EP2684836A1

EP2684836A1 - Direction and speed control device for telescopic and articulated hydraulic lifting equipments.

Info

Publication number: EP2684836A1
Application number: EP13382264.3A
Authority: EP
Inventors: Miguel Leon Gonzalez
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-07-12
Filing date: 2013-07-03
Publication date: 2014-01-15

Abstract

A direction and speed control device (10) for telescopic/articulated lifting equipment , enabling the movement of its basket (9) or alternative tool (9a) according to the instantaneous operating direction η(t) of a single joystick (8a), achieving a continuous interaction between actual direction of motion and actual direction of joystick η(t), in order to perform curvilinear or partially linear trajectories which correspond directly to the real direction of command at any instant , keeping the basket (9) or tool (9a) at constant height.

There are 3 control options:
- The control device automatically orients the basket/tool (9) or (9a) according to the current direction of movement defined by only one joystick (8a), keeping the basket/tool aligned with the trajectory of its center of rotation.
- An additional control axis (8ab), together with the axes of the joystick (8a), define the actual direction , speed and orientation of the basket/tool (9) (9a).
- The control device automatically keeps constant the orientation angle (ρ) of the basket/tool (9) with respect to the fixed frame of reference.

Similarly, the control device allows vertical movements with changes of direction (λx,λy), without the need of intermediate stops. To improve the accuracy, the control device comprises a system to take into account the bending deformations of the lifting mechanism, in the position and synchronism calculations. Optionally, the control device comprises additional means for performing automatic curvilinear movements without operator.

Description

Technical Field of the invention:

The present invention relates to a control system for mobile lift equipment , telescopic and articulated type , more particularly , aerial platforms and telescopic handlers with tools at the end tip of the telescopic boom.

