Patent Description:
Construction machines such as excavators, backhoes, mining shovels, and the like are used for excavation work. These excavating machines typically comprise an upper carriage, also called superstructure, and an undercarriage, to which the superstructure is rotatably mounted. On the electronic side, construction machines usually comprise operator assist systems such as the Caterpillar HMS Operator Assist system, which are designed to prevent mechanical components of the construction machine's attachment from hitting mechanical endstops or at least mitigate an impact of the attachment by slowing it down accordingly.

Due to the harsh environments in which excavators, backhoes, mining shovels and the like are typically operating, there exists a tendency in the art to keep the undercarriage largely clear of electronic and/or sensitive components. Following this approach, the electronic infrastructure of the construction machine is almost entirely realized within the superstructure. In some cases, the superstructure retrieves vital control data such as orientation, acceleration or the like vastly independent from the undercarriage. As an example, current level sensor technologies such as the Caterpillar RISER or the R2 module retrieve an absolute angle of the superstructure which is entirely uncorrelated to the orientation of the undercarriage. Consequently, the relative position of the undercarriage towards the superstructure may be unknown to the Operator Assist system. Since the undercarriage is not mapped in the Operator Assist system, it falls within the remit of the operator to avoid hitting and damaging the track chains of the undercarriage with the work implement. In an effort to further increase operation safety, it is desired to shift the task of avoiding hitting and damaging the undercarriage from the operator to an Operator Assist system.

Placing an angle sensor in the center of the swivel between the superstructure and the undercarriage is not always feasible. As an example, construction machines that are AC powered usually have their power cables routed through the middle section of the machine's vertical center line, allowing no space for implementing angle sensors. To integrate such an angle sensor into the swivel, several more far-reaching design changes are required. In view thereof, such an angle sensor placement has been identified as a too costly upgrade with regard to the expected benefits.

From <CIT> a method for determining a yaw angle between a superstructure and an undercarriage about the vertical axis of a work machine, in particular an excavator, is known, which is based on an integrated rotation speed. Furthermore, <CIT> discloses an excavator and an excavator rotation angle detection device.

In view of the prior art, it is an objective of the present invention to provide an improved method for operating a construction machine in a simple, robust and cost-effective way for a wide range of different design configurations of the construction machines is required. Further, a construction machine configured to carry out the method should be provided.

This is solved by means of a method of operating a construction machine comprising a superstructure and an undercarriage coupled thereto with the features of claim <NUM> as well as a construction machine according to claim <NUM>. Preferred embodiments are set forth in the present specification, the Figures as well as the dependent claims.

Accordingly, a method of operating a construction machine comprising a superstructure in an undercarriage rotatably coupled thereto is provided. The method comprises the step of retrieving a trigger signal at a predetermined relative angle between the superstructure and the undercarriage while operating the construction machine and a step of retrieving an absolute angle of the superstructure, the retrieved absolute angle being uncorrelated to the orientation of the undercarriage. The method furthermore comprises a step of calculating a current relative angle between the superstructure and the undercarriage on the basis of the trigger signal and the absolute angle, wherein the absolute angle is known for the time the trigger signal is retrieved and for the time the current relative angle is calculated.

Further, a construction machine comprising an undercarriage in the superstructure rotatably mounted thereto is provided. The construction machine comprises an absolute angle detection means for detecting an absolute angle of the superstructure being uncorrelated to the orientation of the undercarriage, a sensor unit configured to retrieve a trigger signal when the superstructure is in a predetermined relative angle with the undercarriage and an operator assist system for calculating a current relative angle based on the absolute angle and the trigger signal, wherein the absolute angle is known for the time the trigger signal is retrieved and for the time the current relative angle is calculated.

The present invention will be more readily appreciated by reference to the following detailed description when being considered in connection with the accompanying drawings in which:.

In the following, the invention will be explained in more detail with reference to the accompanying Figures. In this respect, some embodiments of the present invention are explained with reference numerals and repeated description thereof may be omitted in order to avoid redundancies.

The present invention is generally directed towards a method of operating a construction machine comprising a superstructure and an undercarriage rotatably coupled thereto. According to embodiments of the present invention, the method provides safe and simple operation methods suitable for a wide range of different construction machines such as excavators and mining shovels. In particular, the method is suitable for a wide range of different configurations of rotational interconnections between the undercarriage and the superstructure. The method according to the present invention prevents accidentally hitting and damaging components of the undercarriage with components of the superstructure while operating the construction machine.

