EP4269705A1 - A method for improving the levelling angle control of a working machine - Google Patents

Abstract

The invention relates to a method for controlling a work machine (1), which comprises a main body (2) and a movement device (3), which is connected to the main body (2) of the work machine (1) and which is configured to accommodate loads and with respect to the To move the main body (2), the movement device having a boom with one or more boom elements (4, 5) and a holding element (6) arranged on an end section of the boom for receiving load, the boom elements (4, 5) and that Holding element (6) can be moved by one or more independently acting actuators (7, 8, 9), sensors being provided which are set up to record status data of the movement device (3), the method comprising the following steps:a. Detecting a movement of at least one boom element (4, 5);b. Detecting a command to keep a target inclination (ϕ) of the holding element (6) constant during the movement of the at least one boom element (4, 5), the target inclination (ϕ) relative to a target angle of the holding element (6). to the main body (2) of the work machine (1);c. Calculating a weight of a load received by the holding element (6);d. Calculating a target movement of one of the actuators (9), which is responsible for the movement of the holding element (6), so that the target inclination (ϕ) of the holding element (6) remains constant during the movement of the at least one boom element (4, 5). remains, the calculation taking into account the in step c. calculated weight and the detected movement of the at least one boom element (4, 5).e. Control of the actuator (9), which is responsible for the movement of the holding element, based on the steps in step d. calculated target movement.

Description

TECHNICAL PART

The invention relates to a method for controlling a work machine, which makes it possible to keep an inclination of a holding element constant while at least one boom element is moved.

STATE OF THE ART

Mobile work machines with the “Bucket Retain” assistance function are used worldwide. Such a feature is in the patent application DE 11 2017 000 130 T5 disclosed. The purpose of the “Bucket Retain” assistance function is to regulate a set leveling angle of a work machine. The leveling angle describes the angle of the bucket in relation to the external, higher-level coordinate system and is dependent on the boom, stick and bucket angles in their respective coordinate systems. The "Bucket Retain" function adjusts the bucket angle in a controlled manner to maintain a desired leveling angle. The boom and stick can still be adjusted by the vehicle driver.

Such a feature can find applications in various types of machines. In fact, excavators (standard, mini, midi, mining, mobile), wheel loaders, telehandlers, forestry machines with appropriate functionality can be found on the market. In the present invention, therefore, the word "work machine" means any of these or other machines known from the prior art.

However, the control accuracy and control speed of this function is not particularly high due to the different weight of the attached holding element (e.g. load in a spoon) and the associated dynamics. For this reason, the purpose of the invention is to improve the existing function.

SHORT VERSION

1. a. Erfassen einer Bewegung mindestens eines Auslegerelements;
2. b. Erfassen eines Befehls, eine Soll-Neigung des Halteelements während der Bewegung des mindestens einen Auslegerelements konstant zu behalten, wobei die Soll-Neigung einen Soll-Winkel des Halteelements in einem Koordinatensystem, das unabhängig von dem mindestens einen Auslegerelement ist, beschreibt;
3. c. Berechnen eines Gewichts einer von dem Halteelement aufgenommenen Last;
4. d. Berechnen einer Soll-Bewegung eines der Aktuatoren, der für die Bewegung des Halteelements zuständig ist, sodass die Soll-Neigung des Halteelements während der Bewegung des mindestens einen Auslegerelements konstant bleibt, wobei die Berechnung unter Berücksichtigung des im Schritt c. berechneten Gewichts und der erfassten Bewegung des mindestens einen Auslegerelements erfolgt;
5. e. Regeln des Aktuators, der für die Bewegung des Halteelements zuständig ist, auf Basis der im Schritt d. berechneten Soll-Bewegung.

According to an embodiment of the present invention, there is provided a method for controlling a work machine comprising a main body and a moving device connected to the main body of the work machine and configured to receive and move loads with respect to the main body, the moving device including a boom one or more boom elements and a holding element arranged at an end section of the boom for receiving load, the boom elements and the holding element being movable by one or more independently acting actuators, with sensors being provided which are set up to record status data of the movement device , the process comprising the following steps:

1. a. Detecting a movement of at least one boom element;
2. b. Detecting a command to keep a target inclination of the holding element constant during movement of the at least one boom element, the target inclination describing a target angle of the holding element in a coordinate system that is independent of the at least one boom element;
3. c. Calculating a weight of a load received by the holding element;
4. d. Calculating a target movement of one of the actuators that is responsible for the movement of the holding element, so that the target inclination of the holding element remains constant during the movement of the at least one boom element, the calculation taking into account the in step c. calculated weight and the detected movement of the at least one boom element;
5. e. Rules of the actuator, which is responsible for the movement of the holding element, based on the steps in step d. calculated target movement.

