EP3556969B1 - Concrete pump - Google Patents

Description

The present invention relates to a concrete pump with a feed pump, a concrete line and an articulated arm forming a distribution boom, along which the concrete line is guided, the articulated arm having a rotary stand which can be rotated about a vertical axis and/or at least one which can be pivoted about a horizontal axis by means of a joint Segment, wherein the turntable can be moved about the vertical axis via an actuator and / or the at least one segment can be pivoted about the horizontal axis via an actuator, the concrete pump further having a control for controlling the actuators of the distribution boom, the control being a Disturbance input to reduce the vibrations of the placing boom induced by concrete delivery. In particular, the concrete pump is a truck-mounted concrete pump.

The relevant prior art is explained in detail in the introductory section of the description of the figures. In particular, it shows DE 101 01 570 B4 a disturbance variable feed-in combined with feedback-based vibration damping based on the principle of a virtual spring-damper element, through which a hydraulic cylinder of the articulated arm is to be described. The disturbance variable connection should be carried out using pressure or flow sensors in the delivery line. For this purpose, the control device comprises a pressure measuring device on the delivery line of the concrete, in which two pressure sensors are preferably provided distributed over the delivery line and can determine pressure differences in the delivery line. For example, by measuring the delivery pressure at two measuring points, the development of a pressure difference and the course of such a pressure wave through the delivery line can be estimated.

Pamphlet JP 2000 282687 A describes a concrete pump in which the pump frequency is changed in order to avoid excessive excitation of the vibrations of the placing boom.

The object of the present invention is to provide a concrete pump with an improved disturbance variable feed-in.

This object is achieved in a first aspect by a concrete pump according to claim 1 and in a second aspect by a concrete pump according to claim 9.

Preferred embodiments of the present invention are the subject of the subclaims.

In a first aspect according to claim 1, the present invention comprises a concrete pump with a feed pump, a concrete line and an articulated arm forming a distribution boom, along which the concrete line is guided, the articulated arm having a turntable rotatable about a vertical axis and/or at least one means a joint has a segment that can be pivoted about a horizontal axis, wherein the rotary stand can be moved about the vertical axis via an actuator and / or the at least one segment can be pivoted about the horizontal axis via an actuator, and wherein the concrete pump continues to provide a control Control of the actuators of the distribution boom, the control comprising a disturbance variable feed-in to reduce the vibrations of the distribution boom induced by the concrete delivery. The first aspect is characterized in that the disturbance variables are applied on the basis of a physical model of the concrete delivery, which describes the flow-related disturbance forces of the concrete delivery on the placing boom. The use of the physical model and the determination of the disruptive forces on the placing boom based on it results in a significantly improved reduction in vibrations induced by concrete delivery.

In a first embodiment of the present invention, the physical model describes frictional forces of the concrete on the inner wall of the concrete pipe and/or inertial forces due to the concrete flow deflection in the pipe bends. These two forces essentially determine the disruptive forces acting on the articulated arm.

In a second embodiment of the present invention, at least one operating parameter of the feed pump is included in the disturbance variable feed-in. This can be, for example, one or more of the following operating parameters: pumping frequency, cylinder speed of the cylinders of the feed pump and/or the cylinder position of the cylinders of the feed pump.

In a possible embodiment of the present invention, the physical model of concrete delivery takes into account the current position of the placing boom and in particular the articulation angles of the joints.

The current position of the distribution boom is preferably determined on the basis of sensors assigned to the swivel joints for indirect or direct measurement of the respective angle of rotation of the joints of the articulated arm.

The determination of the disruptive forces of the concrete delivery on the placing boom is preferably carried out without measuring the vibration state of the placing boom or the segments.

The position of the placing boom and in particular the articulation angles of the joints are preferably included in the description of the concrete flow deflection by the physical model. Alternatively or additionally, the physical model can take into account the hydrostatic pressure loss of the flow, taking into account the current position of the placing boom.

In a possible embodiment of the present invention, at least one material property of the pumped fluid that is included in the modeling by the physical model is determined from operating parameters of the delivery pump and/or the concrete delivery. This can improve the accuracy of the model.

Preferably, at least the viscosity of the pumped fluid is determined, in particular from the concrete pressure and the flow velocity of the concrete.

The density of the pumped fluid can be determined by the static concrete pressure. Alternatively, a stored average value for the density of concrete can be used for the density of the pumped fluid.

In a possible embodiment of the present invention, the disturbance variable connection is further based on a physical model of the placing boom, which is coupled to the physical model of the concrete delivery in order to determine the influence of the disturbance forces determined by the physical model of the concrete delivery on the entire placing boom.

The physical model of the distribution boom used for this preferably takes into account the elastic deformation of at least one of the segments.

According to the present invention, the vibrations of the placing boom induced by the conveying of concrete are reduced by switching on the disturbance variables by controlling the actuators of the articulated arm.

In a possible embodiment of the present invention, the disturbance variable feed-in takes place as a feedforward control without feedback of the dynamic state of the distribution boom. This simplifies control. Preferably, the pilot control is based on a control of a virtual model of the distribution boom. The disturbance variable connection preferably regulates the virtual model of the placing boom, which is coupled to the model of the concrete delivery as part of the determination of the disturbance forces. In particular, this control can be carried out in such a way that the influence of the disruptive forces is compensated for at least one point on the articulated arm.

In a possible embodiment of the present invention, the disturbance variable control controls the actuators of the articulated arm in such a way that the influence of the disturbance forces on the tip of the distribution boom is reduced and preferably eliminated.

The feed pump is preferably a double piston pump. Such a double piston pump includes two pistons that work in push-pull to pump the concrete. Such feed pumps are known.

The damping of induced vibrations by the disturbance variable feed-in according to the present invention is based on controlling the actuators of the articulated arm.

The feed pump, on the other hand, is preferably controlled independently of the disturbance variable input. In particular, the disturbance variable connection can be based solely on controlling the actuators of the articulated arm.

In a possible embodiment of the present invention, the control, in addition to the input of disturbance variables, also includes a regulation which is based on a measurement and/or feedback of the position and/or the vibration state of the distribution boom.

In particular, the control includes vibration damping for damping horizontal and/or vertical vibrations of the distribution boom, which is based on a measurement and/or feedback of the position and the vibration state of the distribution boom. In particular, the vibration damping can be designed in such a way that it dampens natural vibrations of the distribution boom.

The vibration damping is preferably based on a physical model of the distribution boom. In particular, this physical model can be the same model that is also used to determine the influence of the disruptive forces of concrete delivery on the placing boom.

The control and/or vibration damping is preferably designed in such a way that it only intervenes when the state of the distribution boom deviates from the state of the virtual model, which is regulated as part of the disturbance variable feed-in.

In a second aspect according to claim 9, the present invention comprises a concrete pump with a feed pump, a concrete line and an articulated arm forming a distribution boom, along which the concrete line is guided, the articulated arm having a turntable rotatable about a vertical axis and/or at least one means a joint has a segment that can be pivoted about a horizontal axis, wherein the rotary stand can be moved about the vertical axis via an actuator and / or the at least one segment can be pivoted about the horizontal axis via an actuator, and wherein the concrete pump also has a control for controlling the actuators of the distribution boom, the control comprising a disturbance variable feed-in to reduce the vibrations of the distribution boom induced by the concrete delivery, which takes the concrete pressure into account. The second aspect is characterized in that the disturbance variable feed-in determines the concrete pressure at the inlet of the concrete line based on the operating parameters of the feed pump.

The indirect determination of the concrete pressure according to the invention based on operating parameters of the feed pump has the considerable advantage that pressure sensors on the concrete line, which are extremely susceptible to wear, can be dispensed with.

The determination of the concrete pressure at the inlet of the concrete line is preferably based on the hydraulic pressure of the delivery cylinders of the delivery pump and the piston area ratio of the delivery pump. The concrete pressure can thereby be determined using a measured value that can be reliably determined in the hydraulic system of the feed pump.

