EP4299858A1 - Method for monitoring the stability of a working machine - Google Patents

Abstract

The invention relates to a method for monitoring the stability of a work machine, in particular a truck-mounted concrete pump, which comprises an undercarriage, a structure rotatably mounted thereon and an adjustable support. According to the invention, in the method a current three-dimensional center of gravity vector is determined based on at least one measured current position of the work machine and projected onto an auxiliary plane. Furthermore, a current tilting edge of the work machine defined by the support is projected onto the auxiliary plane. From these projections, a boundary vector is determined which extends within the auxiliary plane from the origin of the projected center of gravity vector along the direction specified by the latter to the projected tipping edge. A difference between the projected center of gravity vector and the limit vector is calculated and an action is automatically carried out based on the calculated difference, which may include controlling at least one drive of the work machine and/or outputting a signal. The invention further relates to a work machine with a control unit for carrying out the method according to the invention and a corresponding computer program product.

Description

The present invention relates to a method for monitoring the stability of a work machine, in particular a truck-mounted concrete pump, according to the preamble of claim 1, a work machine with a control unit that is set up to carry out the method according to the invention, and a corresponding computer program product.

Many work machines known from the prior art, such as mobile cranes or truck-mounted concrete pumps, have a mobile undercarriage, a structure rotatably mounted on the undercarriage (for mobile cranes this is the superstructure with boom, for truck-mounted concrete pumps the generally foldable distribution boom) and a support device. The latter serves to transfer the loads of the body and any other forces acting on the undercarriage into the ground and to ensure that the machine is stable.

The following statements refer to truck-mounted concrete pumps with a distribution boom that is rotatably mounted on an undercarriage. The latter can, for example, be rotatably mounted on a mast frame connected to a vehicle frame. However, the statements apply analogously to other generic work machines such as mobile cranes or crawler concrete pumps with placing booms.

Taking into account various load assumptions - in Europe and large parts of the world based on the German standard DIN 24117 - stability verification for truck-mounted concrete pumps is usually carried out by a simple comparison of the tipping torques (tilting moments) with the restoring torques (standing moments) of the machine around a tipping point. If the standing moments are greater than the tipping moments, the machine is considered stable.

The tipping moments in truck-mounted concrete pumps essentially result from the placing boom including its own and operating loads as well as unfavorable external influences such as wind. From a mathematical superposition of the center of gravity of the distribution boom with the center of gravity of the undercarriage, the so-called center of gravity of the working machine results as a circular area within which the center of gravity of the entire machine is located when the distribution boom moves.

The connecting lines between two adjacent support feet of the machine's support or support system at the height of the contact area are referred to as tipping edges. A truck-mounted concrete pump (or generally any supported machine) has at least three, but usually four, support feet and thus tilting edges, whereby the number of support feet and tilting edges is unlimited. All tilting edges of the machine enclose any geometric surface. If the overall center of gravity of the machine is within this area, the machine is considered stable. One goal in the design of truck-mounted concrete pumps is to make the best possible use of the area enclosed by the tipping edges.

The support geometries of truck-mounted concrete pumps are usually discretely dimensioned so that the tilting edges do not touch the center of gravity circle at the respective point of the shortest distance to the center of the center of gravity circle. The most unfavorable placing boom position permitted or intended for the respective support configuration is usually assumed. The advantage of this approach, which focuses on borderline situations, is the comparatively simple calculation regardless of the actual position of the placing boom.

In addition to an increase in the workload with a modern number of support options for modern truck-mounted concrete pumps, the disadvantage of this approach lies in its conservative approach: the assumption of a support-specific maximum outreach of the placing boom, especially with narrow supports, unnecessarily restricts the pivoting ranges of the placing boom compared to a high probability that in reality it is not the case unfavorably placed distribution boom. On the other hand, the mapping of the tilting moment as a center of gravity circle is not congruent with the area formed by the tilting edges - there remain areas outside the center of gravity circle but within the area enclosed by the tilting edges that are not used as the working area of the placing boom.

In the case of truck-mounted concrete pumps, a tilting moment can be determined by measuring the hydraulic pressure in the cylinder drive of the first distribution boom joint in conjunction with recording the angle of inclination of this arm and the pivot angle of the distribution boom. The further mast position is only taken into account to the extent that further discrete data signals are available. An inclination of the machine that is relevant to stability is also not recorded in real time (e.g. a shortening of the lever arms due to an inclination compared to an ideally horizontal structure), but is usually taken into account indirectly using conservative assumptions when designing the support system. The determined load moment can then be compared with a standing moment from specified machine data and a path or swivel angle measurement of the horizontal support leg drives and thus with the respective support leg position. Such a system works two-dimensionally horizontally, but vertical effects are not taken into account.

A further disadvantage is that experience has shown that real-time measurement of load data such as hydraulic pressures brings with it the problem of a large degree of uncertainty in the measurement data due to measurement noise, which must be compensated for by the system using appropriate filters and thus at the expense of compromises in performance.

