CONTROL OF A HANDLING MACHINE

Abstract

The invention relates to a control method for controlling an actuating device in a handling machine, comprising: comparing (24) a magnitude representative of the movement speed executed or to be executed in response to a movement request signal to a threshold representative of a maximum authorised speed and controlling an actuating device according to the result of said comparison, so as to: execute or sustain (25) the movement of a handling arm as long as the magnitude representative of the speed of the movement executed or to be executed is less than said threshold, and prevent or stop (26) the movement of the handling arm as soon as the magnitude representative of the speed of movement executed or to be executed is greater than said threshold.

Claims

1. A handling machine comprising: a main body; a handling arm intended to receive a load that must be moved; an actuating device configured to execute a movement of the handling arm relative to the main body; a control component operable by a user in order to generate a movement request signal intended to direct the actuating device to execute or to stop a movement of the handling arm by the actuating device in response to the movement request signal, the movement request signal having an attribute representing a speed of the movement to be executed, the control component being operable by the user in order to adjust the attribute of the movement request signal from a plurality of attribute values respectively representing a stop state and a plurality of speed values; a control unit configured to compare a magnitude representing the speed of the movement executed or to be executed in response to the movement request signal to a threshold representing a maximum authorized speed and to control the actuating device as a function of the result of said comparison, so as to: execute or sustain the movement of the handling arm as long as the magnitude representing the speed of the movement executed or to be executed is less than said threshold; and prevent or stop the movement of the handling arm as soon as the magnitude representing the speed of the movement executed or to be executed is greater than said threshold.

2. The machine as claimed in claim 1, further comprising an overturning moment indicator sensor (11) that is sensitive to a magnitude indicating an overturning moment applied on the main body relative to an overturning axis and a threshold determination module configured to determine the threshold representing a maximum authorized speed as a function of a measurement signal produced by the overturning moment indicator sensor (11).

3. The machine as claimed in claim 2, wherein the control unit is further configured to form an overturning risk signal cumulatively comprising: an actual contribution dependent on the measurement signal generated by the overturning moment indicator sensor; and a virtual contribution dependent on said magnitude representing the speed of a movement of the handling arm executed or to be executed by the actuating device.

4. The machine as claimed in claim 2, wherein the threshold representing an authorized maximum speed has a downward trend when the overturning moment increases.

5. The machine as claimed in claim 1, wherein the actuating device is configured to execute a pivoting movement of the handling arm about an axis that is substantially horizontal relative to the main body.

6. The handling machine as claimed in claim 1, further comprising measurement means for measuring an instantaneous speed of the handling arm relative to the main body, wherein said comparison is a comparison between said instantaneous speed and said threshold.

7. The handling machine as claimed in claim 1, wherein the control unit is configured to receive the movement request signal generated by the control component and said comparison is a comparison between the attribute of the movement request signal and said threshold.

8. The machine as claimed in claim 1, wherein the control component operable by the user is coupled to the control unit in order to supply the control unit with the movement request signal in the form of an electrical signal.

9. The machine as claimed in claim 1, wherein the actuating device comprises a hydraulic actuator and a variable flow device for regulating a hydraulic flow to be supplied to the hydraulic actuator.

10. The machine as claimed in claim 9, wherein the control component operable by the user is functionally coupled to the variable flow device so as to move a component for regulating the flow of the variable flow device as a function of the action of the user on the control component, and wherein the actuating device further comprises a solenoid valve arranged between the variable flow device and the hydraulic actuator or the control component, the solenoid valve being able to be controlled by the control unit in order to prevent or stop the movement of the handling arm as soon as the magnitude representing the speed of the movement executed or to be executed is greater than said threshold.

11. The machine as claimed in claim 10, wherein the solenoid valve is a progressive start-up valve.

12. The machine as claimed in claim 9, wherein the variable flow device comprises a proportional distributor.

13. The machine as claimed in claim 3, further comprising a display panel connected to the control unit to display a visual scale as a function of the overturning risk signal.

