EP0713474B1 - Method for controlling the swinging motion of an oscillating load and device for applying same - Google Patents

Abstract

PCT No. PCT/FR94/01005 Sec. 371 Date Feb. 13, 1996 Sec. 102(e) Date Feb. 13, 1996 PCT Filed Aug. 12, 1994 PCT Pub. No. WO95/05336 PCT Pub. Date Feb. 23, 1995Method and device for controlling the swinging motion of an oscillating load suspended from a movable support, wherein the movement of the support is controlled by a speed setpoint. The method includes a step (AS1) for automatically controlling the actual swaying value of the oscillating load by means of a zero swaying value and a step (37) for adjusting the speed setpoint (CV) of the support according to a correction value (E1) determined during the automatic swaying control step (AS1). The invention can be used, for example, for moving a load by means of a harbour crane.

Description

The present invention relates to a method for controlling the swing of a pendulum load.

It also relates to a device for implementing this method.

In the field of handling and lifting of loads, in particular for moving containers using cranes or container gantries, it is very important to carry out the movement of loads from one point to another with precision, and more particularly to obtain a zero swing of the load at the end of the journey.

A load, such as a container, suspended by cables from a mobile support, consisting for example of a motorized trolley adapted to move horizontally along the rails of a gantry, forms a pendulum which is generally subject at great swings due to the high speeds of use, which can reach 3 meters per second, and the long length of the lifting cables, between 10 and 40 meters.

In reality, there is a damping caused by the friction of the cables on the pulleys, by the elastic deformation of the cables, by the friction of the ambient air.

However, this is not enough to completely dampen the oscillation movement of the load and to obtain zero swing of the latter at the end of the trajectory.

We know in patent application EP-A-467,783 or EP-A-394,147 a method of controlling the displacement of a pendulum load in which the actual position of the pendulum load is controlled by a theoretical position, the latter satisfying to a theoretical law ensuring a zero swing of the load at the end of the journey.

This process therefore implies that the displacement of the mobile support also follows a law theoretical deduced from the theoretical displacement of the load and the theoretical balancing of this one.

The setpoint for moving the mobile support is therefore imposed and the control method cannot therefore be used for manual driving and any movement of the mobile support.

In addition, the theoretical law of displacement of the load must meet conditions of continuity and differentiability which, associated with the boundary conditions of the trajectory, restrict the possibilities of choice of this law. The known control method is therefore not applicable to any laws of displacement of the load and the mobile support.

Finally, the condition of nullity of the swinging of the load is only required for the end of the trajectory and is a priori not ensured during the displacement of the load.

The load sway can therefore remain very important during its movement.

The present invention aims to solve the aforementioned drawbacks and to provide numerous advantages in the field of moving suspended loads, in particular by port lifting devices.

It makes it possible in particular to ensure the displacement of a pendulum load by limiting as best as possible the swinging of the latter while removing all constraints in the movement of the mobile support.

The subject of the invention is a method of controlling the swinging of a pendulum load suspended from a mobile support, in which the movement of the mobile support is controlled by any speed reference of the support.

According to the invention, this method is characterized in that it comprises a step of controlling the real value of the swing of the pendulum load at a zero swing setpoint and a step of regulating the speed reference of the support as a function of a correction value determined during the swinging step.

Thus, thanks to the method of the invention, the speed of the mobile support is continuously regulated so as to constantly maintain a low swing of the pendulum load.

The slaving control makes it possible to take into account, during the displacement of this load, all the damping effects or deviations which are likely to move this load from its vertical position.

In addition, the displacement of this pendulum system does not require a reference model. Only the set point of the load swing is zero, that is to say that the pendulum constituted by the load suspended from the mobile support remains vertical, neither the support nor the load following a predetermined theoretical law of displacement.

The method according to the invention can therefore make it possible to control the swinging of the load even for manual driving.

According to an advantageous version of the invention, the control method further comprises a step of reading a manual setpoint for the speed of the mobile support, the manual setpoint being regulated as a function of the correction value determined during step d slaving.