The first and second aspects of the present invention can each be used independently of one another. In particular, the disturbance variable input based on a physical model of concrete delivery can also take place according to the first aspect without determining the concrete pressure according to the second aspect. Furthermore, a determination of the concrete pressure according to the second aspect can also be used in a disturbance variable feed-in, which is based on a different principle than the disturbance variable feed-in according to the first aspect.

However, the first and second aspects are preferably used in combination.

Preferred developments of a concrete pump according to the first and/or second aspect are presented in more detail below.

In a possible embodiment of the present invention, the disturbance variable feed-in takes into account the frequency of the feed pump and/or the position and/or speed of the feed pistons of the feed pump. Here too it acts These are easily accessible operating parameters of the feed pump, which can be determined either by measurement or from the control of the feed pump, and from which operating variables for concrete delivery can be determined.

In particular, the disturbance variable connection can determine the flow speed of the concrete in the concrete pipe from the speed of the delivery pistons of the delivery pump. This feature of the present invention can also be used independently of the first and second aspects of the present invention, in particular as a further development of a concrete pump according to the preamble of claim 1.

In a possible embodiment of the present invention, the concrete pump comprises at least one yaw rate sensor, which is arranged on a segment of the articulated arm, wherein the control for the input of disturbance variables and/or vibration damping determines a oscillation state of the entire distribution boom based on the measured values of the yaw rate sensor from the vibrations of the individual segments .

In a possible embodiment of the present invention, the concrete pump comprises at least one rotation rate sensor, which is arranged on a segment of the articulated arm, with the control for feeding in disturbance variables and/or vibration damping taking place without the use of geodetic sensors and/or deformation sensors.

In a possible embodiment of the present invention, the concrete pump comprises at least one rotation rate sensor, which is arranged in a front region of a segment which is arranged between the rotating stand and a segment forming the mast tip in the articulated arm.

The signal from the rotation rate sensor is preferably used to determine vibrations of the segment on which it is arranged. The front region of a segment in the sense of the present invention is preferred the front 25% of the length of the respective segment, ie the one facing the top of the mast, is considered, more preferably the front 10% of the length of the length.

In a possible embodiment of the present invention, rotation rate sensors are arranged on at least two segments. The signals from these rotation rate sensors are preferably used to determine vibrations of the segments on which they are arranged.

Preferably, the vibration damping determines a vibration state of the segments and/or the entire arm based on the measured values of the at least two rotation rate sensors.

The rotation rate sensors are preferably each arranged in a front region of the segments. This improves the detection of vibrations in these segments.

Preferably, the at least two segments on which the yaw rate sensors are arranged are arranged between the turret and a segment forming the mast tip in the articulated arm. More preferably, a further rotation rate sensor is arranged on the segment forming the mast tip, which is preferably used to determine vibrations of the mast tip.

In a possible embodiment of the present invention, the articulated arm further comprises sensors assigned to the swivel joints for indirectly or directly measuring the respective angle of rotation of the joint, with the measurement signals from the sensors being incorporated into the control of the articulated arm. These sensors are preferably provided in addition to the yaw rate sensors and can be used in particular to compensate for a drift in the measured values, which cannot be avoided due to the design of yaw rate sensors.

The measurement signals from the sensors are primarily used for vibration damping. Alternatively or additionally, the measurement signals from the sensors can be used to determine the current position of the articulated arm, and in particular can be used for position control of the articulated arm.

In a possible embodiment of the present invention, the disturbance variable input and/or vibration damping takes place using a physical model of the distribution boom, in which the flexibility of at least one segment is described by a virtual joint arranged within this segment.

Preferably, at least the flexibility of the segment arranged directly on the rotating stand is taken into account by a corresponding virtual joint, since the vibrations of this segment have the greatest influence on the vibration state of the articulated arm. Alternatively or additionally, the flexibility of the last segment, which forms the mast tip, can be taken into account. This is usually the least stable and therefore the most flexible. However, the virtual joint can also be provided in another segment.

The flexibility of several and more preferably all segments is preferably described by at least one virtual joint arranged within the respective segment.

In a possible embodiment of the present invention, the physical model is a rigid body model with actuated joints. The model preferably describes several and more preferably all segments of the articulated arm, and thus simultaneously reflects the position of the articulated arm. The ability to oscillate at least one and preferably several and more preferably all segments is then described by at least one virtual joint in the rigid bodies describing the actual segments.

In a possible embodiment of the present invention, a spring element and a damper element are assigned to the virtual joint. This allows the flexibility of the segment to be described. The spring constant and the damper constant are preferably chosen so that the virtual joint describes the size of the deflection and/or torsion and/or the first natural frequency of the real segment. The virtual joint can therefore be viewed as a first description of the segment's first natural oscillation in terms of frequency and amplitude.

In a possible embodiment of the present invention, less than 10, more preferably less than 5, more preferably less than 3 and, in a possible embodiment, exactly one virtual joint are provided within the segment. This reduces the complexity of the model.

If only vertical or horizontal vibration is to be taken into account, a virtual joint with only one axis of rotation is sufficient. In particular, a virtual joint with a horizontal axis of rotation can be used to dampen vertical vibrations.

In a preferred embodiment of the present invention, however, the virtual joint has at least two and preferably three degrees of freedom of movement.

In a possible embodiment of the present invention, the vibration damping takes into account torsion of at least one segment and/or the articulated arm.

In a possible embodiment of the present invention, the torsion of at least one segment and/or the articulated arm is taken into account by using a physical model of the articulated arm, which describes a torsion of the articulated arm and/or one or more segments of the articulated arm. This is more preferably done via a virtual swivel joint, like this was described above, and which extends in the longitudinal direction of the segment.

In a possible embodiment of the present invention, the articulated arm comprises at least two yaw rate sensors arranged on different segments, the torsion being determined from a comparison of the measured values of the yaw rate sensors.

For example, the measured values of a first yaw rate sensor, which is arranged within the articulated arm closest to the turret, can be compared with the measured values of a second yaw rate sensor, which is arranged within the articulated arm closest to the mast tip, in order to determine the torsion of the articulated arm between the two yaw rate sensors to determine.

Alternatively or additionally, the measured values of a first yaw rate sensor, which is arranged on a first segment, can be compared with the measured values of a second yaw rate sensor, which is arranged on a segment following the first segment within the articulated arm, in order to determine the torsion of the articulated arm between the to determine both rotation rate sensors and in particular the torsion of the first or second segment. For this purpose, the yaw rate sensors can each be arranged in a front region of the segments.

Alternatively or additionally, the articulated arm can comprise at least two yaw rate sensors arranged at different positions of the same segment, the torsion of the segment being determined from a comparison of the measured values of the yaw rate sensors. For this purpose, the rotation rate sensors are preferably arranged in a front and a rear area of the segment.

Furthermore, at least one of the yaw rate sensors, which is used to determine the torsion, can be arranged on the turntable and/or in a rear region of the segment arranged directly on the turntable, and/or at least one of the rotation rate sensors, which is used to determine the torsion, can be arranged on the last segment of the articulated arm and in particular in the area of the mast tip.

The rotation rate sensors, whose measured values are used to determine the torsion, preferably have at least two sensitivity directions, in particular a first horizontal sensitivity direction and a second sensitivity direction running in a vertical plane. This means that the torsion can be determined relatively easily through comparison.

However, regardless of the determination of the torsion, the rotation rate sensors, whose measured values are included in the vibration damping according to the invention, preferably have at least two sensitivity directions, in particular a first horizontal sensitivity direction and a second sensitivity direction running in a vertical plane.

In a possible embodiment of the present invention, the control of the articulated arm includes an observer who estimates the state of the articulated arm. In particular, the observer can include a physical model of the articulated arm and estimate its condition based on the model and based on measured values from sensors.

The estimate is preferably carried out on the basis of the measured values from sensors, as already described above, in particular on the basis of at least one angle of rotation sensor and/or sensors assigned to the joints for indirectly or directly detecting the angle of rotation of the joints.

