EP1246973A1

EP1246973A1 - Mobile machine with device for controlling the position of working devices and method for controlling the position

Info

Publication number: EP1246973A1
Application number: EP00991646A
Authority: EP
Inventors: Reinhard Vonnoe; Michael Brand
Original assignee: Brueninghaus Hydromatik GmbH
Current assignee: Brueninghaus Hydromatik GmbH
Priority date: 2000-01-11
Filing date: 2000-12-28
Publication date: 2002-10-09
Anticipated expiration: 2020-12-28
Also published as: DE10000771C2; DE10000771A1; US6968241B2; EP1246973B1; DE50004035D1; WO2001051717A1; US20020173900A1

Abstract

The invention relates to a device for controlling the position for work devices (41) of mobile machines (40). The inventive device comprises a measuring device (1, 2) for measuring an angle (α) which is formed between a level (42) that is determined by the position of the work device (41) and the direction of the gravitational force (g). The inventive device also comprises an angle transmitter (5) for predetermining an angle (α') which is formed between a level (42) that is determined by the position of the work device (41) and the direction of the gravitational force (g). The inventive device further comprises a controller (3, 4, 6-16) for controlling the angle (α) between the level (42) of the work device (41) and the direction of the gravitational force (g) in such a way that the measured angle (α) matches the predetermined angle (α').

Description

Device and method for position control for mobile work facilities

machinery

The invention relates to a device for position control for work devices of mobile machines and a method for position control for work devices of mobile machines.

From DE 197 52 439 AI, a micromechanical inclination sensor, in particular for motor vehicles, is known as such, which has a carrier plate, the inclination of which to the horizontal is determined. Furthermore, at least two pressure sensor units integrated on the carrier plate are provided for determining a pressure applied to the carrier plate at the respective points. A ground plate is connected to the carrier plate via the pressure sensor units. An evaluation unit determines the inclination of the carrier plate to the horizontal from the data produced by the pressure sensor units. Depending on the inclination of the device in which the inclination sensor is installed, the mass plate exerts a force of different strength on the respective pressure sensor unit. At least two pressure sensors must be provided to measure the angle of inclination. These are formed in DE 197 52 439 AI as piezoresistive pressure transducers.

A device for level control in a harbor crane is known from DE 39 38 766 AI. A level control using a hydraulic control valve for controlling one or more hydraulic actuators for a part to be maintained at a certain level is proposed here, the part being coupled to another part which can be changed in any position. In order to ensure a high level of operational safety without using expensive electronics, that stands Control valve with a pendulum fixed in its position by gravity as an actuating device m mechanical actuating connection.

If the device is inclined, a damped pendulum deflection takes place in a defined spatial direction, which is transmitted to the hydraulic actuator via the control valve. In DE 39 38 766 AI, a loading and unloading crane, which is particularly suitable for loading and unloading of ships, is aligned by this measure so that when the crane boom is raised and lowered, a loading and unloading device located there relative to a fixed position remains for the rest of the construction.

A disadvantage of the level control known from DE 39 38 766 AI is in particular the one-dimensional design. For the embodiment of the level control on a loading and unloading crane, preferably for ships, disclosed in the above-mentioned laid-open specification, the device is quite sufficient for mobile work machines such. B. earthmoving machines, which move preferably on construction sites and therefore on uneven ground, a one-dimensional position correction is not sufficient.

The object of the present invention is thus to provide an apparatus and a method for position control for work devices of mobile work machines, whereby the work devices can be reliably adapted both in several directions and on the road surface in accordance with the respective position of the work machine without m uneven terrain Charge loss on ride.

The object is achieved with respect to the device by the features of claim 1 and with respect to the method by the features of claim 11. The invention is based on the finding that the alignment of a work device of a mobile work machine is important not only in the immovable state or when picking up material, but in particular when transporting the picked up material in the field to avoid load losses. Accordingly, a device suitable for this purpose must enable alignment with respect to a plane defined by the force of gravity and in a satisfactorily short time. The device according to the invention and the corresponding method provide an arrangement which enables a position correction with respect to a plane perpendicular to the gravitational force and possibly inverse acceleration force.