The basic methods of operating a construction machine comprising a superstructure and an undercarriage rotatably coupled thereto are well known to a person skilled in the art and are thus not further specified. Rather, characteristics of the method of operating a construction machine comprising a superstructure and an undercarriage rotatably coupled thereto according to the present invention are addressed and specified in the following.

Thereto, the present invention and its underlying principles are explained exemplary for a construction machine comprising tracks on the undercarriage and an excavator boom and stick assembly on the superstructure. However, besides the excavator, any other construction machine may be used interchangeably in combination with the undercarriage and vice versa in the undercarriage may be used interchangeably with the superstructure as disclosed the following.

<FIG> schematically illustrates a typical range of motion of a work implement with respect to the undercarriage from a side view according to a construction machine known from the state of the art. To this end, the shown construction machine <NUM> comprises a superstructure <NUM> which is rotatably coupled to an undercarriage <NUM>. The superstructure <NUM> comprises a boom and stick assembly <NUM> having a work tool <NUM> attached to the proximal end of the boom and stick assembly <NUM>. The undercarriage <NUM> comprises a basis <NUM> as well as chain tracks <NUM>. As can be seen from <FIG>, the entire range of motion of the work tool <NUM>, represented by the plotted curves in the diagram, intersects at least with the basis <NUM> and the chain tracks <NUM> of the undercarriage <NUM>.

Consequently, an operator may theoretically hit and damage the undercarriage <NUM> with the work tool <NUM> if this operation is not otherwise prohibited by an operator assist system. According to the definition set forth in the present description, hitting and damaging the undercarriage <NUM> may occur if the current relative distance D between a component of the superstructure <NUM>, such as the work tool <NUM>, and the undercarriage <NUM> becomes zero.

<FIG> shows a flow diagram schematically illustrating a first embodiment of the method for operating a construction machine <NUM>. During operation of the construction machine <NUM> the superstructure <NUM> may be rotated with respect to an undercarriage <NUM>. Regardless of its relative position towards the undercarriage <NUM>, the superstructure <NUM> retrieves in step S1 a trigger signal T at a predetermined relative angle α between the superstructure <NUM> and the undercarriage <NUM> while operating the machine <NUM>.

As set forth in <FIG>, retrieving a trigger signal T requires a condition in which the superstructure <NUM> is in a predetermined relative angle α with respect to the undercarriage. As the trigger signal T is retrieved at a predetermined relative angle α, the trigger signal T corresponds to this known predetermined relative angle α. In other words, this predetermined relative angle α may be understood as a known, predetermined angle at which a trigger signal may be retrieved. There may be several different predetermined relative angles α at which a trigger signal may be provided. Trigger signals T may be constant or may differ time-wise and/or location-wise.

According to a further step S2, an absolute angle β is retrieved. Such an absolute angle β may be retrieved from an existing component such as a level sensor in a Caterpillar RISER or an R2 module. Herein, the absolute angle β is uncorrelated with the orientation of the undercarriage <NUM> to which the superstructure <NUM> is rotatably coupled to. As an example, the absolute angle β may have an arbitrary initial orientation. Alternatively, the absolute angle β may be correlated with an external orientation, for example a compass direction or any other cardinal direction. Retrieving the absolute angle β of the superstructure <NUM> in step S2 of the method may be conducted continuously or intermittently during operation or may alternatively be coupled to further conditions.

In a subsequent step S3, a current relative angle γ between the superstructure <NUM> and the undercarriage <NUM> is calculated. The current relative angle γ represents the actual current orientation of the superstructure <NUM> with respect to the undercarriage <NUM>. Accordingly, the current relative angle γ is calculated on the basis of the trigger signal T and the absolute angle β. The calculation of the current relative angle γ in step S3 may thus be understood as a combination of the predetermined relative angle α with the uncorrelated absolute angle β.

In other words, the current relative angle γ is a function of a predetermined relative angle α serving as a calibration input, and an uncorrelated absolute angle β serving as an indicator of the angular change. In order to calculate the current relative angle γ, both the relative angle and the absolute angle must be combined. To do so, for any retrieved trigger signal T a corresponding absolute angle β needs to be retrieved. The current relative angle γ may then be calculated using the predetermined relative angle α provided by the trigger signal T and the absolute angle β. The absolute angle β must be known for both the time a trigger signal T was retrieved and the time for which the calculation of the current relative angle γ shall be conducted. In view thereof, the retrieving the absolute angle β in step S2 may preferably be conducted continuously and even before retrieving a trigger signal T in step S1.