The observer preferably uses a physical model of the articulated arm, as described in more detail above, in particular a physical model which is also used to determine the influence of the disturbing forces on the articulated arm through the input of disturbance variables.

The observer preferably estimates the position and/or the vibration state of the articulated arm.

If, in the context of the present invention, it is said that a state is determined, this includes in particular an estimate of the state by an observer.

According to the invention, in one possible embodiment, the vibration damping could take place solely as a pilot control. However, the vibration damping preferably includes regulation by feedback of at least one variable obtained using a measurement signal.

In a possible embodiment of the present invention, the vibration damping comprises a control which takes place by feedback of at least one of the following variables: speed and position of one or more of the joints, speeds and positions of the bending and/or torsion of one or more of the segments.

The variable or variables that are returned by the control are preferably estimated by an observer. In particular, the observer can be used for this, which was described in more detail above.

In a possible embodiment of the present invention, an estimation of the system state and/or the vibration damping and/or the determination of the influence of the disturbing forces on the articulated arm is carried out on the basis of a linearization of a physical model, and in particular on the basis of a linearization of the physical model, as it is was described above. In particular, the estimation is carried out by an observer and/or the control and/or the input of disturbance variables, as described above, on the basis of linearization.

The linearization preferably takes place around the equilibrium position of the current position of the articulated arm. The linearization can be carried out by the control depending on the current position of the articulated arm.

In a possible embodiment of the present invention, the control comprises a pilot control, which calculates control signals from a setpoint specified by an operator, through which the desired mast movement is carried out and vibration excitation of the articulated arm is reduced.

The pilot control is preferably designed in such a way that the natural frequencies of the articulated arm are suppressed. The natural frequencies of the articulated arm, which are taken into account by the pilot control, can be determined depending on the current position of the articulated arm.

In a possible embodiment of the present invention, the control comprises axis controllers assigned to the respective joints, the control generating control signals for the target angular speed of the axes, on the basis of which the axis controller assigned to the respective joint generates control signals for the respective actuator, the axis controller preferably being on an inverse Deflection kinematics are based and/or include an inverse nonlinearity.

In a possible embodiment of the present invention, the articulated arm comprises a turntable which can be rotated about a vertical axis and at least two segments which can be pivoted about horizontal axes by means of joints, the turntable being movable about the vertical axis via an actuator and the segments being pivotable about the horizontal axes via actuators are. More preferably, the articulated arm comprises at least three and more preferably at least four segments. The control and in particular the disturbance variable feed-in and/or the vibration damping preferably controls all actuators of the segments and/or the turret.

In a possible embodiment of the present invention, at least vertical vibration damping and/or disturbance variable feed-in takes place. For this purpose, the vibration damping and/or disturbance variable control appropriately controls the actuators through which the segments of the articulated arm are rotated about their horizontal axes of rotation.

In a possible embodiment of the present invention, at least horizontal vibration damping and/or disturbance variable feed-in takes place. For this purpose, the vibration damping and/or disturbance input controls the actuator of the lathe accordingly.

The actuators are preferably hydraulic actuators. The hydraulic actuators are preferably driven via a hydraulic pump, which is driven via the drive motor of the concrete pump.

Hydraulic cylinders are preferably used as actuators for pivoting the segments.

A hydraulic motor is preferably used as the actuator for rotating the lathe.

Preferably, the segments of the articulated arm can be folded into a transport position via the joints, with the individual segments preferably running essentially parallel in the transport position.

In a possible embodiment of the present invention, the control comprises a geometry control, which generates the actuators of the joints of the articulated arm based on a user's specifications, which are preferably done via hand levers, and/or based on a predetermined trajectory of the mast tip, which is preferably generated automatically a corresponding movement of the mast tip.

The present invention further comprises a control according to claim 14.

The control preferably comprises a microprocessor and a memory in which control software is stored, which, when executed by the microprocessor, implements the above-described structure and/or the above-described functionality of the control according to the invention. The controller also has one or more inputs via which it is connected to sensors, in particular the sensors described above, and/or one or more outputs via which it controls the actuators described above.

The disturbance variable connection and/or vibration damping according to the invention is preferably carried out automatically by the control of the concrete pump.

The present invention further comprises control software according to claim 13.

The control software implements the control according to the invention. The control software can be stored in memory and/or represent a computer program product.

In particular, the concrete pump according to the invention is a truck-mounted concrete pump. The concrete pump preferably includes a chassis via which it can be moved. The chassis preferably includes several wheeled axles.

The present invention further comprises a method according to claim 15.

According to a first aspect of the present invention, it is provided in the method according to the invention that the disturbance variable connection takes place on the basis of a physical model of the concrete delivery, which describes the flow-related disturbance forces of the concrete delivery on the placing boom.

According to a second aspect of the present invention, the method according to the invention provides that the concrete pressure at the inlet of the concrete line is determined based on operating parameters of the feed pump, in particular based on the hydraulic pressure of the feed cylinders and the piston area ratio of the feed pump.

The processes of the present invention are preferably carried out as already described above.

The present invention will now be described in more detail using exemplary embodiments and drawings.

Fig. 1

ein Ausführungsbeispiel einer erfindungsgemäßen Autobetonpumpe,

Fig. 2

eine schematische Darstellung eines Ausführungsbeispiels einer erfindungsgemäßen Steuerung mit einer Schwingungsdämpfung und einer Störgrößenaufschaltung,

Fig. 3

eine schematische Darstellung einer Vorsteuerung, wie sie in einer erfindungsgemäßen Steuerung zum Einsatz kommen kann,

Fig. 4

eine schematische Darstellung eines Ausführungsbeispiels einer erfindungsgemäßen Steuerung mit einer Schwingungsdämpfung,

Fig. 5

eine schematische Darstellung eines Achsreglers, wie er in einer erfindungsgemäßen Steuerung zum Einsatz kommen kann,

Fig. 6

eine schematische Darstellung der durch die Betonförderung auf den Gelenkarm wirkenden Störkräfte,

Fig. 7

eine schematische Darstellung eines Ausführungsbeispiels einer erfindungsgemäßen Steuerung mit einer Störgrößenaufschaltung,

Fig. 8

eine schematische Darstellung eines weiteren Ausführungsbeispiels einer erfindungsgemäßen Steuerung mit einer Störgrößenaufschaltung, welche auf einem physikalischen Modell der Betonförderung beruht,

Fig. 9

eine schematische Darstellung eines weiteren Ausführungsbeispiels einer erfindungsgemäßen Steuerung mit einer Störgrößenaufschaltung, welche auf einer Schätzung der Störkräfte aus Messwerten der Stellung und/oder des Schwingungszustands des Verteilermastes beruht.

Show:

Fig. 1

an embodiment of a truck-mounted concrete pump according to the invention,

Fig. 2

a schematic representation of an exemplary embodiment of a control according to the invention with vibration damping and a disturbance variable feed-in,

Fig. 3

a schematic representation of a pilot control as it can be used in a control according to the invention,

Fig. 4

a schematic representation of an exemplary embodiment of a control according to the invention with vibration damping,

Fig. 5

a schematic representation of an axis controller as it can be used in a control according to the invention,

Fig. 6

a schematic representation of the disruptive forces acting on the articulated arm due to the concrete delivery,

Fig. 7

a schematic representation of an exemplary embodiment of a control according to the invention with a disturbance variable feed-in,

Fig. 8

a schematic representation of a further exemplary embodiment of a control according to the invention with a disturbance variable feed-in, which is based on a physical model of concrete delivery,

Fig. 9

a schematic representation of a further exemplary embodiment of a control according to the invention with a disturbance variable feed-in, which is based on an estimate of the disturbance forces from measured values of the position and / or the vibration state of the distribution boom.

0. Introduction

New construction methods, materials and electronic systems have meant that concrete pumps have continued to develop over the past few decades. The use of multi-link articulated arms with increasingly longer segments enables improved accessibility to areas that are difficult to access. However, increasing the number and length of the segments also increases the weight and dimensions of the vehicle. The result is restrictions on road travel, handling and functionality of the concrete pump.

