CONTROL OF A HANDLING MACHINE

Abstract

The invention relates to a handling machine (1) comprising: a tilt sensor (11) configured to produce a signal relating to a tilting moment applied to the main body about a tilting axis; displacement sensors (18) configured to produce a signal relating to movements of the handling arm relative to the main body; and a control unit (10) configured to: prevent or stop the movement of the handling arm if the signal representative of the tilting moment is greater than an effective threshold; assign a lowering threshold value to the effective threshold in response to a handling arm lowering movement being determined; and assign an extension threshold value to the effective threshold in response to a handling arm extension movement being determined.

Claims

1. A handling machine comprising: a main body, a telescopic handling arm mounted on said main body and that can be displaced in rotation about a horizontal axis of rotation, and that can be deployed and retracted in a longitudinal direction of said handling arm, actuators configured to raise and lower and deploy and retract said handling arm; a tilt detector configured to produce a signal relating to a tilting moment applied to the main body about a tilting axis of said handling machine; displacement detectors or displacement request detectors configured to produce a signal relating to movements or requests for movement of the handling arm with respect to the main body; and a control unit configured to receive the signals from the tilt detector and from the displacement detectors or displacement request detectors and to: slow down, prevent or stop the movement of the handling arm if the signal representative of the tilting moment is above an effective threshold; assign a lowering threshold value to said effective threshold in response to a determination of a handling arm lowering movement or lowering movement request; assign an extension threshold value to said effective threshold in response to a determination, explicit or implicit, of a handling arm movement or extension movement request; and wherein the lowering threshold value is lower than the extension threshold value.

2. The machine as claimed in claim 1, wherein the control unit is configured to assign the lowering threshold value to the effective threshold in response to a determination of a lowering and an extension movement or movement request, simultaneously, of the handling arm.

3. The machine as claimed in claim 1, in which the lowering threshold and/or the extension threshold is predetermined.

4. The machine as claimed in claim 1, wherein the displacement detectors comprise an angle sensor configured to measure a tilt angle of the handling arm with respect to a horizontal plane or with respect to the main body of the handling machine.

5. The machine as claimed in claim 4, wherein the control unit is configured to detect a reduction of the tilt angle measured by the angle sensor and determine a lowering movement of said handling arm in response to the reduction of the tilt angle.

6. The machine as claimed in claim 1, wherein the displacement detectors comprise a length sensor configured to measure an amplitude of extension of the handling arm.

7. The machine as claimed in claim 6, wherein the control unit is configured to detect an increase in the length of the handling arm and determine an extension movement of said handling arm in response to the increase in the length of the handling arm.

8. The machine as claimed in claim 1, wherein the handling arm can be oriented about an axis transverse to the main body situated at a first end of the handling arm and the main body is mounted on wheels borne by axles, and wherein the tilt detector comprises a strain gauge arranged at an axle opposite a second end of the handling arm, and wherein the signal relating to a tilting moment is a signal relating to a deformation of the axle opposite the second end of the handling arm.

9. A method for controlling a handling machine comprising a main body and a telescopic handling arm mounted on said main body and that can be displaced in rotation about a horizontal axis of rotation, and that can be deployed and retracted in a longitudinal direction of said arm, said method comprising: determining a signal relating to a tilting moment applied to the main body with respect to a tilting axis of said machine, determining a signal relating to movements or requests for movement of the handling arm with respect to the main body, slowing down, preventing or stopping a movement of the handling arm if the signal representative of the tilting moment is above an effective threshold, assigning a lowering threshold value to said effective threshold in response to a determination of a lowering movement or a request for lowering movement of the handling arm, assigning an extension threshold value to said effective threshold in response to a determination, explicit or implicit, of an extension movement of the handling arm, and wherein the lowering threshold value is lower than the extension threshold value.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0049] The invention will be better understood, and other aims, details, features and advantages thereof will become more clearly apparent, from the following description of several particular embodiments of the invention, given in a purely illustrative and nonlimiting manner, with reference to the attached drawings.

[0050] FIG. 1 is a schematic representation of a handling machine.

[0051] FIG. 2 is a representation of a tilt detector that can be implemented by the handling machine of FIG. 1.

[0052] FIG. 3 is a schematic representation of a control method that can be implemented by the handling machine of FIG. 1.

[0053] FIG. 4 is a schematic representation of a method for determining an effective threshold that can be implemented by the handling machine of FIG. 1.

DESCRIPTION OF THE EMBODIMENTS

[0054] In FIG. 1, a handling machine 1, of forklift truck type, is represented. The handling machine 1 comprises a chassis 2 supported on the ground via a front axle 3 and a rear axle 4. The handling machine 1 comprises a handling arm 6 of telescopic type mounted on the chassis 2 and that can be oriented about an axis of rotation 7, horizontal with respect to the chassis 2. The handling arm 6 comprises a load carrier 14 articulated on the handling arm 6 by the link 15 and configured to carry a payload 9.

