EP3459899A1 - Dynamic optimisation of a crane load curve - Google Patents

Abstract

Means for controlling the lifting of a load suspended from a jib, carried by a mast of a crane, in particular means for determining: €¢ as a function of the mass of the suspended load, of a specified load factor quantifying an acceptable overrun with respect to a predetermined maximum allowable load for said crane; €¢ a maximum permissible lifting acceleration, depending on the mass of the suspended load, the specified load factor and the position in distribution of the suspended load on the jib in relation to the mast; €¢ from lifting speed setpoints, optimized lifting speed setpoints intended to be executed by a motor device to move the suspended load according to a lifting movement so that the acceleration relative to the lifting movement remains, in absolute value, less than or equal to the maximum authorized acceleration.

Description

The present invention relates to the field of cranes, and more specifically tower cranes, and in particular to the monitoring of the maximum load displaced.

According to a usual configuration, a tower crane comprises a vertical mast, a substantially horizontal boom carried by the mast and orientable in azimuth around the mast in a so-called orientation movement, and a carriage which is mounted to move in radial translation on the mast. along said arrow thus achieving a so-called distribution movement. The carriage carries a load, suspended from the carriage by a cable whose length is modifiable by means of a winch which thus controls the vertical movement of said load, said lifting movement.

An essential feature of the crane is the maximum mass of the suspended load that the crane can move, according to an operating point defined by the distance from said load to the axis passing through the mast - called the dispensing position - and by the mass of the load.

The maximum limit is typically described by means of a load curve, on a graph representing, on a first axis (conventionally on the abscissa), the distribution position and, on a second axis (conventionally on the ordinate), the mass of the charge.

Conventionally, a tower crane has a monitoring and control system configured to limit the lifting speed of the load when the operating point approaches the load curve.

When the operating point reaches the load curve, the monitoring and control system stops the movements of the crane, in order to avoid any overtaking really dangerous for the stability or the structure of the crane.

The load curve is generally established, with regard to the mechanical arrangement of the crane, firstly from a first term called "static" which assumes that the crane is in a static mechanical state or in a steady state comparable to a quasi-static regime (in particular with a substantially constant lifting speed, or zero), and secondly by providing, in relation to this first static limit, a dynamic margin, which corresponds to an overshoot maximum tolerated with respect to this static limit, called load factor Ψ.

Said load factor Ψ makes it possible to take into account the stress supplements which are exerted on the boom, and more generally on the crane, when the suspended load is subjected to transient phenomena, for example at the beginning of a lifting movement. when the inertia of the suspended load is added to the weight of the suspended load.

Safety standards, such as the European standard EN 13001, require the load factor Ψ to remain below 30%.

In practice, the greater the load factor Ψ is, ie the greater the safety margin imposed, the lower the maximum limit of the load that the crane can move.

That is why it is desirable, to improve the performance of the crane, to reduce the load factor Ψ, without compromising the operating safety of the crane.

It is thus known, for example from the patent document EP-0 849 213 , to implement control means, using a first relatively restrictive load curve in view of the potential capabilities of the crane, and a second extended load curve. However, the second load curve can be used only for a predetermined reduced range of speed / acceleration of movement, when the conditions for such exceeding are met. In particular, use is made of a switch for selecting, depending on the circumstances, the appropriate load curve. The operator can thus manually force the control means to operate the crane using the second extended load curve. This solution therefore relies on the use of two predefined load curves and only partially makes it possible to optimize the compromise between dynamic performance of the crane and load capacity, according to the real instantaneous capacities of the crane.

That is why there is still a need for improved and automated means, for tower crane, monitoring and motion control according to a load curve, offering an optimized compromise between load lifting capacity, and performance dynamic use.

One of the objects of the invention is to enable the improved means of monitoring and control to take account of the capacity at a given moment. a crane, including a tower crane, to reduce the influence of dynamic factors and uncertainties to a certain level.

Another object of the invention is to provide means capable of taking into account, in order to determine the load factor, the capacities and the performances of a crane to be applied and to control instructions on the speed and acceleration of the lifting motor. .

Another object of the invention is to provide improved means of monitoring and control for crane capable of limiting the lifting movements of the payload, in speed and acceleration, by means of dynamic calculation rules depending on the mechanical load current, the range, the lifting speed and optionally other characteristic sizes of said crane.

One of the objects of the invention is to increase the lifting capacity of a crane, while ensuring a high level of safety.

One of the objects of the invention is to increase the dynamic performance of use of a crane, while ensuring a high level of security.

One of the objects of the invention is to provide improved means of crane monitoring and control, which require during their use any action of the crane operator to select from among several load curves that adapted to the context to control the lifting movements of the charge.

One of the objects of the invention is to provide improved means of crane monitoring and control, using a single load curve to continuously adapt the speed and acceleration requested by the crane operator to meet the dynamic constraints that the crane can support.

It is an object of the invention to provide improved crane monitoring and control means adapted to be used in conjunction with the safety and cut-off devices usually deployed in a crane.

One or more of these objects are filled by the device according to the independent claim. The dependent claims further provide solutions to these objects and / or other advantages.

More particularly, according to a first aspect, the invention relates to a control method of lifting control of a load suspended from an arrow, carried by a mast of a crane, including a tower crane. The invention can also be applied to other families of cranes - luffing jib crane, etc. - in transposing the calculations made according to the model of the invention to the geometry of said cranes.

• une première étape de détermination, en fonction de la masse de la charge suspendue, d'un facteur de charge spécifié quantifiant un dépassement acceptable par rapport à une charge maximale admissible prédéterminée pour ladite grue ;
• une deuxième étape de détermination d'une accélération de levage maximale autorisée, en fonction de la masse de la charge suspendue, du facteur de charge spécifié et de la position en distribution de la charge suspendue sur la flèche par rapport au mât;
• une troisième étape de détermination, à partir de consignes de vitesse de levage, de consignes de vitesse de levage optimisées destinées à être exécutées par un dispositif moteur pour déplacer selon un mouvement de levage la charge suspendue de telle sorte que l'accélération relative au mouvement de levage reste, en valeur absolue, inférieure ou égale à l'accélération maximale autorisée.