A special phenomenon of large manipulators is the ability of the placing boom to oscillate. The vibrations make it difficult for the operator to control the mast and for the end hose operator to distribute the concrete. The ability to vibrate is linked to the slenderness and inertia of the segments and the elastic properties of the material.

The vibration excitation arises from the movement of the articulated mast and the concrete delivery. The double piston pump typically used to convey concrete transmits impulse-like disturbing forces to the placing boom and thus causes continuous vibration excitation. Depending on the mast position and conveying frequency, excitation close to the natural frequencies of the mast is also possible.

The combination of traversing movement and concrete delivery exposes the placing boom to continuous vibration excitation during normal operation. This has an impact on machine life and operator safety.

The aim of the present invention is to dampen vibrations of the placing boom to improve the manageability and functionality of the concrete pump.

1. State of the art

The EP 2 103 760 B1 (Cifa ) proposes a model-based vibration damping using a modal model. The control algorithm estimates the state of the system using an observer and feeds back the estimated signal via control gains. The gains are retrieved from a list and interpolated depending on the mast position. The method is based on a modal model that is obtained through modal transformation and subsequent model reduction to the first vibration modes. The individual states of the model are therefore modal coordinates and have no physical interpretation. The method has the disadvantage that, in addition to the control gains, the observer's reduced, modal model also depends on the current mast position. The modal model must therefore be regenerated for each mast position or is only valid for certain mast positions. Due to the large number of possible mast positions, this represents a limitation for the usability of the vibration damping. The vibration damping proposed below avoids these problems through a different type of modeling. The model reduction is physically motivated and leads to physically interpretable, elastic coordinates. The sensor combination used to dampen vibrations also differs.

The WO 2014165889 A1 (TTControl ) presents vibration damping based on the feedback of position and deformation signals of the mast segments. The position is recorded using an inertial measuring unit and the deformation using strain gauges. The inertial measuring unit includes a rotation rate sensor and an acceleration sensor, which are only used in combination and for position estimation (see claim 2). The method has the advantage that the vibration of the segments is recorded independently of the traversing movement. This eliminates the need for additional signal processing to separate traversing movement and superimposed structural vibration. However, the use of strain gauges has the disadvantage that installation is complex and has to be carried out in highly stressed areas of the segment. In addition, the sensor is very temperature sensitive and requires a lot of calibration effort. The vibration damping proposed below avoids these disadvantages by choosing a rotation rate sensor to detect vibrations in the distribution boom.

The WO 2016 131977 A1 (vibration ) uses inertial measuring units to control the position of the mast tip. The measuring units are attached to the segments in the middle of the bar. There is an additional sensor at the top of the mast. The acceleration and yaw rate signals from the sensors are fused using a rigid body approach and estimate the position of the mast tip. To improve the position estimation, the acceleration signal from the sensor at the top of the mast is integrated twice and merged with the existing estimate. An absolute determination of the position is not possible due to the rigid body approach used and the double integration. Instead, the dynamic components of the mast tip position are calculated using a high-pass filter and fed back using a PID controller. A subordinate position control at the joint level prevents drift effects of the mast tip. The fusion algorithm only includes the reconstruction of the position of the mast tip. Because of the positioning The inertial measuring units and the rigid body approach used only estimate the inclination of the segments and not the vibration state of the placing boom. This differs from the model-based approach to estimating and controlling the vibration state of the placing boom presented below. The vibration state of the entire mast is taken into account. In contrast to the position control of the mast tip, the number of sensors used can be reduced and limited to the use of yaw rate sensors.

The EP 1 537 282 B1 (Putzmeister ) suggests geodetic angle sensors to determine the position and dampen vibrations of the placing boom. The sensors are attached to the segments and provide the respective absolute inclination. Taking the kinematics into account, the signals are divided into a low-frequency component for coordinate control and a high-frequency component for vibration damping. The tilt sensors typically used react sensitively to translational acceleration peaks. The application for vibration damping, taking into account traversing movement and concrete delivery, is therefore very limited.

The EP 2 778 466 A1 provides vibration damping in the horizontal plane.

The EP 1 122 380 B1 (Putzmeister ) suggests a control device for periodically varying or modulating the pump frequency. Varying or modulating the pump frequency prevents excitation frequencies near the mast's natural frequency from occurring. The result is reduced vibration excitation of the placing boom. The process changes the delivery of concrete in order to dampen the vibrations in the placing boom. This differs from the disturbance input shown below, which uses the actuators of the placing boom and leaves the concrete delivery unaffected.

The EP 1 537 282 B1 (Putzmeister ) names a disturbance variable controller for reducing vibrations in the placing boom. However, the procedure is not a disturbance variable feed-in, since not a disturbance variable, but a measured variable from the placing boom is used to dampen vibrations. The measured variable is the dynamic portion of the position detection of the mast. It is amplified by a controller and fed back to the actuators of the placing boom. The method therefore represents classic, feedback-based vibration damping and does not involve the addition of disturbance variables.

DE 101 01 570 B4 (vibration ) describes a disturbance variable feed-in combined with feedback-based vibration damping based on the principle of the virtual spring-damper element. The measured disturbance variable depends on the concrete delivery - however, there is no explicit, model-based conversion into the disturbance forces of the placing boom. The method presented is also applied decentrally for each joint. The influence of the disruptive forces on the entire placing boom is therefore not taken into account. The proposed sensor system for measuring the pressure of the concrete flow in the delivery line cannot be used in practice because it is expensive and is subject to heavy wear during operation.

2. Structure of the exemplary embodiment in the form of a truck-mounted concrete pump

In Fig. 1 The relevant elements of the truck-mounted concrete pump are shown. This has an undercarriage with a chassis with several tire axles, through which the truck-mounted concrete pump can be moved on the road. Front and rear support cylinders 9 and 10 are provided on the undercarriage, which are arranged on fold-out and / or telescopic struts 10 and 12. Furthermore, a transfer case 11 is shown.

The undercarriage carries a pump group 1 at the rear and an articulated arm via a mast block 2, along which a delivery line (not shown) is guided.

The articulated arm consists of a rotating stand 3 and four segments 4 to 7 (any number of segments possible), which are coupled via joints A to E. Joint A on the vehicle enables the rotation of the turntable 3 about the vertical axis, joints B to E enable the pivoting of the segments 4 to 7 about horizontal tilting axes. The actuator system of the concrete pump consists of hydraulic cylinders 14 to 17 at the respective joints B to E and a hydraulic motor for the swivel joint A of the lathe. The hydraulic cylinders 14 to 17 enable the movement of the placing boom in the vertical plane. The hydraulic motor rotates the entire mast around the vertical axis. The mast top 22 (TCP) is the top of the distribution boom.

A delivery line is attached to the distribution mast and conveys concrete to the top of the mast 22. From there, the concrete is guided to an operator via a hose section 8. The required delivery pressure is generated by a double piston pump in the pump unit 1.

The planned structure of the vibration damping is divided into: Fig. 2 Subsystems shown: geometry control, feedforward control, regulation (with observer) and disturbance variable feed-in.

For each subsystem, the structure and functionality are discussed below and characteristic features are presented.

3. Geometry control (TCP control)

The geometry control is used to generate movement paths for the placing boom. The trajectories are a time function for the position, speed, acceleration and/or jerk of the joint axes of the placing boom. They are adapted to the dynamics of the system in the feedforward control and given to the control system as a setpoint.

4. Pilot control 4.1 Function

• Messung der Position des Verteilermasts.
• Bestimmung der (ersten) Eigenfrequenzen und Dämpfung des Verteilermasts in der jeweiligen Mastposition (Ruhelage) in der horizontalen und vertikalen Ebene.
• Filterung der Sollwertsignale mit Eigenfrequenzen (Notch-Filter, Input-Shaping).
• Vorsteuerung wirkt auf jeden vertikalen und horizontalen Aktor.

