JP2023161577A - Method for improving closed-loop control of work machine grading angle - Google Patents

Abstract

To relate to a method for controlling a work machine.SOLUTION: A method comprises steps of a. detecting movement of at least one jib element, b. detecting a command for maintaining a constant target tilt of a holding element during the movement of the at least one jib element, c. calculating the weight of a conveyance scooped up by the holding element, d. calculating a target movement of an actuator responsible for the movement of the holding element among the plurality of actuators such that the desired inclination of the holding element during the movement of at least one jib element is maintained constantly.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for controlling a work machine, making it possible to maintain a constant inclination of a holding element while at least one jib element is being moved.

BACKGROUND OF THE INVENTION Mobile working machines equipped with a support function called "bucket retain" are used all over the world. Such functionality is disclosed in German patent application no. 112017000130 (DE112017000130T5). The assist function "Bucket Hold" has the purpose of providing closed-loop control of the adjusted grading angle of the work machine. The grading angle represents the angle of the bucket relative to an external superordinate coordinate system and is dependent on the boom angle, arm angle, and bucket angle in the respective boom, arm, and bucket coordinate systems. The "Bucket Hold" function adjusts the bucket angle in closed loop control to maintain the desired grading angle. The boom and arm are further adjustable by the vehicle operator.

Such functionality is available in a variety of different types of machines. In practice, excavators (standard, small, medium, mining, mobile), wheel loaders, telehandlers, forestry machines with corresponding functionality can be found on the market. The term "work machine" in the present invention therefore means any of the machines mentioned above or other machines known from the prior art.

Translation of German patent application No. 112017000130 (DE112017000130T5)

However, the closed-loop control accuracy and closed-loop control speed of this function is not very high due to the different weights of the attached holding elements (eg, the load in the bucket) and the dynamics associated therewith. For this reason, the task of the invention is to improve the existing functionality.

SUMMARY According to one embodiment of the invention, a method for controlling a work machine includes a main body and a motion device, the motion device being connected to the main body of the work machine. , configured to scoop up and move a conveyed object relative to the main body, the movement device comprising a jib with one or more jib elements and a conveying device arranged in an end section of the jib; a holding element for scooping up an object, the jib element and the holding element being movable by one or more actuators acting independently of each other and configured to detect state data of the movement device. In the method, a sensor is provided.
a. detecting movement of at least one jib element;
b. detecting a command for maintaining a constant target inclination of the holding element during movement of the at least one jib element, the target inclination of the holding element in a coordinate system being independent of the at least one jib element; a step representing the target angle;
c. calculating the weight of the conveyance scooped up by the holding element;
d. calculating a target movement of an actuator responsible for the movement of the holding element among the plurality of actuators such that a desired inclination of the holding element during the movement of the at least one jib element is maintained constant; is step c. carried out taking into account the calculated weight and the detected movement of the at least one jib element;
e. Step d. controlling in a closed loop an actuator responsible for the movement of the holding element based on the target movement calculated in;
A method is provided that includes.

The invention is particularly advantageous. This is because this feature particularly increases the accuracy of the "keep bucket" function. In particular, functional tests and measurements on an excavator have shown that the improvement in closed-loop control when taking into account the material to be transported is significant. In the current implementation, a linear controller is used for all operating points without considering the cargo. However, we observed that the dynamics of the system is strongly dependent on bucket orientation and loading. In particular, the inventors observed that the optimal control parameters when the bucket is full are significantly different from the optimal control parameters when the bucket is empty. If the current load is not taken into account, it is only possible to use a set of control parameters (as a compromise between different operating points). However, such solutions lead to extremely large inaccuracies, such as fluctuations and long-term control deviations, when compared to the accuracy achieved by the method according to the invention.

The invention will now be described with reference to the accompanying drawings. It should be noted that identical reference numbers relate to identical and/or similar parts and/or corresponding parts of the system.

1 is a schematic diagram of a working machine with movable elements; FIG. 1 is a schematic diagram illustrating a method according to one embodiment of the invention; FIG.

DETAILED DESCRIPTION The invention will now be described with reference to specific embodiments as illustrated in the accompanying drawings. However, the invention is not limited to the particular embodiments illustrated in the drawings, which are explained in the following detailed description, and the described embodiments illustrate several aspects of the invention. However, the protection scope of the present invention is defined by the claims.