The pendulum load can therefore be moved by means of a manual control actuated by a driver, the speed setpoint given by the driver can be arbitrary and being automatically regulated by the method according to the invention so as to ensure zero swing of the load at the end of the trajectory.

According to another version of the invention, the method comprises a second step of controlling the actual position of the movable support to a position setpoint, simultaneous with the first step of controlling the sway of the load, the speed setpoint of the mobile support being regulated as a function of the correction value determined during the sway control step and a second correction value determined during the second position control step.

The position of the mobile support position can therefore be arbitrary, the method making it possible, thanks to two servo loops in parallel, to regulate the speed of the mobile support so as to obey the support position setpoint and the rocking setpoint no charge.

According to another aspect of the invention, the device for controlling the swinging of a pendulum load suspended from a mobile support for implementing the method according to the invention, comprises a lifting machine having means for lifting the load and means for moving the mobile support and control and processing means adapted to receive information representative of the length of the pendulum, the angle of swing of the pendulum load and the real position of the mobile support respectively from length acquisition means, angle acquisition means, and position acquisition means.

According to the invention, this device is characterized in that the control and processing means are adapted to further receive information representative of a manual speed reference of the mobile support or a position reference of the mobile support and to send back a regulated speed reference from the mobile support to a control-command system, for example a speed controller of said mobile support.

Other features and advantages of the invention will appear in the description below.

• la figure 1 est une vue générale d'un engin de levage pouvant être équipé du dispositif selon l'invention;
• la figure 2 est un schéma illustrant des variables géométriques utilisées dans le procédé selon l'invention;
• la figure 3 est un schéma bloc illustrant le procédé selon l'invention; et
• la figure 4 est une vue schématique d'une réalisation d'un dispositif selon l'invention.

In the appended drawings, given by way of nonlimiting examples:

• Figure 1 is a general view of a lifting device which can be fitted with the device according to the invention;
• FIG. 2 is a diagram illustrating geometric variables used in the method according to the invention;
• Figure 3 is a block diagram illustrating the method according to the invention; and
• Figure 4 is a schematic view of an embodiment of a device according to the invention.

We will first describe, with particular reference to Figures 1 and 4, an embodiment of a device which allows the implementation of the method according to the invention.

The object of the device according to the invention is to make it possible to control the swinging of a mobile pendular load 13 as shown in an example of practical application in FIG. 1.

The loads 13 which must be moved from one point to another, in particular during the loading and unloading of ships, are generally transported by means of port lifting devices 10 such as cranes or container gantries.

These loads 13 are suspended by cables 15 from a mobile support 14, similar to a carriage 14 adapted to move horizontally along a rail 11, for example by means of rollers rolling along the rail.

The lifting cables 15 have a length variable thanks to winches generally on board the mobile carriage 14.

Thus, the load 13 is lifted from its starting point, transported under the rail 11 and then re-deposited at the end of its trajectory.

During the movement of this load 13, it can be subjected to strong oscillations around its vertical position, in line with the mobile support 14.

The main aim of the device according to the invention is therefore to control and avoid this rocking of the suspended load 13 or of the suspended tool 42 which thus constitutes a pendulum 12.

As illustrated in FIG. 4, the device comprises a machine 45 for lifting the load 13, constituted in a known manner of several winches 45 on which the lifting cables 15 can be wound up so as to modify the length of the pendulum 12.

The mobile support 14 can move on the horizontal rail 11 by means of rollers 40 which can roll along the rail 11.

Displacement means 48, 47 conventionally comprising a motor 47 coupled to a reduction gear 48 make it possible to move the support 14 in translation.

The control and processing means CPU proper consist of a central unit in which is stored the regulation program which makes it possible to carry out part of the steps of the method according to the invention which will be described later.

The control and processing means CPU are adapted to receive information representative of the length 1 of the pendulum 12, of the angle of swing of the pendulum load 13 and of the real position x of the movable support 14 along the rail, as well as logical information (for example an emergency stop).

These geometric variables 1, α and x are illustrated in Figure 2.