The present invention is therefore based on the object of specifying a method which enables safe and efficient monitoring of the stability of work machines of the generic type and which knows how to overcome the aforementioned disadvantages.

According to the invention, this object is achieved by a method with the features of claim 1, a work machine with the features of claim 13 and a computer program product with the features of claim 15. Advantageous embodiments of the invention result from the subclaims and the following description.

Accordingly, on the one hand, a method for monitoring the stability of a work machine, in particular a truck-mounted concrete pump, is proposed. The work machine includes an undercarriage, a structure rotatably mounted on the undercarriage and an adjustable support for supporting the work machine. The undercarriage is preferably movable and can have a wheeled or crawler chassis.

According to the method, a current three-dimensional center of gravity vector is determined based on at least one measured current position of the work machine. The center of gravity vector therefore has not only horizontal but also a vertical component. The determined current center of gravity vector is projected onto an auxiliary plane, resulting in a two-dimensional projected center of gravity vector, the coordinates of which depend on the choice of the auxiliary plane.

The measured current position of the work machine can relate to a single movable component, for example an articulated arm of the body, or to several movable components. In addition to measured values, the current center of gravity vector can also be based on other information such as geometric data of one or more moving parts of the work machine or the structure.

In addition, a current tilting edge of the work machine defined by the support is projected onto said auxiliary plane. From these projections, a boundary vector is determined which extends within the auxiliary plane from the origin of the center of gravity vector or the projected center of gravity vector along the direction specified by the latter to the projected tipping edge. The tipping edge may itself be defined by vectors that refer to the same origin as the center of gravity vector. In particular, the tilting edge mentioned can be a tilting edge vector. It is also conceivable that several or all tilting edges of the current support are projected onto the auxiliary plane at the same time.

According to the invention, a difference between the projected center of gravity vector and the limit vector is calculated, said difference being the amount of the difference vector or the difference between the amounts of the projected center of gravity vector and the limit vector. In the last-mentioned and presently preferred case, the sign obtained says something about whether the center of gravity associated with the center of gravity vector is located inside or outside the tipping edge and thus whether an increase in range is possible through a continued movement of the body (for example a further unfolding of a distribution boom) or not.

According to the invention, an action is automatically carried out on the basis of the calculated difference, for example by a control unit of the work machine that carries out the calculations described above. Said action, which therefore depends on the value of the calculated difference, can include the control of at least one drive of the work machine (for example an actuator of the body) and/or the output of a signal. The output of a signal can include a simple display of a value and/or a graphical representation on a display unit, for example a monitor in a driver's cab or on a driver's cab of the work machine or on a mobile control device for controlling the work machine. There is also a regulation of one or more Actuators of the work machine based on the signals from the control unit and thus based on a regular calculation of the difference are conceivable.

The basic idea of the present invention is therefore to spatially assign both the position of a center of gravity of the work machine relevant to tipping safety (characterized by the current center of gravity vector) and the position of the tipping edge(s) (e.g. characterized by corresponding tipping edge vectors) in relation to a common origin describe and equate it as a stability condition by projecting onto a common reference plane (auxiliary plane). The stability condition corresponds to the mathematical comparison by forming the difference between the projected center of gravity vector and the limit vector, in particular the amounts of the projected center of gravity vector and the limit vector.

For any position of the structure and the support configuration, the value of the difference provides information about how far the center of gravity is from the tipping edge relevant to the current movement, so that if an approach occurs, an early warning can be displayed or countermeasures can be initiated. If the tilting moments are equal to the standing moments, the difference is zero.

The vectorial approach makes it possible to allow the center of gravity relevant to the tipping safety of the machine, for example the center of gravity of the body or, in the case of a truck-mounted concrete pump, the center of gravity of the placing boom, to follow, as far as geometrically and mechanically possible, any surface enclosed by a theoretically unlimited number of tipping edges and thus not to give away any possible work areas.

The common origin to which the center of mass vector and the boundary vector refer can be any point in the auxiliary plane. It is also conceivable that the origin is determined in one, two or three dimensions by a mechanical or geometric condition of the work machine, for example by an articulation point of a movable part of the structure or an axis of rotation of the structure or a part thereof.

In one possible embodiment, it is provided that the center of gravity vector and/or the limit vector is determined at regular time intervals during operation of the work machine. This enables continuous or real-time monitoring of the stability of the machine. The actually available working area, within which stability is guaranteed, is preferably fully utilized for each movement of the work machine.

In a further possible embodiment, it is provided that the determination of the center of gravity vector and/or the limit vector occurs during operation of the work machine in response to a movement of the work machine, in particular a movement or change in the support and/or the structure. If the machine is at a standstill, the calculation of the vectors or the difference does not need to be updated. However, if a movement occurs, the values are updated or recalculated.