14. A control method for controlling an actuating device in a handling machine comprising a main body and a handling arm intended to receive a load that must be moved, the actuating device being configured to execute a movement of the handling arm relative to the main body; the method comprising: comparing a magnitude representing the speed of a movement executed or to be executed in response to a movement request to a threshold representing an authorized maximum speed; and controlling the actuating device as a function of the result of said comparison so as to: execute or sustain the movement of the handling arm as long as the magnitude representing the speed of the movement executed or to be executed is less than said threshold; and prevent or stop the movement of the handling arm as soon as the magnitude representing the speed of the movement executed or to be executed is greater than said threshold.

15. The method as claimed in claim 14, further comprising a step of receiving a movement request signal intended to direct the actuating device to execute a movement of the handling arm by the actuating device, the movement request signal having an attribute representing a movement speed to be executed.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0078] The invention will be better understood, and further aims, details, features and advantages thereof will become more clearly apparent throughout the following description of several particular embodiments of the invention, which are provided solely by way of a non-limiting illustration, with reference to the accompanying drawings, in which:

[0079] FIG. 1 is a schematic representation of a telescopic truck, in which embodiments of the invention can be implemented;

[0080] FIG. 2 is a diagram of a step representing a control method, according to a first embodiment, that can be used in the telescopic truck;

[0081] FIG. 3 is a diagram of a step representing a control method, according to a second embodiment, that can be used in the telescopic truck;

[0082] FIG. 4 is a schematic representation of a hydraulic actuating device, according to a first embodiment, that can be used in the telescopic truck;

[0083] FIG. 5 is a schematic representation of a hydraulic actuating device, according to a second embodiment, that can be used in the telescopic truck;

[0084] FIG. 6 is a schematic representation of a hydraulic actuating device, according to a third embodiment, that can be used in the telescopic truck;

[0085] FIG. 7 is a schematic representation of a signaling device that can be used in the telescopic truck;

[0086] FIG. 8 is a functional schematic representation of a control unit that can be used in the telescopic truck;

[0087] FIG. 9 is a schematic representation of a wheel support arm equipped with an extensometer that can act as an overturning moment indicator device.

DETAILED DESCRIPTION OF EMBODIMENTS

[0088] Embodiments of a handling machine will be described hereafter that is in the form of a movable telescopic truck supporting a handling arm projecting toward the front of the vehicle. In this configuration, the risk of overturning manifests in the forward direction about the overturning axis formed by the front wheels of the vehicle. Consequently, monitoring and controlling this overturning risk involves taking into account the inertial forces oriented in the forward direction, i.e. the movements involving a significant amount of movement in this direction.

[0089] In a handling machine with a different configuration, the overturning axis can be located in a different manner. The movements to be taken into account then must be selected as a function of the location of this axis.

[0090] With reference to FIG. 1, the telescopic truck 1 comprises a frame 2 supported on the ground by means of a front axle 3 and a rear axle 4. Stabilizing feet 5 optionally can be deployed for lifting the front axle 3, in which case the stabilizing feet 5 define the overturning axis toward the front. The frame 2 has a relatively high mass due to its construction and the mechanical elements that it supports, according to the known technique.

[0091] The handling arm 6 is articulated on the frame 2 about a horizontal axis 7. A lifting actuator, for example, a hydraulic cylinder 8, allows the handling arm 6 to move upward and downward about the horizontal axis 7, under the control of a control system. The control system comprises a control unit 10 and a control component 12 operable by an operator, which are schematically outlined in FIG. 1.

[0092] FIG. 1 illustrates the handling arm 6 and a payload 9 in an upper position as a solid line and in a plurality of lower positions as a dashed line. With all other things being equal, the static overturning moment exerted by the handling arm 6 in the forward direction increases as its position descends toward the horizontal.

[0093] An indicative measurement of this static overturning moment can be obtained using an overturning moment indicator sensor that can be positioned in various ways. FIG. 1 illustrates an overturning moment indicator sensor 11 positioned on the rear axle, according to the known technique.

[0094] The overturning moment indicator sensor 11 generates a measurement signal that represents a stability reserve of the handling machine 1 relative to the overturning axis.

[0095] A known method for monitoring and controlling the overturning risk involves processing the measurement signal of the overturning moment indicator sensor 11 using the control unit 10 in order to, on the one hand, display an indicator of visual stability in the cabin of the machine, for example, on a luminous display panel 13 disposed in the cabin and, on the other hand, interrupt the downward movement of the handling arm 6 when the measurement signal drops below a predefined threshold. However, due to the inertial forces generated by interrupting the movement, this method requires setting the threshold with a high safety margin, which limits the capabilities of the machine, and/or controlling an automatic slowing down of the movement before the interruption, which deprives the operator of control of the speed.