The length 1 corresponds to the distance separating the suspended load 13 from the movable support 14 and is therefore variable when the length of the lifting cables 15 is modified.

The angle α is representative of the swing of the load 13 around its vertical axis. The aim of the present invention is to keep this angle α small and zero at the end of the trajectory.

The position x of the carriage 14 along the rail 11 varies between the initial position of the trajectory, to which the load 13 to be moved is hung, and a final position to which the operator of the vehicle wishes to deposit the load 13.

These geometric data 1, α and x are measured by means of acquisition, then are transmitted to the processing means CPU.

The acquisition means 46 of the length 1 of the pendulum 12 may consist in a known manner of a pulse generator mechanically linked to one of the lifting winches 45 on which a variable length of cable 15 is wound.

The means 41 for acquiring the position x of the movable carriage 14 can also consist of a pulse generator mechanically linked to a wheel of the carriage and making it possible to count the distance traveled by the latter along the rail 11.

The pulses generated, representative of the length 1 and of the position x, are transmitted to the processing means CPU at two fast counting inputs.

The measurement of the swing angle α of the load 13 is carried out by angle acquisition means 43, 44 which include an infrared camera 44 installed on the movable carriage 14 and directed downwards, in the direction of the load suspended 13. A transmitter 43 or infrared beacon is placed at the level of the load 13, by example on the gripping tool, such as a pulley holder in the case of container gantries.

This emitter is directed upwards so as to send an infrared ray towards the camera 44, the latter being adapted to analyze the emitted ray and in particular its angle of incidence relative to the vertical.

The measurement of the angle α is then transmitted by serial link to the control and processing means CPU. The latter are also adapted to receive information representative of either a manual CVM speed setpoint of the mobile support 14, or a position setpoint xc of this support 14. In practice, the processing means CPU have separate inputs for the two types of information mentioned above and are suitable for reading information from one or the other entry.

A control button can be placed on the lifting device to allow the driver to select one or other of the inputs which must be taken into account by the processing and control software.

The information relating to the manual CVM speed setpoint of the carriage 14 is acquired by the processing and control means CPU by means of an analog input, of the ± 10 volt type for example, connected to a combiner 50 controlled manually by the driver of the 'contraption.

The manual speed setpoint CVM of the mobile support 14 therefore comes from a control lever 50 for moving the mobile support 14, actuated manually.

The device according to the invention also comprises means of acquisition and storage 51 of the position setpoint xc of the mobile support 14, such as a control console on which the operator of the lifting machine can program the final position of pendulum 12 as position setpoint xc. The latter is then stored in the device for use by the processing and control means CPU.

The latter are adapted to furthermore issue a regulated speed reference CV of the mobile support 14 intended for a control-command system, such as a speed variator 34 of this mobile support.

The CV speed setpoint is output by means of an analog output of the ± 10 volt type which allows control of the control-command system 34.

According to the CV speed setpoint transmitted, the control-command system 34 acts on the motor 47 controlling the movement of the mobile support 14 to accelerate or slow it down.

A dynamo-tachometer 49 makes it possible to measure the speed of the motor at the level of the motor 47 and to return to the device, via an analog input, a measurement of the speed of the mobile support in order to regulate the operation of the system. 34. This feedback on the actual speed of the support makes it possible to ensure that it is indeed equal to the speed setpoint CV transmitted to the control-command system 34.

The device also includes a 220 volt 50 Hz power supply and an on / off type M / A button for operating the device.

The operation of this device will now be described for the implementation of the method according to the invention, with particular reference to FIG. 3.

The method according to the invention controls the swinging of the pendulum load 13 suspended from a mobile support 14, the movement of the latter being controlled by a speed reference CV.

The method comprises a step AS1 of the real value of the swing of the pendulum load 13 to a zero swing swing setpoint and a regulation step 37 of the speed setpoint CV of said support 14 as a function of a correction value E1 determined during the slaving step AS1.