The method comprises the following steps:

• a first step of determining, based on the weight of the suspended load, a specified load factor quantifying an acceptable exceedance to a predetermined maximum allowable load for said crane;
• a second step of determining a maximum allowed lifting acceleration, as a function of the weight of the suspended load, the specified load factor and the distribution position of the load suspended on the boom relative to the mast;
• a third step of determining, from lifting speed instructions, optimized lifting speed setpoints to be executed by a motor device to move the suspended load in a lifting motion such that the acceleration relative to the movement the lift remains, in absolute value, less than or equal to the maximum permitted acceleration.

The control method according to the invention allows in particular to adapt the control of the crane according to the actual dynamics of the load.

The method therefore makes it possible to control the crane by taking into account the effects of the load when the latter is in a static or quasi-static mechanical state, but also in a transient state during which the inertial effects related to the accelerations / decelerations of the load are observed.

Indeed during transient conditions, especially at the beginning of lifting when the winch accelerates the load, a stress greater than the strict mass of the suspended load is exerted on the boom of the crane: the latter suffers accordingly the equivalent of a load heavier than that actually suspended from the winch, and therefore reacts with a pitch deformation greater than the deformation observed quasi-static regime.

The invention thus makes it possible to dynamically optimize the control of the crane with respect to the predetermined maximum permissible load for said crane, by limiting the lifting acceleration, according to measurable current parameters. such as the mass of the suspended load, and the distribution position of the suspended load.

Optimization also requires no operator intervention.

While maintaining the same level of safety, it results from the invention an improvement of the compromise lifting capacity / dynamic performance of use, compared to conventional approaches in which only the predetermined maximum allowable load for said crane would have been taken into account, or approaches based on the use of two static curves of maximum allowable load.

The method is furthermore easily configurable to suit various needs, in particular as regards the choice of the predetermined maximum allowable load.

dans laquelle :

• x_c correspond à la position en distribution de la charge suspendue ;
• M correspond à la masse de la charge suspendue;
• J_z correspond à un modèle de raideur et d'inertie du premier ordre relative à la structure de la grue ;
• Ψ₀* est le facteur de charge spécifié.

The maximum permitted lifting acceleration can be determined by the following mathematical expression: $$\frac{{\mathit{gJ}}_z}{{x_c}^{2}M+J_z}{\psi }_0^{*}$$

in which :

• x _c corresponds to the distribution position of the suspended load;
• M is the mass of the suspended load;
• J _z corresponds to a model of stiffness and inertia of the first order relative to the structure of the crane;
• Ψ ₀ * is the specified load factor.

Thus, the method according to the invention makes it possible in particular to optimize the control of the crane by dynamically limiting the acceleration and the speed of the suspended load by means of a pre-established mathematical formula.

The specified load factor is, for example, determined by means of a maximum load curve, corresponding to a limit load factor and a maximum static load.

Thus, a single maximum allowable load curve can be used, dynamically adapted to the actual current conditions by means of a mathematical formula making it possible to take into account the real conditions such as the weight of the suspended load or the distribution position of the suspended load.

It is thus possible to avoid any exceeding of the predetermined maximum permissible load for the crane, while approaching, safely, closer to said maximum permissible load.

The limit load factor can be determined from a first theoretical threshold function of the theoretical load capacity supported by the crane and a second threshold function of measurement uncertainties relating to the mass of the suspended load and / or lifting movement of the suspended load.

The specified load factor can be obtained by multiplying the limit load factor by the ratio between the maximum static load corresponding to the maximum allowable load curve and the mass of the suspended load.

Thus, thanks to a better mastery of the dynamic aspects allowed by the invention, it is possible to use a limit load factor approximating the limits enacted by the standards.

• ∘ l'accélération de levage de la charge suspendue, en valeur absolue, reste inférieure ou égale à l'accélération maximale autorisée (L"MAX) ; en l'espèce, ladite accélération maximale autorisée L"MAX correspond à une accélération théorique qui est calculée de manière à ne pas provoquer un dépassement du facteur dynamique considéré ;

ainsi qu'une ou plusieurs des conditions supplémentaires suivantes:

• ∘ la vitesse de levage de la charge suspendue, en valeur absolue, reste inférieure à une vitesse de levage maximale autorisée, la vitesse de levage maximale autorisée étant déterminée en fonction des capacités de la grue à freiner les mouvements de la charge suspendue; et/ou,
• ∘ la vitesse de levage de la charge suspendue, en valeur absolue, reste inférieure à une vitesse de levage maximale de sécurité, déterminée en fonction des capacités de la grue à supporter une pose au sol de la charge suspendue brutale et/ou un arrêt d'urgence; et/ou,
• ∘ l'accélération de levage de la charge suspendue, en valeur absolue, reste inférieure à une accélération de levage maximale atteignable par le dispositif moteur; et/ou,
• ∘ l'accélération de levage de la charge suspendue, en valeur absolue, reste supérieure à une accélération de levage minimale de confort.