The present invention is particularly advantageous because this function particularly increases the accuracy of the "bucket retain" function. In particular, testing the function and measurements on the excavator have shown that there is a huge improvement in the control when the load is taken into account. In the current implementation, a linear controller is used for all operating points, without taking the load into account. However, the inventor observed that the dynamics of the system strongly depend on orientation and charge of the spoon. In particular, the inventor observed that optimal control parameters when the spoon is full differ greatly from those when the spoon is empty. If the current load is not taken into account, only one set of control parameters (as a compromise of the different operating points) can be used. However, such a solution causes enormous inaccuracies, such as oscillations and long-term control deviations, when compared to the accuracy that a method according to the present invention enables.

BRIEF DESCRIPTION OF THE FIGURES

• Figur 1 zeigt schematisch eine Arbeitsmaschine mit beweglichen Elementen;
• Figur 2 zeigt schematisch ein Verfahren nach einer Ausführungsform der vorliegenden Erfindung.

The present invention will be described with reference to the accompanying figures, where like reference numerals refer to like parts and/or to similar parts and/or to corresponding parts of the system. About the characters:

• Figure 1 shows schematically a work machine with moving elements;
• Figure 2 shows schematically a method according to an embodiment of the present invention.

DETAILED DESCRIPTION

The present invention will be described below with reference to certain embodiments as shown in the accompanying figures. Nevertheless, the present invention is not limited to the particular embodiments described in the following detailed description and shown in the figures, but the described embodiments merely illustrate some aspects of the present invention, the scope of which is defined by the claims.

Other modifications and variations of the present invention will be apparent to those skilled in the art. The present description therefore includes all modifications and/or variations of the present invention, the scope of which is defined by the claims.

Figure 1 shows an excavator 1 as an example of a work machine. The excavator 1 has a main body 2 and a moving device 3 connected to the main body 2 of the work machine 1. The movement device is configured to receive loads and move them with respect to the main body 2. The movement device 1 has a boom, which in turn has a plurality of boom elements in order to move a holding element 6. The boom elements here are, for example, a lifting arm 4 (or simply as “Boom”) and an arm 5 (or also known as “stick”), which are rotatably or pivotally connected to each other or to the main body 2 of the excavator 1. In addition, the in Figure 1 excavator shown has a bucket 6 which is arranged at an end portion of the arm 5. The boom elements 4, 5 and the bucket can be moved by means of actuators 7, 8, 9, ie the rotation or pivoting movement about the axes is caused by a movement of the actuators.

A first actuator 7 is provided for the lifting arm 4, which causes the movement or rotation of the lifting arm 4 relative to the main body 2. Likewise, a second actuator 8 is provided for the arm 5, which causes the movement or rotation of the arm 4 relative to the lifting arm 4. Likewise, a third actuator 9 is provided for the spoon, which moves or rotates (tilts) the spoon (or also called "shovel").

The actuators 7, 8, 9 can be controlled by a controller, with directional control valves being provided in the case of hydraulic cylinders, which control the flow of hydraulic fluid to the hydraulic cylinders.

Sensors are provided (in Figure 1 not shown) that record force data and position data. Force data is data or measurement data that characterizes or displays the forces applied by the actuators. In particular, pressure sensors can be used for this purpose, for example the pressure on both sides of the piston can be measured on the hydraulic cylinders, in which case the force applied by the hydraulic cylinder is characterized by the pressure difference. Position data are data or measurement data that characterize or display the position (eg angle) of the cantilever elements, in particular their relative position or their position relative to the cantilever support (in particular also relative angles). For this purpose, angle sensors in particular can be provided, or sensors that determine the deflection of the hydraulic cylinders.

In particular, force data and position data and corresponding sensors are discussed. These are preferred examples of status data or sensors; in general, status data from other sensors can also be acquired in addition or alternatively, for example to capture pressure data, torque data, torque data, speed data, acceleration data and / or voltage data (which, as noted, in principle can also be understood as force and/or position data).

Since the geometric relationships of the boom elements and their weights or masses are known, the weight or mass of a picked up load can be calculated or estimated from the force and position data. For this purpose, a so-called weighing function is used, the implementation of which is known to those skilled in the art. The time or period at which the force and position data is collected, based on which the load carried is calculated, is referred to as the weighing time or period.

An example of a weighing function is in the patent application DE 102021205407.2 disclosed, which had not yet been published on the filing date of this patent application.

As in Figure 1 is shown, the angle θa corresponds to the inclination of the lifting arm 4 with respect to a horizontal plane, the angle θb corresponds to the inclination of the arm 5 with respect to the axis of the lifting arm 4, the angle θc corresponds to the inclination of the bucket 6 with respect to the axis of the arm 5. The angle ϕ corresponds to the inclination of the bucket 6 with respect to a horizontal plane. The angle φ is represented in a coordinate system that is independent of the other cantilever elements 4, 5.