The event- or movement-based monitoring can be superimposed on the determination of the center of gravity and/or boundary vectors, which occurs at regular intervals, for example by regularly updating the values at larger time intervals, regardless of a movement.

In a further possible embodiment it is provided that the auxiliary plane is oriented horizontally. It is also conceivable that the orientation of the auxiliary plane can be determined, for example by an input from the machine operator into an input means.

In general, the orientation of the auxiliary plane is preferably independent of the actual orientation or inclination of the work machine, so that an inclination of the work machine that affects the stability can be taken into account during monitoring.

In a further possible embodiment it is provided that the current three-dimensional center of gravity vector relates to the overall center of gravity of the work machine. Alternatively, the current three-dimensional center of gravity vector can refer to the overall center of gravity of the structure (in the case of a truck-mounted concrete pump, therefore to the overall center of gravity of the placing boom) or even just to a center of gravity of a part of the structure, in particular a first articulated arm of the structure.

For monitoring the stability of a truck-mounted concrete pump, it may be sufficient, for example, to manipulate the angle of attack of a first articulated arm of the placing boom in order to keep the center of gravity of the placing boom within the usual tilting edges when the placing boom is otherwise in any position. This means that the exact position of the distribution boom or the positions of all moving parts of the distribution boom do not have to be recorded and/or manipulated, which considerably simplifies monitoring.

If greater accuracy is desired in stability monitoring, a complete recording of the exact position of the structure (or all of its moving parts) can of course also be carried out in order to include the most precise possible value for the actual center of gravity in the calculations.

• eine Neigung bzw. Schrägstellung der Arbeitsmaschine, insbesondere des Unterwagens, welche beispielsweise mittels eines Neigungsgebers erfasst werden kann;
• ein Drehwinkel des Aufbaus relativ zum Unterwagen, z.B. durch eine Messung über einen Drehwinkelgeber;
• ein Schwenkwinkel mindestens eines schwenkbar gelagerten Teils des Aufbaus, beispielsweise eines Verteilermastgelenks, welcher z.B. mittels eines Drehwinkelgebers und/oder per Wegmesser in einem Gelenkantriebszylinder gemessen werden kann; selbstverständlich können hierbei Schwenkwinkel von mehr als einem schwenkbaren Teil gemessen werden, beispielsweise die Gelenkwinkel aller Verteilermastgelenke bei einer Autobetonpumpe;
• eine Ausschublänge mindestens eines teleskopierbaren Teils des Aufbaus, beispielsweise gemessen durch einen Weggeber;
• ein Druck in einem Hydraulikkreis oder Hydraulikantrieb, insbesondere in einem Hydraulikzylinder, mittels welchem sich ein erster Gelenkarm des Aufbaus verschwenken lässt, wobei die Messung über einen Drucksensor erfolgen kann; bei dem genannten Hydraulikantrieb kann es sich beispielsweise um den Hydraulikzylinder des A-Gelenks eines Verteilermasts einer Autobetonpupe handeln, aber auch um einen Hydraulikmotor oder eine Hydraulikpumpe;
• eine Windstärke und/oder Windrichtung, beispielsweise gemessen über ein oder mehrere Anemometer, die an einer oder verschiedenen Positionen an der Arbeitsmaschine angeordnet sein können.

In a further possible embodiment it is provided that one or more of the following variables is recorded to determine the current three-dimensional center of gravity vector:

• an inclination or inclination of the work machine, in particular of the undercarriage, which can be detected, for example, by means of a tilt sensor;
• an angle of rotation of the body relative to the undercarriage, for example by measuring via a rotation angle sensor;
• a pivot angle of at least one pivotally mounted part of the structure, for example a distribution boom joint, which is measured, for example, by means of a rotary angle sensor and/or a odometer in a joint drive cylinder can be; Of course, pivot angles of more than one pivotable part can be measured, for example the joint angles of all distribution boom joints on a truck-mounted concrete pump;
• an extension length of at least one telescopic part of the structure, for example measured by a displacement sensor;
• a pressure in a hydraulic circuit or hydraulic drive, in particular in a hydraulic cylinder, by means of which a first articulated arm of the structure can be pivoted, the measurement being able to take place via a pressure sensor; The hydraulic drive mentioned can be, for example, the hydraulic cylinder of the A-joint of a distribution boom of a truck-mounted concrete pump, but also a hydraulic motor or a hydraulic pump;
• a wind strength and/or wind direction, for example measured via one or more anemometers, which can be arranged at one or different positions on the work machine.

In order to best determine the current center of gravity vector, the machine is preferably equipped with comprehensive measurement technology for recording the aforementioned measured variables. With the help of these measured variables, the vector calculation necessary for the stability statement can be carried out in real time, for example on the control device or the control unit of the working machine and preferably taking machine-specific constants such as articulated arm and/or support leg lengths into account. The measured real-time data from the machine is preferably low-noise geometry data from path and angle measurements. A measurement of the hydraulic pressure in relation to a hydraulic drive of the work machine, for example the hydraulic cylinder of the A-joint of a distribution boom, can then optionally be used in addition to improving the informative value of the stability monitoring, as described further below.