[0055] The handling arm 6 can be displaced in rotation by a cylinder 8 linked to the chassis 2 and to the handling arm 6. The handling arm 6 comprises at least two segments 6.sub.1 and 6.sub.2 that can be deployed using an extension cylinder, not represented, arranged between the at least two segments 6.sub.1 and 6.sub.2.

[0056] The handling machine 1 further comprises an actuation member 12 of the handling arm 6 configured to manually drive the handling arm 6 making it possible to raise and lower and deploy and retract the handling arm 6.

[0057] FIG. 1 shows the handling arm 6 bearing the payload 9 in a high and retracted position by a continuous line and in several lower and deployed positions by broken lines. The static tilting moment exerted by the handling arm 6 in the forward direction increases as it lowers toward the horizontal and/or as the length of the handling arm 6 increases.

[0058] The handling machine 1 also comprises displacement detectors 18 configured to produce a signal relating to a position of the handling arm 6, in particular a tilt angle of the handling arm 6 with respect to the chassis 2 and/or a length of extension of the handling arm 6.

[0059] The displacement detectors 18 comprise, for example, a first sensor situated at the axis 7 and arranged to measure the tilt angle of the handling arm 6. The displacement detectors are configured to produce a signal representative of the tilt angle of the handling arm 6 with respect to the chassis 2 as a function of the data from the first sensor. The displacement detectors 18 comprise, for example, a second sensor situated at the extension cylinder and arranged to measure a travel of said extension cylinder. The displacement detectors 18 are configured to produce a signal representative of the length of extension of the handling arm 6 as a function of the data from the second sensor.

[0060] The displacement detectors 18 allow the control unit 10 to determine a lowering movement and/or an extension movement of the handling arm 6. In particular, the control unit 10 determines a lowering movement of the handling arm 6 in response to a reduction of the tilt angle. Similarly, the control unit 10 determines an extension movement of the handling arm 6 in response to an increase in the length of extension of the handling arm 6, for example an increase in the travel of the extension cylinder.

[0061] The control unit 10 determines the nature of the movement of the handling arm 6. For that, several methods are possible. For example, the control unit 10 comprises a processing means configured to determine a signal representative of the speed of rotation of the handling arm 6 toward the axis 7. In this embodiment, the control unit 10 determines a lowering movement if the speed of rotation is non-zero toward the ground. In particular, the signal relating to the speed of rotation can be determined by measuring a hydraulic supply flow rate of the cylinder 8. Alternatively, the signal relating to the speed of rotation can be determined as a function of a variation in time of the tilt angle of the handling arm 6. Furthermore, the processing means is configured to determine a signal representative of the speed of extension of the handling arm 6. In this embodiment, for example, the control unit 10 determines an extension movement if the speed of extension is non-zero in a direction moving away from the chassis 2. In particular, the signal relating to the speed of extension can be determined by measuring a hydraulic supply flow rate of the extension cylinder. Alternatively, the signal relating to the speed of extension can be determined as a function of the variation in time of the length of the handling arm 6.

[0062] The handling machine 1 further comprises a tilt detector 11 configured to produce a signal relating to a tilting moment applied to the chassis 2 about a tilting axis, situated at the front axle 3. Stabilizer feet 5 can optionally be deployed to raise the front axle 3, in which case the stabilizer feet 5 define the tilt axis.

[0063] In one embodiment, the tilt detector 11 is arranged at the cylinder 8. In another embodiment, represented in FIG. 2, the tilt detector 11 is arranged at the rear axle 4.

[0064] In FIG. 2, the rear axle 4 of the handling machine 1 comprises two wheel support arms 60 bearing rear wheels 62. Each wheel support arm 60 comprises a strain gauge 61 configured to measure a tensile deformation of said wheel support arm 60 in a direction at right angles to said arm 60. Alternatively, the strain gauges 61 are configured to measure a bending deformation of the wheel support arm 60, in particular a variation of length between two bounds spaced apart on the wheel support arm 60. The measurement signals from the strain gauges 61 can be employed to form the signal indicative of the tilting moment, for example in the form of an average of the two measurement signals. Alternatively, it is possible to employ a single strain gauge 61 to produce the signal indicative of the tilting moment. Preferably, the rear axle 4 is swivelingly linked to the chassis 2 by means of a pivot 66 of longitudinal axis passing through a central part 65 of the axle.

[0065] The handling machine 1 further comprises a control unit 10 configured to receive the signals from the tilt detector 11 and from the displacement detectors 18 and slow down, prevent or stop the movement of the handling arm 6 if the signal representative of the tilting moment is above an effective threshold. For example, the control unit 10 is configured to prevent or stop the movement of the handling arm 6 by reducing or stop the movement of the handling arm 6 by reducing or stopping the hydraulic supply flow rate of the cylinder 8 and/or of the extension cylinder.

[0066] The control unit 10 is also configured to: [0067] assign a lowering threshold value to said effective threshold in response to a determination of a lowering movement of the handling arm 6; [0068] assign an extension threshold value to said effective threshold in response to a determination of an extension movement of the handling arm 6 combined with an absence of lowering movement.