Advantageously, the optimized lifting speed instructions are determined so that their execution by the motor device to move the suspended load according to the lifting movement respects the following condition:

• ∘ the lifting acceleration of the suspended load, in absolute value, remains less than or equal to the maximum permitted acceleration (L "MAX), in this case, the said maximum permitted acceleration L" MAX corresponds to a theoretical acceleration which is calculated so as not to cause the dynamic factor in question to be exceeded;

as well as one or more of the following additional conditions:

• ∘ the lifting speed of the suspended load, as an absolute value, remains below a maximum permissible lifting speed, the maximum permissible lifting speed being determined according to the crane's ability to brake the movements of the suspended load; and or,
• ∘ the lifting speed of the suspended load, in absolute value, remains below a maximum safe lifting speed, determined according to the crane's capacity to withstand the sudden suspended load on the ground and / or 'emergency; and or,
• ∘ the lifting acceleration of the suspended load, in absolute value, remains lower than a maximum lifting acceleration achievable by the motor device; and or,
• ∘ the lifting acceleration of the suspended load, in absolute value, remains greater than a minimum lifting acceleration of comfort.

It is therefore possible to optimize both the safety of the crane, while optimizing the operating performance experienced by the crane operator.

The optimized lifting speed setpoints can be determined so that the absolute value of the lifting speed of the suspended load increases, over a predefined period of time, along a ramp whose slope corresponds to the maximum permitted lifting acceleration. It is then possible to limit the inertial effects.

According to a second aspect, the invention relates to a computer program comprising instructions for performing the steps of the method according to the first aspect, when said program is executed by a processor.

Each of these programs can use any programming language, and be in the form of source code, object code, or intermediate code between source code and object code, such as in a partially compiled form, or in any form what other form is desirable. In particular, it is possible to use the C / C ++ language, the language ™ of scripting languages, such as tcl, javascript, python, perl, which allow "on demand" code generation and do not require overloading. significant for their generation or modification.

According to a third aspect, the invention relates to a computer-readable recording medium on which is recorded a computer program comprising instructions for executing the steps of the method according to the first aspect.

The information carrier may be any entity or any device capable of storing the program. For example, the medium may comprise storage means, such as a ROM, for example a CD-ROM or a microelectronic circuit ROM, or a magnetic recording means, for example a diskette or a hard disk. On the other hand, the information medium can be a transmissible medium such as an electrical or optical signal, which can be conveyed by an electrical or optical cable, by radio or by other ways. The program according to the invention can be downloaded in particular on an Internet or Intranet network. Alternatively, the information carrier may be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the method in question.

• de moyens de détermination, en fonction de la masse de la charge suspendue, d'un facteur de charge spécifié quantifiant un dépassement acceptable par rapport à une charge maximale admissible prédéterminée pour ladite grue ;
• de moyens de détermination d'une accélération de levage maximale autorisée, en fonction de la masse de la charge suspendue, du facteur de charge spécifié et de la position en distribution de la charge suspendue sur la flèche par rapport au mât;
• de moyens de détermination, à partir de consignes de vitesse de levage, de consignes de vitesse de levage optimisées destinées à être exécutées par un dispositif moteur pour déplacer selon un mouvement de levage la charge suspendue de telle sorte que l'accélération relative au mouvement de levage reste, en valeur absolue, inférieure ou égale à l'accélération maximale autorisée .

According to a fourth aspect, the invention also relates to a crane, in particular a tower crane, adapted to implement the method according to the first aspect. The crane comprises an arrow-supporting mast on which is mounted a carriage for carrying a suspended load. The crane further comprises control means for controlling the lifting of the suspended load, provided:

• means for determining, based on the weight of the suspended load, a specified load factor quantifying an acceptable exceedance to a predetermined maximum allowable load for said crane;
• means for determining a maximum allowed lifting acceleration, as a function of the weight of the suspended load, the specified load factor and the distribution position of the load suspended on the boom relative to the mast;
• means for determining, from lifting speed instructions, optimized lifting speed setpoints for execution by a driving device for moving the suspended load in a lifting motion such that the acceleration relative to the lifting remains, in absolute value, less than or equal to the maximum acceleration allowed.

The invention can also be applied to other families of cranes - luffing jib crane, etc. - by transposing the calculations made according to the model of the invention to the geometry of said cranes.

• la figure 1 est un schéma d'architecture d'un système de contrôle de levage d'une charge, selon un mode de réalisation;
• la figure 2 est un synoptique des étapes d'un procédé de contrôle de commande de levage d'une charge suspendue, selon un mode de réalisation;
• la figure 3 représente un schéma de principe du dispositif de surveillance et de contrôle, selon un mode de réalisation de l'invention ;
• la figure 4 représente, un schéma de principe utilisé pour décrire un modèle mécanique de type oscillateur, utilisé, selon un mode de réalisation du procédé selon l'invention pour déterminer l'accélération de levage maximale autorisée ;
• la figure 5 représente un diagramme comportant un ensemble de courbes surfaciques décrivant l'accélération de levage maximale autorisée, en fonction de la masse M de la charge et de la position en distribution de la charge, chaque courbe surfacique correspondant à un facteur de charge spécifié.

Other features and advantages of the present invention will become apparent from the following description of embodiments with reference to the accompanying drawings, in which:

• the figure 1 is an architecture diagram of a load lifting control system, according to one embodiment;
• the figure 2 is a block diagram of the steps of a lifted load control control method, according to one embodiment;
• the figure 3 represents a block diagram of the monitoring and control device, according to one embodiment of the invention;
• the figure 4 represents a block diagram used to describe an oscillator-type mechanical model used, according to an embodiment of the method according to the invention for determining the maximum permitted lifting acceleration;
• the figure 5 represents a diagram comprising a set of surface curves describing the maximum allowed lifting acceleration, as a function of the mass M of the load and the distribution position of the load, each surface curve corresponding to a specified load factor.

We refer to the figure 1 , on which is represented a lifting control system 1 of a suspended load 2.

This system is applicable to a crane 3, including a tower crane 3.