In a further possible embodiment, it is provided that, in addition to the measured real-time data, stored information from the work machine is used to determine the current three-dimensional center of gravity vector. This information can be geometric data relating to at least one component of the undercarriage and/or the structure and/or the support, for example articulated arm lengths, component masses, support leg lengths and the like. This data can be stored in a database of the work machine, for example on a memory of the control unit of the work machine or on a separate memory module to which the control unit has access. It is also conceivable that the data is stored on an external computer unit or in a cloud with which the work machine is in a wireless communicative connection, so that the required data can be made available to the control unit.

In a further possible embodiment it is provided that the determination of the current three-dimensional center of gravity vector and/or the determination of the current tilting edge is based exclusively on measured variables that are obtained through path and/or angle measurements. Such measurements are particularly low-noise and therefore meaningful.

Of course, in an advantageous embodiment, it is conceivable to supplement the measured geometric data with measured values added using additional measurement technology and thus increase the efficiency of stability monitoring - a hydraulic pressure measurement in the cylinder of the A-joint of a distribution boom of a truck-mounted concrete pump could, for example, provide information about whether the assumed maximum density of the pumped medium is actually achieved. At a lower density, a greater reach of the placing boom could be permitted depending on the support geometry. The measurement of wind strength and/or direction already mentioned can also provide additional data for stability monitoring in order to improve its informative value.

In a further possible embodiment, a planning mode is provided which makes it possible, depending on a spatial target position desired by the operator of the work machine, for example in the case of a truck-mounted concrete pump Distribution boom tip, a minimum support geometry required, that is to say ensuring stability, must be calculated before the machine is put into use.

The planning mode allows a desired position of the work machine, in particular the structure, to be determined, in particular by input via an input means. A corresponding future three-dimensional center of gravity vector is then calculated for the desired position and projected onto the auxiliary plane. Based on this, a safe support position and/or tipping edge is determined, the projection of which onto the auxiliary plane results in a difference in the amounts of the projected center of gravity vector and limit vector, which corresponds to a specific value. This value can be zero (i.e. the stability condition is exactly fulfilled at the calculated tipping edge), or a tipping edge is determined at a certain safety distance, i.e. the value of the difference between the vector amounts corresponds to a defined and in particular definable negative value (since the projected center of gravity is within the tilting edges). The safety distance can be set or adjustable by the operator or at the factory.

It is conceivable that the planning can be carried out by the operator of the work machine himself, i.e. the target position is entered using an input device directly on or in the work machine (e.g. on a driver's cab or in a driver's cab). Alternatively or additionally, it can be provided that the planning takes place outside the work machine and the corresponding data is sent wirelessly to the work machine or the planning module/planning means that carries out the planning.

The planning mode can be carried out by a planning agent. This can be a computer that is separate from the control unit of the work machine and can be located in the work machine or at another location. The planning means can also be a software module that is executed, for example, in the control unit of the work machine.

In a reverse planning mode, the planned movement of the work machine or the structure could optionally be "run through" without actually moving the machine, with the difference for the virtual movement or the corresponding positions being calculated according to the method according to the invention and the stability being checked. This makes it possible, for example, to show the operator for a desired target position of the work machine whether this is possible or not at the current support position. If this is not possible, the operator could possibly be presented with a suggestion for an alternative, safe movement/position or for a change in the support that allows the desired movement to be carried out safely.

In a further possible embodiment it is provided that the support comprises at least three support feet, the support feet preferably being able to be extended and retracted in a direction parallel to the axis of rotation of the structure (i.e. in the case of a horizontal base, the support feet move in and out vertically, for example via corresponding ones hydraulic support cylinders, which themselves can form the support feet). Alternatively or additionally, at least two support feet are preferably each arranged on a support leg which is pivotably and/or telescopically mounted on the undercarriage. Preferably there are four support feet and correspondingly four pivotable and/or telescopic support legs. However, there are no upper limits to the number of support feet and legs.

• eine Ausschublänge mindestens eines Stützfußes in einer zur Drehachse des Aufbaus parallelen Richtung, z.B. per Wegmesser; vorzugsweise können alle Stützfüße mittels hydraulischen Abstützzylindern ein- und ausgefahren werden, wobei die Ausschublängen aller Abstützzylinder über eine entsprechende Anzahl von Wegmessern erfasst werden;
• eine Ausschublänge mindestens eines teleskopierbaren Stützbeins, z.B. per Wegmesser;
• ein Schwenkwinkel mindestens eines schwenkbar am Unterwagen gelagerten Stützbeins, beispielsweise per Drehwinkelgeber oder über Wegmesser in einem die Schwenkbewegung steuernden Stützbeinantriebszylinder.