The pilot control according to Fig. 3 serves to enable the placing boom to move quickly without exciting the natural frequencies.

• Measuring the position of the placing boom.
• Determination of the (first) natural frequencies and damping of the placing boom in the respective boom position (rest position) in the horizontal and vertical planes.
• Filtering of the setpoint signals with natural frequencies (notch filter, input shaping).
• Pilot control affects every vertical and horizontal actuator.

4.2 Sensors

• Position of the placing boom
• Rotary encoder for the angle of rotation around the vertical axis

4.3 Actuators

• Hydraulic cylinder (vertical plane)
• Hydraulic motor (horizontal plane)

5. Regulation

The regulation, which in Fig. 4 is reproduced again, is divided into two parts: the axis control ( Fig. 5 ) and the control for damping the vibrations and position control with the controller and the observer.

5.1 Axis controller

• Das Übertragungsverhalten des Hydrauliksystems von Ansteuerung bis Geschwindigkeit des Aktors weist ein nichtlineares Verhalten auf.
• Die Achsregelung kompensiert die Nichtlinearitäten der Hydraulik und der Umlenkkinematik.
• Der Regelalgorithmus besteht aus den invertierten statischen Kennlinien der Hydraulik und Umlenkkinematik. Eventuell ist eine Rückführung des Drucks bzw. der Zylinderposition oder -geschwindigkeit vorgesehen.
• Die Achsregelung ist dezentral an jedem Gelenk eingesetzt und stellt die unterste Ebene der gesamten Schwingungsdämpfung dar.

The axis controller according to Fig. 5 serves to transfer the target angular speed of the joint to the real actuator speed:

• The transmission behavior of the hydraulic system from control to the speed of the actuator has a non-linear behavior.
• The axis control compensates for the non-linearities of the hydraulics and the deflection kinematics.
• The control algorithm consists of the inverted static characteristics of the hydraulics and deflection kinematics. A feedback of the pressure or the cylinder position or speed may be provided.
• The axis control is used decentrally at each joint and represents the lowest level of overall vibration damping.

In its function of converting the target speed into the real actuator speed, axis control is implicitly assumed for all other control and regulation concepts.

5.2 Vibration damping based on rotation rate sensors 5.2.1 Structure of vibration damping

The process includes active vibration damping to reduce vibrations in the placing boom. A distinction is made between the target movements of the segments by the operator and the vibrations caused by the traversing movement. Vibration damping takes the desired target movement into account and only dampens the resulting structural vibrations. The vibrations due to concrete delivery are also reduced.

The goal of vibration damping is to reduce vibrations throughout the entire placing boom. For this purpose, the vibrational state of the entire Arms estimated from the vibrations of the individual segments. The placing boom has variable natural frequencies depending on the position and inclination of the segments. The vibration damping takes into account this variability of the natural frequencies depending on the position of the mast. The first natural frequencies have the greatest influence on the vibration behavior.

5.2.2 Sensors

The vibration state of the distribution boom is detected by rotation rate sensors 18 to 21. The sensors are mounted on one or more segments 4 to 7 and measure the rotation rate around the joint axes. The advantage of these sensors for detecting vibrations is that, in contrast to conventional sensors (e.g. strain gauges), they can be easily installed. The sensor can be attached to all outside and inside sides of the segment. The MEMS-based rotation rate sensors are also cost-effective, robust and low-maintenance.

The rotation rate sensor 18 to 21 is mounted in the front area of the respective segments 4 to 7 in order to optimally record the structural vibrations. Due to the serial kinematics of the manipulator, the measured rotation rate of a segment also contains the oscillation of the previous segment. This circumstance will be taken into account in the draft regulation.

The position of the placing boom is determined by a direct or indirect measurement of the relative joint angles between the segments. For example, as a measuring arrangement, the relative joint angles can be recorded using rotary angle sensors.

5.3.3 Modeling

The draft regulation is based on a mathematical model of the placing boom. For this purpose, the mechanical system is represented by a dynamic model.

The placing boom is modeled by a rigid body model with actuated joints B to E. Additional virtual joints take the flexibility in the segments into account. An additional virtual joint with spring and damper elements is introduced for each segment. The spring and damping constants are chosen so that the deflection and the first natural frequency of the real segment are preserved. The distribution boom model is made up of several segments. The rigidity of the overall structure results from the rigidity of the individual segments. Since the overall structure is made up of several segments, higher natural frequencies are also reproduced.

This type of modeling represents a physically motivated discretization of the infinitely dimensional, elastic placing boom. The advantage is that well-developed and efficient rigid body formalisms can be used for modeling. The resulting model also has a relatively low system order. Unlike a modal model reduction, the system state of the virtual joints is still a physical variable. It describes the concentrated deflection and vibration of the segment.

$$\mathit{y}=\mathit{Cx}.$$

The nonlinear model of the placing boom is linearized around the equilibrium position of the current boom position. Depending on the position and load situation of the mast, this results in a linear system that represents small deviations from the equilibrium position $$\dot{x}=\mathit{Ax}+\mathit{Bu},$$

$$\mathit{y}=\mathit{Cx}.$$

5.3.4 Observer

Based on the linearized model, an observer is used to estimate the system states $$\dot{\widehat{x}}=A\widehat{x}+\mathit{Bu}+\mathit{L}\left(\mathit{y}-C\widehat{x}\right).$$

The observer reconstructs the system state x̂ using the inputs and outputs of the system . The inputs of the system u are the setpoints of the hydraulics. The outputs y are the measured values of the position and vibration state of the placing boom. By fusing the different measurement signals, the robustness of the vibration damping improves compared to the drift phenomena of the rotation rate sensors caused by the measuring principle. The model-based observer also ensures that the measurement signal from the yaw rate sensors is divided into the separate components of the joint movement and the vibration. The control system specifically dampens the structural vibrations without influencing the target movement. The observer gain L is determined by a suitable method such as B. Pole specification or selected by a Kalman filter.

5.3.5 Control gain

The linearized model is used to design the feedback gains K of the control loop $$\mathit{u}=K\widehat{x}.$$

The poles are positioned in the complex half-plane in such a way that the damping of the system increases. The vibrations in the placing boom are thus dampened. The controller receives the estimated state of the observer x̂ , amplifies the signals and supplies them to the hydraulics as setpoints (see Fig. 4 ). The control gain K is determined by a suitable method such as B. pole specification or optimization-based method (LQR).

The observer and controller design process described above applies to a specific equilibrium position of the placing boom. To change the position of the mast, the design process is repeated and adapted to the current position. By tracking the control parameters, the functionality of the vibration damping is guaranteed for every mast position.

The cyclic design of the observer and controller results in the gains depending on the current position and load situation of the placing boom. The variable natural frequency of the mast is therefore implicitly taken into account in the draft regulation.

5.3.6 Horizontal vibration damping

Vibration damping can also be used for vibrations in the horizontal plane. The hydraulic motor on the mast trestle serves as an actuator. The mast position around the vertical axis is recorded by an angle sensor. In this case, the rotation angle sensors for vibration measurement are designed or extended by a detection direction in the horizontal plane and torsion. The sensors are mounted on one or more segments and measure the rotation rate around the vertical axis and the longitudinal axis.

In the horizontal plane, horizontal bending is coupled to the torsion of the segments. The distribution boom therefore experiences a horizontal bend and a torsion at the same time, depending on the position. This effector is taken into account in the modeling.

The dynamic model of the placing boom (Section 5.3.3) is supplemented by a horizontal component. The virtual joints in the segments are designed as multi-axis swivel joints that record bending in the horizontal plane and torsion. The rotation around the vertical axis is taken into account by a joint on the lathe. The type and structure of the model remain the same as in Section 5.3.3.

Analogous to the procedure in Sections 5.3.3, 5.3.4 and 5.3.5, an observer and a feedback amplifier are designed for the linearized extended model. Either separate horizontal vibration damping or combined vertical and horizontal vibration damping can be implemented. The model-based observer ensures that the measurement signal from the yaw rate sensors is divided into the separate parts of the vertical axis movement and the vibration. The control system specifically dampens the structural vibrations of horizontal bending and torsion without influencing the target movement.