The aim of the present invention is therefore to automatically keep the angle φ constant while changing the other angles θa and θb. The leveling angle ϕ is therefore automatically kept constant by the third actuator 9 (if the "Bucket Retain" function is active).

Figure 2 shows schematically a method for the "bucket retain" function according to an embodiment of the present invention.

In a first step, the information about a target leveling angle φ is obtained using an input device (e.g. a joystick or a button). This information 108 can either be a value of the target leveling angle ϕ or the command to keep the current leveling angle ϕ constant. In addition, sensor data 109 is collected to detect the position of the boom 4, 5 and the bucket 6. In the first step, the weight 110 calculated during the weighing time is also recorded. A bus system 107 records all the information 108, 109 and 110 and transmits it to a control unit 103, which is responsible for controlling the third actuator 9. The control unit 103 can control the position 106 of the third actuator by means of a pump 104 and a main control valve 105.

The control takes place in the loop 100, 101, 102, 103. In a first step, the target inclination φ of the holding element 6 is recorded 100 during the movement of the at least one cantilever element 4, 5 and compared with the actual inclination φ of the holding element 6 and the difference 101 is communicated to the control unit 103.

The control unit 103 will then use the information 101 and the information acquired from the bus system 107 to generate a control signal for the main control valve 105.

The signal is therefore calculated taking into account the weight of the load received by the holding element 6. The information about the weight can be used, for example, as a control parameter in gain scheduling or in model-based control.

Control parameters can also be selected depending on the positioning (e.g. the angle) of the boom 4, 5. I.e. different control parameters when moving the spoon close to the main body 2 than when moving further away from the main body 2.

The estimated charge mass can also be used in other functions where variable dynamics play a role. E.g. in the workspace limitation assistance function.

The core of the present invention is therefore that a further assistance function is used to estimate the current load mass in order to take this information into account in the control of the leveling angle. This can be done in the form of operating point-dependent control methods, such as gain scheduling, or a general, model-based approach. By combining the two functions, better control behavior that is independent of the operating point is expected.

Claims (9)

Method for controlling a work machine (1), which comprises a main body (2) and a movement device (3) which is connected to the main body (2) of the work machine (1) and which is configured to receive loads and with respect to the main body (2) to move, the movement device having a boom with one or more boom elements (4, 5) and a holding element (6) arranged on an end section of the boom for receiving load, the boom elements (4, 5) and the holding element (6) can be moved by one or more independently acting actuators (7, 8, 9), sensors being provided which are set up to record status data of the movement device (3), the method comprising the following steps: a. Detecting a movement of at least one boom element (4, 5); b. Detecting a command to keep a target inclination (ϕ) of the holding element (6) constant during the movement of the at least one boom element (4, 5), wherein the target inclination (ϕ) represents a target angle of the holding element (6). a coordinate system that is independent of the at least one cantilever element (4, 5); c. Calculating a weight of a load received by the holding element (6); d. Calculating a target movement of one of the actuators (9), which is responsible for the movement of the holding element (6), so that the target inclination (ϕ) of the holding element (6) remains constant during the movement of the at least one boom element (4, 5). remains, the calculation taking into account the in step c. calculated weight and the detected movement of the at least one boom element (4, 5); e. Control of the actuator (9), which is responsible for the movement of the holding element, based on the steps in step d. calculated target movement. The method according to claim 1, wherein the holding element (6) is a bucket, and wherein the target inclination (ϕ) is a target leveling angle of the bucket (6). Method according to one of claims 1 or 2, wherein the boom exclusively comprises a first (4) and a second (5) boom element. Method according to one of claims 1 to 3, wherein in step d. the calculation continues to take into account the position of the holding element (6) with respect to the main body (2). Method according to one of claims 1 to 4, wherein in step d. at least one control parameter for taking into account the in step c. calculated weight is used, the control parameter being dependent on the position of the holding element (6). Computing unit which is set up to carry out a method according to one of the preceding claims. Work machine (1), which comprises a main body (2) and a movement device (3) which is connected to the main body (2) of the work machine (1) and which is configured to receive loads and to move them with respect to the main body (2), wherein the movement device has a boom with one or more boom elements (4, 5) and a holding element (6) arranged at an end section of the boom for receiving load, the boom elements (4, 5) and the holding element (6) being supported by one or more independently acting actuators (7, 8, 9) are movable, with sensors being provided which are set up to record status data of the movement device, a controller being provided which implements a weighing function which is set up to evaluate recorded status data in order to to determine a weight of a load picked up by the movement device (3); having a computing unit according to claim 6. Computer program that causes a computing unit to carry out a method according to one of claims 1 to 6 when it is executed on the computing unit. Machine-readable storage medium with a computer program stored thereon according to claim 8.

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