Construction machine, in particular for construction site, and method for controlling such a machine

Abstract

Work machine (1) comprising: - a rolling chassis (2), - an arm (4) carried by said chassis (2), pivoting by means of a first actuator (5), and of adjustable length by means of a second actuator (6), - a pivoting bucket carrier (7) mounted by means of a third actuator (8), - a first control element (9) for the arm (4) and the bucket carrier (7), - a second control element (10) for the exit of the arm (4), - a control unit (11) configured to control the actuators according to the data provided by said control elements (9, 10).The device (1) includes two selectively activatable operating modes, the pilot unit (11) is configured to, in the first operating mode, control the third actuator (8) from the data of the first control unit (9), and the second actuator (6) from the second control unit (10), and, in the second operating mode, control the second (6) and third (8) actuators from the first control unit (9).

Description

FIELD OF THE INVENTION

[0001] The invention relates to a work machine, in particular a construction site machine, as well as a method for controlling such a machine.

[0002] It relates more specifically to a construction machine, particularly a construction site machine, comprising: a chassis equipped with a powertrain, an arm carried by said chassis and mounted by means of a first actuator movable to pivot between a high position and a low position, said arm formed of at least two arm sections, being a telescopic arm of adjustable length between a retracted position and an extended position of the arm by means of an actuator for driving relative movement of the arm sections called the second actuator, a bucket holder arranged at the free end of the arm, this bucket holder, coupleable to a bucket, being mounted, by means of an actuator, called the third actuator, movable to pivot about an axis orthogonal to the longitudinal axis of the arm between a digging position and a dumping position, the dumping position corresponding to the extreme position of pivoting towards the ground of the bucket holder;a first member, such as a joystick, for controlling the movement of the arm and the bucket holder, actuable by the driver of the machine; a second member for controlling the movement of the arm between a retracted position and an extended position, actuable by the driver of the machine and; a control unit configured to control the first, second and third actuators as a function of the data provided by said control members.; PRIOR ART

[0003] Such a work machine is known as illustrated in patent EP 2,805,910. In such a machine, during the dumping operation, there is a risk of damage to the bucket into which the contents of the bucket are to be dumped, as illustrated in figure 1 which corresponds to the state of the art. Indeed, generally, to carry out an operation of dumping the contents of the bucket into a skip, the driver of the machine controls the elevation of the bucket-carrying arm to bring the base of the bucket into a position in which it extends parallel to the plane of the bottom of the skip and above the skip. The bucket holder is then driven in pivoting movement towards the dumping position. To do this, the driver of the machine actuates the control member for driving the movement of the bucket holder, generally formed by a joystick. During this pivoting movement, there is a risk that the bucket will hit the wall of the skip and damage it if the bucket has not been sufficiently moved away from the top of the skip. PURPOSE AND SUMMARY

[0004] An aim of the invention is to propose a work machine and a method for controlling said machine, the designs of which make it possible to reduce the risks of damage to a skip during operations of dumping material into the skip.

[0005] To this end, the invention relates to a work machine according to claim 1.

[0006] Thus, the control unit is configured to, in the second operating mode, control the second and third actuators as a function at least of the data provided by the first control member to allow, in the stressed state of said first control member, in parallel with a pivoting movement of the bucket holder, a relative movement of the arm sections. The control unit is therefore configured to, in the second operating mode, control in parallel the second and third actuators from the first control member forming a control member common to the first and second actuators to allow, in the coupled state of the bucket to the bucket holder, a rotation of the bucket, in particular of the leading edge of the bucket around a substantially constant instantaneous center of rotation.Indeed, thanks to the simultaneous control of the first and second actuators from the first control member forming a control member common to the first and second actuators, it is possible to shift the center of rotation of dumping to the level of the leading edge of the bucket. Thus, any risk of damage to the bucket is avoided.

