CN113795635A

CN113795635A - Method for placing a tool of a work machine

Info

Publication number: CN113795635A
Application number: CN202080036195.9A
Authority: CN
Inventors: C·克劳斯; K·刘; H·瓦格纳; B·曼加
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2019-05-16
Filing date: 2020-05-07
Publication date: 2021-12-14
Also published as: DE102019207164A1; US20220195705A1; EP3969674B1; EP3969674A1; WO2020229277A1; JP2022532756A

Abstract

The invention relates to a method for placing an implement (2) of a work machine (1) on a ground surface (8). The position and orientation of the tool (2) relative to the work machine (1) or relative to the direction of the earth gravity is determined by means of one or more of the following sensors-inertial measurement unit, angle sensor, linear sensor-by an algorithm for determining the kinematics chain of the work machine (1). Furthermore, an orientation of at least one component (7) of the work machine (1) contacting the ground (8) is determined relative to earth gravity, which component characterizes the orientation of the work machine (1) relative to the ground (8). On this basis, the movement of the tool (2) is adjusted in order to bring the underside of the tool (2) into the same level and in the same orientation as at least one component (7) contacting the ground (8) for placing the tool (2).

Description

Method for placing a tool of a work machine

Technical Field

The invention relates to a method for placing a Tool of an engineering machine on the ground by means of Tool Center Point Estimation. Furthermore, the invention relates to a computer program implementing each step of the method when the computer program runs on a computing device; and a machine-readable storage medium storing the computer program. Finally, the invention relates to an electronic control unit which is designed to carry out the method according to the invention.

Background

One of the basic operations in many work machines, such as for example excavators, wheel loaders, bulldozers and the like, is to place the implement of the work machine on the ground. In this case, the tool must be placed on the ground reliably, i.e. without it tilting or slipping (sliding off) and with as low an impact force as possible. This operation is often difficult for an untrained operator in particular when the view onto the tool and/or the ground is obstructed.

Algorithms for determining a kinematic chain are known. To this end, one or more of the following sensors are arranged at each link of the tool arm: an Inertial Measurement Unit (IMU), an angle sensor, a linear sensor, said sensor sending sensor data to a computing device. The sensor data thus ascertained are individually filtered for each sensor and combined to form a state estimate of the orientation of the respective sensor relative to the positionally fixed inertial coordinate system. Such an algorithm is used, for example, in tool center point estimation. The tool center point estimate is an algorithm for state estimation of the orientation and position of the end effector. The end effector is in particular a tool or a part of a tool, which has a tool arm with a plurality of links connected by joints.

Typically used methods are in the article Nikolas transferred und Stergios I.Roumeeliotions. "Indirect Kalman filter for 3D attribute evaluation" University of Minnesota, depth of Comp.Sci. & Eng., Tech. Rep 2 (2005) (Niglas. Thoroff and Stereos I. Rumery Oe, "Indirect Kalman filter for 3D attitude estimation", Minnesota University, computer science and engineering system, technical representatives 2 (2005)), in Robert hony, Tarek Hamel, und Jean-Michel pflimelin, "Nonliner complex filters on the same general grade grip", IEEE Transacteris journal 53.5 (2008. Quadrature March 1218), "IEEE 1203-Michel II.", Michel II Korea "", Michel, And in the paper Sebastian Maggwick, "An effective orientation filter for inertial and inertial/magnetic sensor arrays," Report x-io and Bristol (UK) 25 (2010), Sambuta Mayvick, "high efficiency orientation filters for inertial and inertial/magnetic sensor arrays," Report x-io and Bristol University (UK) 25 (2010), to which reference is made.

The orientation of the connecting rod at which the sensor is arranged is first determined from the thus estimated orientation of the sensor. This is done for all links of the tool arm. The joint angle of the joint, which connects the two connecting rods, can be calculated from the relative orientation of the two connecting rods following one after the other with known kinematics, for example with known parameters of the danawett-Hartenberg (Denavit-Hartenberg). If all joint angles and link dimensions are finally known, the overall configuration of the tool arm and hence the orientation and position of the end effector is derived directly from the forward kinematics.

