Large-scale manipulator comprising a vibration damper

ES 2 301 552 T3

DESCRIPTION

Large manipulator with oscillation damper.

The invention relates to a large manipulator, especially for concrete pumps, with a boom support trestle arranged on a frame and preferably rotatable on a vertical axis of rotation, with a flexible boom composed of at least three boom arms , preferably configured as a concrete distribution boom in which the boom arms are respectively pivotable in a limited way in pairs, relative to the adjacent boom support stand or boom arm around horizontal folding axes parallel to each other, each by means of a drive unit, with a command device, preferably remotely operable, for the movement of the boom with the help of the regulating elements assigned to the different drive mechanisms, and with elements for damping mechanical oscillations in the flexible boom. A large manipulator of this type is known (DE-19520166 A1). However, there are no damping elements arranged there.

The flexible boom of a large manipulator of this type is in its construction a system that can oscillate elastically, excitable to its own oscillations. Resonant excitation of oscillations of this type can cause the pen tip to oscillate with amplitudes of one meter or greater. An oscillation excitation is possible, for example, by the pulsating operation of a concrete pump and by the resulting periodic acceleration and deceleration of the compressed concrete column through the transport pipe. This has the consequence that the concrete can no longer be distributed evenly and the worker handling the final hose is in danger. To avoid this, in a known flexible boom concrete pump (DE-A 195 03 895) it was proposed to use a position regulating closed loop that stabilizes the level of the boom tip with respect to a fixed horizontal reference plane, within a predetermined range of variation. For this, a sensor device is provided by means of which output signals a coordinate regulator drive for compensatory deflection of the boom tip or end hose can be controlled. These measures have been shown to be quite complex and do not always produce the desired results. The sensor of the movement of the arms necessary for the regulation is activated only when the movement has already been carried out, that is, when it is too late. In other words, with this it is not possible to achieve sufficient regulatory quality.

Based on this, the invention has the object of adopting precautions and procedural measures whereby by simple means an optimal damping of the pen is possible.

To achieve this aim, the combinations of characteristics indicated in claims 1 and 15 are proposed. Advantageous configurations and developments of the invention result from the dependent claims.

The solution according to the invention is based on the idea that a measurement value derived from the time of the mechanical oscillation of the corresponding boom arm is determined in at least one of the drive mechanisms or in the respective boom arm, which is processed in an evaluation unit, forming a damping signal and additionally connected to a regulating element that controls the drive mechanism.

According to a preferred embodiment of the invention, in which the drive mechanism is designed as a double-acting hydraulic cylinder, the pressure difference as a function of time between the piston head side and the piston rod side of the hydraulic cylinder is determined as a measured value and evaluated in the evaluation unit to form the dynamic damping signal. In signal preparation, the dynamic part of the pressure difference as a function of time is appropriately filtered above a defined cutoff frequency and is phase shifted and / or amplified to form the damping signal. The cutoff frequency is adjusted as a function of the natural frequency of the respective boom arm, preferably in the range of 0.2 to 10 Hz. In any case, the cutoff frequency of the high pass filter should be chosen somewhat lower than the natural frequency of the respective boom arm. Since the damping of the boom without position control can lead to unwanted drift of the boom tip, it is proposed, according to an advantageous configuration of the invention, that in a flexible boom extended to a defined working position Measure at defined time intervals the inclination and ground clearance of the terminal arm and compare with a previously stored nominal value and that when a drift occurs, the flexible boom is restored by means of the control of at least one of the actuating mechanisms.

In order to carry out the procedure described, it is proposed, according to the invention, that at least one of the drive mechanisms or boom arms have at least one sensor assigned to determine the measurement value as a function of time derived from the mechanical oscillation of the boom arm. as well as a subsequent evaluation unit to the at least one sensor connected on the output side to the respective regulating element, to produce a damping signal.

According to a preferred configuration of the invention, each actuating mechanism has a double-acting hydraulic cylinder, the hydraulic cylinders being able to be pressurized with oil under pressure by means of a multi-way proportional valve that forms the corresponding regulating element. In this case, according to the invention, a pressure transducer is arranged at the end of the piston rod side and of the piston head side of at least one of the hydraulic cylinders, which is connected to the unit. of evaluation through an element of comparison or differential. Advantageously, the evaluation unit comprises a high-pass filter that can be analog or digital. Preferably, the cutoff frequencies of the high-pass filters

ES 2 301 552 T3 belonging to each boom arm can be adjusted separately as a function of the natural frequencies of the respective boom arm. Typical cutoff frequencies for high-pass filters are 0.2 to 10 Hz.