[0007] Thus, the control unit is configured to, in the second operating mode, in the requested state of said first control member corresponding to the positioned state of said first control member in said first control zone, control at least the second and third actuators from and as a function of the data provided by said first control member forming a control member common to the second and third actuators.

[0008] Again, this design allows, in the coupled state of the bucket to the bucket holder, rotation of the bucket and, in particular, of the leading edge of the bucket, around a substantially constant instantaneous center of rotation.

[0009] According to one embodiment of the invention, the machine comprises an interface for inputting or selecting data relating to the size of the bucket and the control unit is configured to, in the second operating mode, control at least the second and third actuators as a function at least of the data provided by said first control member and the size of the bucket.

[0010] Taking into account the size of the bucket makes it possible, within the framework of a possibility of mounting buckets of different sizes on the machine, to guarantee again, in the coupled state of the bucket to the bucket holder, a rotation of the bucket and, in particular, of the leading edge of the bucket, around a substantially constant instantaneous center of rotation.

[0011] According to one embodiment of the invention, the machine comprises at least one sensor for measuring a parameter representative of the angular position of the bucket holder relative to the arm, and the control unit is configured to, in the second operating mode, control the second and third actuators as a function at least of the data provided by said first control member and the angular position of the bucket holder.

[0012] Taking into account the data provided by such a sensor makes it possible to control the movements of the bucket holder and the arm in a closed loop, and therefore to correct, if necessary, the offset observed between the movements of the bucket holder and the arm.

[0013] Preferably, the or at least one of the sensors for measuring a parameter representative of the angular position of the bucket holder relative to the arm is a sensor for measuring the angle formed between the bucket holder and the arm or a sensor for measuring the stroke of the third actuator.

[0014] According to one embodiment of the invention, the control unit is configured to, in the second operating mode, control the first, second and third actuators as a function at least of the data provided by said first control member, in the positioned state of said first control member in said first control zone.

[0015] Thus, the control unit is configured to, in the second operating mode, control the first, second and third actuators at least from and as a function of the data provided by the first control member, this first control member forming a member common to the first, second and third actuators to allow, in parallel with a pivoting movement of the bucket holder, a relative movement of the arm sections and an upward and downward movement of the arm.

[0016] According to one embodiment of the invention, the machine comprises at least one sensor for measuring a parameter representative of the angular position of the arm relative to the chassis, and the control unit is configured to, in the second operating mode, control the first, second and third actuators as a function at least of the data provided by said first control member and the angular position of the arm.

[0017] Taking into account data provided by such a sensor makes it possible to control the movements of the bucket holder and the arm, and to correct any observed offsets if necessary.

[0018] Preferably, the or at least one of the sensors for measuring a parameter representative of the angular position of the arm relative to the chassis is a sensor for measuring the angle formed between the arm and the ground support plane of the chassis or a sensor for measuring the stroke of the first actuator.

[0019] According to one embodiment of the invention, the machine comprises at least one sensor for measuring a parameter representative of the length of the arm, and the control unit is configured to, in the second operating mode, control at least the second and third actuators as a function at least of the data provided by said first control member and the length of the arm.

[0020] According to one embodiment of the invention, the first and second operating modes of the machine can be selectively activated by means of an activation member such as a button that can be operated by the driver of the machine.

[0021] The invention also relates to a method for controlling a work machine, in particular a construction site machine of the aforementioned type, the bucket holder of said machine being coupled to a bucket, characterized in that said method comprises, in the activated state of the second operating mode of the machine, by actuation by the driver of the machine of the first control member, a step of driving the arm sections in relative movement, preferably in the direction of an extension of the arm and driving the bucket holder in pivoting movement towards the dumping position. BRIEF DESCRIPTION OF THE FIGURES

[0022] The invention will be clearly understood upon reading the following description of exemplary embodiments, with reference to the appended drawings in which: There figure 1 represents a schematic side view of a machine conforming to the state of the art. The figure 2 represents a schematic side view of a machine according to the invention. The figure 3 represents another schematic side view of a machine according to the invention. The figure 4 represents a schematic side view, in transparency, of a machine in accordance with the invention, in the bucket dumping position, a detail of the dashboard and the first and second control members being represented. figure 5 represents a partial view of the interior of the machine's cabin. The figure 6 schematically represents the movement of the bucket obtained by parallel movement of a section of arm and the bucket holder. DETAILED DESCRIPTION

[0023] As mentioned above, the subject of the invention is a work machine 1, in particular a construction site machine, such as a hydraulic mechanical shovel, also called an excavator or bucket machine as shown.