The sub-claims 2 to 10 and 12 contain advantageous developments of the invention.

In particular, the possibility of executing the comparison device both in a conventional analog design and in integrated circuit technology is advantageous, since it allows the special requirements of individual machines to be met.

The arrangement is simple to manufacture and easy to equip with commercially available sensors.

The arrangement is suitable for execution in one spatial direction as well as in two spatial directions. In the case of earthmoving machines in particular, a position correction in the longitudinal and transverse directions is advantageous. In a particularly preferred embodiment, the natural vibrations caused by the control runtime and their multiples are eliminated.

The predetermined angle is particularly preferably set such that the plane defined by the position of the working device is perpendicular to the resultant of gravitational force and inverse acceleration force. In the drawing, preferred embodiments of the device according to the invention are shown and explained in more detail below with reference to the drawing. As a result, even with accelerations of the work equipment, for. B. by driving movements, the working device positioned so that loss of charge is avoided.

The drawing shows:

Fig. 1 in a first circuit diagram a first

Embodiment of the invention

Device for regulating and controlling hydraulic actuating elements for position control of mobile work equipment

Machinery;

2 shows a second exemplary embodiment of the device according to the invention in a second circuit diagram;

3A-3B the basic structure of a digital filter unit designed as a second-order bandstop filter and the associated amplitude response;

4A-4B in a simplified representation the movement of a mobile machine in the field according to the prior art and the use of the position control device according to the invention in a mobile machine when moving in the

Terrain;

Fig. 5 in a perspective view

Example of a work facility of a mobile work machine with the possible ones

Pivoting directions; F g. 6 shows a schematic mobile work machine with the device according to the invention for position control on uneven terrain; and

7 shows a sketch with regard to a charge control that takes the acceleration into account.

1 shows a first block diagram of a first exemplary embodiment of the device according to the invention for position control for work devices of mobile work machines. The circuit comprises a first sensor 1, which measures a first angle m of a first spatial direction, hereinafter referred to as x. This first angle is referred to below as α _x . A second sensor 2 accordingly measures a second angle m of a second spatial direction y. The second angle is referred to below as α _γ . The measured angles α _x and α _y are determined via a first comparator 3 and a second comparator 4 with an angle α _x 'for the spatial direction x and α _y ' for the spatial direction y, which angle can be determined by an angle transmitter 5 and which can be 90 °, for example , compared. The comparators 3 and 4 form a comparison device 6. The angle transmitter 5 can either provide a fixed predetermined angle or an angle α _x 'or α _y ' which can be adjusted manually using a manual control transmitter 5a.

The signal m x direction passes through a first bandstopper 7 after the first comparator 3, the signal m y direction passes through a second bandstopper 8 after the second comparator 4. The bandstopper 7 and 8 have the purpose of being caused in the system by the control time τ Eliminate natural vibration f _R and, if necessary, their multiples 2 f _R , 3 f _R , ..., so that the dynamic behavior of the system remains controllable and no resonances occur.

After passing through the bandstop 7, the signal m x direction is amplified by a first amplifier 9 in order to to be able to control a first electromagnet 10. The first electromagnet 10 is required to actuate a first control valve 11, which in turn controls a first hydraulic actuating element 12 for position correction in the first spatial direction x. Accordingly, the signal in the y-direction is amplified by a second amplifier 13 after passing through the bandstop 8 in order to control a second electromagnet 14 and thus a second control valve 15. The second control valve 15 actuates a second hydraulic control element 16. As a result, the working device is aligned in the second spatial direction y.

To actuate the hydraulic actuators 12 and 16, a hydraulic fluid located in a tank 17 is pumped into a front or rear cylinder space of a first cylinder 19 of the first hydraulic actuating element 12 or into the front or rear cylinder space of a second cylinder 20 of the second hydraulic Control element 16 pressed. As a result, a first piston 21 or a second piston 22 experiences a change in position, which in turn ensures the position control of the working device 41.

