EP1834920B1 - Method for automatic handling of a crane load with sway damping and path control - Google Patents

Abstract

The method involves establishing the work space by selecting two points, fixing one of the two points as the target point through direction specifications by means of a hand lever, and setting the ideal speeds for the rotary and tipper mechanism through the hand lever signals. The ideal position of the load can be divided up into components which are each taken into consideration in the axle regulator for the rotary mechanism or tipper mechanism.

Description

The invention relates to a method for handling a load suspended on a load rope of a crane or excavator, comprising a computer-controlled control for damping the load oscillation and a path planner, and more particularly to a method for automatically handling the load.

The invention includes load-swing damping in cranes or excavators which permits movement of the load suspended on a rope in at least three degrees of freedom. Such cranes or excavators have a slewing gear, which can be mounted on a chassis, which serves for rotating the crane or excavator. Furthermore, a luffing mechanism for erecting or tilting a boom is available. Finally, the crane or excavator includes a hoist for lifting and lowering the load suspended on the rope. Such cranes or excavators are used in various designs. Examples include harbor mobile cranes, ship cranes, offshore cranes, caterpillar cranes and rope excavators.

When handling a hanging on a rope load by means of such a crane or excavator oscillations arise, on the one hand on the movement of the crane or excavator itself or even on external disturbances, such as wind are due. Efforts have already been made in the past to suppress pendulum vibrations in load cranes.

That's how it describes DE 127 80 79 an arrangement for the automatic suppression of oscillations of a suspended by means of a rope at a movable level rope suspension point load on movement of Seilaufhängepunktes in at least one horizontal coordinate, wherein the speed of Seilaufhängepunktes in the horizontal plane by a control loop as a function of one of the Auslenkwinkel of the load rope against the Endlot derived size is influenced.

The DE 20 22 745 shows an arrangement for the suppression of pendulum vibrations of a load suspended by means of a rope on the cat of a crane, the drive is equipped with a speed device and a path control device, with a control arrangement, the cat taking into account the oscillation period during a first part of so accelerated and retarded during a last part of this path, that the movement of the cat and the vibration of the load at the destination immediately become zero.

From the DE 321 04 50 a device has been known on hoists for the automatic control of the movement of the load carrier with reassurance of the pendulum of the load occurring during acceleration or deceleration of the load hanging on it during an acceleration or deceleration time interval. The basic idea is based on the simple mathematical pendulum. The cat and load mass is not included in the calculation of the movement. Coulombic and velocity-proportional friction of the cat or bridge drives are not considered.

To be able to transport a load body as quickly as possible from the location to the destination, the DE 322 83 02 to control the speed of the drive motor of the trolley by means of a computer so that the trolley and the load carrier are moved during the steady drive at the same speed and the pendulum damping is achieved in the shortest possible time. The from the DE 322 83 02 known computer works according to a computer program to solve the differential equations applicable to the undamped two-mass vibration system formed from trolley and load body, the coulomb and speed-proportional friction of the cat or bridge drives are not taken into account.

In the from the DE 37 10 492 have become known methods, the speed between the destinations on the way chosen so that after covering half the total distance between the starting place and destination of the pendulum deflection is always equal to zero.

That from the DE 39 33 527 Known method for damping of load oscillations comprises a normal speed position control.

The DE 691 19 913 deals with a method for controlling the adjustment of a swinging load, in which in a first control loop the deviation between the theoretical and the actual position of the load is formed. This is derived, multiplied by a correction factor and added to the theoretical position of the mobile carrier. In a second control loop, the theoretical position of the mobile carrier is compared with the actual position, multiplied by a constant and added to the theoretical speed of the mobile carrier.

The DE 44 02 563 deals with a method for the control of electric traction drives of hoists with a load suspended on a rope, which generates due to the dynamics descriptive equations the desired course of the speed of the trolley and gives to a speed and current regulator. Furthermore, the computing device can be extended by a position controller for the load.

The from the DE 127 80 79 . DE 393 35 27 and DE 691 19 913 have become known control method need for load swing damping a cable angle sensor. In the extended version according to the DE 44 02 563 this sensor is also required. Since this rope angle sensor causes considerable costs, it is advantageous if the load oscillation can be compensated without this sensor.

The procedure of DE 44 02 563 in the basic version also requires at least the crane speed. Also at the DE 20 22 745 Several sensors are required for load swing damping. So must in the DE 20 22 745 at least one speed and position measurement of the trolley are made.

Also the DE 37 10 492 requires at least the cat or bridge position as an additional sensor.