[0024] This machine 1 comprises a rolling chassis 2 equipped with a machine control cabin and a power unit 3 for driving the machine on the ground.

[0025] The powertrain group 3 comprises a heat engine, itself associated with a hydraulic pump capable of supplying fluid to a plurality of actuators which will be described below.

[0026] Machine 1 also includes an arm 4 carried by chassis 2.

[0027] This arm 4 is a pivoting arm pivotally mounted about a so-called horizontal axis, orthogonal to the longitudinal axis of the arm 4, and parallel to the ground support plane of the machine 1, in the configuration of use of the machine 1 for the passage of the arm 4 from a low position to a high position and vice versa, using an actuator, such as a jack, called first actuator 5 and arranged between the arm 4 and the rolling chassis 2. In the example shown, a single double-acting jack is shown, supplied with fluid by the hydraulic pump. A pair of parallel single-acting jacks supplied in turn with fluid could have been used in an equivalent manner.

[0028] This arm 4 is a telescopic arm formed, in the example shown, of two arm sections 41, 42 mounted with sliding interlocking, and driven in relative movement by an actuator, called second actuator 6, for the passage of the arm from a retracted position to an extended position and vice versa.

[0029] This second actuator 6 is formed by a hydraulic cylinder whose body is mounted integral with one arm section and the rod with the other arm section.

[0030] The arm 4 is equipped at its free end with a bucket holder 7 intended itself to carry a bucket 20. This bucket holder 7 is mounted by means of an actuator, called third actuator 8, pivotable about a so-called horizontal axis, orthogonal to the longitudinal axis of the arm 4 between a digging position and a dumping position. The dumping position corresponds to the extreme position of pivoting towards the ground of the bucket holder 7, while the digging position corresponds to an upward pivoting position of the bucket holder 7 and the associated bucket 20. The third actuator 8 is arranged between the bucket holder 7 and the arm 4 and can again consist of a double-acting hydraulic cylinder or a pair of single-acting cylinders. The pivoting movement drive of the bucket holder takes place about an axis parallel to the pivot axis of the arm.

[0031] The machine 1 also comprises, arranged inside the driver's cabin, a first member 9 for controlling the movement of the arm 4 and the bucket holder 7, which can be actuated by the driver of the machine, and a second member 10 for controlling the movement of the arm 4 between a retracted position and an extended position, which can be actuated by the driver of the machine.

[0032] The machine 1 also comprises a control unit 11 configured to control the first, second and third actuators according to the data provided by the control members 9 and 10.

[0033] The fluid supply to the actuators using the hydraulic pump is controlled as a function of the control signals provided by the control unit 11. These control signals are themselves a function of the input data received by the control unit 11. The control unit comprises, for example, a microcontroller or a microprocessor associated with a memory. Thus, when it is specified that the unit or means of said unit are configured to carry out a given operation, this means that said unit comprises computer instructions and the corresponding execution means which make it possible to carry out said operation.

[0034] The control signals supplied by the control unit 11 generally act on members, such as distributors or valves, arranged on the connection between the pump and the actuator, to allow an appropriate supply of fluid to the actuators, in a manner known per se.