In a further possible embodiment it is provided that one or more of the following variables are recorded to determine the current tipping edge(s):

• an extension length of at least one support leg in a direction parallel to the axis of rotation of the structure, for example by means of an odometer; Preferably, all support feet can be extended and retracted using hydraulic support cylinders, with the extension lengths of all support cylinders being recorded using a corresponding number of odometers;
• an extension length of at least one telescopic support leg, for example using a odometer;
• a swivel angle of at least one support leg pivotably mounted on the undercarriage, for example via a rotary angle sensor or via an odometer in a support leg drive cylinder that controls the swivel movement.

In order to best determine the position of all tilting edges, the work machine is preferably equipped with comprehensive measuring technology for recording the aforementioned measured variables, in particular in all existing support feet or legs. In addition to the angle and/or path measurements, additional information can also be obtained here via one or more pressure sensors for detecting one or more hydraulic pressures, with low-noise angle and path measurements preferably primarily being used for the calculations.

In a further possible embodiment it is provided that a current movement of the structure is automatically braked or stopped as soon as the calculated difference between the projected center of gravity vector and the limit vector corresponds to a value of zero or a defined and in particular definable value. This prevents the tipping edge from being driven over and the machine from tipping over. In order to avoid an abrupt stop when the tipping edge is reached and thus potentially harmful vibrations, it can be provided that a controlled braking process takes place as soon as the calculated difference reaches a defined value, i.e. before the tipping edge is reached.

Alternatively or additionally, a warning signal can be issued as soon as the calculated difference between the projected center of gravity vector and the limit vector corresponds to a value of zero or a defined and, in particular, definable value. This can be, for example, a visual and/or acoustic warning signal.

Of course, at the same time as this/these measures, a continuous display of the relevant values and/or a graphical display of the work machine can be carried out and/or the actual or projected center of gravity and/or the actual or projected tilting edges on a display unit so that the operator can keep an eye on the current operating situation and stability of the work machine.

The present invention further relates to a work machine with a control unit which is set up to carry out the method according to the invention. This obviously results in the same advantages and properties as for the method according to the invention, which is why a repeated description is omitted.

The work machine preferably comprises at least one sensor which is in communicative connection with the control unit. This can be one or more of the above-mentioned sensors for detecting the variables included in the calculation of the difference.

In a possible embodiment it is provided that the work machine according to the invention is a truck-mounted concrete pump with a concrete distribution boom which is rotatably mounted on the undercarriage and in particular is foldable. The latter can be mounted on a mast frame which is mounted on a vehicle frame.

The present invention further relates to a computer program product which comprises commands which, when the program is executed by a control unit of a work machine, cause the control unit to carry out the method according to the invention. The computer program product can include a calculation means that determines the center of gravity and boundary vectors and calculates the difference. Alternatively or additionally, the computer program product can include a control means which, based on the calculated difference, generates control commands and/or signals for corresponding displays in order to carry out or initiate the respective intended action. Alternatively or additionally, the computer program product may include a planning means, as above described. Alternatively or additionally, the computer program product can include a display means that generates a corresponding numerical display of one or more of the calculated values and/or a graphical display that is displayed to an operator on a display unit such as a display provided in/on the work machine or a mobile device becomes.

Figur 1:

eine schematische Darstellung verschiedener Komponenten zur Durchführung des erfindungsgemäßen Verfahrens gemäß einem Ausführungsbeispiel;

Figur 2:

eine schematische Darstellung der vektoriellen Zusammenhänge bei der erfindungsgemäßen Standsicherheitsüberwachung; und

Figur 3:

eine schematische Darstellung der ersten beiden Gelenkarme des Verteilermasts einer Autobetonpumpe gemäß einem Ausführungsbeispiel der Erfindung;

Further features, details and advantages of the invention result from the exemplary embodiments explained below with reference to the figures. Show it:

Figure 1:

a schematic representation of various components for carrying out the method according to the invention according to an exemplary embodiment;

Figure 2:

a schematic representation of the vector relationships in the stability monitoring according to the invention; and

Figure 3:

a schematic representation of the first two articulated arms of the distribution boom of a truck-mounted concrete pump according to an embodiment of the invention;

The Figure 1 shows various components of a work machine according to the invention according to an exemplary embodiment for carrying out the method according to the invention for stability monitoring, with only the most important components being shown schematically here.

A control unit 10 of the work machine receives measurements from a series of sensors, which are collectively designated by the box 12. Although this can in principle be a single sensor 12, it is preferred if several sensors 12 deliver different measured values for the position of the work machine and its support in order to obtain the most precise information possible about stability. The sensors 12 can be angle sensors, odometers, pressure sensors, anemometers, inclination sensors, acceleration sensors, optical sensors, acoustic sensors, etc., which deliver their measured values to the control unit 10.