A preferred configuration of the invention provides that the high-pass filter is formed by a low-pass filter, the input of which is connected to its output by means of a differential element. To avoid overshoots, each high-pass filter forms a transient response. In addition, each high-pass filter preferably has an evaluation and safety circuit or routine downstream that can be triggered on the input side additionally with the output signals from both pressure transducers of the assigned hydraulic cylinders.

A preferred configuration of the invention provides that the control device has a microcontroller with a coordinate sensor to control the regulation elements, which on the input side can be activated by means of a bus system and a remote control device with command data for the boom movement, which each regulating element has additionally assigned, forming the damping unit, a carrier which on the input side can be loaded with the measurement values ​​of the respective boom arm and on the output side is connected to the regulating element. With these precautions, the flexible boom is controlled by the pump operator based on the preset command data by means of the remote control device, while the damping of the boom during boom movement and in the working position it is done automatically. In this, the damping units are coupled to the control circuits of the various drive mechanisms. The different carriers are appropriately configured as second-order high-pass filters, whose transient responses exhibit an aperiodic behavior. This ensures that no additional disturbances are applied to the system through the filter and its carrier. A peculiarity of the damping device according to the invention therefore consists in that each boom arm is assigned a separate damping unit.

Suitable pressure sensors are, for example, membrane sensors or piezoelectric sensors, to which a microcontroller is assigned a transmitter with an analog-digital converter. It is important that the pressure sensors have sufficient dynamics.

According to a favorable configuration of the invention, in the absence of a position control, an arrangement is provided for compensating the drift of the flexible boom, which has at least one inclination or distance sensor arranged on one of the boom arms. pen, a setpoint memory as well as a dial gauge connected on the input side to the setpoint memory and to the output of the tilt or distance sensor, to control at least one of the regulating elements. The inclination or distance sensor is advantageously arranged on the terminal arm of the flexible boom, while the setpoint memory can be loaded via a control routine with the digital output signal of the inclination or distance sensor. The control routine ensures that the momentary tilt value or ground clearance of the terminal arm is stored in the setpoint memory when the flex boom reaches a working position.

In the following, the invention is shown in more detail on the basis of the manufacturing examples represented in the drawing in schematic form. They show 1a:

Figure 1, a side view of a mobile concrete pump with a folded flexible boom;

figure 2, a mobile concrete pump according to figure 1, with flexible boom in working position;

Figure 3, a diagram of the control device for the movement and damping of the boom;

Figure 4, a diagram with a flow diagram of the software carrier contained in the microcontroller, for the damping of the pen.

The mobile concrete pump 10 comprises a transport vehicle 11, a thick material pulsating pump 12 configured, for example, as a two-cylinder piston pump, as well as a distribution boom 14 rotatable on a vertical axis 13 fixed to the vehicle, as a carrier. of a concrete transport pipe 16. Liquid concrete, which during concreting continuously enters a supply receptacle 12, is transported through the transport pipe 16 to a concreting site 18 remote from the location of the vehicle 11.

The placing boom 14 consists of a boom support stand 21 rotatable on the vertical axis 13 by means of a hydraulic swing drive 19 and a flexible boom 22 that can be pivoted on the boom support stand and continuously adjustable to reach. variable and height difference between the vehicle 11 and the concreting place 18. The flexible boom 22 shown in the manufacturing example is made up of five boom arms 23 to 27 connected in an articulated manner with one another, pivotable on axes 28 to 32 parallel to each other and orthogonal to the vertical axis 13 of the boom support stand 21 . The folding angles ε1 to ε5 (figure 2) of the folding joints formed by the joint axes 28 to 32 and their relative disposition to each other, are coordinated in such a way that the distribution boom 14 can be deposited on the vehicle 11 in a compact multi-fold transport configuration, as can be seen in Figure 1. By program-controlled activation of drive mechanisms 34 to 38 individually assigned to link shafts 28 to 32, the flexible boom 22 can be deployed between the concreting site 18 and the vehicle site at different distances and / or height differences. (figure 2).

ES 2 301 552 T3

The boom operator controls, for example by remote control 50, the movements of the boom by which the boom tip 33 with the end hose 43 is moved above the area to be concreted. The end hose 43 has a typical length of 3 to 4 m and can, due to its articulated suspension in the area of ​​the boom tip 33 and on the basis of its inherent flexibility, be held by a sleeve operator with its end of outlet in the convenient position to the place of concreting 18.