[0096] To avoid this, the control system can implement control methods that will be described with reference to FIGS. 2 and 3. These control methods are based on the principle of allowing the operator to control the movement of the handling arm 6 using the control component 12. In particular, the control system adjusts the speed of the movement to be executed as a function of a movement request generated by the operator by activating the control component 12, and in particular a quantitative magnitude generated by the action of the user on the control component 12 and representing a speed level requested by the user. For example, the quantitative magnitude is an angle of incline of a pivoting lever of the control component 12, in which a higher angle represents a higher speed request and a zero angle of incline (neutral position) represents a stop request. The control system immediately stops the movement in response to the stop request generated by the operator.

[0097] FIG. 2 illustrates a control method using a measurement of the effective speed of the handling arm 6. FIG. 3 illustrates a control method using a speed request generated by the operator. These methods can be executed as a loop by an electronic circuit.

[0098] The method of FIG. 2 comprises the following steps:

[0099] Step 21: acquiring the measurement signal from the overturning moment indicator sensor 11.

[0100] Step 22: determining an authorized speed threshold as a function of the measurement signal. This determination can be based on reading a table stored in a memory and containing threshold values associated with values of the measurement signal or value ranges of the measurement signal.

[0101] Step 23: acquiring the measurement signal from a speed sensor of the handling arm 6. This speed sensor is, for example, an angular speed sensor 18 outlined in FIG. 1.

[0102] Step 24: comparing the speed of the handling arm 6 with the authorized speed threshold.

[0103] Step 25, if the measured speed is less than the authorized speed threshold: executing or continuing the execution of the movement in accordance with the movement request generated by the operator.

[0104] Step 26, if the measured speed is greater than the authorized speed threshold: stopping or preventing the movement of the handling arm 6 despite the request of the operator. This stopping or preventing expresses the fact that the operator has requested an excessively high movement speed relative to the stability reserve available at the same instant. The control system does not authorize the execution of this request. In other words, if a movement was ongoing, it stops immediately and if no movement was ongoing, the stop state remains despite the request of the operator.

[0105] Based on the stop state generated in step 26, it is preferable to stipulate a positive resetting action by the operator before they are again able to send a movement request, for example, a new request with a lower speed level. This resetting action preferably can be executed by means of the control component 12, by an ergonomics measurement. For example, the resetting action involves returning the pivoting lever to the neutral position before re-inclining it forward.

[0106] The authorized speed threshold read in step 22 may have been determined by tests. In a qualitative manner, this authorized speed threshold represents an amount of movement or kinetic energy that the handling truck 1 is able to absorb without overturning in the event that the movement of the handling arm 6 is instantly stopped. This authorized speed threshold therefore decreases during a lowering movement of the handling arm 6 as the stability reserve decreases that is indicated by the measurement of the overturning moment indicator sensor 11. In another embodiment, the authorized speed threshold may have been determined by a computation and stored or can be determined by a real-time computation in step 22.

[0107] One effect of the control method described above therefore is that, starting from the upper position illustrated in FIG. 1, if the operator generates a constant lowering movement request, the movement is executed at a constant speed as long as the authorized speed threshold remains greater than this speed and is instantly interrupted when the authorized speed threshold is exceeded.

[0108] As the control system equally reacts to a given movement request, and in particular does not modify the movement speed executed in response to a given request, the operator is able to acquire, through experience, detailed knowledge of the response of the machine and is capable of best adapting their request as a function of the circumstances.

[0109] In FIG. 3, the steps modified compared to the method of FIG. 2 use the same reference number increased by 100. The unchanged steps use the same number and are not described again.

[0110] Step 28: acquiring the movement request signal generated by the operator, for example, in the form of an electrical signal.

[0111] Step 123: determining a requested movement speed as a function of the movement request signal. For example, the requested speed is encoded in the amplitude or another attribute of the movement request signal.

[0112] Step 124: comparing the requested movement speed with the authorized speed threshold.

[0113] Step 25, if the requested speed is less than the authorized speed threshold.