, welcher auf eine (im hier beschriebenen Ausführungsbeispiel) horizontale Hilfsebene H projiziert wird. Eine schematische Darstellung der relevanten Größen und Vektoren findet sich in der Figur 2.From these measured values, the control unit 10 determines a three-dimensional center of gravity vector corresponding to the current position of the work machine (or the part of it used for the center of gravity calculation - this can, for example, only be the structure 1 rotatably mounted on the undercarriage). $\stackrel{\rightharpoonup }{S}$

, which is projected onto a horizontal auxiliary plane H (in the exemplary embodiment described here). A schematic representation of the relevant quantities and vectors can be found in the Figure 2 .

In the exemplary embodiment shown, the working machine is supported by a support comprising four support feet (schematically represented by points 20), which can be extended and extended via hydraulic support cylinders. The support feet can be located on pivoting and/or telescopic support legs that are connected to the undercarriage of the work machine. The connecting straight lines between the support feet 20 form tilting edges K.

In order to include the inclination of the working machine in the calculations, the tilting edges K are also projected onto the common auxiliary plane H. The projected tilt edges H' can be represented by vectors or tilt edge vectors.

und/oder der Kippkanten K greift die Steuereinheit 10 auf Maschinendaten wie z.B. Konstanten, Bauteilmassen oder geometrische Daten von Bauteilen der Arbeitsmaschine zu, die auf einem Speicher oder einer Datenbank 14 hinterlegt sind. Diese(r) kann sich innerhalb oder außerhalb der Arbeitsmaschine befinden oder Teil der Steuereinheit 10 sein.For calculating the center of gravity vector $\stackrel{\rightharpoonup }{S}$

and/or the tilting edges K, the control unit 10 accesses machine data such as constants, component masses or geometric data of components of the work machine, which are stored in a memory or a database 14. This can be located inside or outside the work machine or be part of the control unit 10.

eine der projizierten Kippkanten K' schneidet.In the in Fig. 2 In the situation shown, the center of gravity of the system under consideration is outside the tilting edges K, which is reflected in the fact that the projected (two-dimensional) centroid vector $\stackrel{\rightharpoonup }{S\prime }$

one of the projected tilting edges K' intersects.

, der sich vom Ursprungspunkt U des Schwerpunktvektors $\stackrel{\rightharpoonup }{S}$

entlang einer durch den projizierten Schwerpunktvektor $\stackrel{\rightharpoonup }{S\prime }$

definierten Geraden bis zur projizierten Kippkante K` erstreckt. Der Grenzvektor $\stackrel{\rightharpoonup }{Q}$

liegt also ebenfalls innerhalb der gemeinsamen Hilfsebene H und verläuft parallel zum projizierten Schwerpunktvektor $\stackrel{\rightharpoonup }{S\prime }$

.In order to quantify this circumstance, the control unit 10 determines a limit vector $\stackrel{\rightharpoonup }{Q}$

, which is from the origin point U of the center of mass vector $\stackrel{\rightharpoonup }{S}$

along a through the projected center of mass vector $\stackrel{\rightharpoonup }{S\prime }$

defined straight line extends to the projected tipping edge K`. The boundary vector $\stackrel{\rightharpoonup }{Q}$

also lies within the common auxiliary plane H and runs parallel to the projected center of gravity vector $\stackrel{\rightharpoonup }{S\prime }$

.

der Beträge des projizierten Schwerpunktvektors $\stackrel{\rightharpoonup }{S\prime }$

und des Grenzvektors $\stackrel{\rightharpoonup }{Q}$

. Ist diese Differenz gleich Null, so befindet sich der Schwerpunkt genau auf der Kippkante K`. Hat die Differenz ein negatives Vorzeichen, so befindet sich der Schwerpunkt innerhalb der Kippkanten K`, sodass die Standsicherheit gewährleistet ist. Ein positives Vorzeichen zeigt an, dass sich der Schwerpunkt außerhalb der Kippkanten K` befindet (wie in der Figur 2 zu sehen). In dieser Situation droht ein Kippen der Arbeitsmaschine, was es zu vermeiden giltThe control unit 10 now calculates the difference $\left|\stackrel{\rightharpoonup }{S\prime }\right|-\left|\stackrel{\rightharpoonup }{Q}\right|$

the magnitudes of the projected center of gravity vector $\stackrel{\rightharpoonup }{S\prime }$

and the boundary vector $\stackrel{\rightharpoonup }{Q}$

. If this difference is zero, the center of gravity is exactly on the tipping edge K`. If the difference has a negative sign, the center of gravity is within the tipping edges K`, so that stability is guaranteed. A positive sign indicates that the center of gravity is outside the tilting edges K` (as in the Figure 2 to see). In this situation there is a risk of the machine tipping over, which must be avoided

The control unit 10 is connected to a display unit 40 and transmits signals to it. It is conceivable that the relevant values, for example the calculated difference and/or some or all of the recorded measured values and/or variables derived therefrom, are displayed numerically and/or graphically on the display unit 40.