For a detailed description see the paper Mark W. Spong et al, "Robot modeling and control", Vol.3. New York: Wiley, 2006 (Mark W. Spang et al, Robot modeling and control, volume 3, New York: Willi, 2006).

Disclosure of Invention

A method for placing an implement of a work machine on a ground surface is proposed. Here, "placing" is understood to mean the following process: the tool is guided to the ground until the underside of the tool lies securely on the ground.

During the entire method, the position and orientation of the link of the kinematics chain including the tool relative to the engineering machine or the earth gravity is determined by means of one or more of the following sensors — inertial measurement unit, angle sensor, linear sensor-by an algorithm for determining the kinematics chain. The algorithm for determining the kinematics chain is based on sensor signals of sensors arranged at least at least one component of the tool and preferably at each link of the kinematics chain between the work machine and the tool. The inertial measurement unit can be easily and cost-effectively retrofitted and used for other methods.

Furthermore, an orientation of at least one component of the work machine contacting the ground with respect to earth gravity is determined, the component characterizing the orientation of the work machine with respect to the ground. The orientation between at least one component of the work machine that contacts the ground and a component of the work machine that specifies the orientation of the work machine is known or at least can be ascertained. Due to the direct contact between the at least one component contacting the ground surface and the surface of the ground surface, the two orientations correspond to each other at least at the location of the contact. Since the orientation of the surface on a section of the road, which corresponds to the spacing between the at least one component contacting the ground and the tool, typically changes only slightly for the case in which the construction machine is not located directly at the obstacle (Klippe), the orientation of the surface of the ground at the location of placement of the tool can be estimated from the orientation of the surface of the ground at the location of contact and thus substantially corresponds to the orientation of the at least one component of the construction machine contacting the ground.

Preferably, the orientation of at least one component of the construction machine contacting the ground is determined by an inertial measurement unit and particularly preferably by the algorithm already mentioned for determining the kinematics chain. For this purpose, sensor signals of the inertial sensors of the inertial measurement unit are used at the engineering machine. The inertial sensor is arranged on the construction machine in such a way that the orientation between the inertial sensor and at least one component of the construction machine which contacts the ground is known from the structure of the construction machine or can at least be determined. Optionally, the orientation of the longitudinal axis of the work machine relative to earth gravity can be determined in order to determine the orientation of at least one component of the work machine contacting the ground.

In particular, at least one of the components of the work machine that contacts the ground is realized by wheels or tracks, that is to say elements that come into contact with the ground in order to bring the work machine into forward motion. The work machine is also typically capable of standing on the ground with at least one component contacting the ground; examples for this are brackets or feet.

If the implement should now be placed, either as a result of an operator's command or as a result of automatic control of the work machine, the movement of the implement is adjusted taking into account the position and orientation of the implement and the orientation of at least one component of the work machine that contacts the ground. The adjustment of the movement of the tool during the placement of the tool is carried out in such a way that the underside of the tool, which after placement should lie on the ground, is brought to the same level as the at least one component contacting the ground, and thus in particular to the same height and in the same orientation. As already explained, the orientation of the at least one component of the work machine contacting the ground surface substantially corresponds to the orientation of the surface of the ground surface at the placement location.

Advantageously, the inclination of the implement is determined when determining the orientation of the implement and the inclination of at least one component of the work machine contacting the ground is determined when determining the orientation of the component. In this case, at least one joint angle of the joint between the implement and the work machine can be adjusted during the adjustment in such a way that the underside of the implement is placed horizontally and/or parallel to the ground also for the case in which the ground is not horizontal. In other words, the joint angle is adjusted such that the inclination of the underside of the implement corresponds to the inclination of at least one component of the work machine that contacts the ground, which to an equal extent substantially corresponds to the inclination of the surface of the ground at the place of placement.

The placement of tools is a fundamental operation in many engineering machines. The placement of the tool is at least partially automated by means of the adjustment according to the method according to the invention. The placement of the tool can be triggered, for example, by a button press by the operator. Automation of this specialized operation can be performed independent of autonomous control. However, the autonomous control of the work machine can take such an automated placement of the tool in accordance with the method.