[0114] Step 26, if the requested speed is greater than the authorized speed threshold.

[0115] It will be understood that in these methods no movement is executed other than a movement in accordance with the movement request generated by the operator.

[0116] The control system for executing such a control method can be implemented in various ways. Three embodiments will now be described with reference to FIGS. 4 to 6.

[0117] In FIG. 4, the control system is suitable for implementing the method of FIG. 2. FIG. 4 shows the hydraulic cylinder 8, a hydraulic pressure source 30, a hydraulic distributor 31 interposed between them to control a hydraulic flow to be supplied to the hydraulic cylinder 8, the control component 12 in the form of a lever directly coupled to the slide of the hydraulic distributor 31, the control unit 10, the overturning moment indicator sensor 11 and the angular speed sensor 18 connected to the control unit 10, and a solenoid valve 32 interposed between the hydraulic distributor 31 and the hydraulic cylinder 8. The solenoid valve 32 is controlled by the control unit 10.

[0118] In this system, as the control unit cannot prevent the hydraulic distributor 31 from opening under the action of the user when the speed is too high, it is the solenoid valve 32 that is used to interrupt the hydraulic flow in order to immediately stop the movement in step 26.

[0119] Preferably, the solenoid valve 32 is a progressive start-up valve. The use of a progressive start-up valve prevents the possible restarting of the movement by the operator following the resetting action from occurring too quickly relative to the speed measurement taken by the speed sensor 18.

[0120] In FIG. 5, the elements that are similar or identical to those of FIG. 4 use the same reference number. In this embodiment, the hydraulic distributor 31 does not have a mechanical control directly connected to the control component 12, but it has a hydraulic control. In particular, the hydraulic flow 38 corresponding to the lowering movement of the handling arm 6 can be obtained by sending a pilot pressure 36 into a control port 35.

[0121] The control component 12 is coupled to a control valve 34 controlling this pilot pressure. The control unit 10 is configured to control a solenoid valve 33 arranged between the control valve 34 and the control port 35. Thus, in step 26, the control unit 10 can switch the valve 33 in order to return the hydraulic distributor 31 to a neutral position. Preferably, the solenoid valve 33 is a progressive start-up valve.

[0122] In FIG. 6, the control system is suitable for implementing the method of FIG. 3. The control component 12 generates electrical request signals 39 and the hydraulic distributor 31 is controlled using an electrical signal applied on a control port 37. The control unit 10 is interposed between the control component 12 and the hydraulic distributor 31 and therefore can directly control the hydraulic distributor 31 in steps 25 and 26. A speed sensor for the handling arm 6 is not essential in this embodiment, since the control unit 10 can determine the requested speed directly from the request signal 39.

[0123] Other control systems can be designed depending on the nature of the actuator to be controlled. The handling arm 6 can have degrees of movement other than the pivoting movement about the horizontal axis 7, in particular a degree of linear telescoping movement and a degree of pivoting of the tool about a horizontal axis 15. The control methods described above can be used to control one or more of these degrees of movement. When several degrees of movement are present, the actuators responsible for executing the corresponding movements are not necessarily all controlled in the same way.

[0124] FIG. 9 represents an embodiment of the rear axle 4 of the telescopic truck 1. The rear axle 4 comprises two wheel support arms 60 supporting the rear wheels 62. One or each of the wheel support arms 60 is equipped with an extensometer 61 arranged to measure bending deformations of the wheel support arm 60. More specifically, the extensometer 61 measures the variation in length between two separate limits on the wheel support arm 60. The measurement signals of the extensometers 61 can be used to form the overturning moment indicator signal, for example, as an average of the two measurement signals. Alternatively, it is possible to use a single extensometer 61 to generate the overturning moment indicator signal. Preferably, the rear axle 4 is connected in an oscillating manner to the frame 2 by means of a pivot 66 with a longitudinal axis passing through a central part 65 of the axle.

[0125] With reference to FIG. 7, a signaling method will now be described that can be used in the telescopic truck 1 to assist the operator in controlling the handling arm 6 in a safe and efficient manner.

