier practical implementation, it employs approximations, which again result in inaccuracies in the control methods if the cable length changes during the hoisting movement. For this reason, this procedure cannot completely compensate the oscillation generated during traversal.
- The object of the present invention is to achieve a procedure for controlling a crane whereby the oscillation of the load can be compensated even when the oscillation length of the hoisting cable changes during traversal. This is implemented via the actions defined in the characterization part of claim 1.
- In a manner defined by the invention, the changes in the hoisting cable length, which has an effect on the oscillation, are taken into account in the control procedure. Therefore, the control substantially follows the actual oscillation of the load and changes the motor acceleration periods accordingly. Even in the case of high hoisting speeds, the oscillations can be compensated. With the procedure of the invention, the load can be moved without oscillation when the hoisting height changes even without speed feedback by using acceleration periods determined in the control procedure. Deceleration periods are to be understood as corresponding to acceleration periods, only the direction of the change of velocity is reversed.
- In the following, the invention is described in detail by the aid of one of its embodiments by referring to the drawings, in which
- Fig. 1 presents the principle of a crane,
- Fig. 2 presents the acceleration periods of a crane during the control of the traversing motion when the length of the hoisting cable remains constant,
- Fig. 3 presents acceleration periods when the length of the hoisting cable changes, and
- Fig. 4 illustrates the crane control according to the invention.
- As illustrated by Fig. 1, the trolley 1 of the crane is moved by its traversing motor along the supporting
rails 2 in direction x at a speed v determined by the control. A hangingload 4 is supported by a hoistingcable 3 fixed to the trolley 1. During traversal, oscillations of the hoisting cable and the load supported by it are generated as a result of control actions, these oscillations being determined by the oscillation equation of the system. The length of the hoisting cable is calculated here as the distance between the cable suspension point in the trolley 1 to the centre of gravity of theload 4. As theload 4 oscillates, the hoistingcable 3 forms an angle Θ with respect to the vertical direction y. The following oscillation equation now applies:
where - L
- = length of hoisting cable
- L'
- = rate of change of hoisting cable length, i.e. hoisting speed
- Θ
- = angle of deflection
- Θ'
- = 1st time derivative of the angle of deflection, i.e. oscillation velocity
- Θ''
- = 2nd time derivative of the angle of deflection, i.e. angular acceleration
- u
- = acceleration of trolley, i.e. 2nd time derivative of trolley position
- g
- = acceleration of free fall = 9,81 m/s².
- Correspondingly, the time T of the oscillation cycle of the oscillating motion is given by the equation:
If the length L of the hoisting cable remains constant during traversal or control, the second term in the right-hand part of equation (1) will be omitted because the time derivative L' of the cable length L is zero. In this case, the oscillation time T of the oscillating motion remains constant. The oscillation equation (1) is reduced to the form:
The solution of equation (3) is a periodic function whose cycle duration, i.e. the oscillation cycle, is T. If the motor of the trolley is controlled using equal acceleration periods with a phase difference of T/2 between them, the oscillation resulting from the change of acceleration will be compensated at the end of the acceleration periods, as is implemented e.g. in the solution of patent application FI 920751. A situation according to equation (3) is illustrated by Fig. 2a), where anacceleration period 21 of magnitude u₁ is started at instantacceleration period 22 of a magnitude and duration equal to those ofperiod 21, ending at instantdeceleration periods - Fig. 2b) illustrates the variation of the oscillation angle Θ with respect to time resulting from the acceleration periods in Fig. 2a). The broken lines represent the oscillations caused by individual changes in acceleration while the solid lines represent the oscillation angle of the total load oscillation.
- When the length of the hoisting cable changes during motor control as in Fig. 2a) while the load is being hoisted by the hoisting machinery, the oscillation compensating effect of the control will not be completely realized because the hoisting-speed-dependent term of equation (1) has not been taken into account and because the duration of the oscillation cycle changes simultaneously according to equation (2).
- In the procedure of the present invention, the motor acceleration period is modified by including in it a correction term which takes the effect of the hoisting speed into account. For this purpose, the change in the length of the hoisting cable as well as the hoisting speed of the load are determined. When the
acceleration period 21 presented in Fig. 2 is corrected by the quantity - The diagrams in Fig. 3 illustrate the generation of the control period according to the invention. Fig. 3a) shows an
additional control period 31 according to the correction term at the beginning of the traversal and a corresponding additional control period 31' at the end of it. In the example depicted, the hoisting speed is assumed to be constant during the control period. To clarify the presentation, the corrections made in connection with acceleration and deceleration are depicted as having equal magnitudes and beginning at an instant when the oscillation angle and the oscillation velocity are zero. -
Additional control period 31 affects the velocity of the trolley, increasing it to a value larger than the desired value (=control command). Therefore, the additional control has to be altered so that the target speed is reached. Since the control period occurring in the opposite direction after half the period generates an oscillation of a corresponding magnitude, this can be achieved by dividing thecontrol period 31 into twoparts parts additional control 31 and the latter part begins at an instant when the former part of the additional control is in opposite phase. The latter additional control also occurs in the opposite direction, i.e. if the first additional control is in the accelerating direction at a given instant, then the second part is in the decelerating direction after T/2, T being the duration of the prevailing oscillation cycle. In this way, theadditional control periods total control periods - Fig. 4 presents a diagram of the control principle for implementing the procedure of the invention. Based on the crane operator's control actions, the control periods are generated in
unit 41, whose output is taken into acorrection unit 42, where the control is modified by a correction term uk. The input quantities ofunit 41 are the cable length L, the oscillation angle Θ. The input quantities ofunit 42 are, in addition to the correction term uk, the output quantity u₁ ofunit 41 and the duration T of the oscillation cycle. The correction term uk is generated byunit 43, whose input quantities are the angular velocity Θ' of the oscillation and the rate of change L' of the cable length. The output quantity obtained fromunit 42 is the motor control period U as a function of time. - The invention has been described above by the aid of one of its embodiments. However, the presentation is not to be regarded as limiting the invention, but instead the embodiments of the invention may vary within the limits defined by the following claims.