[0069] The lowering threshold value is lower than the extension threshold value, such that the lowering threshold represents a smaller tilting moment than the tilting moment represented by the extension threshold. In other words, for an approach to the limit of stability of the handling machine by lowering of the handling arm 6, the movement is stopped further away from the stability limit, in tilting moment terms, than for an approach by extension of the handling arm 6 without lowering.

[0070] This setting takes account of the fact that the inertia forces implemented upon the interruption of a lowering movement of the arm are oriented more influentially on the stability of the machine than the inertia forces implemented upon the interruption of an extension movement of the arm.

[0071] The handling machine 1 comprises a display 13 linked to the control unit 10 and configured to display a warning signal if the signal relating to the tilting moment is above the effective threshold.

[0072] In one embodiment, the handling machine comprises a detector 16 of extension of the handling arm 6 configured to determine an extension of the handling arm 6.

[0073] In another embodiment, the extension of the handling arm is not expressly measured and the extension sensor is not necessary. In this case, the effective threshold can be determined on the basis of the tilt angle of the handling arm without taking into account an extension measurement. In fact, the increase in the tilting moment of the handling machine without lowering of the handling arm can be considered in certain cases as an implicit detection that an extension movement of the handling arm is in progress.

[0074] Alternatively, the setting of the effective threshold can be performed, not as a function of the movement of the arm, but as a function of the request for movement of the arm, that the control unit receives from the actuation member 12. In this case, the control unit 10 (or a movement request detector not represented in the figures) linked to the actuation member 12 is configured to determine a movement to be performed by the handling arm 6. In this case, the control unit 10 can be configured to: [0075] assign a lowering threshold value to said effective threshold in response to a determination of a request for lowering movement of the handling arm 6; [0076] assign an extension threshold value to said effective threshold in response to a determination of a request for extension movement of the handling arm 6 combined with an absence of lowering movement.

[0077] In all cases, the control unit 10 can be configured to implement a control method 200 for the handling machine 1, as represented in FIG. 3.

[0078] The control method 200 serves to slow down, prevent or stop the movement of the handling arm 6 in order to avoid a tilting of the handling machine 1.

[0079] The method 200 comprises: [0080] a step 201 of determination of a signal relating to a tilting moment that the chassis 2 undergoes, for example by determination of an elongation of the rear axle 3, [0081] a step 202 of comparison of the signal relating to the tilting moment to an effective threshold, [0082] a step 203 of slowing down, of stopping or of preventing the movement of the handling arm 6 when the signal relating to the tilting moment is above the effective threshold.

[0083] In one embodiment, the control unit 10 is configured to determine the effective threshold by implementing the method 100 represented in FIG. 4.

[0084] The method 100 comprises: [0085] a step 102 of determination of a signal relating to the tilt angle of the handling arm 6 with respect to the ground or with respect to the chassis of the machine or with respect to a horizontal reference, and of determination of a signal relating to the length of extension of the handling arm 6 [0086] a step 103 of assignment of a lowering threshold value to the effective threshold in response to a determination of a reduction of the tilt angle of the handling arm 6, [0087] a step 104 of assignment of an extension threshold value to the effective threshold in response to a determination of an increase in the length of the handling arm 6.

[0088] Alternatively, the step 102 can consist in a step of determination of a movement request relating to a lowering or a raising of the handling arm 6. The movement request can be determined by determination of a particular actuation of the actuation member, for example orientation of the actuation member by a user in a predetermined direction. In this case, the step 103 of assignment of the lowering threshold to the effective threshold is performed in response to the determination of a request for lowering of the handling arm and the step 104 of assignment of the extension threshold to the effective threshold is performed in response to the determination of a request for extension of the handling arm 6.

[0089] The lowering and extension thresholds are chosen such that the tilting moment represented by the lowering threshold is smaller than the tilting moment represented by the extension threshold.

[0090] According to one embodiment, the lowering threshold and/or the extension threshold are previously determined and stored in a table or a database. In particular, the lowering threshold and/or the extension threshold can be constant or variable.

[0091] According to one embodiment, the lowering threshold and the extension threshold are preferably variable as a function of the deployment or not of the stabilizer feet 5.

[0092] Some elements represented, notably the control unit, can be produced in different forms, unitarily or distributed, by means of hardware and/or software components. Hardware components that can be used are custom integrated circuits ASIC, programmable logic arrays FPGA or microprocessors. Software components can be written in different programming languages, for example, C, C++, Java or VHDL. This list is not exhaustive.

[0093] Although the invention has been described in relation to several particular embodiments, it is quite obvious that it is in no way limited thereto and that it encompasses all the technical equivalents of the means described as well as their combinations provided the latter fall within the context of the invention.

[0094] The use of the verb “comprise” or “include” and its conjugate forms does not exclude the presence of elements or steps other than those stated in a claim.

[0095] In the claims, any reference symbol between parentheses should not be interpreted as a limitation on the claim.