Further modifications and variations of the invention will be apparent to those skilled in the art. Accordingly, this specification includes all modifications and/or variations of the invention whose scope of protection is defined by the claims.

FIG. 1 shows an excavator 1 as an example of a working machine. The excavator 1 has a main body 2 and an exercise device 3, and the exercise device 3 is connected to the main body 2 of the working machine 1. The exercise device is configured to scoop up a conveyed object and exercise it relative to the main body 2. The movement device 3 has a jib, which itself has a plurality of jib elements for moving the holding element 6 . The jib elements are here illustratively the boom 4 (also known simply as the "jib") and the arm 5 (also known as the "forearm"), which are connected to each other or to the excavator. It is rotatably or pivotably connected to the main body 2 of 1. Furthermore, the excavator shown in FIG. 1 includes a bucket 6 arranged in the end section of the arm 5. The jib elements 4, 5 and the bucket are movable using actuators 7, 8, 9, ie rotational or pivoting movements about the axis are brought about by the movement of these actuators.

A first actuator 7 for the boom 4 is provided, which brings about a movement or rotation of the boom 4 relative to the main body 2. Similarly, a second actuator 8 for the arm 5 is provided, which brings about a movement or rotation of the arm 5 relative to the boom 4. Similarly, a third actuator 9 for the bucket is provided, which moves or rotates (tilts) the bucket (also referred to as "shovel").

The actuators 7, 8, 9 can be driven by a control device and, in the case of hydraulic cylinders, are provided with directional control valves for controlling the flow of hydraulic fluid to the hydraulic cylinders.

Sensors (not shown in FIG. 1) are provided to detect force and position data. Force data is data or measured data that is indicative or representative of a force applied by an actuator. For this purpose, pressure sensors can in particular be used, for example to measure the pressure on both sides of a piston in a hydraulic cylinder, in which case the force applied by the hydraulic cylinder is indicated by the pressure difference. has been done. The position data indicates the position (e.g. angle) of the jib element, in particular the relative position of the jib element or the position of the jib element relative to the jib carrier (in particular also the relative angle of each) or representative data or measured data. For this purpose, in particular an angle sensor can be provided or a sensor can be provided which determines the displacement of the hydraulic cylinder.

In particular, force and position data and corresponding sensors will be described. These sensors are preferred examples for status data or sensors, and typically in addition or in place of, for example, pressure data, moment data, torque data, velocity data, acceleration data, and/or It is also possible to detect state data of other sensors in order to detect voltage data (which, as mentioned above, can basically also be understood as force data and/or position data).

Since the geometric relationship between the jib elements and the weight or mass of the jib elements are known, the weight or mass of the scooped cargo can be calculated or estimated from the force and position data. For this purpose, a so-called metering function is used, the implementation itself of which is known to the person skilled in the art. The point in time or period in which the force and position data, which are the basis for calculating the scooped cargo, is detected is referred to as the metering point or metering period.

An example of a metering function is disclosed in DE 102021205407.2, a patent application not yet published as of the filing date of the present application.

As shown in FIG. 1, the angle φa corresponds to the inclination of the boom 4 with respect to the horizontal plane, the angle φb corresponds to the inclination of the arm 5 with respect to the axis of the boom 4, and the angle φc corresponds to the inclination of the arm 5 with respect to the axis of the arm 5. This corresponds to the inclination of the bucket 6 with respect to . The angle φ corresponds to the inclination of the bucket 6 with respect to the horizontal plane. The angle φ is shown in a coordinate system that is independent of the other jib elements 4,5.

The aim of the invention is therefore to automatically keep this angle φ constant while the other angles φa and φb are changed. The grading angle φ is therefore automatically held constant by the third actuator 9 (if the "bucket hold" function is active).

FIG. 2 schematically illustrates a method for the "keep bucket" function according to one embodiment of the invention.