The position control is carried out until the comparators 3 and 4 determine no difference between the measured angle α _x or α _y and the preset angle α _x 'or α _y ¹ . The differences α _x '-α _x and α _y ' -α _y are almost zero in magnitude or are at least below a value which can still be tolerated for an angular deviation Δα, for example ± 3 °.

Once this state has been reached, there is no more signal change to the control valves 11 and 15, which then switch back to a central position without further changing the position of the actuators 12 and 16. The system remains in the middle position until a different signal is received from comparators 3 and 4. Fig. 2 shows a second embodiment of an inventive device for position control for work equipment of mobile machines. Components that have already been described in FIG. 1 are provided with the same reference symbols and are not described again below. 1 is an exemplary embodiment in analog technology, the exemplary embodiment shown in FIG. 2 is implemented in digital technology.

The device shown in FIG. 2 differs from the device shown in FIG. 1 mainly by the use of a digital control unit 34, which performs both the function of the band-stopper 7 and 8 and that of the comparison device 6.

The comparison device 6 is accordingly constructed as follows: The angle α _x output by the sensor 1 is preamplified by a first preamplifier 30 and then by a first analog-digital converter 32 from an analog measured angle value to a digital one which can be processed by a digital control unit 34 Value implemented. Likewise, the angle α _y is amplified by a second preamplifier 31 and converted into a digital value by a second analog-digital converter 33. In order to be able to compare the predetermined angle α _x 'or α _y ' with the angles α _x and 0C _y determined by the sensors 1 and 2, the predetermined angle α _x 'or α _y ' is determined by the angle transmitter 5 by a third analog -Digital converter 35 also implemented and supplied to the digital control unit 34, which can be designed as a microprocessor.

In addition to comparing the angle values, the digital control unit 34 is also responsible for filtering the signals. For this purpose, the filter unit is designed as a digital filter with a bandstop characteristic. The

Band-stop characteristic, as in the exemplary embodiment shown in FIG. 1, corresponds, for example, to the second-order digital band-stop shown in FIGS. 3A and 3B and is provided by a corresponding program m of the control unit 34. The digital control unit 34 has a memory 36 which, for. B. offers the possibility to save the measured and adjusted data and to make it available for later external processing.

The adjusted signals from sensors 1 and 2 are converted back to analog signals by a first digital-to-analog converter 37 and a second digital-to-analog converter 38. The analog signals are amplified by amplifiers 9 and 13 and fed to the electromagnets 10 and 14. Hydraulic actuators 12 and 16 are actuated by the control valves 11 and 15, the pump 18 and the tank 17 analogously to the first exemplary embodiment. These then ensure the correct position of the working device 41.

In Fig. 3A, a second-order digital bandpass filter and Fig. 3B, the associated frequency response is explained in principle. FIG. 3A shows a digital filter which, by means of various delay elements for delaying the sampling values (designated m in FIG. 3A with z ^~ ) and coefficient elements a ₀ , a ^ and a ₂ for changing the amplitude of the sampling values, a bandstop filter with the m FIG. 3B shown resonance frequency f _R generated. This leads to the natural oscillation f _{R of} the system, which is caused by the control time τ, and its odd multiples (3f _R , 5f _R etc.) being filtered out. This prevents the system from rocking. This allows a highly dynamic and extremely precise function of the device according to the invention to be achieved. A further digital filter can be provided to filter out the double resonance frequency 2f _R.

In FIG. 4, a work machine 40 with an excavator shovel is used as a schematic illustration Work device 41 explains an application of the invention in one dimension.

4A illustrates the prior art. In the lower position of the excavator bucket 41 (on the left in the picture), the excavator bucket 41 is oriented in such a way that an imaginary plane 42, which is laid through the opening of the excavator bucket 41 at the top, is always parallel to the surface of the earth. Common work machines 40 have a lifting mechanism for the working device 41, which is designed so that the excavator bucket 41 is raised so that the plane 42, which is determined by the opening of the excavator bucket 41, always remains parallel to the ground.