<FIG> shows a flow diagram schematically illustrating a second embodiment of the method for operating a construction machine <NUM>. According to this embodiment, the method comprises a step S30 of recalculating the current relative angle between the superstructure <NUM> and the undercarriage <NUM> every time a trigger signal T is received. In this way, upon such a recalculation, the accuracy of the calculation may be improved. Optionally, the method may comprise a step of retrieving S <NUM> at least one further trigger signal T at at least one further predetermined relative angle α between the superstructure <NUM> and the undercarriage <NUM>.

The underlying principle of this method may best be explained on behalf of <FIG>. Therein, an excerpt of a cross-section of a construction machine <NUM> comprising an undercarriage <NUM> and a superstructure <NUM> coupled thereto is shown in various relative positions. According to the <FIG>, three angles are important, namely the absolute angle β, corresponding to an orientation of the superstructure <NUM> independent from the undercarriage <NUM>, the predetermined relative angle α, corresponding to a predetermined relative orientation of the superstructure <NUM> with respect to the undercarriage <NUM>, and the current relative angle γ, corresponding to the current relative orientation of the superstructure <NUM> with respect to the undercarriage <NUM>. Within the <FIG>, the superstructure <NUM> comprises a sensor unit <NUM>. The undercarriage <NUM> according to the embodiment set forth in <FIG> comprises a trigger unit <NUM> provided at a predetermined relative angle α = <NUM>°.

<FIG> provides an explanation of the individual angles based on an arbitrary posture of the superstructure <NUM> relative to the undercarriage <NUM>. The predetermined relative angle α is predetermined to be <NUM>°. This predetermined relative angle α is for example structurally implemented into the undercarriage <NUM>. The predetermined relative angle α is based on a reference point <NUM> provided on the undercarriage <NUM>. In other words, said predetermined relative angle α is not altered by rotating the superstructure <NUM> relative to the undercarriage <NUM>. Instead, the predetermined angle α is defined by the position of the undercarriage-components trigger unit <NUM> and the reference point <NUM> alone, regardless of a posture of the superstructure <NUM>.

Accordingly, the absolute angle β is an angle provided by the superstructure <NUM> which is by its nature entirely uncorrelated with any other angle α and γ. The absolute angle β may be understood for example as an angle of the superstructure <NUM> having a reference point beyond or outside the undercarriage <NUM>. In summary, there is a hardware-implemented predetermined angle α and an uncorrelated superstructure-only angle, the absolute angle β. To correlate those two angles α and β, the current relative angle γ is defined. How this correlation may be achieved will be explained on the basis of the subsequent Figures.

<FIG> represents an initial condition for example at the time of starting up the construction machine <NUM> without prior rotation of the superstructure <NUM>. Since at this time the superstructure <NUM> has not been rotated relative to the undercarriage <NUM>, the absolute angle β is an arbitrary angle (not depicted). According to the representation of <FIG>, the superstructure <NUM> is positioned at an angular displacement, clockwise at about γ = <NUM>°, with respect to the undercarriage <NUM>. However, at this stage, this current relative angle γ is still unknown to the Operator Assist system.

<FIG> represents a position in which the superstructure <NUM> is rotated, starting from the original displacement, in a clockwise direction about the undercarriage <NUM>. As soon as a rotation between the superstructure <NUM> and the undercarriage <NUM> occurs, the absolute angle β is retrieved according to step S2. At this stage, the current relative angle γ between the superstructure <NUM> and the undercarriage <NUM> is still unknown to the Operator Assist system.

<FIG> represents a position in which the superstructure <NUM> is rotated further in a clockwise direction until the sensor unit <NUM> reaches the trigger unit <NUM> at the predetermined relative angle α. In this case, a trigger signal T is retrieved according to step S <NUM> of the method. At the time the trigger signal T is retrieved, the current relative angle γ is set to be equal to the predetermined relative angle α, hence <NUM>° according to the embodiment shown in <FIG>. At the same time, the absolute angle β may be calibrated based on the predetermined relative angle α. As an example, the absolute angle β may be set to zero for the angle representing the predetermined relative angle α.