[0035] In the example shown, in particular at the figure 5 , the first control member 9 is a control lever also called a joystick. This first control member 9 is equipped at its base with two encoders to allow the transmission of two position signals of said first control member to the control unit 11, in a manner known per se. An example of such a control member is for example described in patent FR 2 858 861. This first control member 9 can thus be moved forward, backward, to the left, or to the right of the machine. Generally, the movements, towards the front and rear of the machine, of the first control member 9 control the upward and downward movement of the arm 4, while the movements, towards the left and to the right of the machine, of the first control member 9 control the pivoting movement of the bucket holder, as illustrated in the figures where the figure 4 illustrates a movement to the right of the first control member 9 and the positioning of the bucket holder in the dumping position. These forward / rearward and left / right directions correspond to the main directions, and the first control member can be driven in an infinite number of directions, the movement of the first control member in any direction corresponding to a combined action, proportional to the position of the first control member relative to the main directions. Generally, this first control member 9 is returned by a spring to the neutral position, that is to say in an intermediate position between right / left and front / rear, in the unstressed state.

[0036] The position information sent to the control unit is therefore generally information relating to the angular position of the first control member, relative to the position it occupies in the neutral position.

[0037] In this neutral position, when the first control member is moved angularly to the right within a predetermined angular sector, it controls the pivoting movement of the bucket holder in the direction of dumping of the bucket holder and the associated bucket. This first angular sector is called the first control zone 13. When the first control member is, from the neutral position, moved angularly to the left within a predetermined angular sector, it controls the pivoting movement of the bucket holder in the direction of digging of the bucket holder and the associated bucket.In the same way, when the first control member is, from the neutral position, moved angularly forwards within a predetermined angular sector, it controls the raising of the arm, while when the first control member 9 is, from the neutral position, moved angularly backwards within a predetermined angular sector, it controls the lowering of the arm. Obviously, the right / left, front / rear positions can be reversed without departing from the scope of the invention.

[0038] These angular sectors can overlap to allow, by actuation of the first control member 9, in parallel with a pivoting of the bucket holder 7, an upward and downward movement of the arm.

[0039] The second control member 10 is formed by a wheel positioned on the first control member 9. Actuation of this wheel allows the arm to be moved between a retracted position and an extended position. In fact, rotation of the wheel carried by the first control member 9 in one direction allows the arm to be extended by sliding movement, in the direction of extension of the arm, of the second arm section, and rotation of the wheel carried by the first control member 9 in an opposite direction allows the arm to be retracted.

[0040] To enable such movements of the arm and the bucket holder from the first and second control members, the control unit 11 controls the supply of hydraulic fluid to the first, second and third actuators as a function of the position data provided by the first and second control members. Thus, the first, second and third actuators are each arranged on a hydraulic circuit equipped with at least one valve or distributor controllable by the control unit 1.

[0041] This control unit 11 is here implemented in the form of a controller or microprocessor in which computer instruction sets have been implemented to perform the functions of the control unit. However, the functions of the control unit 11 can be performed by dedicated electronic components or FPGA or ASIC type components. It is also possible to combine computer parts and electronic parts.

[0042] Computer programs or computer instructions may be contained in program storage devices, for example, computer-readable digital data storage media or executable programs. Programs or instructions may also be executed from program storage devices.

[0043] Generally, a control unit 11 is configured to receive the position signals addressed to it by the first and second control members and to emit output signals to the valves or distributors equipping the hydraulic circuits of the first, second and third actuators, generally via solenoids equipping said valves or distributors.

[0044] The first, second and third actuators control, depending on their hydraulic flow supply, a movement of the arm for the first and second actuators, or a movement of the bucket holder for the third actuator.

[0045] From this general operation, the machine 1 comprises two selectively activatable operating modes. In the example shown, these two operating modes are selectively activatable by means of an activation member 12 formed here by a button actuated by the driver of the machine. This button is arranged in the cabin of the machine, at the level of the dashboard. When the machine is started, the machine is in the first operating mode. In this first operating mode, in the state requested by the driver of the machine, that is to say in the state driven in movement out of its neutral position, the first control member 9 sends signals to the control unit 11.This control unit 11 is configured to, from the signals received from the first control member, as a function of said signals, act on the supply circuit of the first and / or third actuator, and thus control the lifting or lowering of the arm and / or the pivoting movement of the bucket holder in one direction or the other, as a function of the position signals sent by the first control member to the control unit 11.