With reference to the figure 4 it is conceivable to apply the system 1 to any type of crane 3 comprising an arrow 4 which is pivotable in a yaw around a vertical axis (ZZ '), according to an orientation movement, and which is arranged so that the suspended load 2 is suspended from said boom 4 by a cable 5, and this in such a way that said crane 3 can modify the radial distance of said suspended load 2 with respect to the vertical axis, according to a dispensing movement, as well as the length of the cable 5 which connects the arrow 4 to the suspended load 2, according to a so-called lifting movement, in order to be able to modify the altitude of the suspended load 2.

The crane 3 can thus form for example a luffing jib crane (tilting boom), a telescopic crane, or, particularly preferably, a tower crane.

In the following nonlimiting example, the tower crane comprises a vertical mast 6, which materializes the vertical axis (ZZ '), a substantially horizontal arrow 4 carried by the mast 6 and orientable in azimuth (lace) around the mast 6 , and a carriage 7 which is mounted movably in radial translation along said arrow.

The carriage 7 carries the load 2, suspended from the carriage by a cable 5 whose length can be modified by means of a winch.

In the following, we will assimilate, for convenience of description, the crane 3 to a tower crane, and the vertical axis (ZZ ') to a mast 6.

The control control system 1 comprises in particular a control device 10, a monitoring and control device 20, a controller 30, and a command execution system 40.

• un dispositif moteur 41 de levage couplé au treuil, apte à déplacer la charge 2 selon un mouvement de levage, en fonction de consignes reçues;
• un dispositif moteur 42 de distribution couplé au chariot 7, apte à déplacer ledit chariot 7 selon un mouvement de distribution, en fonction de consignes reçues;
• un dispositif moteur 43 d'orientation couplé à la flèche 4, apte à déplacer ladite flèche, et donc le chariot 7 et la charge suspendue 2 selon un mouvement d'orientation, en fonction des consignes reçues.

The command execution system 40 typically comprises:

• a lifting motor device 41 coupled to the winch, able to move the load 2 according to a lifting movement, according to received instructions;
• a delivery device 42 coupled to the carriage 7, adapted to move said carriage 7 according to a dispensing movement, according to received instructions;
• a steering motor device 43 coupled to the boom 4, able to move said boom, and thus the carriage 7 and the suspended load 2 according to an orientation movement, according to the received instructions.

The command execution system 40 also comprises a measurement system 45 configured to deliver a set of MES physical and mechanical measurements, relating to the motor devices 41-42-43, to the load, as well as to the environment of the crane 3.

More particularly, the measuring system 45 comprises a set of sensors for measuring the mass of the load.

The measurement system 45 also comprises a set of sensors for determining, at each instant, the position, the speed and the acceleration of the main organs of the control execution system 40, in particular the carriage 7, the arrow 4, and the devices mechanically coupled to the load 2.

The control device 10 is configured to generate CMD lifting speed instructions as a function of interactions with a crane operator and to transmit said CMD lifting speed instructions to the monitoring and control device 20. The CMD lifting may include in particular positioning instructions, and / or speed, and / or acceleration, intended in particular to be transmitted to the hoist motor device 41.

The control device 10 generally comprises a user interface, for example of the joystick type, which is intended to be handled by a crane operator to produce the lifting speed instructions CMD. However, the CMD lifting speed instructions can also be produced by other means, such as an automated control device.

The monitoring and control device 20 is coupled to the control device 10 to receive the lifting speed instructions CMD and to the measurement system of the command execution system 40 to receive the set of measurements MES.

The monitoring and control device 20 is configured to produce, according to the CMD lifting speed instructions and the measurement set MES, optimized lifting speed instructions CMD 'intended to be executed by the driving device 41 of FIG. hoist for moving the suspended load 2 in such a manner that the acceleration relative to the hoisting movement remains, in absolute value, less than or equal to a maximum allowable lifting acceleration L " _MAX .

The controller 30 is coupled to the control executing system 40 and the monitoring and control device 20 to receive the optimized optimized lift speed instructions CMD '.

The controller 30 is configured to control the hoist motor device 41 belonging to the control execution system 40, in accordance with the optimized optimized hoist speed instructions CMD '.

Typically, the controller 30 comprises automated control means, for example in a closed loop, in order to control, as a function of the information transmitted by the sensors of the measurement system and the information included in the optimized lifting speed instructions CMD ', the positioning, speed and / or acceleration of the mechanical parts of the control system 40.

We refer to the figure 2 , on which is represented a block diagram of the steps of a method, according to the invention, control of lifting control of a load 2 suspended from an arrow 4, carried by a mast 6 of a crane 3 (here of a tower crane).

The method is particularly suitable for being implemented by the control control system 1, previously described, and more particularly by the monitoring and control device 20.

During a first step 110, a specified load factor Ψ ₀ * is determined, depending on the mass M of the suspended load.

The specified load factor Ψ ₀ * quantifies an acceptable exceedance to a predetermined maximum allowable load for said crane. The specified load factor Ψ ₀ * can be determined by means of a load curve maximum permissible, corresponding to a pre-determined load factor Ψ ₀ and to a maximum static load.

In one embodiment, the load factor Ψ ₀ limit is determined from a first theoretical threshold function of the theoretical load capacity supported by the crane and a second threshold function of measurement uncertainties relating to the mass of the crane. the suspended load and / or the lifting motion of the suspended load. The first theoretical threshold is typically defined from a theoretical mechanical model of an ideal crane.

The load factor Ψ ₀ limit is for example obtained by adding the first theoretical threshold and the second threshold. For example, if we consider a first theoretical threshold permitting a 10% overshoot of the maximum load, and a second threshold, an additional overshoot of 7.5% due to measurement uncertainties, the load factor Ψ ₀ limits is then equal to 10% + 7.5% = 17.5%.