The automated placement of the tool brings about the following advantages for the operator: when the operator's view onto the tool is obstructed, for example by the working machine itself, manual control for placing the tool is often difficult and can only be implemented by trained operators. The automated placement of the tool according to the method thus makes the operation easy, especially for untrained operators. Automation simplifies the operation when the working sequence, in which the tools are placed, is repeated continuously, as is the case, for example, in the so-called Y-cycle for loading and unloading, for example, wheel loaders. The tool can be automatically placed when the operator parks and leaves the vehicle, in order to improve safety. In this case, however, it must be ensured that the tool can indeed be placed reliably at that location and also at that time, without causing damage.

An environment sensor device can be provided on the construction machine, with which the environment of the construction machine is detected. The environmental sensing device is often capable of detecting the orientation and level of the ground in the environment. Thus, an obstruction can be detected by means of the environment sensing device. The data of the environment sensing device can be taken into account when adjusting the movement of the tool. Generally, the environment sensor device can be dispensed with by this method.

A further advantage is that the placement of the tool can be adjusted more accurately by the present method than by a method based solely on environmental sensing means or by a method in which variations in hydraulic pressure are analysed.

A computer program is provided for carrying out each step of the method, in particular when the computer program is executed on a computing device or a controller. The implementation of the method can be implemented in conventional electronic controllers without structural changes being necessary here. For this purpose, the computer program is stored on a machine-readable storage medium.

An electronic control is obtained by loading (Aufspielen) the computer program onto a conventional electronic control, which is set up to adjust the placement of the tool.

Drawings

Embodiments of the invention are illustrated in the drawings and explained in more detail in the description that follows. Wherein:

fig. 1 shows a schematic view of a working machine, in which a tool is placed on the ground from a starting state (a) by means of the method according to the invention (b);

fig. 2 shows a flow chart of the method according to the invention.

Detailed Description

Fig. 1 shows a schematic view of a working machine 1 in the form of a wheel loader with a tool 2 configured as a bucket. The implement 2 is connected to the work machine 1 via a working arm 3, wherein a joint 4 is arranged between the work machine 1 and the working arm 3 and between the implement 2 and the working arm 3, respectively, which joint can kinematically connect the respective components. In a further exemplary embodiment, which is not shown, the working arm can also be designed as a multi-link arm, wherein in this case joints are likewise arranged between the individual links in each case. The work machine 1, the work arm 3 and the tool 2 form a kinematic chain. At each link of the kinematics chain, an inertial sensor 5, 5' of an inertial measurement unit is thus arranged at the work machine 1, the work arm 3 and the tool 2, respectively. Here, the inertial sensor 5 'arranged at the work machine 1 is of particular importance (see below) and is therefore marked with a symbol ('). The inertial sensors 5, 5' are connected to an electronic control unit 6 of the work machine 1. The work machine 1 in the form of a wheel loader has wheels 7 which are connected to the work machine 1 by means of axles (not shown) and which contact the ground 8. In a further embodiment, which is not shown here, the working machine 1 is constructed, for example, in the form of a bulldozer, in which tracks contact the ground instead of wheels. In yet a further embodiment, the work machine 1 can contact the ground with a stand or foot, for example when the work machine 1 is a stationary work machine 1 or is supported in an operating mode.

In fig. 1, two states a) and b) are shown, which are recorded at different times. In the starting state a), the tool 2 is still lifted. In the end state b) the tool 2 is located on the same level as the underside of the wheel 7 and the orientation of the tool 2 corresponds to the orientation of the floor 8, so that the tool 2 is placed on the floor 8. The joint 4 is directed differently in the two states.