[0046] In this first operating mode, in the state requested by the driver of the machine, that is to say driven in rotation, the second control member 10 formed by the wheel arranged on the joystick sends signals to the control unit 11. The control unit 11 is configured to, from the signals received from the second control member 10, act on the power supply circuit of the second actuator and thus control the retraction or extension of the arm.

[0047] In this first operating mode, the actuation by the driver of the machine of the first control member 9 does not cause any actuation of the second actuator and, consequently, no extension or retraction of the arm.

[0048] When the second operating mode is activated, for example by pressing the button 12 by the driver of the machine, in the state requested by the driver of the machine, that is to say in the state driven in movement out of its neutral position, the first control member 9 sends signals to the control unit 11. This control unit 11 is configured to, from the signals received from the first control member, as a function of said signals, act on the supply circuit at least of the second and third actuators, to thus allow, in parallel, a pivoting movement of the bucket holder and a variation in the length of the arm.

[0049] The control unit 11 is configured to, in the second operating mode, in the requested state of the first control member 9 corresponding to the positioned state of the first control member in the first control zone 13, control at least the second and third actuators, as a function of the data provided by the first control member 9.

[0050] The control unit 11 is, in these circumstances, configured to control the second actuator 6 in the direction of an extension of the arm 4 and the third actuator 8 in the direction of a pivoting movement of the bucket holder 7 towards the dumping position.

[0051] The extension length of the arm 4 and the pivot angle of the bucket holder 7 for a given position of the first control member 9 within the first control zone 13 are defined in correspondence. Thus, if it is assumed that, at the time of the dumping command, the arm 4 of the machine forms an angle close to 45° with the ground support plane of the machine and that the bottom of the bucket 20, that is to say the surface in support of the ground in the placed state of the bucket, extends parallel to the ground support plane of the machine and therefore forms, with the arm, an angle equal to 45° as illustrated in figure 6, it is necessary, to ensure a 90° pivoting movement of the bottom of the bucket via the bucket holder, to increase the length of the arm by L' = L / cosine 45°, L corresponding to the distance taken between two parallel planes perpendicular to the ground support plane of the bucket and passing, one through the leading edge of the bucket, the other through the pivot axis connecting the bucket holder to the arm. Thus, simultaneous movements of arm extension and bucket holder pivoting can be pre-calibrated in the factory, so that for example a 1° rotation of the bucket holder corresponds to an arm extension of a length of L' / 90.

[0052] This results in a pivoting movement of the bucket holder and the associated bucket around a quasi-constant instantaneous center of rotation located at the leading edge of the bucket.

[0053] In the case where the machine is designed to be able to be equipped with buckets of different dimensions, the machine 1 comprises an interface 14 for inputting or selecting data relating to the dimension of the bucket 20, and the control unit 11 is configured to, in the second operating mode, control the second and third actuators as a function of the data provided by said first control member 9 and the dimension of the bucket 20. The above formula is applied with L, a function of the dimension selected or entered by the driver of the machine. This interface may comprise a simple touch screen on which the different dimensions of the bucket can be displayed, the driver of the machine selecting the dimension corresponding to the bucket equipping the machine.

[0054] To safely and synchronously obtain an extension of the arm and a pivoting of the bucket holder, the machine 1 comprises a sensor 15 for measuring a parameter representative of the angular position of the bucket holder 7 relative to the arm 4, and the control unit is configured to, in the second operating mode, control the second and third actuators as a function of the data supplied by the first control member 9 and the angular position of the bucket holder.

[0055] This sensor 15 for measuring a parameter representative of the angular position of the bucket holder 7 relative to the arm 4 may be a sensor for measuring the angle formed between the bucket holder 7 and the arm 4, or a sensor for measuring the stroke of the third actuator 8.