The specified load factor Ψ ₀ * may in particular be obtained by multiplying the predetermined predetermined load factor Ψ ₀ by the ratio between, on the one hand, the maximum static load corresponding to the maximum load curve established for the limit load Ψ ₀ , and secondly the effective mass M of the suspended load 2 handled by the crane 3 at the moment considered.

Thus, for a given load factor Ψ ₀ , and thus for a given basic maximum load curve, the lower the mass M of the suspended load 2, the higher the specified load factor Ψ ₀ *.

The load factor Ψ ₀ predetermined limit can in particular be chosen according to business rules, and / or vary according to the crane's field of use.

During a second step 120, a maximum authorized lifting acceleration L " _MAX is determined, according to the mass M of the suspended load, the specified load factor Ψ ₀ *, the distribution position X _c of the suspended load 2 with respect to the mast 6.

Preferably, the maximum authorized lifting acceleration L " _MAX is determined also according to the components of inertia J _z specific to the structure of the crane 3.

For example, the figure 5 represents a diagram comprising a set of surface curves describing the maximum authorized lifting acceleration L " _MAX , expressed in g (1g corresponding to the gravitational acceleration), as a function of the mass M of the suspended load 2, expressed in kilograms , and the distribution position X _c of said suspended load, expressed in meters.

Each surface curve corresponds to a distinct specified load factor Ψ ₀ *.

As a reminder, the load factor Ψ ₀ limit used to determine the specified load factor Ψ ₀ * can be freely chosen by the person in charge of configuring the crane.

In the example of the figure 5 , the set comprises three surface curves corresponding to a specified load factor Ψ ₀ * equal, respectively, to 0.15, 0.175, 0.2.

It is of course possible to use a set having a higher number of surface curves, so as to cover more finely and / or over a larger range different values for the specified load factor Ψ ₀ *.

Thus, during the second step 120, the maximum permitted lifting acceleration L " _MAX can be determined, at any time, as a function of the mass M and the distribution position Xc, by determining by means of the surface curve corresponding to the load factor Ψ ₀ * specified.

In a third step 130, optimized lifting speed instructions CMD 'are determined from CMD lifting speed instructions.

The optimized CMD 'hoisting speed instructions are intended to be executed by the hoist motor device 41 for moving the suspended load 2 in a lifting movement so that the acceleration specific to the hoisting movement remains, in absolute value, less than or equal to the maximum allowed lifting acceleration L " _MAX .

It should be noted that the maximum permitted lifting acceleration L " _MAX is variable, depending on the specified load factor Ψ ₀ *.

The maximum allowed lifting acceleration The _MAX is thus used as a value limiting the suspended load speed variations imparted by the motor device 41 at the origin of the lifting movement.

• une vitesse de levage V_{MAX BRK} maximale autorisée, déterminée en fonction des capacités de la grue à freiner les mouvements de la charge 2 suspendue notamment pour garantir la sécurité du freinage de la charge à tout moment;
• une vitesse de levage V_{MAX SEC} maximale de sécurité, déterminée en fonction des capacités de la grue 3 à supporter une pose au sol de la charge 2 suspendue brutale ou un arrêt d'urgence, de manière à s'assurer que la dynamique résultante reste dans une enveloppe acceptable pour la structure - ladite enveloppe étant différente de la courbe de charge nominale ;
• une accélération de levage maximale L"_SEC atteignable aux moyens du dispositif moteur 41 de levage;
• une accélération de levage minimale L"_MIN, dite « accélération minimale de confort », qui est prédéterminée de sorte à fixer une valeur d'accélération de levage qui est suffisamment élevée pour assurer un certain confort du levage, mais dont la valeur est suffisamment basse (en valeur absolue) pour ne jamais mettre en danger la grue ; en pratique, cette accélération minimale de confort peut être utilisée en lieu et place de l'accélération maximale L"_MAX pour ne pas immobiliser inutilement la grue.

The optimized lifting speed instructions CMD 'can also be determined, according to the CMD lifting speed instructions received from the control device 10, so that their implementation by the command execution system 40 also respects a or more of the constraints of the following non-exhaustive list:

• a maximum permitted maximum lifting speed V _{MAX BRK} , determined according to the capacity of the crane to slow down the movements of the suspended load 2, in particular to guarantee the safety of the braking of the load at all times;
• a maximum safety maximum V _{MAX SEC} safety rate, determined according to the capabilities of the crane 3 to support a floor installation of the load 2 sudden suspension or emergency stop, so as to ensure that the resulting dynamic remains in an envelope acceptable for the structure - said envelope being different from the nominal load curve;
• a maximum lifting acceleration L " _SEC achievable by means of the lifting motor device 41;
• a minimum lifting acceleration L " _MIN , called" minimum comfort acceleration ", which is predetermined so as to set a lift acceleration value which is high enough to ensure a certain lifting comfort, but whose value is sufficiently low (in absolute value) to never endanger the crane, in practice, this minimum acceleration of comfort can be used instead of the maximum acceleration L " _MAX not to immobilize the crane unnecessarily.

We now refer to the figure 4 , on which is represented a block diagram used to describe an oscillator type mechanical model, used, according to an embodiment of the invention, during the second step 120, to determine the maximum authorized lifting acceleration L " _MAX .