A flow chart of an embodiment of the method according to the invention is shown in fig. 2. At the beginning and during the entire method, the orientation, in particular the inclination and the position, of the implement 2 and of the working arm 3 relative to the work machine 1 or the earth gravity are determined 10 by means of inertial sensors 5, 5' at the work machine 1, the working arm 3 and the implement 5 by an algorithm for determining a kinematics chain. For this purpose, the sensor data of the inertial sensors 5, 5' are used along the kinematics chain. The current actual joint angle 11 for the joint 4 is then determined from the orientation or inclination and position of the tool 2 and of the working arm 3 by means of so-called Denavitt-Hartenberg parameters (see, for example, Spong et al, "Robot modeling and control", Vol. 3. New York: Wiley, 2006-Sponta et al, Robotic modeling and control, Vol. 3, New York: Willi, 2006) using the so-called Denavier-Hartenberg parameters

. Likewise, the support point of the wheel 7 with respect to the earth's gravity is initially determined 20, which substantially represents the orientation of the surface of the ground 8. Preferably, the orientation of the inertial sensor 5 'arranged at the work machine 1 can be performed by means of a part of the same algorithm for determining the kinematics chain, wherein only the sensor data of the inertial sensor 5' is used. In the wheel loader shown here, there is a fixed relationship between the bearing point of the wheel 7 and the orientation of the inertial sensor 5 ', so that from the orientation of the inertial sensor 5' the bearing point of the wheel 7 and thus the orientation of the ground 8 can be deduced.

If the placement of the tool 2 is activated 30 by the operator, for example, in the following way: the operator actuates the button provided for this purpose, and the orientation of the tool 2 in the inertial system, that is to say the inclination relative to the earth's gravity, is then determined 40. Then by said tool 2 in an inertial systemOrientation and bearing point of said wheel 7 to target-joint angle

The calculation 41 is performed.

In a further embodiment, not shown, the movement trajectory for the tool 2 is determined when the placement of the tool 2 is activated 30 by the operator. For the movement path, a path curve is described in the coordinates of the body-fixed coordinate system. For this purpose, the position of the implement 2 in the coordinate system of the working machine 1 is indicated. Then, the motion track is used to align the target joint angle

And (4) obtaining.

Finally, an adjustment 50 for placing the tool 2 on the ground 8 is provided, wherein the actual joint angle is adjusted

Adjustment to target-joint angle

So that the underside of the tool 2 is parallel to the plane of the bearing point of the wheel 7 and thus parallel to the ground 8, and thus in this embodiment is brought horizontally to the same level, that is to say to the same height, as the plane of the bearing point of the wheel 7.

Claims

1. Method for placing an implement (2) of a work machine (1) on a ground (8), characterized by the following steps:

-determining (10) the position and orientation of the tool (2) relative to the work machine (1) or relative to the direction of earth gravity by means of one or more of the following sensors-inertial measurement unit, angular sensor, linear sensor-through an algorithm for determining a kinematic chain of the work machine (1);

-determining (20) an orientation of at least one component (7) of the work machine (1) contacting the ground (8) relative to earth gravity, the component characterizing the orientation of the work machine (1) relative to the ground (8);

-adjusting (50) the movement of the implement (2) in order to bring the underside of the implement (2) to the same level and in the same orientation as at least one component (7) of the work machine (1) contacting the ground (8) for placing the implement (2).

2. The method according to claim 1, characterized in that the orientation of at least one component (7) of the work machine (1) contacting the ground is determined by means of an inertial measurement unit, wherein sensor signals of an inertial sensor (5') of the inertial measurement unit are used at the work machine (1).

3. A method according to any one of the foregoing claims, characterised by determining the inclination of the implement (2) when determining (10) the orientation of the implement (2) and determining the inclination of a component (7) of the work machine (1) contacting the ground (8) when determining (20) the orientation of this component (7).

4. Method according to claim 3, characterized in that at least one joint angle of at least one joint between the tool (2) and the work machine (1) is so paired when adjusting (5) the movement of the tool (2) (5)

) Adjustment is made such that the underside of the tool (2) is placed horizontally and/or parallel to the ground (8).

5. The method according to any one of the preceding claims, characterized in that the at least one component (7) of the working machine (1) contacting the ground (8) is one or more wheels or a transmission chain.

6. Computer program arranged for carrying out each step of the method according to any one of claims 1 to 5.

7. A machine-readable storage medium on which the computer program according to claim 6 is stored.

8. An electronic controller (6) set for placing a tool (2) by means of a method according to any one of claims 1 to 5.