Claims (3)
- Procedure for controlling the traversing motion of a crane when the length (L) of its hoisting cable (3) changes simultaneously, in which procedure the traversing motion of the crane is controlled by using motor acceleration periods (21-24) determined on the basis of control commands and in which procedure the length (L) of the hoisting cable is determined, characterized in that, when the length (L) of the hoisting cable changes, at least one additional motor acceleration period (31-33,31'-33') proportional at least to the hoisting speed (L') of the load and to the angular velocity (Θ') of the load oscillation is generated.
- Procedure according to claim 1, characterized in that the additional acceleration periods (31-33) are proportional to the product of the hoisting speed (L') of the load (4) and the angular velocity (Θ') of load oscillation.
- Procedure according to claim 1 or 2, characterized in that the additional acceleration period is divided into two parts (32,33) which are effected with an interval of half an oscillation cycle (T/2) between them.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FI932416A FI93201C (en) | 1993-05-26 | 1993-05-26 | Procedure for controlling a crane |
FI932416 | 1993-05-26 |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0626337A1 true EP0626337A1 (en) | 1994-11-30 |
Family
ID=8538015
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP94108141A Withdrawn EP0626337A1 (en) | 1993-05-26 | 1994-05-26 | Procedure for controlling a crane |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0626337A1 (en) |
JP (1) | JPH0769581A (en) |
FI (1) | FI93201C (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2023179583A1 (en) * | 2022-03-24 | 2023-09-28 | 江苏苏港智能装备产业创新中心有限公司 | Control method and apparatus for inhibiting swings of grab bucket, and device and storage medium |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6588610B2 (en) * | 2001-03-05 | 2003-07-08 | National University Of Singapore | Anti-sway control of a crane under operator's command |
JP5293977B2 (en) * | 2011-03-17 | 2013-09-18 | 富士電機株式会社 | Crane steady rest control method and steady rest control apparatus |
CN112919324B (en) * | 2021-01-15 | 2023-07-25 | 深圳海星港口发展有限公司 | Stacking method and device for transporting goods by crane, medium and electronic equipment |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1923887A1 (en) * | 1968-05-10 | 1969-11-20 | English Electric Co Ltd | Electric motor control system for cranes |
DE3627580A1 (en) * | 1985-08-16 | 1987-03-05 | Hitachi Ltd | METHOD FOR CONTROLLING A CRANE |
EP0402790A2 (en) * | 1989-06-12 | 1990-12-19 | KCI Konecranes International Corporation | Procedure for damping the sway of the load of a crane |
DE4208717A1 (en) * | 1991-03-18 | 1992-10-22 | Kone Oy | CONTROL METHOD FOR A CRANE |
-
1993
- 1993-05-26 FI FI932416A patent/FI93201C/en active
-
1994
- 1994-05-25 JP JP6133898A patent/JPH0769581A/en not_active Withdrawn
- 1994-05-26 EP EP94108141A patent/EP0626337A1/en not_active Withdrawn
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1923887A1 (en) * | 1968-05-10 | 1969-11-20 | English Electric Co Ltd | Electric motor control system for cranes |
DE3627580A1 (en) * | 1985-08-16 | 1987-03-05 | Hitachi Ltd | METHOD FOR CONTROLLING A CRANE |
EP0402790A2 (en) * | 1989-06-12 | 1990-12-19 | KCI Konecranes International Corporation | Procedure for damping the sway of the load of a crane |
DE4208717A1 (en) * | 1991-03-18 | 1992-10-22 | Kone Oy | CONTROL METHOD FOR A CRANE |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2023179583A1 (en) * | 2022-03-24 | 2023-09-28 | 江苏苏港智能装备产业创新中心有限公司 | Control method and apparatus for inhibiting swings of grab bucket, and device and storage medium |
Also Published As
Publication number | Publication date |
---|---|
JPH0769581A (en) | 1995-03-14 |
FI93201C (en) | 1995-03-10 |
FI932416A0 (en) | 1993-05-26 |
FI93201B (en) | 1994-11-30 |
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Legal Events
Date | Code | Title | Description |
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PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
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AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): DE FR GB |
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17P | Request for examination filed |
Effective date: 19950224 |
|
RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: KCI KONECRANES INTERNATIONAL CORPORATION |
|
17Q | First examination report despatched |
Effective date: 19960821 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
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18D | Application deemed to be withdrawn |
Effective date: 19970301 |