5.3.7 Other properties

The operator's movement specifications are explicitly taken into account by the vibration damping. This means that the desired movement is permitted by the control and only the superimposed structural vibrations are dampened. In order to reduce the vibration excitation during the process, a pilot control is also provided. This calculates control signals from the operator's setpoint that carry out the desired mast movement and do not stimulate any vibration. For this purpose, a notch filter is used which, depending on the current mast position, suppresses the natural frequencies of the placing boom during the movement (see Fig. 3 ).

The setpoint signals for the hydraulics are implemented by a subordinate axis control on the cylinders. The axis control converts a target angular velocity specification u of the joints into the actual translational velocity of the cylinders. The deflection kinematics and non-linearities of the hydraulics are taken into account by a pilot control (see Fig. 5 ). Either the pressure, the cylinder position or the cylinder speed can be used as the feedback measurement variable. As an alternative, the cylinder speed can also be calculated from the position using separate signal processing. The cylinders transmit the force F _u to the placing boom and thus generate movement of the joints. As described above, the axis control is decentralized and subordinate to each joint separately.

6. Disturbance input

Traditionally, feedback-based vibration damping is used to reduce vibrations in the placing boom. These regulations are based on the Feedback of the static and dynamic parameters of the placing boom. To do this, the vibrations in the structure are measured, processed using a control algorithm and fed back to the actuators of the concrete pump as a control signal. The movement generated by the actuators acts on the placing boom and actively dampens vibrations. A disadvantage of this method is that vibrations can only be compensated for when they are measured on the mast. This means that the vibrations must first occur in the structure in order to be dampened. The method presented below follows a different approach based on the principle of switching on disturbance variables. This dampens oscillations in the system based on the cause instead of - as with feedback-based methods - based on the effect (see Fig. 7 ). The vibration excitation in the placing boom is largely due to the cause of concrete delivery. It therefore represents a disturbance to the system that should be compensated for.

The advantage of feeding in disturbance variables compared to traditional vibration damping is that the disturbance variables can be compensated for before they have an impact on the system. This means that the excitation of concrete delivery is eliminated before it becomes visible as vibration in the placing boom.

The aim of the disturbance variable connection is therefore to reduce vibrations in the placing boom on the basis of characteristic measured variables of concrete delivery. The measured variables describe the condition of the concrete delivery and not the vibration condition of the placing boom. Typical measured variables for concrete delivery are the pressure at the inlet of the delivery line, the frequency of the pumping process and the position and speed of the delivery piston.

The measured variables are used to reconstruct the disruptive forces on the placing boom using a model of concrete delivery and are then increasingly applied to the actuators. The reinforcement can be designed in such a way that the influence of the disruptive forces on a specific point on the placing boom is eliminated. For this purpose, the top of the mast is chosen to keep the position of the end hose steady and constant.

Two methods are proposed to reduce the swinging due to concrete delivery: the classic model-based disturbance input and the disturbance input with a disturbance observer.

6.1 Classic model-based disturbance input 6.1.1 Overview 6.1.1.2 Function

• Berechnung der Störkräfte auf den Verteilermast aus Messsignalen der Betonförderung (Druck, Frequenz, Zylinderposition) über Betonfördermodell (siehe Fig. 8).
• Berechnung des Einfluss der Störkräfte auf den Verteilermast im Störmodell.
• Zustandsregelung des Störmodells. Die Stellgröße u _d des geregelten Störmodells ist die Stellgröße u der Hydraulik der Betonpumpe.
• Die Zustandsregelung kann durch eine Ausgangsrückführung erweitert werden. Dabei werden die Bewegungen der Mastspitze gedämpft.
• Der Arbeitspunkt ist die aktuelle Position des Verteilermasts. Bei Veränderung der Mastpostion durch eine Verfahrbewegung wird der Arbeitspunkt nachgeführt. D.h. die Höhe der Mastspitze nach dem Verfahren stellt den neuen Arbeitspunkt dar.
• Abweichungen vom Sollwert y _d (siehe Fig. 8) werden über einen Regelkreis mit den realen Messwerten der Betonpumpe y kompensiert. Dieser Regelkreis kann die Schwingungsdämpfung aus Abschnitt 5.2 darstellen.

The calculation of the in Fig. 6 The disruptive forces shown are carried out via a mathematical model of the concrete delivery along the mast.

• Calculation of the disruptive forces on the placing boom from measurement signals of the concrete delivery (pressure, frequency, cylinder position) using the concrete delivery model (see Fig. 8 ).
• Calculation of the influence of the disruptive forces on the placing boom in the disruptive model.
• State control of the disturbance model. The manipulated variable u _d of the controlled disturbance model is the manipulated variable u of the hydraulics of the concrete pump.
• The state control can be expanded by output feedback. The movements of the mast tip are dampened.
• The operating point is the current position of the placing boom. If the mast position is changed by a movement, the working point is updated. Ie the height of the mast tip after the procedure represents the new working point.
• Deviations from the target value y _d (see Fig. 8 ) are compensated via a control loop with the real measured values of the concrete pump y . This control loop can represent the vibration damping from Section 5.2.

6.1.1.2 Notes

• The additional control loop of the disturbance model enables compensation of the disturbance variables F _d independently of the external control for vibration damping (measurement signal y ). Since the state controller applies a virtual disturbance model, the complete state x _d is available.
• Restrictions on the manipulated variable can easily be taken into account through restrictions in the control loop for feeding in the disturbance variables.

6.1.1.3 Sensors

• Distribution boom position
• Measured values for concrete delivery: amplitude or cylinder position, cylinder speed, frequency of the pump and/or concrete pressure at the inlet of the delivery line

6.1.1.3 Actuators

• All hydraulic cylinders (vertical plane)

6.1.2 Example embodiment 6.1.2.1 Modeling

The modeling of concrete delivery depicts the flow of concrete in the delivery line from the delivery pump in the vehicle to the end hose at the top of the mast. The flow-related disruptive forces of concrete delivery on the placing boom are calculated.

The creation of the disruptive forces is primarily due to frictional forces on the inner pipe wall and inertial forces caused by the concrete flow deflection in the pipe bends. The unsteady, periodic delivery creates impulse-like forces that are transmitted to the placing boom via the pipe fastenings. The forces depend on a variety of factors. The The biggest influence is the rheological properties and the composition of the concrete. Depending on the type and consistency of the concrete, there are very different vibration excitations in the placing boom. Another factor is the so-called wall effect. Due to the viscosity and inhomogeneous composition of the fluid, a boundary layer with a low yield point and viscosity forms in the wall area during delivery. The boundary layer acts like a lubricating film and reduces the friction forces in the wall area. Other factors include the variable fill level factor in the delivery piston and the amount of dissolved air in the concrete. The uncertainty and variability of the factors mentioned above mean that direct, purely substance-based modeling is associated with great difficulties. For this reason, measurement-based modeling is proposed. The basic idea is to forego the exact representation of the flow conditions within the pipe and instead only take into account the forces acting on the pipe wall.

The approach uses an equivalent Newtonian fluid to model the frictional and inertial forces of the fluid on the pipe wall.

The material properties of the equivalent fluid are determined from the measured variables of concrete delivery. In particular, at least the viscosity of the equivalent fluid is determined from the concrete pressure and the flow velocity of the concrete. A stored average value for the density of concrete is used as the density of the equivalent fluid.

By assuming ambient pressure at the end hose and measuring the inlet pressure, the pressure difference across the entire pipeline can be calculated. By taking the position of the mast into account, the hydrostatic pressure loss of the flow is also determined. The output variables of the model are the concentrated disturbance forces F _d in each joint of the concrete pump (see Fig. 6 ).