As an alternative to this method proposes another approach, for example, from the DE 32 10 450 and the DE 322 83 02 is known to solve the system underlying differential equations and based on a control strategy for the system to determine to suppress a load swing, in the case of DE 32 10 450 the rope length and in the case of DE 322 83 02 the rope length and load mass is measured. In these systems, however, the frictional effects of static friction and velocity-proportional friction, which are not negligible in the crane system, are not taken into account. Also the DE 44 02 563 does not consider friction and damping terms.

In order to develop a crane or excavator for transferring from a load suspended on a load rope, which can move the load at least three degrees of freedom, so that the pendulum movement of the load actively occurring during the movement can be damped and the load so accurately on a given path the applicant already has in her DE 100 64 182 A1 proposed to equip the crane or excavator with a computer-controlled control for damping the load oscillation, the a Bahnplanungsmodul (hereinafter referred to as Bahnplaner), a Zentripetalkraftkompensationseinrichtung and at least one axis controller for the slewing, an axis controller for the luffing and an axis controller for the hoist has.

A method according to the preamble of claim 1 is known from WO 2004/106215 A1 known.

When handling loads, it is necessary to use the crane or excavator, for example a mobile harbor crane, to approach two destination points as quickly as possible and in the correct position. One of the target points lies in the object to be unloaded, the other in the object to be loaded. A largely automated handling of the loads is referred to as a so-called teach-in operation.

The object of the invention is to provide a method for the implementation of the so-called. Teach-in operation for cranes or excavators, especially mobile harbor cranes.

The solution results from the combination of the features of the main claim.

Particular embodiments of the invention will become apparent from the dependent claims.

The fully automatic path planner is integrated into an active load swing damping system for a mobile harbor crane. The requirement for the crane operator to repeatedly approach two points in the work space serves as a starting point for the development of fully automatic operation. As in FIG. 1 These two points are defined by the crane operator. Depending on the direction given by the hand lever, one of the two points is set as the target point. The aim is to approach the target point as fast as possible and with exact position and to minimize load oscillation. Furthermore, the target speeds for the lathes and luffing mechanism are specified by the hand lever signals. Thus, the crane operator retains control of the mobile harbor crane even in fully automatic operation. Obstacles that are in the workspace can be bypassed, because the load can be moved freely in the entire workspace without being bound to a specific trajectory. The active load oscillation damping ensures, as in the patent application DE 100 64 182 A1 described for minimizing the load oscillation. If it is necessary to leave the working space, the crane operator must press a corresponding key. Through this mode of operation, the so-called teach-in operation, high Achieves handling performance and minimizes the requirements placed on the crane operator. In addition, the crane behaves in fully automatic operation almost as in semi-automatic operation, in which the hand lever signal is used for crane control and the active load oscillation damping ensures the minimization of the load oscillation. Thus, the dynamic behavior of the crane remains predictable and familiar to the crane operator.

Further details and advantages of the invention are explained below with reference to the figures.

The control of the crane is supported by secondary vibration damping ( DE 100 64 182 A1 ) realized. The substructures for the luffing and luffing mechanism essentially consist of the trajectory generation, the disturbance observers and the state controllers with precontrol (see FIG. 2 ). In fully automatic operation, both the lever signal φ̇ _DZiel and ṙ _ALZiel and the start / end points in the working area are evaluated. With this information, modified reference signals for the load speed in the direction of rotation and the radial direction are calculated. In the trajectory planners, target trajectories are generated from the reference signals, which are converted in the axis controllers for luffing gear and luffing gear into the corresponding drive voltages for the hydraulic drives.

As in FIG. 1 is represented, the two points defined by the crane operator in the working space are projected into the φ _D -r _AL plane. This allows the setpoint positions of the load to be separated into the components φ _{D_destination} and r _{AL_destination} . FIG. 2 shows the consideration of these components in the axis controllers for the luffing and luffing gear. Depending on the deflection of the hand lever, the target position set by the crane operator to the right or left is specified as the target point and separated into the components just listed.

Structure and mode of operation of the fully automatic path planner for the slewing gear:

The basic idea of the fully automatic path planner is the modification of the reduced hand lever _{signal as a} function of the remaining turning range up to the target position φ _{D_Ziel} and the required braking distance. It is accelerated at a deflection of the hand lever by the crane operator first with the deposited in the path planner ramp. If the remaining range of rotation is greater than the angle of rotation required for deceleration, a phase follows in which is driven at a predetermined maximum speed. On the other hand, the acceleration phase directly follows the braking phase, if the rotation range is correspondingly small. As in FIG. 3 shown, the remaining area must first be determined by the difference between the setpoint and actual position. In order to find the right time from which to delay, the required braking distance is included. Depending on the direction of rotation, the difference between the remaining range of rotation and the braking distance becomes negative or positive at exactly the right delay time. In order to improve the behavior of the mobile harbor crane when approaching the target position, the reduced hand lever signal φ̇ _{DZielred is} not set to zero until the deceleration time is reached, but is already reduced when approaching this point in time via an adapted look-up table.