[0056] Indeed, the hydraulic flow rate inside the hydraulic supply circuits of the second and third actuators can vary in an undesirable manner, due to the fact that the hydraulic source of the machine is requested by other parts of the machine such as the brakes, the steering, the fan or others. The presence of a sensor makes it possible to avoid a drift in the movements between extension of the arm and pivoting movement of the bucket holder.

[0057] To perfect the machine, the control unit 11 can be configured to, in the second operating mode, control in synchronism and in parallel not only the second and third actuators, but also the first actuator, depending on the data provided by the first control member in the positioned state of the first control member in the first control zone 13.

[0058] In this case, in the second operating mode, in the positioned state of the first control member 9 in said first control zone 13, the control unit 11 is configured to control the first actuator in the direction of lifting the arm, the second actuator in the direction of extending the arm and the third actuator in the direction of pivoting the bucket holder towards the dumping position, the extension length of the arm and the pivot angles of the arm and the bucket holder being, for a given position of the first control member 9 within the first control zone 13, defined correspondingly.

[0059] The objective is always to obtain, at the level of the leading edge of the bucket, a rotation of the latter around a quasi-constant instantaneous center of rotation.

[0060] Again, and for the same reasons of risk of drift of movement in synchronism as mentioned above, the machine comprises a sensor 16 for measuring a parameter representative of the angular position of the arm 4 relative to the chassis 2, and the control unit 11 is configured to, in the second operating mode, control the first, second and third actuators as a function of the data provided by the first control member 9 and the angular position of the arm. This sensor 16 for measuring a parameter representative of the angular position of the arm relative to the chassis may be a sensor for measuring the angle formed between the arm and the ground support plane of the chassis, or a sensor for measuring the stroke of the first actuator 5. Additional sensors may be provided to refine the settings and control the movements in synchronism, as a function of the data provided by said sensors.Thus, the machine can also comprise a sensor 17 for measuring a parameter representative of the length of the arm 4, and the control unit 11 can be configured to, in the second operating mode, control the second and third actuators as a function of the data provided by the first control member 9 and the length of the arm 4.

Claims

1. A construction vehicle (1), in particular for a construction site, comprising: a chassis (2) equipped with a power train, an arm (4) supported by said chassis (2) and mounted by means of a first actuator (5) pivotably movable between a high position and a low position, said arm (4), formed by at least two arm sections (41, 42), being a telescoping arm with a length adjustable between a withdrawn position and a deployed position of the arm (4) by means of an actuator driving relative movement of the arm sections called second actuator (6), a bucket-holder (7) arranged at the free end of the arm (4), a bucket (20) intended to be carried by the bucket-holder (7), the bucket-holder (7), able to be coupled to the bucket (20), being mounted, by means of an actuator called third actuator (8), pivotable around an axis orthogonal to the longitudinal axis of the arm (4) between a tilt position and a discharge position, the discharge position corresponding to the extreme pivoting position toward the ground of the bucket-holder (7), a first member (9), such as a joystick, for controlling driving of the movement of the arm (4) and the bucket-holder (7), able to be actuated by the driver of the vehicle, a second member (10) for controlling driving of the movement of the arm (4) between a withdrawn position and a deployed position, able to be actuated by the driver of the vehicle, a steering unit (11) configured to control the first (5), second (6) and third (8) actuators as a function of data provided by said control members (9, 10), the vehicle (1) comprising at least a first and a second operating mode able to be activated selectively, the steering unit (11) being configured in order, in the first operating mode, to control the third actuator (8) as a function at least of the data provided by said first control member (9), and the second actuator (6) as a function at least of the data provided by the second control member (10), characterized in that the first control member (9), which can be actuated by the driver of the vehicle, is mounted movably between a neutral position and a control zone by pivoting the bucket-holder (7) in the direction of a pouring operation and called first control zone (13), in that the steering unit (11) is configured in order, in the second operating mode, in the stressed state of said first control member (9) corresponding to the state of said first control member (9) positioned in said first control zone (13), to command the second (6) and third (8) actuators as a function at least of data provided by said first control member (9), the steering unit (11) being configured, in this second operating mode, in the state of the first control member (9) positioned in said first control zone (13), to control the second actuator (6) in the direction of an elongation of the arm (4) and the third actuator (8) in the direction of a pivoting movement of the bucket-holder (7) toward the pouring position, the elongation length of the arm (4) and the pivot angle of the bucket-holder (7) being, for a given position of the first control member (9) inside said first control zone (13), defined to match to ensure a pivoting movement of the bucket-holder (7) and the associated bucket (20) around a quasi-constant instantaneous center of rotation arranged at the leading edge of the bucket (20).