The AS1 swinging servo step is a proportional and derived servo loop.

   où P et D sont respectivement une fonction proportionnelle et une fonction dérivée et où K₁ et K₂ sont des coefficients déterminés par l'expérience, qui dépendent de la masse de la charge à déplacer, de la géométrie du pendule 12.From the actual measurement of the load swing, that is to say from an acquisition step 31 of the swing angle α and a acquisition step 30 of the length 1 of the pendulum 12, and from the comparison of the measurement of the sway to a zero value (corresponding to an angle α of 0 degrees), a correction value E1 is determined such that: $${\text{E}}_{\text{1}}{\text{= K}}_{\text{1}}{\text{x P (dangling) + K}}_{\text{2}}\text{x D (dangling)}$$

where P and D are respectively a proportional function and a derived function and where K ₁ and K ₂ are coefficients determined by experience, which depend on the mass of the load to be moved, on the geometry of the pendulum 12.

The correction value E1 is therefore equal to the sum of a first element proportional to the real value of the swing of the load 13 and a second element proportional to the derivative over time of the real value of the swing.

The regulation step 37 is carried out by means of an adder 37 which makes it possible to regulate the value of the speed reference CV by adding the correction value E1 calculated to the speed reference.

During manual operation assisted by the method according to the invention, the driver himself controls the speed of the support 14 via the combiner 50.

The process then includes a reading step 38 of the CVM manual speed reference for the mobile support 14.

This manual speed setpoint CVM is regulated by the adder 37 as a function of the correction value E1 so as to transmit to the control-command system 34 a regulated speed setpoint CV such that CV = CVM + E1.

During an automatic operation of the device, the method comprises a second step of servo AS2 of the real position x of the movable support 14 to a position setpoint xc, simultaneous with the first step of servo AS1 of the sway of the load 13 .

The position setpoint xc of the mobile support is preferably equal to a predetermined end position to which it is desired to deposit the load 13.

The actual position x of the mobile support 14 is measured during an acquisition step 32 of this position using acquisition means 41 described above.

• où P est une fonction proportionnelle,
• Δx correspond à la différence entre la position réelle x mesurée du support mobile et la consigne de position xc, et
• K₃ est un coefficient d'expérience prenant en compte des paramètres du procédé, tels que la masse de la charge, la géométrie du pendule...

The servo step in position AS2 is a proportional type servo loop during which a second correction value E2 is determined as follows: $${\text{E2 = K}}_{\text{3}}\text{P (Δx)}$$

• where P is a proportional function,
• Δx corresponds to the difference between the actual measured position x of the mobile support and the position reference xc, and
• K ₃ is an experience coefficient taking into account process parameters, such as the mass of the load, the geometry of the pendulum ...

The speed reference CV of the mobile support is, during this automatic operation, regulated as a function of the correction value E1 determined during the control step AS1 of the sway and of the second correction value E2 determined during the second position control step AS2.

This regulation is implemented by means of the adder 37 so that the speed setpoint CV is equal to the sum of E1 and E2.

Depending on the choice of operation, manual or automatic, the adder performs the regulation of the speed setpoint CV, either by considering the manual speed setpoint CVM given by the driver, or the correction value E2 determined from the position setpoint. final xc of the mobile support.

The method further comprises a step 33 of limiting, upstream of the control-command system 34, the speed and the acceleration of the mobile support 14, respectively to a maximum speed and to a maximum acceleration.

Beyond the maximum speed and acceleration values, the CV speed setpoint is not limited so as not to exceed the imposed limit values.

The speed setpoint is then sent to the control-command system 34 which controls the speed of rotation of the motor 47 as already described previously with reference to the device according to the invention.

A speed regulation step 35 makes it possible to continuously compare the real speed of the motor 47 and the speed setpoint CV addressed to the control-command system, and to adjust the speed of the motor 47 so as to comply as best as possible with the setpoint CV speed.

This regulation system makes it possible to quickly and vigorously amortize the sway whatever the CVM speed setpoint of the trolley requested by the driver, even for trolley speeds reaching 3 m / s for example, regardless of the torque resistant and the mass of the load 13 to be moved.