As in FIG. 4 shown, the direction of rotation is first determined in block "modification hand lever signal " on the basis of the sign of the reduced hand lever signal _{φ̇ DZielred} . In order to make the fully automatic path planner robust with respect to rope length changes, the crane is braked even before reaching the actual deceleration time. The difference between position deviation and braking distance is converted via look-up tables to factors between zero and one. If the distance to the deceleration point, which is the angle of rotation from which it must be braked to reach the target angle, is greater than 25 degrees, the reduced hand lever signal is weighted with one and converted into target trajectories in the path planner. Decreases the Distance, the hand lever signal is nonlinear reduced. If the signal diff _DW negative, the factor, with which the reduced hand lever signal is weighted, zero and thus the delay time is reached.

Since the state controller for the slewing gear has no position bond, ie, the rotational angle φ _{D is} not returned, a P controller is implemented, which returns the position deviation. However, the manipulated variable of the P controller is only applied when the destination point is passed over (see FIG. 5 ). It can thus be guaranteed for t → ∞ reaching the target angle. The gain of the P controller is determined by a fixed factor P _factor weighted by the absolute value of the hand lever signal. The hand lever signal is normalized from -1 to 1. This adjusts the P-controller to the dynamics of the system.

The basis for the calculation of the braking distance is the general solution of the state space model of the controlled subsystem slewing gear. The solution of equations of state is divided into two parts, the homogeneous solution and the particulate solution. The particulate solution can be approximated for the slewing gear by the relationship shown in equation (0.1). The first part of the braking distance φ _{Dbrems 1} is determined by the consideration of the measured

Rotational speed φ̇ _D and the maximum acceleration φ̈ _{D _max} calculated. $${\phi }_{\mathit{Dbrems}1}=\frac{{\dot{\phi }}_{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="imgf0007.png"\; state="\{\{state\}\}">D</figure-callout>}}^2}{2\cdot {\ddot{\phi }}_{D\mathrm{\_Max}}}$$

The second part of the braking distance φ _{Dbrems 2} results from the calculation of the homogeneous solution of the controlled subsystem slewing gear.

Homogeneous solution of the controlled subsystem Slewing:

The vibration damping of the load in the tangential direction implemented for the slewing gear leads to compensation movement of the crane in the direction of rotation. The dynamics of the state control, defined by the pole positions, have a decisive influence on the required braking distance of the slewing gear. In order to determine the angle of rotation, which results at a deflection of the controlled system, the homogeneous solution of this system is calculated. With the homogeneous solution shown in equation (0.2) all states can be determined by measuring the initial states. $${\underset{}{x}}_{\mathrm{hom}}\left(t\right)=e^{{\underset{}{A}}_R\left(t-{\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="imgf0004.png,imgf0005.png"\; state="\{\{state\}\}">t</figure-callout>}}_0\right)}\cdot \underset{}{x}\left({\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="imgf0004.png,imgf0005.png"\; state="\{\{state\}\}">t</figure-callout>}}_0\right)$$

Here, A _{R is} the system matrix of the controlled system. With the four states of rotation angle, rotational angular velocity, tangential rope angle and tangential rope angular velocity and the driving voltage of the proportional valve of the hydraulic circuit as an input, the state vector and the input vector result $${\underset{}{x}}_D={\left[{\phi }_D{\dot{\phi }}_D{\phi }_{\mathit{St}}{\dot{\phi }}_{\mathit{St}}\right]}^T;\underset{}{u}=u_{\mathit{Hours}}$$

With these definitions, the state space of the slewing gear is as follows $$\begin{array}{l}\underset{{\underset{}{A}}_D}{{\dot{\underset{}{x}}}_D=\underset{\}}{\left[\begin{array}{cccc}0& 1& 0& 0\\ 0& -\frac{1}{{\mathrm{<figure-callout\; id="0"\; label="T\; D"\; filenames="imgf0004.png,imgf0005.png"\; state="\{\{state\}\}">T\; </figure-callout>}}_D}& 0& 0\\ 0& 0& 0& 1\\ 0& \frac{a}{T_D}& -\frac{G}{l_s}& 0\end{array}\right]}}\cdot {\underset{}{x}}_D+\underset{{\underset{}{B}}_D}{\underset{\}}{\left[\begin{array}{c}0\\ b\\ 0\\ -a\cdot b\end{array}\right]}}\cdot {\underset{}{u}}_D\\ \mathrm{With}a=\frac{l_A\cdot \cos \left({\phi }_A\right)}{l_S}\mathrm{and}b=\frac{K_{VD}\cdot 2\cdot \pi }{i_D\cdot V_{MD}\cdot T_D}\end{array}$$

