METHOD FOR PUTTING DOWN A TOOL OF A CONSTRUCTION MACHINE

Abstract

A method is for putting down a tool of a construction machine. A position and an orientation of the tool relative to the construction machine or to a direction of Earth's gravity is determined by one or more of the following sensors including: an inertial measuring unit, an angle sensor, a linear sensor, and/or by an algorithm for determining a kinematic chain of the construction machine. Moreover, an orientation of at least one part of the construction machine, which part touches the ground, and which orientation characterizes an orientation of the construction machine relative to the ground, is determined relative to Earth's gravity. Based on this determination, movement of the tool is controlled, in order to bring a lower face of the tool to the same level and in the same orientation as the at least one part touching the ground, for putting down the tool.

Claims

1. A method for depositing a tool of a construction machine on the ground, comprising: determining a position and an orientation of the tool relative to the construction machine or to a direction of Earth's gravity using one or more of an inertial measurement unit, an angle sensor, a linear sensor, and/or by use of an algorithm for determining a kinematic chain of the construction machine; determining, relative to Earth's gravity, an orientation of at least one part of the construction machine contacting the ground that characterizes an orientation of the construction machine relative to the ground; and controlling a movement of the tool by closed-loop control in order to bring an underside of the tool to a same level and to the same orientation as the at least one part of the construction machine contacting the ground, for depositing the tool on the ground.

2. The method as claimed in claim 1, wherein: the orientation of the at least one part of the construction machine contacting the ground is determined with the inertial measurement unit, and a sensor signal of an inertial sensor of the inertial measurement unit located on the construction machine is used to determine the orientation of the at least one part of the construction machine contacting the ground.

3. The method as claimed in claim 1, wherein: determining the orientation of the tool includes determining an inclination of the tool, and determining the orientation of the at least one part of the construction machine contacting the ground includes determining an inclination of the at least one part of the construction machine contracting ground.

4. The method as claimed in claim 3, wherein, in controlling the movement of the tool by closed-loop control, at least one joint angle of at least one joint between the tool and the construction machine is controlled by closed loop control, such that the underside of the tool is deposited horizontally and/or parallel to the ground.

5. The method as claimed in claim 1, wherein the at least one part of the construction machine contacting the ground includes one or more wheels and/or a drive chain.

6. The method as claimed in claim 1, wherein a computer program is configured to perform the method.

7. The method as claimed in claim 6, wherein the computer program is stored on a non-transitory machine-readable storage medium.

8. The method as claimed in claim 1, wherein an electronic control device is configured to deposit the tool using the method.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Exemplary embodiments of the invention are represented in the drawings and explained in more detail in the description that follows.

[0021] FIG. 1 shows a schematic representation of a construction machine in which, by means of the method according to the invention, a tool, from an initial state (a), is deposited on the ground (b).

[0022] FIG. 2 shows a flow diagram of the method according to the invention.

EXEMPLARY EMBODIMENTS OF THE INVENTION

[0023] FIG. 1 shows a schematic representation of a construction machine 1 in the form of a wheel loader, having a tool 2 realized as a shovel. The tool 2 is connected to the construction machine 1 via a working arm 3, there being a respective joint 4 arranged between the construction machine 1 and the working arm 3, and between the tool 2 and the working arm 3, which movably connects the respective components. In further exemplary embodiments that are not shown, the working arm may also be of a multi-link design, in which case there is also a joint arranged between each of the individual links. The construction machine 1, the working arm 3 and the tool 2 form a kinematic chain. There is a respective inertial sensor 5, 5′ of an inertial measurement unit arranged on each link of the kinematic chain, i.e. on the construction machine 1, the working arm 3 and the tool 2. The inertial sensor 5′ arranged on the construction machine 1 has a special significance in this case (see below) and is therefore denoted by a dash (′). The inertial sensors 5, 5′ are connected to an electronic control device 6 of the construction machine 1. The construction machine 1 in the form of the wheel loader has wheels 7 that are connected to the construction machine 1 via axles (not shown) and contact the ground 8.

[0024] In further embodiments, not shown here, the construction machine 1 is realized, for example, in the form of a bulldozer, in which, instead of the wheels, a track chain contacts the ground. In still further embodiments, the construction machine 1 may contact the ground with a support or a foot, for example when the construction machine 1 is a stationary construction machine 1 or is supported in a working mode.

[0025] Represented in FIG. 1 are two states a) and b), which were recorded at different times. In the initial state a), the tool 2 is still raised. In the final state b), the tool 2 is at the same level as the underside of the wheels 7, and the orientation of the tool 2 corresponds to the orientation of the ground 8, such that the tool 2 is deposited on the ground 8. The joints 4 are oriented differently in the two states.

[0026] Represented in FIG. 2 is a flow diagram of an exemplary embodiment of the method according to the invention. At the beginning and throughout the method, the orientation, in particular the inclination, and the position of the tool 2 and of the working arm 3 relative to the construction machine 1 or to the earth's gravity are determined, by means of the inertial sensors 5, 5′ on the construction machine 1, the working arm 3 and the tool 5, by use of an algorithm for determining the kinematic chain 10. For this purpose, the sensor data from the inertial sensors 5, 5′ along the kinematic chain are used. From the orientation, or inclination, and the position of the tool 2 and of the working arm 3, current actual joint angles θ.sub.actual for the joints 4 are then determined 11 by means of so-called Denavit-Hartenberg parameters (see, for example, Spong et al. “Robot modeling and control”, Vol. 3. New York: Wiley, 2006). Also determined 20 at the beginning are the contact points of the wheels 7 relative to the earth's gravity, which substantially represent the orientation of the surface of the ground 8. Preferably, the orientation of the inertial sensor 5′ arranged on the construction machine 1 may be determined by means of a part of the same algorithm for determining the kinematic chain, using only the sensor data of this inertial sensor 5′. In the case of the wheel loader shown here, there is a fixed relationship between the contact points of the wheels 7 and the orientation of this inertial sensor 5′, such that the contact points of the wheels 7, and thus the orientation of the ground 8, can be inferred from the orientation of the inertial sensor 5′.

[0027] If the depositing of the tool 2 is activated by an operator 30, for example by pressing a button provided for this purpose, the orientation of the tool 2 in the inertial system, i.e. the inclination with respect to the earth's gravity, is ascertained 40. Then target joint angles θ.sub.target are ascertained 41 from the orientation of the tool 2 in the inertial system and the contact points of the wheels 7.

[0028] In a further exemplary embodiment, not shown, when the depositing of the tool 2 is activated by an operator 30, trajectories of movement for the tool 2 are ascertained. In the trajectories of movement, trajectories are described in the coordinates of a solid coordinate system. For this purpose, the position of the tool 2 is specified in the coordinates of the construction machine 1. Target joint angles θ.sub.target are then ascertained from these trajectories of movement.

[0029] Finally, a closed-loop control 50 is provided for depositing the tool 2 on the ground 8, in which the actual joint angles θ.sub.actual are controlled to the target joint angles θ.sub.target, such that the underside of the tool 2 is brought to the same level, i.e. the same height, as the plane of the contact points of the wheels 7, parallel to the plane of the contact points of the wheels 7 and thus parallel to the ground 8, therefore horizontal in this exemplary embodiment.