<FIG> represents a position in which the superstructure <NUM> is rotated even further in a clockwise direction. At this stage, the absolute angle β is retrieved in step S2 and is calibrated using the trigger signal T, which corresponds to the predetermined relative angle α. In step S3, the current relative angle γ can thus be calculated on the basis of the trigger signal T retrieved in step S1 and the absolute angle β retrieved in step S2.

As a consequence, as soon as the first trigger signal T is detected, information concerning the current relative angle of the superstructure <NUM> with respect to the undercarriage <NUM> is made available.

The underlying principle of the method may also be explained on behalf of a further embodiment of the construction machine <NUM> which is shown in <FIG> schematically illustrate a construction machine <NUM> shown from above on the basis of several different angles. According to this embodiment, the construction machine <NUM> comprises a superstructure <NUM> which is rotatably coupled to an undercarriage <NUM>.

The superstructure <NUM> comprises a boom and stick assembly <NUM> to which a work tool in the shape of a bucket <NUM> is mounted to the proximal end of the tool and stick assembly <NUM>. The superstructure <NUM> further comprises an absolute angle detection means <NUM> as well as one sensor unit <NUM>. The undercarriage <NUM> of the construction machine <NUM> comprises a base <NUM> and chain tracks <NUM>. Further, the undercarriage <NUM> comprises a trigger unit <NUM>. The sensor unit <NUM> on the superstructure <NUM> and the trigger unit <NUM> on the undercarriage <NUM> are positioned such that a rotation of the superstructure <NUM> in a clockwise direction at about <NUM>° relative to the undercarriage <NUM> triggers a trigger signal T. Hence, according to this embodiment, the predetermined relative angle is set to <NUM>° in a clockwise direction.

<FIG> represents an initial condition for example at the time of starting up the construction machine <NUM> without prior rotation of the superstructure <NUM>. Since at this time the superstructure <NUM> has not been rotated relative to the undercarriage <NUM>, the absolute angle β is an arbitrary angle (not depicted). According to the representation of <FIG>, the superstructure <NUM> is positioned in an angular displacement, clockwise at about γ = <NUM>°, with respect to the undercarriage <NUM>. However, at this stage, this current relative angle γ is still unknown to the Operator Assist system.

<FIG> represents a position in which the superstructure <NUM> is rotated even further in a clockwise direction. At this stage, the absolute angle β is retrieved in step S2 and is calibrated using the trigger signal T, which corresponds to the predetermined relative angle α. In step S3, the current relative angle γ can thus be calculated on the basis of the trigger signal T retrieved in step S <NUM> and the absolute angle β retrieved in step S2.

Alternatively, the predetermined relative angle α may at least one of <NUM>°, <NUM>°, <NUM>° and/or <NUM>°. Further, the predetermined relative angle α may be adjustable by the operator. In any case, the predetermined relative angle α is to be selected such that during a normally expected work cycle of a given task, this predetermined angle α is reached during operation.

<FIG> shows a flow diagram schematically illustrating a method of operating a construction machine according to a further embodiment. According to this embodiment, a further step S4 of retrieving geometric information η is provided. Subsequently, a further step S5 of calculating, based on the current relative angle γ between the superstructure <NUM> and the undercarriage <NUM>, at least one current relative distance D between the undercarriage <NUM> and a component of the superstructure <NUM> is provided. Finally, a step S6 of restricting an actuation of a component of the superstructure and/or the undercarriage is provided, if the at least one current relative distance D fulfills a predetermined condition P. In this way, upon having calculated the current relative angle γ, the current relative distance D of any component potentially hitting and damaging the track chains may be calculated. Thereby, operator inputs may be checked and validated against potentially harmful outcomes, without the necessity of additional complex electronic components and by largely keeping the undercarriage clear of electronic components. In an ideal case, the undercarriage may only comprise additional mechanical switches for retrieving the predetermined relative angle α in step S1. This renders the upgraded undercarriage equally resilient against dirt and other harsh environment impacts as known undercarriages.

<FIG> shows a flow diagram schematically illustrating a method of operating a construction machine according to a further embodiment. According to this embodiment, a further step S4 of retrieving geometric information η is provided. Subsequently, a further step S50 may be provided. According to this step, a virtual envelope E corresponding to the shape of the undercarriage <NUM> is calculated, preferably wherein the virtual envelope E follows the contour of the undercarriage <NUM> at a predetermined distance E1. Finally, a further step S60 is provided, restricting an actuation of a component of the superstructure and/or the undercarriage <NUM>, if said component reaches or intersects the virtual envelope E. In this way, upon having calculated the current relative angle γ, the current relative distance D of any component potentially hitting and damaging the track chains may be calculated. Thereby, operator inputs may be checked and validated against potentially harmful outcomes, without the necessity of additional complex electronic components and by largely keeping the undercarriage clear of electronic components. In an ideal case, the undercarriage according to this disclosure may only comprise additional mechanical switches for retrieving the predetermined relative angle α in step S1. This renders the upgraded undercarriage equally resilient against dirt and other harsh environment impacts as known undercarriages.