Where l _{A is} the boom length, l _{S is} the free pendulum length, i _{D is} a gear ratio, V _{MD is} the displacement of the hydraulic motor, T _{D is} the deceleration time of the hydraulic drive, K _{VD is} the proportionality constant between the drive voltage and flow rate of the pump and φ _{A is} the angle of elevation of the boom , The output of the system is the unloading of the load. Thus, the output matrix C _{D is} given by $${\underset{}{C}}_{D=\left[10\frac{l_s}{\cos \left({\phi }_{A0}\right)\cdot {\mathrm{<figure-callout\; id="0"\; label="l\; A"\; filenames="imgf0004.png,imgf0005.png"\; state="\{\{state\}\}">l\; </figure-callout>}}_A}0\right]}$$

In order to be able to calculate the angle of rotation that results when the controlled system is deflected, equation (0.2) must be solved for the first state (φ _D ). For this purpose, first the system matrix of the controlled system with the feedback matrix K = [0 k ₂ k ₃ k ₄ ], the elements of which are determined by pole specification, is calculated. (Equation (0.6)). The first gain of the feedback matrix is Zero, since one of the four poles is set to zero and thus the state control of the slewing gear has no positional connection. $${\underset{}{\mathrm{A}}}_{\mathrm{R}}=\left[\begin{array}{cccc}0& 1& 0& 0\\ 0& -\frac{1}{T_D}-b\cdot k2& -b\cdot k3& -b\cdot k4\\ 0& 0& 0& 1\\ 0& \frac{\begin{array}{c}a\end{array}}{T_D}+a\cdot b\cdot k2& -\frac{G}{l_S}+a\cdot b\cdot k3& a\cdot b\cdot k4\end{array}\right]$$

Now calculate the transition matrix Φ = e ^{A _R ( tt 0 )} and considers the limit for t → ∞, the following elements of the first line result. $$\begin{array}{l}{\phi }_{11}=1\\ {\phi }_{12}=-\left(l_1\cdot l_2\cdot T_D^2+l_1\cdot T_D+l_1\cdot T_D^2\cdot \mathrm{b}\cdot \mathrm{k}2+l_1\cdot l_3\cdot T_D^2+l_2\cdot T_D+l_2\cdot T_D^2\cdot \mathrm{b}\cdot \mathrm{k}2+l_2\cdot l_3\cdot T_D^2-T_D^2\cdot b^2\cdot \mathrm{a}\cdot k_2\cdot k_4+2\cdot T_D\cdot \mathrm{b}\cdot k_2-T_D\cdot \mathrm{b}\cdot \mathrm{a}\cdot k_4+T_D^2\cdot b^2+k_2^2+1+l_3\cdot T_D+l_3\cdot T_D^2\cdot \mathrm{b}\cdot k_2\right)/\cdot \left(l_1\cdot l_2\cdot l_3\cdot T_D^2\right)\\ {\phi }_{13}=-\left(l_1\cdot T_D\cdot k_3+l_2\cdot T_D\cdot k_3+k_3+T_D\cdot \mathrm{b}\cdot k_2\cdot k_3+T_D\frac{G}{l_S}\cdot k_4-T_D\cdot \mathrm{b}\cdot \mathrm{a}\cdot k_3\cdot k_4+l_3\cdot T_D\cdot k_3\right)\cdot b/\left(l_1\cdot l_2\cdot l_3\cdot T_D\right)\\ {\phi }_{14}=-\left(l_1\cdot T_D\cdot k_4+l_2\cdot T_D\cdot k_4+k_4+T_D\cdot \mathrm{b}\cdot k_2\cdot k_4-T_D\cdot k_3-T_D\cdot \mathrm{b}\cdot \mathrm{a}\cdot k_4^2+l_3\cdot T_D\cdot k_4\right)\cdot b/\left(l_1\cdot l_2\cdot l_3\cdot T_D\right)\end{array}$$

The three remaining poles of the controlled subsystem of rotation, which are not equal to zero, are symbolized by l ₁ , l ₂ and l ₃ .