The mechanical model presented below allows to establish an inequality between the maximum authorized lifting acceleration L " _MAX and the load factor Ψ ₀ * specified. As long as this inequality is respected, the corresponding effective instant load factor Ψ the conditions of transport of the load at the moment considered - remains below the specified load factor Ψ ₀ * Thus, the static and dynamic load undergone at the instant considered by the crane never exceeds the maximum permissible exceedance set by the maximum allowable load curve.

$$J_z{\ddot{\theta }}_0=-{\mathit{K\theta }}_0+x_c{F}_{z0}$$

$$M\ddot{L}=\left(F_z-\mathit{Mg}\right)$$

$$M{\ddot{L}}_0=\left(F_{z0}-\mathit{Mg}\right)$$

dans lesquelles

• θ représente l'angle de fléchissement en tangage de la flèche 4 (c'est-à-dire l'angle formé en tangage par la déformée de la flèche 4 par rapport à la position de ladite flèche à vide, du fait de la déformation par flexion en basculement de ladite flèche 4 sous l'effet de la charge) ;
• ΔF_z = F_z - Mg corresponds à la variation d'effort vertical lié à la charge, F_z étant la charge verticale à l'instant considéré ;
• J_z, K corresponds à un modèle de raideur et d'inertie du premier ordre relative à la structure de la grue ; plus particulièrement, K correspond à la raideur de la flèche 4 en flexion de tangage, et Jz l'inertie de la flèche 4 par rapport à son point d'intersection avec le mât 6 ;
• M correspond à la masse de la charge;
• θ̃ = θ - θ ₀ corresponds à la variation de l'angle horizontal de la flèche ;
• L̃ = L - L ₀ corresponds à la variation de hauteur de charge directement proportionnelle à la longueur de câble enroulée / déroulée au niveau du treuil de levage, ou grandeur directement liée ;

on en déduit : $$J_z\ddot{\tilde{\theta }}=-\mathit{K}\tilde{\theta }+x_c\mathrm{\Delta }{F}_z$$

$$M\ddot{L}=\mathrm{\Delta }{F}_z$$

The mechanical model can thus be described by means of the following mathematical expressions: $$J_z\ddot{\theta }=-\mathit{K\theta }+x_c{F}_z$$

$$J_z{\ddot{\theta }}_0=-{\mathit{K\theta }}_0+x_c{F}_{z0}$$

$$M\ddot{\mathrm{The}}=\left(F_z-\mathit{mg}\right)$$

$$M{\ddot{\mathrm{The}}}_0=\left(F_{z0}-\mathit{mg}\right)$$

in which

• θ represents the pitch deflection angle of the deflection 4 (that is to say the pitch angle formed by the deflection of the deflection 4 relative to the position of said empty deflection, due to the deformation bending bending said boom 4 under the effect of the load);
• Δ F _z = F _z - Mg corresponds to the variation of vertical force related to the load, F _z being the vertical load at the moment considered;
• J _z , K corresponds to a model of stiffness and inertia of the first order relative to the structure of the crane; more particularly, K corresponds to the stiffness of the arrow 4 in pitch bending, and Jz the inertia of the arrow 4 relative to its point of intersection with the mast 6;
• M is the mass of the load;
• θ = θ - θ ₀ corresponds to the variation of the horizontal angle of the arrow;
• L = L - L ₀ corresponds to the load height variation directly proportional to the length of the cable wound / unwound at the hoist winch, or directly connected quantity;

we can deduce : $$J_z\ddot{\tilde{\theta }}=-\mathit{K}\tilde{\theta }+x_c\mathrm{\Delta }{F}_z$$

$$M\ddot{\mathrm{The}}=\mathrm{\Delta }{F}_z$$

It should be noted that the effect of damping stiffness is neglected because it does not amplify the dynamic effects of the arrow when the dynamic factor is important - (as is the case in the loading phase or significant variation).

We can ask: $$-K\tilde{\theta }+x_c{\mathrm{\Delta }\mathit{F}}_z\le x_c{\mathrm{\Delta }\mathit{F}}_z$$

et que par conséquent : $$x_c{\mathrm{\Delta }\mathit{F}}_z=x_{c}M\ddot{L}$$

on obtient ainsi l'expression mathématique suivante : $$J_z\ddot{\tilde{\theta }}=-\mathit{K}\tilde{\theta }+x_c\mathrm{\Delta }{F}_z\le {\mathit{Mx}}_c\ddot{\tilde{L}}$$

Since $$M\ddot{\mathrm{The}}=\mathrm{\Delta }{F}_z$$

and therefore: $$x_c{\mathrm{\Delta }\mathit{F}}_z=x_{c}M\ddot{\mathrm{The}}$$

we thus obtain the following mathematical expression: $$J_z\ddot{\tilde{\theta }}=-\mathit{K}\tilde{\theta }+x_c\mathrm{\Delta }{F}_z\le {\mathit{mx}}_c\ddot{\widetilde{\mathrm{The}}}$$

The actual instantaneous load factor correspond corresponds to the quotient of the sum of the vertical acceleration of the suspended load - that is to say of the winding acceleration or unwinding of the cable - and the acceleration due to the pitch bending of the boom of the crane, to the numerator, by the acceleration of gravity g, to the denominator, that is to say corresponds to the sum, relative to the gravitational acceleration, of the vertical acceleration of the load and of the acceleration linked to the deflection of the deflection 4. Thus, the actual instantaneous load factor peut can be described by the expression following mathematical: $$\mathit{\Psi }=\frac{\ddot{\widetilde{\mathrm{The}}}}{g}+\frac{x_c\ddot{\theta }}{g}$$

Thus, we obtain the following inequality: $$\mathit{\Psi }=\frac{\ddot{\widetilde{\mathrm{The}}}}{g}+\frac{x_c\ddot{\theta }}{g}\le \frac{{x_c}^{2}M+J_z}{{\mathit{gJ}}_z}\ddot{\widetilde{\mathrm{The}}}$$

de telle sorte que l'on respecte : $$\ddot{\tilde{L}}<\frac{{\mathit{gJ}}_z}{\left({x_c}^{2}M+J_z\right)}{\mathit{\Psi }}_0^{*}$$

Therefore, if one chooses to limit the lifting acceleration $\ddot{\widetilde{\mathrm{The}}}$

so that we respect: $$\ddot{\widetilde{\mathrm{The}}}<\frac{{\mathit{gJ}}_z}{\left({x_c}^{2}M+J_z\right)}{\mathit{\Psi }}_0^{*}$$

Then we will necessarily have: $$\mathit{\Psi }\le \frac{{x_c}^{2}M+J_z}{{\mathit{gJ}}_z}\ddot{\widetilde{\mathrm{The}}}<\frac{{x_c}^{2}M+J_z}{{\mathit{gJ}}_z}\frac{{\mathit{gJ}}_z}{\left({x_c}^{2}M+J_z\right)}{\mathit{\Psi }}_0^{*}$$

Is : $$\mathit{\Psi }<{\mathit{\Psi }}_0^{*}$$

Thus, the actual instantaneous load factor sera will always be less than the specified load factor Ψ ₀ *.