In a first step, information regarding the target smoothing angle φ is obtained via an input device (eg a joystick or a button). This information 108 may be the value of the target smoothing angle φ, or it may be an instruction to maintain the current actual smoothing angle φ constant. Furthermore, sensor data 109 is detected to detect the positions of the jibs 4, 5 and the bucket 6. In the first step, the weight 110 calculated at the time of weighing is also detected. The bus system 107 detects and transmits all information 108, 109, 110 to the control unit 103, which is responsible for the closed-loop control of the third actuator 9. The control unit 103 can control the position 106 of the third actuator using the pump 104 and the main control valve 105.

Closed loop control is performed in loops 100, 101, 102, and 103. In a first step, the target inclination φ of the holding element 6 during the movement of at least one jib element 4, 5 is detected 100 and compared with the actual inclination φ of the holding element 6, and the difference 101 is communicated to the control unit 103. be done.

Control unit 103 then utilizes information 101 and information detected by bus system 107 to generate a control signal for main control valve 105 .

The signal is therefore calculated taking into account the weight of the conveyance scooped up by the holding element 6. Information regarding weight can be used, for example, as a control parameter in gain scheduling or in model-based closed loop control.

The control parameters can additionally be selected depending on the position (eg angle) of the jib 4, 5. That is, the control parameters when guiding the bucket near the main body 2 are different from the control parameters when moving the bucket away from the main body 2.

The estimated load mass can also be used in other functions where variable dynamics play an important role, for example in support functions that limit the working space.

The core of the invention therefore lies in using further aids for estimating the current load mass and taking this information into account in the closed-loop control of the grading angle. This can be implemented, for example, in the form of an operating point-dependent closed-loop control method, such as gain scheduling or a general model-based approach. By combining both features, a better closed-loop control behavior independent of the operating point is expected.

Claims (9)

A method for controlling a work machine (1), the work machine (1) including a main body (2) and a movement device (3), the movement device (3) controlling the work machine (1). ) and configured to scoop up and move a conveyed object relative to the main body (2), the movement device comprising one or more jibs. a jib with elements (4, 5) and a holding element (6) arranged in the end section of said jib for scooping up the conveyed material, said jib elements (4, 5) and said The holding element (6) is movable by one or more actuators (7, 8, 9) acting independently of each other and configured to detect state data of said movement device (3). In the method, a sensor is provided.
a. detecting movement of at least one jib element (4, 5);
b. detecting a command for maintaining constant a target inclination (φ) of the holding element (6) during the movement of the at least one jib element (4, 5), represents a target angle of the holding element (6) in a coordinate system that is independent of the at least one jib element (4, 5);
c. calculating the weight of the conveyance scooped up by said holding element (6);
d. Of the plurality of actuators, the holding element ( 6) calculating a target movement of the actuator (9) responsible for the movement of step c. and the detected movement of the at least one jib element (4, 5);
e. Said step d. controlling the actuator (9) responsible for the movement of the holding element in a closed loop based on the target movement calculated in
method including. the holding element (6) is a bucket and the target inclination (φ) is the target grounding angle of the bucket (6);
The method according to claim 1. the jib includes only a first jib element (4) and a second jib element (5);
The method according to claim 1 or 2. Said step d. wherein said calculation is further carried out taking into account the position of said retaining element (6) with respect to said main body (2).
A method according to any one of claims 1 to 3. Said step d. In step c. at least one control parameter is utilized to take into account the weight calculated in, said control parameter being dependent on the position of said holding element (6);
A method according to any one of claims 1 to 4. Computing unit configured to implement the method according to any one of claims 1 to 5. A working machine (1), the working machine (1) includes a main body (2) and an exercise device (3), and the exercise device (3) is a main body (1) of the working machine (1). 2) and configured to scoop up and move a conveyed object relative to said main body (2), said movement device comprising one or more jib elements (4, 5). and a holding element (6) arranged in the end section of said jib for scooping up the conveyance, said jib elements (4, 5) and said holding element (6) is movable by one or more actuators (7, 8, 9) acting independently of each other and is provided with a sensor configured to detect state data of said motion device; is provided, the control device implementing a weighing function configured to evaluate the detected condition data in order to determine the weight of the conveyance scooped up by the movement device (3). and the working machine (1) has a calculation unit according to claim 6,
Working machine (1). 6. A computer program for causing a computing unit to perform the method according to any one of claims 1 to 5 when executed on the computing unit. A machine-readable storage medium on which the computer program according to claim 8 is stored.