Likewise, for easier visual monitoring of the stability by the operator and for better clarity, the relevant vectors could be displayed graphically, for example in a schematic manner similar to Figure 2 . A representation of the working device and/or structure 1 in combination with the tilting edges K, K` and the determined center of gravity (each projected onto the auxiliary plane H and/or in three dimensions) is also conceivable, so that the operator can monitor the geometric relationships and distances at a glance.

In order to intervene in good time before a potentially dangerous overrun of the center of gravity via a tipping edge K, the control unit 10 can be connected to at least one actuator 30 of the implement and send corresponding control signals to it in order to automatically stop the current movement or brake it in a controlled manner. This can be done fully automatically or initially only a warning can be displayed to the operator. Preferably, several actuators 30, for example the entire structure (or distribution boom in the case of a truck-mounted concrete pump), can be controlled by the control unit 10.

In the control unit 10, a planning means 16 can also be implemented in the form of a software module in order, for example, to calculate a required minimum support geometry or safe tipping edge for a desired target position of the structure 1 (e.g. in the case of a truck-mounted concrete pump, a target position of the distribution boom tip).

The work machine can be a truck-mounted concrete pump with a distribution boom 1 rotatably mounted on an undercarriage. The mast 1 is in particular designed to be foldable and comprises a plurality of articulated arms which are connected to one another in an articulated manner and which can be moved or pivoted by corresponding actuators (in particular hydraulic cylinders).

In the Figure 3 An exemplary embodiment of a distribution boom 1 of a truck-mounted concrete pump is shown schematically in a side view, with only the first two articulated arms 3, 4 and the mast trestle 5 being shown. The first articulated arm 3 is articulated on the mast frame 5 via a first joint 2 (so-called A-joint) and can be pivoted via a first hydraulic cylinder (not shown).

kann sich auf den Gesamtschwerpunkt der Autobetonpumpe (also Unterwagen und Verteilermast 1 kombiniert) beziehen. Um die Berechnungen und Messtechnik zu vereinfachen, kann aber auch nur der Schwerpunkt des Verteilermasts 1 zugrunde gelegt werden.The center of gravity vector on which the monitoring method according to the invention is based $\stackrel{\rightharpoonup }{S}$

can refer to the overall center of gravity of the truck-mounted concrete pump (i.e. undercarriage and placing boom 1 combined). In order to simplify the calculations and measurement technology, only the center of gravity of the distribution boom 1 can be used as a basis.

By accepting compromises in the quality of the stability statement, the ideal machine equipment with measurement technology can be reduced if necessary - with normal machine inclinations and excavations, for example, differences in excavation of the support cylinders are usually of little importance.

wobei l _Arm1 die Länge des ersten Gelenkarms 3 des Verteilermasts 1 bezeichnet.For example, for monitoring the stability of a truck-mounted concrete pump, it may be sufficient to manipulate the angle of attack α ₁ of a first articulated arm 3 of the placing boom 1 in order to keep the center of gravity of the placing boom 1 within the usual tilting edges K in any otherwise arbitrary position of the placing boom. Reduced to the angle of attack α ₁ of the first distribution boom joint 2 (so-called A-joint) as a control variable, the mathematical connection to the stability statement in the sense of the present invention results according to the following equation: $$\cos \left({\alpha }_1\right)=1-\frac{\left|\stackrel{\rightharpoonup }{S}\prime \right|-\left|\stackrel{\rightharpoonup }{Q}\right|}{l_{\mathit{poor}1}},$$

where l _{arm 1} denotes the length of the first articulated arm 3 of the distribution boom 1.

List of reference symbols:

  Grenzvektor
$\stackrel{\rightharpoonup }{S}$

  Dreidimensionaler Schwerpunktvektor
$\stackrel{\rightharpoonup }{S\prime }$

  Projizierter Schwerpunktvektor
U  Ursprungspunkt1 structure (distribution boom)
2 First joint (A joint)
3 First articulated arm
4 Second articulated arm
5 masthead
10 control unit
12 sensors
14 Database/Storage
16 planning tools
20 support feet
30 actuator
40 display unit
α ₁ angle of attack
H auxiliary level
K tipping edge
K' Projected tipping edge
l _{Arm 1} Length of the first articulated arm
$\stackrel{\rightharpoonup }{Q}$

Border vector
$\stackrel{\rightharpoonup }{S}$

Three-dimensional center of gravity vector
$\stackrel{\rightharpoonup }{S\prime }$

Projected center of mass vector
U origin point

Claims (15)

Method for monitoring the stability of a work machine, in particular a truck-mounted concrete pump, wherein the work machine comprises an undercarriage, a structure (1) rotatably mounted on the undercarriage and an adjustable support for supporting the work machine,
characterized in that - a current three-dimensional center of gravity vector (5) is determined based on at least one measured current position of the work machine and projected onto an auxiliary plane (H), - a current tilting edge (K) of the working machine, defined by the support, is projected onto the auxiliary plane (H), - a parallel to the projected center of gravity vector ( $\stackrel{\rightharpoonup }{S\prime }$