The effect of the concentrated disturbance forces F _d is calculated via a coupling with a mechanical model of the placing boom. The mechanical model takes into account the dynamic and elastic deformation of the segments under the influence of the disruptive forces across the entire placing boom.

6.1.2.2 Activation

The coupled model of concrete delivery and placing boom is used to design a model-supported dynamic disturbance variable feed-in. The model is expanded to include a control loop to reduce the disturbance variables in the placing boom (see disturbance model control loop in Fig. 8 ). In contrast to the classic return, the real route is not controlled, but only the “virtual” model. This has advantages for the draft regulation, as no route uncertainties or disturbances occur. In addition, the entire state vector is available without the use of an observer. The control is designed in such a way that the influence of disruptive forces on the top of the mast is minimized.

To compensate for the disruptive forces in the real system, the manipulated variable of the virtual control loop u _d is now applied to the actuators. This results in a pilot control that does not require feedback of the dynamic state of the placing boom.

6.1.2.3 Regulation

The disturbance input is combined with traditional vibration damping to compensate for vibrations from the mast's movement and uncertainties in the modeling. The vibration damping is based on the measurement and feedback of the position and vibration state of the placing boom. By taking into account the virtual outputs y _d and the measured variables y , the control is designed so that the manipulated variables of the disturbance variable feed u _d act unhindered on the system. The vibration damping only intervenes if the conditions of the real route differ from the conditions of the virtual model.

6.1.2.4 Other properties

To determine the concrete pressure at the entrance to the route, the hydraulic pressure of the delivery cylinders can also be measured. The corresponding concrete pressure results from a conversion using the piston area ratio.

Furthermore, the flow speed of the concrete can also be determined from the speed of the delivery cylinders.

This avoids the use of an expensive and wear-prone pressure sensor and/or flow sensor in the delivery line.

The performance of the disturbance input described above depends heavily on the accuracy of the concrete delivery and mechanical model. This leads to performance limitations due to parameter uncertainty and parameter variability.

6.2 Asymptotic interference compensation 6.2.1 Overview 6.2.1.1 Function

• Estimation of the disturbance variable from the vibration measurements of the placing boom and the pumping frequency of the concrete delivery (see Fig. 9 ).
• Amplification of the interference signal in the interference controller and connection to the actuators of the concrete pump.
• For reasons of stability, the disturbance variable compensation requires vibration damping, which can, for example, be constructed as described in Section 5.2.
• Compared to the classic disturbance variable feed-in, the disturbance observer has the advantage the advantage that the interference signal is estimated entirely from the existing vibration damping sensors. This makes the process robust against changes in the parameters of concrete delivery.
• The estimation algorithm can, for example, be designed as asymptotic interference compensation according to Davison.
• The disturbance variable compensation is based on the disturbance variable being estimated/learned from a freely selectable measurement output y _d . The aim is to regulate this measurement output y _d to a constant value using suitable manipulated variables. A possible choice of measurement output y _d is the height of the mast top in the vertical plane. The interference compensation thus reduces oscillatory movements of the mast tip.
• The operating point is the current position of the placing boom. If the mast position is changed through movement, the working point is updated. This means that the height of the mast tip after the procedure represents the new working point.

6.2.1.2 Sensors

• Distribution boom position
• Pumping frequency of concrete delivery
• Measuring the vibration condition of the placing boom: yaw rate sensors on certain segments

6.2.1.3 Actuators

• All hydraulic cylinders (vertical plane)

6.2.1.2 Notes

• Asymptotic interference compensation is based on representing attacking interference signals using a fictitious interference model. The disturbance model is integrated into the control loop and excited by a selected measurement output until the disturbances are compensated for in a selected measurement output. The interference model has the property of delivering a non-disappearing output signal even when the excitation signal disappears (boundary stable). As a result, the disturbance compensation generates the required manipulated variables to compensate for the effect of the disturbance.
• Due to the estimation process, the disturbance variables have at least a temporary effect on the system outputs. This means that the interference compensation is subject to a transient response at the beginning and when there are large parameter changes.

6.2.2 Example embodiment 6.2.2.1 Modeling

Below we present an alternative method to the above disturbance variable feed-in. The basic idea of the method is to estimate the disruptive forces from the measured values of the placing boom. The periodicity of concrete delivery is used to set up a modal model of the disruptive forces. The model is composed of the fundamental frequency and its multiples. The individual states reproduce the oscillation shape of the disturbance variable as modal coordinates. A modal coordinate has no physical meaning, but only reflects the proportion of the respective frequency in the wave form of the disturbance variable.

6.2.2.2 Estimation procedure

Based on the modal model, the disturbance forces are estimated by a disturbance observer or asymptotic disturbance compensation from the measurement values of the placing boom. The estimation procedures are based on the inner model principle. The principle defines that a stable control loop can only be completely resolved when a disturbance occurs can suppress if it has an internal model of the interference signal. The model is boundary-stable and is composed only of complex conjugate pairs of poles of the conveying frequencies on the imaginary axis of the complex half-plane. The initial state of the modal model is adapted from the measurement signals from the distribution boom using the interference observer or asymptotic interference compensation. This corresponds to an estimate of the unknown amplitude and phase position of the disturbing forces. The more frequencies the model contains, the more accurately the waveform of the disturbance can be represented. However, the larger number of frequencies requires more time to learn the given waveform. During the learning process, a transient motion occurs, the amplitude of which increases with the number of frequencies. For good interference suppression, the number of frequencies must be chosen so that, on the one hand, the interference is reproduced with sufficient accuracy and, on the other hand, the transient response occurs briefly and with a low amplitude.

6.2.2.3 Regulation

The reconstructed disturbance variables are applied to the actuators of the placing boom via a control system (see Fig. 9 ). The disturbance input is combined with vibration damping based on the measured variables of the placing boom y to ensure the stability of the system. The states of the system are estimated based on the boom model and the disturbance model by the disturbance observer. The measured variables include the mast position and the vibration condition of the placing boom. The regulator in Fig. 9 thus amplifies the estimated disturbance variables and states of the system. The disturbance input can be designed in such a way that the influence of the disturbance forces on the top of the mast is minimized.

6.2.2.4 Other properties

Unlike the first method, the disturbance observer or asymptotic disturbance compensation learns the disturbance forces from the measured values y of the dynamic vibration state of the placing boom. This allows the number of sensors for the Concrete delivery can be reduced. The required measurement variable is the pump frequency, which can be determined in the software via the switching times of the delivery cylinders. Another advantage of the method is its robustness against changes in route parameters and variations in concrete properties.

6.3 Further properties of the disturbance variable feed-in

The disturbance inputs described above apply to a specific equilibrium position of the placing boom. To change the position of the mast, the design process is repeated and adapted to the current position. By tracking the control parameters, the functionality of the disturbance variable feed-in is guaranteed for each mast position.

The setpoint signals for the hydraulics are implemented by a subordinate axis control on the cylinders. The axis control converts a target angular velocity specification of the joints into the actual translational velocity of the cylinders. The deflection kinematics and non-linearities of the hydraulics are taken into account through a pilot control. Depending on the version, feedback of the pressure or the cylinder position or speed can be implemented. The axis control is implemented decentrally and is therefore subordinate to each joint separately.

The operator's movement specifications are explicitly taken into account through the input of disturbance variables and vibration damping. This means that the desired movement is permitted by the control and only the superimposed structural vibrations are dampened. In order to reduce the vibration excitation during the process, a pilot control is also provided. This calculates control signals ω _target from the operator's setpoint, which carry out the desired mast movement and do not stimulate any vibration. For this purpose, a notch filter is used which, depending on the current mast position, suppresses the natural frequencies of the placing boom during the movement.

The feedforward control is for the disturbance variable feed-ins presented in the 8 and 9 marked by a signal block. For the model-supported dynamic disturbance input, the pilot control signal ω _{shall is} also taken into account in the disturbance model control loop.