With equation (0.2) and the elements of the transition matrix, the homogeneous solution of the controlled system for the rotation angle can be determined. In equation (0.8) the relationship is shown. $${\phi }_{\mathit{Dhom}}={\phi }_{11}\cdot {\phi }_D+{\phi }_{12}\cdot {\dot{\phi }}_D+{\phi }_{13}\cdot {\phi }_{St}+{\phi }_{14}\cdot {\dot{\phi }}_{St}$$

This calculation makes it possible to take into account the dynamic properties of the slewing gear control in fully automatic path planning. The rotation angle φ _{D hom} is calculated dynamically and understood as an additional component φ _{Dbrems 2 of} the braking distance. Thus, it is possible to generate trajectories that lead to the correct approach of the target point.

Structure and mode of operation of the fully automatic path planner for the luffing gear:

In contrast to the slewing gear control, the pitch angle of the jib φ _{A is} returned for the luffing gear. Thus, the approach of the state controller with position binding can guarantee the achievement of the predefined position for t → ∞ and the fully automatic path planner becomes considerably simpler (see FIG. 6 ). Analogous to the turntable planner, the reduced hand lever signal ṙ _ALZielred is adapted in the block "Modification hand lever signal _" so that the movement of the luffing gear is delayed at the right time to reach the target position. The modified target speed profile of the load in the radial direction generated in fully automatic operation becomes as in FIG. 2 shown converted in the path planner in the target trajectory r _ALref .

The delay time t _delay is obtained by direction-dependent evaluation of the sign of the difference between the deviation from the target radius and the required braking distance (see FIG. 7 ). In order to increase the accuracy of the positioning and to minimize the overshoot, a so-called creep zone is additionally introduced. In this range, five percent of the maximum speed are given. The time t _creep is based on the in FIG. 6 shown parameter d _{Kriech_WW} determined. By adding or subtracting the parameter from the difference of Position deviation and the braking distance is obtained by means of a direction-dependent evaluation of the sign the time t _creep .

The creep speed t _creep serves as a basis for deciding when the reduced hand lever signal is changed from the predetermined maximum speed to five percent of the maximum speed. This gives you the in FIG. 8 schematically illustrated course of the modified hand lever signal.

The braking distance of the luffing gear is determined by including the current speed and the maximum acceleration of the boom in the radial direction as follows: $$r_{\mathit{ALbrems}}=\frac{{\dot{r}}_{A\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="imgf0007.png"\; state="\{\{state\}\}">L</figure-callout>}}^2}{2\cdot \ddot{r_{A\mathrm{\_Max}}}}$$

The consideration of the dynamics of the controlled system in the form of the homogeneous solution of the system and a positional deviation due to a P-controller is not necessary as the axis controller of the luffing gear is position-bound.

Claims (6)

1. A method for the transfer of a load hanging at a load rope of a crane or excavator comprising a slewing gear to rotate the crane or excavator, a luffing mechanism to right or incline a boom and a hoisting gear to raise or lower the load suspended at the rope, comprising a computer-controlled regulator for the damping of the load oscillation which has a trajectory planner,
   characterized by the following steps:

   - fixing the working space by selection of two points;

   - fixing of one of the two points as the destination point by direction presetting by means of a hand lever;

   - presetting of the nominal speeds for the slewing gear and luffing mechanism by hand lever signals so that the load can be moved freely in the total working space;

   - automatic modification of the desired speeds in dependence on the remaining rotational range and/or radial range up to the destination point and on the required braking distance.
2. A method in accordance with claim 1, characterized in that both the hand lever signal and the starting points/destination points in the working space are evaluated; and in that modified reference signals are calculated on the basis of this information for the load speed in the direction of rotation and in the radial direction, wherein nominal trajectories are generated from the reference signals in the trajectory planners and are implemented in a pre-controlled manner in the axis regulators for the slewing gear and luffing mechanism into the corresponding control voltages for the drives.
3. A method in accordance with claim 1 or 2, characterized in that the nominal position of the load can be divided into components which are each taken into account in the axis regulator for the slewing gear or the luffing mechanism.
4. A method in accordance with claim 3, characterized in that, in the automatic trajectory planner, the reduced hand lever signal is modified in dependence on the remaining rotational range up to the destination position and on the required braking distance.
5. A method in accordance with either of claims 3 or 4, characterized in that, in the automatic trajectory planner, the reduced hand lever signal is adapted such that the movement of the luffing mechanism is decelerated to reach the destination position.
6. A method in accordance with claim 5, characterized in that, on the deceleration, a so-called creeping range is provided as a safety range in which the luffing mechanism is slowed down from the maximum speed to a fraction of the maximum speed.

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