<FIG> schematically illustrates the construction machine of <FIG> in a view seen from above. Specifically, it is shown a construction machine <NUM> comprising a superstructure <NUM> which is rotatably coupled to an undercarriage <NUM>. Similar the construction machine <NUM> shown in <FIG>, the superstructure <NUM> comprises a boom and stick assembly <NUM> to which proximal end a bucket <NUM> is attached. Further, the undercarriage <NUM> comprises a base <NUM> as well as chain tracks <NUM>. In <FIG>, the outcome of the calculation step S50 of calculating a virtual envelope E is illustrated. More detailed, the calculated virtual envelope E corresponds to the shape of the undercarriage <NUM> in such a way, that the virtual envelope E follows the contour of the undercarriage <NUM> at a predetermined distance E1. According to the embodiments set forth in <FIG>, the contour may be understood as a three-dimensional hull following the actual physical outline of the undercarriage <NUM>, including the base <NUM> and the track chains <NUM>. In this respect, the predetermined distance E1 may be constant and/or transient time-wise and/or location-wise and/or may depend on further inputs or conditions.

In the embodiment of <FIG>, the bucket <NUM> comprises a current relative distance D with respect to the track chains <NUM> or the undercarriage <NUM> as a whole unit. As a result, according to the embodiment of <FIG>, restricting the actuation of the bucket <NUM> may be conducted on the basis of either the current relative distance D or the relationship of the bucket <NUM> the virtual envelope E, or both. Restricting the actuation on the basis of the current relative distance D may be achieved by checking, if the at least one current relative distance D fulfills a predetermined condition P. On the other hand, restricting the actuation of the bucket <NUM> of the superstructure <NUM> may be achieved by checking, if the bucket <NUM> reaches or intersects the virtual envelope E. In either way, the primary goal in the context of the disclosure of <FIG> may be to stop or slow down further movement of the bucket <NUM>, if restricting the actuation of the bucket and <NUM> was confirmed by a corresponding preceding check.

<FIG> shows a swivel <NUM> of the construction machine <NUM> seen from the inside of an undercarriage <NUM> in a perspective view. According to the embodiments set forth in <FIG>, the swivel <NUM> is a component connecting the superstructure <NUM> with the undercarriage <NUM>. To this end, the swivel <NUM> may comprise a lower part <NUM> mounted to the undercarriage <NUM> and an upper part <NUM> which is rotatably coupled to the lower part <NUM> of the swivel <NUM> and which is mounted to the superstructure <NUM>. A trigger unit <NUM> may be attached to the lower part <NUM> of the swivel <NUM>, moving with the undercarriage <NUM>. Accordingly, a sensor unit <NUM> may be attached to the upper part <NUM> of the swivel <NUM>, moving with the superstructure <NUM>.

It will be obvious for a person skilled in the art that these embodiments and items only depict examples of a plurality of possibilities. Hence, the embodiments shown here should not be understood to form a limitation of these features and configurations. Any possible combination and configuration of the described features can be chosen according to the scope of the invention as defined by the appended claims.

Claim 1:
Method of operating a construction machine (<NUM>) comprising a superstructure (<NUM>) and an undercarriage (<NUM>) rotatably coupled thereto, the method comprising:
retrieving (S1) a trigger signal (T) at a predetermined relative angle (α) between the superstructure (<NUM>) and the undercarriage (<NUM>) while operating the construction machine (<NUM>);
retrieving (S2) an absolute angle (β) of the superstructure (<NUM>), the retrieved absolute angle (β) being uncorrelated to the orientation of the undercarriage (<NUM>); and
calculating (S3) a current relative angle (γ) between the superstructure (<NUM>) and the undercarriage (<NUM>) on the basis of the trigger signal (T) and the absolute angle (β), wherein the absolute angle (β) is known for the time the trigger signal (T) is retrieved and for the time the current relative angle (γ) is calculated.