In addition, the regulation is effective even with a variation in length 1 of the pendulum 12 during the movement of the carriage and the load.

The slaving on the value of the sway makes it possible to obtain a weak swinging of the load during all the duration of the trajectory, while taking into account the dampings already existing in the device, due to the wind, friction ...

Of course, the invention is not limited to the embodiments described above, and numerous modifications can be made to it without departing from the scope of the invention.

Thus, the means for acquiring angle α, length 1 or portions x of the carriage can be any.

Claims (12)

1. Procedure to control the swaying of a pendular load (13) suspended from a mobile support (14), whose movement is controlled by a speed controller (CV), comprising an automatic control stage (AS1) of the actual value of the lateral oscillation of the pendular load (13) to a zero lateral oscillation controller and a regulation stage (37) of the speed controller (CV) of said mobile support (14), characterised in that the speed controller (CV) of said gantry (14) is of any type, and the regulating stage is carried out according to a correction value (E1) determined during said automatic control stage of lateral oscillation (AS1).
2. Procedure according to Claim 1, characterised in that it comprises an acquisition stage (30) of the actual length (1) of the pendulum (12) consisting of the load (13) suspended from the mobile support (14) and an acquisition stage (31) of the angle of lateral oscillation (a) existing between said pendulum (12) and a vertical axis.
3. Procedure according to one of Claims 1 or 2, characterised in that the correction value (E1) is equal to the sum of a first element proportional to the actual value of lateral oscillation of the load (13) and of a second element proportional to the differential of the time of the actual value of lateral oscillation of the load (13).
4. Procedure according to one of Claims 1 to 3, characterised in that in addition it comprises a reading stage (38) for a manual speed controller (CVM) of mobile support (14), said manual controller (CVM) being adjusted in accordance with said correction value (E1).
5. Procedure according to one of Claims 1 to 3, characterised in that it comprises a second automatic control stage (AS2) of the actual position (x) of the mobile support (14) to a position controller (xc), simultaneous with the first automatic control stage (AS1) of the lateral oscillation of load (13), the speed controller (CV) of the mobile support (14) being adjusted according to said correction value (E1) determined during the automatic control stage (AS1) of the lateral oscillation and of a second correction value (E2) determined during the second automatic control stage (AS2) of the position.
6. Procedure according to Claim 5, characterised in that the position controller (xc) of the mobile support (14) is equal to a predetermined final position.
7. Procedure according to one of Claims 5 or 6, characterised in that in addition it comprises an acquisition stage (32) of the actual position (x) of the mobile support (14).
8. Procedure according to one of Claims 5 to 7, characterised in that the second correction value (E2) is proportional to the difference between the actual position (x) of the mobile support (14) and the position controller (xc).
9. Procedure according to one of Claims 1 to 8, characterised in that in addition it comprises a limitation stage (33) for speed and acceleration of the mobile support (14) respectively at a maximum speed and a maximum acceleration.
10. A device to control the swaying of a pendular load (13) suspended from a mobile support (14) for the implementation of a procedure according to one of the previous claims, comprising lifting gear (10) possessing lifting means (45) for the load (13) and movement means (48, 47) for the mobile support (14), and control and processing means (CPU) adapted to receive information representing the length (1) of the pendulum (12), of the angle of lateral oscillation (a) of the pendular load (13) and the actual position (x) of the mobile support (14) originating respectively from the length acquisition means (46), angle acquisition means (43, 44), and position acquisition means (41), characterised in that the control and processing means (CPU) are also adapted to receive information representing a manual speed controller (CVM) of the mobile support (14) or a position controller (xc) for the mobile support (14) and to produce in return a regulated speed controller (CV) for the mobile support (14) travelling to the command-control system (34) of said mobile support (14).
11. A device according to Claim 10, characterised in that the manual speed controller (CVM) for the mobile support (14) issues from a control lever (50) for movement of the mobile support (14), manually activated.
12. A device according to Claim 10, characterised in that it comprises acquisition and storage means (51) for the position controller (xc) of the mobile support (14).

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