Claims (15)

1. Concrete pump, in particular truck-mounted concrete pump, with a delivery pump, a concrete line and an articulated arm forming a distribution boom, along which the concrete line is guided,

   wherein the articulated arm has a rotary stand (3) rotatable about a vertical axis (A) and/or at least one segment (4 - 7) that can be pivoted by means of a hinge (B - E) about a horizontal axis, wherein the rotary stand (3) is movable about the vertical axis via an actuator and/or the at least one segment (4 - 7) is pivotable about the horizontal axis via an (14 - 17) actuator,

   wherein the concrete pump further has a control for controlling the actuators (14 - 17) of the distribution boom, wherein the control comprises disturbance variable activation to reduce the vibrations of the distribution boom induced by the concrete delivery,

   wherein

   the disturbance variable activation takes place based on a physical model of the concrete delivery, which describes the flow-related disruptive forces of the concrete delivery on the distribution boom,

   wherein the physical model describes friction forces of the concrete on the inner wall of the concrete line and/or inertia forces on account of the concrete flow redirection in the pipe bends and/or wherein at least one operating parameter of the delivery pump (1) feeds into the disturbance variable activation.
2. Concrete pump according to claim 1, wherein the physical model of the concrete delivery takes account of the current position of the distribution boom and in particular the articulation angles of the hinges (B - E), wherein preferably the position of the distribution boom and in particular the articulation angles of the hinges (B - E) feed into the description of the concrete flow redirection and/or wherein the determination of the disruptive forces of the concrete delivery on the distribution boom takes place without measurement of the vibration state of the distribution boom or of the segments (4 - 7), and/or wherein the physical model takes account of the hydrostatic pressure loss of the flow, taking the current position of the distribution boom into consideration.
3. Concrete pump according to one of the preceding claims, wherein at least one material property of the pumped fluid feeding into the modelling is determined from operating parameters of the delivery pump (1) and/or of the concrete delivery, wherein preferably the viscosity is determined, in particular from the concrete pressure and the flow velocity of the concrete.
4. Concrete pump according to any one of the preceding claims, wherein the disturbance variable activation is based furthermore on a physical model of the distribution boom, which is coupled to the physical model of the concrete delivery, in order to determine the influence of the disruptive forces determined by the physical model of the concrete delivery on the entire distribution boom, wherein the physical model of the distribution boom preferably takes account of the elastic deformation of at least one of the segments (4 - 7).
5. Concrete pump according to any one of the preceding claims, wherein the disturbance variable activation takes place as feedforward control without feedback of the dynamic state of the distribution boom, preferably on the basis of closed-loop control of a virtual model of the distribution boom.
6. Concrete pump according to any one of the preceding claims, wherein the disturbance variable activation controls the actuators in such a way that the influence of the disruptive forces on the tip (22) of the distribution boom is reduced and preferably eliminated.
7. Concrete pump according to any one of the preceding claims, wherein the control, apart from the disturbance variable activation, further comprises closed-loop control, which is based on measurement and/or feedback of the position and/or of the vibration state of the distribution boom, wherein the closed-loop control preferably comprises vibration damping to damp horizontal and/or vertical vibrations of the distribution boom.
8. Concrete pump according to claim 7, wherein the vibration damping is based on the same physical model of the distribution boom which also serves to determine the influence of the disruptive forces of the concrete delivery on the distribution boom, wherein the vibration damping preferably only intervenes if the state of the distribution boom deviates from the state of the virtual model that is being controlled in the context of the disturbance variable activation.
9. Concrete pump, in particular according to any one of the preceding claims, with a delivery pump (1), a concrete line and an articulated arm forming a distribution boom, along which the concrete line is guided,

   wherein the articulated arm has a rotary stand (3) rotatable about a vertical axis (A) and/or at least one segment (4 - 7) that can be pivoted by means of a hinge (B - E) about a horizontal axis, wherein the rotary stand (3) is movable about the vertical axis via an actuator and/or the at least one segment (4 - 7) is pivotable about the horizontal axis via an actuator (14 - 17),

   wherein the concrete pump further has a control for controlling the actuators of the distribution boom, wherein the control comprises disturbance variable activation to reduce the vibrations of the distribution boom induced by the concrete delivery, which activation takes account of the concrete pressure, characterised in that the disturbance variable activation determines the concrete pressure at the inlet to the concrete line based on operating parameters of the delivery pump (1), in particular based on the hydraulic pressure of the delivery cylinders and the piston area ratio of the delivery pump.
10. Concrete pump according to any one of the preceding claims, wherein the disturbance variable activation takes account of the frequency of the delivery pump (1) and/or the position and velocity of the delivery pistons of the delivery pump.
11. Concrete pump according to any one of the preceding claims with at least one angular rate sensor (18 - 21), which is arranged on a segment (4 - 7), wherein the control for disturbance variable activation and/or vibration damping based on measured values of the angular rate sensor (18 - 21) determines from the vibrations of the individual segments (4 - 7) a vibration state of the entire distribution boom and/or takes place without the use of geodetic sensors, and/or at least one angular rate sensor (18 - 20) is arranged in a front region of a segment (4 - 6), which is arranged between the rotary stand (3) and a segment (7) forming the boom tip (22) in the articulated arm.
12. Concrete pump according to any one of the preceding claims, wherein the disturbance variable activation and/or vibration damping takes place using a physical model of the distribution boom, in which the flexibility of at least one segment (4 - 7) is described by a virtual hinge arranged within this segment (4 - 7), wherein a spring element and a damper element are preferably associated with the virtual hinge, wherein the spring constant and the damper constant are further preferably selected so that the virtual hinge describes the deflection, torsion and/or first natural frequency of the real segment (4 - 7).
13. Control software for a concrete pump according to any one of claims 1 to 12, wherein the control software in its execution implements a control for controlling the actuators of the distribution boom of the concrete pump with disturbance variable activation to reduce the vibrations of the distribution boom induced by the concrete delivery,
    wherein the disturbance variable activation

    a) takes place on the basis of a physical model of the concrete delivery, which describes the flow-related disruptive forces of concrete delivery on the distribution boom,
    wherein the physical model describes friction forces of the concrete on the inner wall of the concrete line and/or inertia forces on account of the concrete flow redirection in the pipe bends and/or wherein at least one operating parameter of the delivery pump (1) feeds into the disturbance variable activation,
    and/or

    b) determines the concrete pressure at the inlet to the concrete line on the basis of operating parameters of the delivery pump (1), in particular on the basis of the hydraulic pressure of the delivery cylinders and the piston area ratio of the delivery pump.
14. Control for controlling the actuators of the distribution boom of a concrete pump according to any one of claims 1 to 12, wherein the control comprises disturbance variable activation to reduce the vibrations of the distribution boom induced by the concrete delivery,
    wherein the disturbance variable activation

    a) takes place on the basis of a physical model of the concrete delivery, which describes the flow-related disruptive forces of concrete delivery on the distribution boom,
    wherein the physical model describes friction forces of the concrete on the inner wall of the concrete line and/or inertia forces on account of the concrete flow redirection in the pipe bends and/or wherein at least one operating parameter of the delivery pump (1) feeds into the disturbance variable activation,
    and/or

    b) determines the concrete pressure at the inlet to the concrete line on the basis of operating parameters of the delivery pump (1), in particular on the basis of the hydraulic pressure of the delivery cylinders and the piston area ratio of the delivery pump.
15. Method for controlling the actuators of the distribution boom of a concrete pump according to any one of claims 1 to 12, wherein the disturbance variable activation

    a) takes place on the basis of a physical model of the concrete delivery, which describes the flow-related disruptive forces of concrete delivery on the distribution boom,
    wherein the physical model describes friction forces of the concrete on the inner wall of the concrete line and/or inertia forces on account of the concrete flow redirection in the pipe bends and/or wherein at least one operating parameter of the delivery pump (1) feeds into the disturbance variable activation,
    and/or

    b) determines the concrete pressure at the inlet to the concrete line on the basis of operating parameters of the delivery pump (1), in particular on the basis of the hydraulic pressure of the delivery cylinders and the piston area ratio of the delivery pump.

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