In one embodiment, during the third step 130, the limitation of the lifting speed variations, that is to say the limitation of the lifting acceleration, with respect to the specified load factor Ψ ₀ *, limitation which makes it possible to impose the above inequality, is preferably obtained by the application of a LIM function of the ramp limiter type, more commonly referred to by the English expression "ramp limiter". The ramp limiting type LIM function ensures that the requested input speed variation never exceeds a maximum acceleration threshold. Thus, the speed reference at the output of the LIM function respects the objective set by the designer.

In one embodiment, the LIM function describes a ramp whose slope corresponds to the maximum allowed acceleration L " _MAX .

Also, by way of example, in response to a step of speed commands included in the CMD instructions, requested by the crane operator, the optimized instructions CMD 'will comprise speed instructions to be applied, the value of which increases gradually, for a period predefined time, following the ramp described by the LIM function, the slope of which corresponds to the maximum allowable acceleration L " _MAX In this way, the inertial effects are limited.

We now refer to the figure 3 , on which is represented a block diagram of the monitoring and control device 20, according to one embodiment of the invention. In this embodiment, the monitoring and control device 20 is configured to implement the lifting control control method, previously described, by means of the mathematical model as described above, with respect to the figure 4 .

More particularly, the monitoring and control device 20 comprises a speed limiter module 210, an acceleration limiter module 220, and a braking and breaking module 230 (denoted SD & CUTF for "SlowDown & CUToFf").

• la vitesse V_{MAX BRK} maximale autorisée, fonction des capacités de la grue à freiner les mouvements de la charge suspendue ; et,
• la vitesse de levage V_{MAX SEC} maximale de sécurité, déterminée en fonction des capacités de la grue à supporter une pose au sol de la charge suspendue brutale et/ou un arrêt d'urgence (freinage et arrêt du mouvement de levage), de sorte à éviter des à-coups dans des situations d'urgence.

The speed limiter module 210 is configured to produce, to the acceleration limiter module 220, a target target of higher lifting speed CV, according to the lifting speed instructions CMD, sent by the control device 10. target setpoint for higher lifting speed CV is determined by calculating the result of a limiting LIMv function for the value corresponding to the minimum between:

• the maximum authorized _{MAX BRK} speed, depending on the crane's ability to brake the movements of the suspended load; and,
• the maximum safe lifting speed V _{MAX SEC} , determined by the crane's ability to withstand the sudden suspended load and / or an emergency stop (braking and stopping of the hoisting motion) on the ground, to avoid jolts in emergency situations.

The acceleration limiter module 220 comprises a calculation module 240 of the maximum acceleration L " _MAX , as a function of the specified load factor Ψ ₀ *, the distribution position _Xc and the mass M.

The calculation module 240 may include reading means in a preconfigured memory of an abacus / mapping corresponding to a set of surface curves as shown in FIG. figure 5 .

Alternatively, the calculation module 240 may comprise calculation means using an explicit mathematical description, as described previously with regard to the figure 4 , to determine the maximum acceleration L " _MAX .

• ∘ d'une part la valeur minimale entre:
  • ▪ l'accélération de levage maximale L"_MAX déterminée par le module de calcul 240 ; et,
  • ▪ l'accélération de levage maximale L"_SEC atteignable par le dispositif moteur 41 de levage (de manière à ce que la consigne d'accélération ne puisse pas excéder les capacités matérielles du moteur de levage 41) ; la valeur ainsi retenue à l'instant considéré correspond donc avantageusement à l'exigence de sécurité de fonctionnement la plus contraignante, et par conséquent à la condition de fonctionnement la plus défavorable ;
• ∘ et d'autre part une accélération de levage minimale L"_MIN, dite « accélération de levage de confort ».

The acceleration limiter module 220 is configured to determine the speed reference value applicable to the hoist motor 41, and progressively bring said speed reference to the higher hoist speed value CV, by applying as a rate of variation (slope V _{L "} of the acceleration ramp), a value V _L" which corresponds to the maximum between:

• ∘ on the one hand the minimum value between:
  • The maximum lifting acceleration L _MAX determined by the calculation module 240, and
  • ▪ the maximum lifting acceleration L " _SEC reached by the motor 41 lifting device (so that the acceleration setting can not exceed the material capacities of the hoist motor 41), the value thus retained to the moment considered therefore corresponds advantageously to the most restrictive operating safety requirement, and therefore to the most unfavorable operating condition;
• ∘ and on the other hand a minimal lifting acceleration L " _MIN , called" comfort lifting acceleration ".

The minimum lifting acceleration L " _MIN corresponds to a minimum acceleration of comfort for crane control by the crane operator As mentioned above, this minimum acceleration of comfort is chosen sufficiently low not to endanger the crane. being high enough not to unnecessarily immobilize the crane, especially when the maximum lifting acceleration L " _MAX calculated is, in a timely manner, unusually low or abnormally low.

The value of lift acceleration adopted, applicable at the moment considered, and therefore the slope V _{L "} of the corresponding acceleration ramp, thus reflects the best possible compromise, taking into account the requirements of dependability.