As long as the working machine 40 is moving on a flat route, there is no problem associated with this. However, as soon as the working machine 40 moves up an incline or, as shown in FIG. 4A on the right, material 43 is lost, since the plane 42 defined by the excavator shovel 41 is still parallel to the ground and therefore, from a certain incline, the m the excavator bucket 41 transported material 43 slips out. The pitch angle, from which load loss is to be expected, is mainly determined by the shape of the excavator bucket 41 and the filling.

According to the invention, as shown in FIG. 4B, another reference plane 42 'is proposed for the alignment of the excavator bucket 41. Like FIG. 4A, an imaginary plane 42 ′ is also defined on the working device 41 of the working machine 40 shown in FIG. 4B through the opening of the excavator bucket 41 located at the top. This is now no longer necessarily parallel to the earth, but always approximately perpendicular to the direction of the gravitational force, marked m in FIG. 4B with the vector g. This can be achieved both in the lower and in the upper position of the excavator bucket 41. This has the advantage that the Excavator bucket 41 is adjusted according to the invention when driving uphill or downhill as well as when driving on uneven terrain so that the plane 42 running through the excavator bucket 41 is always oriented perpendicular to the direction of gravitational acceleration g. This prevents transport losses from the excavator bucket 41.

The one-dimensional correction of the position of the excavator bucket 41 shown in FIG. 4 can also be carried out without problems in two directions perpendicular to one another, for example lengthways and transversely to the direction of movement.

5 shows a schematic excavator bucket 41 in perspective. Due to the axes A and B which are parallel and perpendicular to the direction of movement, the excavator bucket 41 can be pivoted up and down both transversely to the direction of travel and in the direction of travel. In this way, load losses to the front or to the side from the excavator bucket 41 can be avoided when driving on uneven terrain.

6 schematically shows a working machine 40 when driving through uneven terrain, the position of the working device 41 also being regulated here by its relative position with respect to the gravitational force g. In this context, it makes sense to assume a limit value for the angle deviation Δα for the angle α between the plane 42 defined by the excavator bucket 41 and the direction of the gravitational attraction g, from which point the position control can be omitted. As a result, a reasonable middle ground is found between an uninterrupted position correction, which requires a lot of energy and can be unfavorable due to the control delay, and charge loss due to a lack of position correction. Resonance peaks that can occur when the control excitation caused by the uneven ground coincides with the resonance frequency f _{R of} the system are suppressed by the filter described. While in the exemplary embodiment shown in FIG. 6 the plane 42 defined by the orientation of the excavator bucket 41 is oriented perpendicular to the direction of the gravitational force g, there is also an improved position correction in that the plane 42 defined by the excavator bucket 41 is not perpendicular to the gravitational force g, but perpendicular to the resultant r from the gravitational force g and the inverse b '

Align acceleration force b. The excavator bucket 41 is shown enlarged in FIG. 7. It is assumed that the mobile work machine 40 is subject to a deceleration due to a braking operation. The decelerating acceleration force b therefore acts on the excavator bucket 41. Based on the reference system of the excavator bucket 41, the bulk material introduced into the excavator bucket 41 is acted on by a reverse acceleration force b 'm in the opposite direction to the acceleration force J decelerating the excavator bucket 41, i. H. the acceleration force b 'acting on the bulk material in the reference system of the excavator bucket 41 has the same amount as the acceleration force b acting on the excavator bucket 41 m, but is rotated by 180 °.

The resultant r from the gravitational force g and the inverse acceleration force b 'therefore acts on the bulk material located in the excavator bucket 41. It is therefore advantageous to regulate the plane 42 by the position control according to the invention so that the plane 42 is perpendicular to the resultant r. For this purpose, in the exemplary embodiments shown in FIGS. 1 and 2, a further measuring device 29 is provided for measuring the acceleration or deceleration of the mobile working machine 40. The acceleration or deceleration can also be measured separately here in the dimensions x and y. While in the exemplary embodiment m analog technology shown in FIG. 1, the measuring device 29 for measuring the acceleration is directly connected to the angle transmitter 5 and the angle α _χl m predetermined by the angle _transmitter 5 x direction and the angle _y given in the y direction. overdriven, the measuring device 29 for measuring the acceleration in the exemplary embodiment shown in FIG. 2 is connected in digital technology via an analog-digital converter 28 to the control unit 34, which performs a computational correction of the predetermined angles α _x 'and α _y ' as a function of the situation of the measured acceleration.