) boundary vector ( $\stackrel{\rightharpoonup }{Q}$

) is determined, - a difference in the projected center of gravity vector ( $\stackrel{\rightharpoonup }{S\prime }$

) and the limit vector ( $\stackrel{\rightharpoonup }{Q}$

) is calculated and - an action is automatically carried out based on the calculated difference, in particular at least one drive of the work machine is activated and/or a signal is output. Method according to claim 1, wherein the determination of the center of gravity vector ( $\stackrel{\rightharpoonup }{S}$

, $\stackrel{\rightharpoonup }{S\prime }$

) and/or the boundary vector ( $\stackrel{\rightharpoonup }{Q}$

) takes place at regular intervals during operation of the machine. Method according to claim 1 or 2, wherein the determination of the center of gravity vector ( $\stackrel{\rightharpoonup }{S},\stackrel{\rightharpoonup }{S\prime }$

) and/or the boundary vector ( $\stackrel{\rightharpoonup }{Q}$

) occurs during operation of the work machine in response to a movement of the work machine, in particular a movement of the support and / or the structure (1). Method according to one of the preceding claims, wherein the auxiliary plane (H) is oriented horizontally or its orientation can be fixed. Method according to one of the preceding claims, wherein the current three-dimensional center of gravity vector ( $\stackrel{\rightharpoonup }{S}$

) refers to the overall center of gravity of the work machine, to the overall center of gravity of the structure (1) or to a center of gravity of a part of the structure (1), in particular a first articulated arm (3) of the structure (1). Method according to one of the preceding claims, wherein to determine the current three-dimensional center of gravity vector ( $\stackrel{\rightharpoonup }{S}$

) one or more of the following variables are detected, in particular measured using at least one sensor (12): - an inclination of the working machine, especially the undercarriage, - an angle of rotation of the body (1) relative to the undercarriage, - a pivot angle of a pivotally mounted part of the structure (1), - an extension length of a telescopic part of the structure (1), - a pressure in a hydraulic circuit or hydraulic drive, in particular in a hydraulic cylinder, by means of which a first articulated arm (3) of the structure (1) can be pivoted, - a wind strength and/or wind direction. Method according to the preceding claim, wherein to determine the current three-dimensional center of gravity vector ( $\stackrel{\rightharpoonup }{S}$

) additional stored information of the work machine, in particular geometric data relating to at least one component of the undercarriage and/or the structure (1) and/or the support. Method according to one of the preceding claims, wherein the determination of the current three-dimensional center of gravity vector ( $\stackrel{\rightharpoonup }{S}$

) and/or the determination of the current tipping edge (K) is based exclusively on measured variables that are obtained through a distance measurement or an angle measurement. Method according to one of the preceding claims, wherein in a planning mode a desired position of the work machine, in particular of the structure (1), is determined, in particular by input via an input means, for the desired position a future three-dimensional center of gravity vector ( $\stackrel{\rightharpoonup }{S}$

) is calculated and projected onto the auxiliary plane (H) and based on this a safe support position or tipping edge (K) is determined, the projection of which onto the auxiliary plane (H) results in a difference in the amounts of the projected center of gravity vector ( $\stackrel{\rightharpoonup }{S}$

) and boundary vector ( $\stackrel{\rightharpoonup }{Q}$

) which corresponds to a value of zero or a defined and in particular definable negative value. Method according to one of the preceding claims, wherein the support comprises at least three support feet (20), wherein the support feet (20) can preferably be extended and retracted in a direction parallel to the axis of rotation of the structure (1) and/or wherein preferably at least two support feet ( 20) are each arranged on a support leg which is pivotably and/or telescopically mounted on the undercarriage. Method according to the preceding claim, wherein in order to determine the current tipping edge (K), one or more of the following variables are recorded, in particular measured using at least one sensor (12): - an extension length of a support foot (20) in a direction parallel to the axis of rotation of the structure (1), - an extension length of a telescopic support leg, - a swivel angle of a support leg pivotally mounted on the undercarriage. Method according to one of the preceding claims, wherein a current movement of the structure (1) is automatically braked or stopped and/or a warning signal is issued as soon as the calculated difference in the projected center of gravity vector ( $\stackrel{\rightharpoonup }{S}$

) and the limit vector ( $\stackrel{\rightharpoonup }{Q}$

) corresponds to a value of zero or a defined and, in particular, definable value. Work machine with a control unit (10) which is set up to carry out the method according to one of the preceding claims, wherein the work machine preferably comprises at least one sensor (12) which is in communicative connection with the control unit (10). Work machine according to the preceding claim, which is a truck-mounted concrete pump with a concrete distribution boom rotatably mounted on the undercarriage. Computer program product comprising commands which, when the program is executed by a control unit (10) of a work machine, cause it to carry out the method according to one of claims 1 to 12.

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