Advantageously, the acceleration limiter module 220 comprises means for limiting, over time, the lifting acceleration corresponding to the target setpoints for the hoisting speed CV received, by the application of the limiting function LIM of the ramp limiting type, describing a ramp whose slope corresponds to the value _{V.sub.L "} . The limiting function LIM of the ramp limiting type makes it possible to clamp down the input speed variation requested so that the lifting acceleration observed in absolute value remains lower than the value. V _{L "} .

Preferably, the braking and breaking module 230 is configured to ensure that the optimized instructions CMD 'produced as a function of the acceleration commands CA, do not cause the displacement of the load according to the distribution movement beyond a limit position X _{C MAX} . If necessary, the cut-off module 230 modifies the optimized setpoints CMD 'so that the load does not exceed the limit position X _{C MAX} after the implementation of the optimized instructions CMD'. It will be noted, more generally, that the invention preferably advantageously superimposes conventional safety devices for stopping the movements of the crane in case of occurrence of a dangerous situation.

Thus, the optimized instructions CMD 'can typically be transmitted to said safety devices and traditional cutting of the crane, so they can remain active to ensure their usual mission.

More particularly, the braking and breaking module 230 can thus slow down the hoist motor 41 or even stop it when the load approaches, or even reaches, the preset limit position X _{C MAX} .

Claims (10)

A control method for controlling the lifting of a load suspended from an arrow, carried by a mast of a crane, characterized in that it comprises the following steps: A first step (110) for determining, based on the mass (M) of the suspended load, a specified load factor (Ψ ₀ *) quantifying an acceptable overshoot relative to a predetermined maximum allowable load for said crane; ; A second step (120) of determining a maximum allowed lifting acceleration (L " _MAX ), as a function of the mass (M) of the suspended load, the specified load factor (Ψ ₀ *) and the position in distribution (X _c ) of the load suspended on the boom relative to the mast; A third step (130) of determining, from lifting speed instructions (CMD), optimized lifting speed setpoints (CMD ') to be executed by a motor device (41) to move in a directional movement; lifting the suspended load so that the acceleration relative to the lifting movement remains, in absolute value, less than or equal to the maximum permitted acceleration (L " _MAX ). The method of claim 1, wherein the maximum allowable lifting acceleration (L " _MAX ) is determined by the following mathematical expression: $$\frac{{\mathit{gJ}}_z}{{x_c}^{2}M+J_z}{\psi }_0^{*}$$

in which : x _c corresponds to the distribution position of the suspended load; M is the mass of the suspended load; J _z corresponds to a model of stiffness and inertia of the first order relative to the structure of the crane. A method as claimed in any one of the preceding claims, wherein the specified load factor (Ψ ₀ *) is determined by means of a maximum load curve, corresponding to a limit load factor (Ψ ₀ ) and a load static maximum. A method according to claim 3, wherein the limit load factor (Ψ ₀ ) is determined from a first theoretical threshold function of the theoretical load capacity supported by the crane and a second threshold function of uncertainties of relative measurements. the weight of the suspended load and / or the lifting motion of the suspended load. A method according to any one of claims 3 to 4, wherein the specified load factor (Ψ ₀ *) is obtained by multiplying the limit load factor (Ψ ₀ ) by the ratio between the maximum static load corresponding to the maximum permissible load and the mass (M) of the suspended load. A method as claimed in any one of the preceding claims in which the optimized lifting speed instructions (CMD ') are determined so that their execution by the driving device (41) to move according to the lifting movement of the suspended load verifies the condition next: ∘ the lifting acceleration of the suspended load, in absolute value, remains less than or equal to the maximum permitted acceleration (L " _MAX ); as well as one or more of the following additional conditions: ∘ the lifting speed of the suspended load, in absolute terms, remains below a lifting speed (V _{MAX BRK)} maximum allowed, the hoisting speed (V _{MAX BRK)} maximum allowed is determined based on the crane's capacity to curb the movements of the suspended load; and or, ∘ the lifting speed of the suspended load, in absolute value, remains below a maximum safe lifting speed (V _{MAX SEC} ), determined according to the crane's ability to withstand the sudden suspended load on the ground, and / or an emergency stop; and or, ∘ the lifting acceleration of the suspended load, in absolute value, remains lower than a maximum lifting acceleration (L " _SEC ) attainable by the driving device (41); and / or, ∘ the lifting acceleration of the suspended load, in absolute value, remains higher than a minimum lifting acceleration (L " _MIN ). A method according to any one of the preceding claims wherein the optimized lifting speed setpoints are determined so that the absolute value of the lifting speed of the suspended load increases, over a predefined period of time, along a ramp whose slope corresponds to the maximum allowed lifting acceleration (L " _MAX ). A computer program comprising instructions for performing the steps of the method according to any one of claims 1 to 7 when said program is executed by a processor. A computer-readable recording medium on which a computer program is recorded including instructions for executing the steps of the methods according to any one of claims 1 to 7. Crane, preferably a tower crane, having an arrow-bearing mast on which is mounted a carriage for carrying a suspended load, characterized in that it further comprises load control means (20) for lifting the load suspended, provided: Means for determining, according to the mass (M) of the suspended load, a specified load factor (Ψ ₀ *) quantifying an acceptable overshoot relative to a predetermined maximum allowable load for said crane; • means for determining a maximum allowed lifting acceleration (L " _MAX ), as a function of the mass (M) of the suspended load, the specified load factor (Ψ ₀ *) and the distribution position (X _(c ) the load suspended on the boom from the mast; • means for determining, from lifting speed instructions (CMD), optimized lifting speed instructions (CMD ') intended to be executed by a motor device (41) for moving the suspended load in a lifting movement such that the acceleration relative to the lifting movement remains, in absolute value, less than or equal to the maximum permitted acceleration (L " _MAX ).

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