The remote control 50 contains multiple control members 60 configured as levers that can be moved back and forth in two control directions perpendicular to each other by transmitting control signals. The control signals are transmitted via a wireless line 61 to the radio receiver 62 fixed in the vehicle, connected to the microcontroller 52 via, for example, a bus system 63 configured as CAN. The microcontroller 52 contains, among others, a computer-assisted coordinate sensor 64 in which the command data transmitted by the radio receiver 62 is converted into coordinate signals for the drive mechanisms 19, 34 to 38 of the six axes 13, 28 to 32. Additionally, the size of the deflection of the control members 60 can be converted into speed determining signals. The operation of the actuating mechanisms 34 to 38 is carried out through the regulating elements 68 to 76, configured as multi-way proportional valves, connected with their outlet pipes 78, 80 to the side of the piston head and to the side of the piston rod of the actuators 34 to 38 configured as double-acting hydraulic cylinders. The drive mechanism 19 for the boom support stand 21 is designed as a rotary hydraulic drive, which can be controlled by the adjusting element 66. In addition to the control by means of the coordinate sensor 64, which, for example, interprets the received command data as cylindrical coordinates and converts them into an appropriate shape (see DE-A 43 06 127), the different drive mechanisms 19, 34 to 36 They can also be controlled directly through the control members 60 and the respective regulating elements 66 to 76.

The flexible boom 22 forms, together with the transport vehicle 11, a system capable of oscillations which, while in operation, can be forced to oscillate by the thick material pump 12 operating in a pulsating manner. The oscillations can lead to deflections of the boom tip 33 and the end hose 43 attached to it, with amplitudes of about one meter and frequencies between 0.5 and a few Hz.

To prevent a growth of the resonant oscillation of the flexible boom 22, the microcontroller 52 additionally contains a number of software-assisted damping units 82, connected in each case to the pre-regulation input of one of the control elements 68 to 76. On the input side, the damping units 82 are activated by a measurement value as a function of time derived from the mechanical oscillations of the respective boom arm 23 to 27. In the exemplary embodiment shown, for this purpose, a pressure sensor 84 is arranged in each case at the end of the piston head and the piston rod of each of the actuating mechanisms 34 to 38 configured as a hydraulic cylinder. , 86, whose outputs ps and pb are connected to a comparator 88 in which a measurement signal is generated as a function of time, corresponding to the pressure difference Ap (t) = ps-pb. The measurement signal Ap (t) is transmitted at predetermined time intervals to a digital high-pass filter 90, 92. In the manufacturing example shown in figure 4, the high-pass filters are formed by a low-pass filter. digital 90 with downstream comparator 92, the input signal of the low-pass filter 90 being additionally imposed on the latter. The cutoff frequency of the high pass filter 90, 92 is set separately for each boom arm 23 to 27 and is chosen somewhat lower than its own mechanical frequency. The damping units 82 additionally contain an evaluation and safety algorithm 93 downstream of the digital high-pass filter 90, 92, for the regulation of the amplification factor necessary for damping the oscillations. Furthermore, the safety algorithm also monitors the movement limit values ​​of the boom arm, for example by means of a stop control. For this, the absolute pressure values ​​ps and pb measured by the pressure sensors 84, 86 on the piston head side and the piston rod side can be evaluated.

Since the axial positions of the folding axes are not controlled, it cannot be excluded that, due to manufacturing tolerances, a drifting movement of the flexible boom 22 occurs. This is especially the case in the working position of the flexible boom during pump operation. Drift can be monitored and compensated for. As can be seen in Figures 2 and 4, for this purpose, a solid angle sensor 94 is arranged on the last boom arm 27, configured for example as a tilt sensor, or a distance sensor as well as a value memory. Nominal values ​​96. That is, in each working position at the end of each process, the angular position of the moment or the distance to the ground of the boom tip 33 can be stored in the nominal value memory 96. By comparing the actual value with the stored setpoint value, a drift can be detected over time and compensated for by controlling at least one of the control elements 68 to 76, for example via the coordinate sensor 64 .

In summary, the following should be concluded: The invention relates to a large handler, especially concrete pumps. The large manipulator has a flexible boom 22 made up of at least three boom arms 23 to 27, preferably configured as a concrete distribution boom, the boom arms of which can rotate in each case to a limited extent on parallel horizontal bending axes 28 to 32 relative to each other, by means of a drive unit 34 to 38, respectively. In addition, a control device 50, 62, 52 is provided for the movement of the boom with the help of the regulating elements assigned to the different drive mechanisms, as well as elements for damping mechanical oscillations in the flexible boom. In order to achieve an effective boom damping with simple resources, it is proposed, according to the invention, that preferably in each drive unit 34 to 38 or in the corresponding boom arm 23 to 27,

ES 2 301 552 T3 a time-dependent measurement value of the mechanical oscillation of the respective boom arm is derived from one of the respective boom arms or drive units, is processed in an evaluation unit 82 forming a dynamic damping signal and is connected to a regulating element 68 to 76 that controls the respective drive equipment.