[0126] FIG. 7 represents an overturning risk signal 40 that can be displayed on the display panel 13 to represent the overturning risk on a visual scale as a function of the instantaneous state of the telescopic truck 1. To this end, the amplitude of the overturning risk signal that controls the height of the scale that must be displayed, for example, the number of lamps that must be illuminated, cumulatively comprises an actual contribution 41 dependent on the measurement signal generated by the overturning moment indicator sensor 11 and a virtual contribution 42 dependent on a magnitude representing the movement speed of the handling arm 6, for example, the requested movement speed, as determined in step 123 of FIG. 3, or the effective movement speed, as measured in step 23 of FIG. 2. The last level 45 of the scale corresponds, for example, to the automatic interruption of the movement by the control unit 10.

[0127] In one embodiment, the contributions of the overturning risk signal 40 can be computed as follows. The actual contribution 41 can be inversely proportional to the magnitude measured by the overturning moment indicator sensor 11 and can be standardized on a scale of 0 to 1, where 0 corresponds to a normal overturning moment value and 1 corresponds to a maximum overturning moment value, i.e. a state in which it must no longer be possible to further lower the handling arm 6, even at low speed.

[0128] The virtual contribution 42 can equal:

B=(1A)*Q,

[0129] where A denotes the actual contribution 41 located between 0 and 1 and Q denotes a ratio between the movement speed requested or executed at a given instant and the authorized threshold speed at the same instant, i.e. a ratio that remains below 1 by design.

[0130] By generating the overturning risk signal 40 in this way, an optimal level exists that is schematically illustrated by number 43, which corresponds to the maximum speed that can be produced without the movement being interrupted by the control unit 10. The operator therefore can use the overturning risk signal 40 as a visual reference for adapting their movement request in order to remain close to the optimum level 43 during the downward movement of the handling arm 6.

[0131] FIG. 8 is a functional representation of an embodiment of the control unit 10. It comprises a functional control module 17 and a functional signaling module 19 that can operate with two input signals. A first input signal 50 is a signal indicating the speed of the movement executed or to be executed, for example, the request signal generated by the control component 12 or the measurement signal of the speed sensor 18. A second input signal 51 is a signal indicating the static stability reserve of the machine, for example, the measurement signal of the overturning moment indicator sensor 11.

[0132] The functional control module 17 comprises: [0133] a speed computation module 52 configured to compute an executed or requested speed value on the basis of the first input signal 50; [0134] a speed threshold computation module 53 configured to determine the authorized speed threshold on the basis of the second input signal 51; [0135] a comparator module 54 for comparing the executed or requested speed value with the authorized speed threshold; and [0136] a control module 55 for controlling the lifting actuator as a function of the result of the comparison, either directly or by controlling intermediate control elements (in particular the valve 32, the valve 33, the distributor 31).

[0137] The functional signaling module 19 comprises: [0138] a virtual contribution computation module 56 configured to compute the virtual contribution 42 on the basis of the first input signal 50; [0139] an actual contribution computation module 57 configured to compute the actual contribution 41 on the basis of the second input signal 51; [0140] an adder module 58 for adding the actual contribution 41 and the virtual contribution 42; and [0141] a control module 59 for controlling the display panel 13 as a function of the overturning risk signal 40.

[0142] The overturning risk signal 40 could be sent to the operator in visual forms other than a scale, for example, a color code. The overturning risk signal 40 could be sent to the operator in an audible or other form.

[0143] Some elements that are shown, in particular the control unit, can be produced in different forms, unitarily or apportionately, by means of hardware and/or software components. Usable hardware components are ASIC specific integrated circuits, FPGA programmable logic arrays or microprocessors. Software components can be written using various programming languages, for example, C, C++, Java or VHDL. This list is not exhaustive.

[0144] The methods and systems described above within the context of a telescopic truck are applicable to other handling machines.

[0145] Although the invention has been described in relation to several particular embodiments, it is obvious that it is by no means limited thereby and that it comprises all the technical equivalents of the means described and the combinations thereof if they fall within the scope of the invention.

[0146] The use of the verb comprise or include and of its conjugated forms does not exclude the presence of other elements or other steps than those stated in a claim. The use of the indefinite article a or an or one for an element or a step does not, unless otherwise specified, exclude the presence of a plurality of such elements or steps.

[0147] In the claims, any reference sign between parentheses cannot be interpreted as a limitation of the claim.