This further development ensures that the position control of the excavator bucket or, in general, of the working device 41 takes place in such a way that bulk material is not lost even when the mobile working machine 40 accelerates or decelerates more strongly.

The invention is not limited to the exemplary embodiments shown, but can also be applied to any work machine using different sensors or filter devices.

Claims

Expectations

1. Device for position control for work devices (41) of mobile work machines (40), with a measuring device (1, 2) for measuring an angle (α), which is determined by a plane (42) determined by the position of the work device (41) and the Direction of the gravitational force (g) is formed, an angle sensor (5) for specifying an angle (α ¹ ) which is formed between a plane (42) determined by the position of the working device (41) and the direction of the gravitational force (g), and a control device (3, 4, 6 - 16; 6, 34, 36, 9 - 16) for controlling the angle (α) between the plane (42) of the working device (41) and the direction of the gravitational force (g), see above that the measured angle (α) is brought into agreement with the predetermined angle (α ¹ ).

2. Device according to claim 1, characterized in that the control device (3, 4, 6 - 16; 6, 34, 36, 9 - 16) a comparison device (6) for comparing the measured angle (α) with the predetermined angle ( α ¹ ) and at least one electromagnetic control valve (11, 15) controlled by the comparison device (6), which acts on a hydraulic control element (12, 16).

3. Apparatus according to claim 2, characterized in that the comparison device (6) is designed as a comparator (3, 4).

4. The device according to claim 2, characterized in that the comparison device (6) is designed as a digital control unit (34, 36).

5. Device according to one of claims 1 to 4, characterized in that the control device (3, 4, 6 - 16; 6, 34, 36, 9 - 16) comprises a filter unit (7, 8; 34, 36), which a natural vibration (f _R ) caused by the control time (τ) is eliminated.

6. The device according to claim 5, characterized in that the filter unit (7, 8; 34, 36) is designed as a bandstop (7, 8) for the natural vibration (f _R ) and / or its multiples.

7. The device according to claim 6, characterized in that the filter unit (7, 8; 34, 36) is designed as a digital filter (34, 36) with band-stop characteristic.

8. Device according to one of claims 1 to 7, characterized in that the device for position control for work equipment (41) of mobile work machines (40) executes an inclination compensation longitudinally and transversely to the direction of movement of the work machine (40), a first adjusting element (12) for correcting the position in a first spatial direction (x) and a second adjusting element (16) for correcting the position in a second spatial direction (y).

9. The device according to claim 8, characterized in that a measuring device (1) for measuring the angle (α _x ) in the first spatial direction (x) and a second measuring device (2) for measuring the angle (α _y ) in the second spatial direction (y) are provided.

10. Device according to one of claims 1 to 9, characterized in that a further measuring device (29) for measuring the acceleration and / or deceleration of the mobile machine (40) is provided and that the predetermined angle (α ') is set so that the plane (42) determined by the position of the working device (41) extends perpendicular to the resultant (r) from the gravitational force (g) and the measured inverse acceleration force (£> ').

11. Process for position control for work equipment (41) of mobile work machines (40) with the following process steps:

Measuring an angle (α) which is formed between a plane (42) determined by the position of the working device (41) and the direction of the gravitational force (g),

- Specifying an angle (α ') which is formed between a plane (42) determined by the position of the working device (41) and the direction of the gravitational force (g), and

- Regulation of the angle (α) between the plane (42) of the working device (41) and the direction of the gravitational force (g), so that the measured angle (α) is brought into agreement with the predetermined angle (α ¹ ).

12. The method according to claim 11, characterized in that the predetermined angle (α ¹ ) is set so that the plane (42) determined by the position of the working device (41) perpendicular to the resultant (r) from the gravitational force (g ) and inverse acceleration force (£>') extends.