2. The construction vehicle (1) according to the preceding claim, characterized in that the vehicle (1) comprises an interface (14) for entering or selecting a datum relative to the size of the bucket (20) and in that the steering unit (11) is configured in order, in the second operating mode, to control at least the second (6) and third (8) actuators as a function at least of the data supplied by said first control member (9) and the size of the bucket (20).

3. The construction vehicle (1) according to one of the preceding claims, characterized in that the vehicle (1) comprises at least one sensor (15) for measuring a parameter representative of the angular position of the bucket-holder (7) relative to the arm (4), and in that the steering unit (11) is configured in order, in the second operating mode, to control the second (6) and third (8) actuators as a function at least of the data supplied by said first control member (9) and the angular position of the bucket-holder (7).

4. The construction vehicle (1) according to the preceding claim, characterized in that the or at least one of the sensors (15) for measuring a parameter representative of the angular position of the bucket-holder (7) relative to the arm (4) is a sensor for measuring the angle formed between the bucket-holder (7) and the arm (4) or a sensor for measuring the travel of the third actuator (8).

5. The construction vehicle (1) according to one of the preceding claims, characterized in that the steering unit (11) is configured in order, in the second operating mode, to control the first (5), second (6) and third (8) actuators as a function at least of the data supplied by said first control member (9), in the state with said first control member (9) positioned in said first control zone (13).

6. The construction vehicle (1) according to the preceding claim, characterized in that the vehicle (1) comprises at least one sensor (16) for measuring a parameter representative of the angular position of the arm (4) relative to the chassis (2), and in that the steering unit (11) is configured in order, in the second operating mode, to control the first (5), second (6) and third (8) actuators as a function at least of the data supplied by said first control member (9) and the angular position of the arm (4).

7. The construction vehicle (1) according to the preceding claim, characterized in that the or at least one of the sensors (16) for measuring a parameter representative of the angular position of the arm (4) relative to the chassis (2) is a sensor (16) for measuring the angle formed between the arm (4) and the bearing plane on the ground of the chassis (2) or a sensor (16) for measuring the travel of the first actuator (5).

8. The construction vehicle (1) according to one of the preceding claims, characterized in that the vehicle (1) comprises at least one sensor (17) for measuring a parameter representative of the length of the arm (4), and in that the steering unit (11) is configured in order, in the second operating mode, to control at least the second (6) and third (8) actuators as a function at least of the data supplied by said first control member (9) and the length of the arm (4).

9. The construction vehicle (1) according to one of the preceding claims, characterized in that the first and the second operating mode of the vehicle (1) are able to be activated selectively by means of an activation member (12), such as a button, able to be actuated by the driver of the vehicle.

10. A method for controlling a construction vehicle (1), in particular for a construction site, according to one of the preceding claims, the bucket-holder (7) of said vehicle (1) being coupled to a bucket (20), characterized in that said method comprises, in the activated state of the second operating mode of the vehicle (1), by actuation by the driver of the vehicle of the first control member (9), a step for driving the relative movement of the arm (4) sections (41, 42), preferably in the direction of an elongation of the arm (4), and driving pivoting movement of the bucket-holder (7) toward the discharge position.

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