Background of the invention

The patent document JP2001341991-A discloses a control device for aerial platforms allowing linear movements , which are performed by means of the automatic synchronization of some degrees of freedom of the lifting mechanism , keeping the height constant . The document JP2002128498-A , discloses a similar control device.
The objective of these inventions, as explained in these documents, is achieving linear movements along certain directions. But the movements are linear, 'from the beginning until the end '. Therefore, in order to change direction, it is necessary to stop the ongoing movement and to command a new linear movement with a different direction of reference.
The drawback of these devices is that they are not able to perform curvilinear movements, along directions that correspond directly to the actual operating direction of the joystick , at any instant of the movement in course.
Patent document JP10017298-A discloses a control device allowing linear movement along any direction of the work space. As in the two previous cases, the objective of the invention is achieving rectilinear movements . In addition, the actual direction of the movement is defined by the composition of the individual speeds linked to each axis of the joystick. This has the disadvantage, in the case of a raising/lowering movement along diagonal directions , that the actual diagonal direction of movement does not match the real direction of any of the 2 joysticks operated . The actual direction of movement is given by the speed ratio between the joystick Z , of a single axis , and the joystick XY , with 2 axes of control. So , the resulting diagonal direction of the raising/lowering movement can not be foreseen by the operator , the control is not intuitive , due to the fact that the resulting direction of movement is linked to the to the infinite combinations of speeds between the 2 joysticks operated simultaneously.
Patent document EP2404862A1 discloses an aerial platform with horizontal/vertical linear movements comprising a lifting mechanism in which the number of degrees of freedom in the plane of movement is excessive , and therefore it is also necessary to establish a logic of synchronization between them or otherwise the number of solutions of synchronism would be infinite. According to this document, it is defined a logic of synchronism between boom and jib so that , for linear horizontal movements , it is kept constant the angle between the jib and the basket and for vertical movements , it is kept constant the angle between jib and boom. This criterion of synchronization between boom and jib has the disadvantage for both kind of movements , horizontal or vertical , that it does not allow achieving the maximum reach, height or lateral , allowable by the lifting mechanism. Therefore, this logic of synchronism limits the mechanical reach of the lift .
All linear control devices existing in the prior state of art, are based on the reading of position sensors located at the elements of the lifting mechanism, which measure the relative position between them and the values linked to its degrees of freedom. With these data, the control device can implement a position analysis of the mechanism, by means of an electronic controller, but it has no means for considering its bending deformation. This leads to a calculation error of position and consequently to an error of synchronism.
The stiffness of the lifting structure depends on variable factors such as the position of the basket at the work space. The deflection of the lifting mechanism depends on its variable stiffness and the load in basket ; both factors are variable. This elastic displacement, which is not taken into account by the control device, brings an error in the position calculations and therefore an imprecision of the linear movements which may leads to interferences with obstacles.
Moreover , control devices described above do not consider the influence of hydraulic oil temperature in the synchronism of the degrees of freedom. The variation of viscosity of the oil may change the relative speed of one of the synchronized movements with respect to others, even in the case of using temperature compensated proportional valves. As hydraulic systems in conventional machines normally have no means to keep stable the oil temperature , if the control device does not consider this factor, movements lose their smoothness and accuracy. Consequently the machine is unstable and unreliable.
The main objective of the invention is a direction and speed control device for hydraulic lift equipment , telescopic or articulated type, allowing a continuous and instantaneous interaction between direction of movement and direction control, so that the actual direction of movement of the basket or tool exactly matches the actual direction of command , at any instant of the motion. The control device should allow moving the basket or alternative tool in the three dimensional space at the same direction that the real instantaneous operating direction of a joystick , and thus achieve curvilinear movements , with or without rectilinear sections , by means of the automatic synchronization of the different degrees of freedom of the lifting mechanism.
It is an objective , that the control device enables curvilinear movements of the basket or tool , with or without rectilinear sections , keeping the basket or tool at constant height , by means of a single joystick operated with one hand , controlling with it , the speed and direction of the instantaneous velocity of the basket or tool.
It is an important objective that the control device allows the operator to interact with the orientation of the basket during the ongoing movement, according to different control options that can be previously chosen. In some cases the operator may prefer that the control device would automatically keep constant the orientation angle of the basket or tool. But sometimes the operator will prefer to keep the basket or tool aligned with the direction of movement , tangent to the work surfaces. The operator in some cases will want to control this orientation himself. This interaction should be intuitive and easy for the operator, with a single joystick, so that the actual orientation of the joystick exactly correspond to the actual orientation of the resulting movement.
For linear raising/lowering movements , the control device should allow changes of the direction in course , without the need of intermediate stops. The direction of the raising/lowering movement must correspond to the real operation direction of a joystick at any instant of the ongoing movement.
Another objective of the invention is that the control device must be able to accurately keep the current direction of movement , rectilinear or curvilinear, regardless of the bending deformation of the lifting mechanism. The accuracy of rectilinear or curvilinear trajectories should not be influenced by the variation of the stiffness of the lifting mechanism, the variation of load or the variation of the temperature of the hydraulic oil.
It is also an objective of the invention that the control device incorporated in aerial platforms with several articulated booms , allows reaching the maximum outreach allowable by the lifting mechanism in a curvilinear or rectilinear movement at constant height. Similarly, and with almost the same logic of synchronization , the control device must allow to reach the maximum height allowable by the lifting mechanism , in a linear or curvilinear raising/lowering movement.
Finally, it is also an objective of the invention that the control device enables fully automatic curvilinear movements without the need of operator or programming requirements. For hydraulic lift equipment without basket, with 4 or more degrees of freedom, equipment that incorporates at the end tip of the boom working tools , such as automatic paint spray guns , blasting nozzles , grit blasting turbines , laser nozzles , washing rollers ... etc , the control device shall allow to move the tool along paths parallel to the curved surfaces to be treated, automatically , keeping exactly constant the distance to the surface and the speed of the tool. The movements carried out may be raising/lowering or movements at constant height .

Disclosure of the invention

For a better understanding of the invention it is defined a global reference frame x, y, z , fixed and Cartesian , linked to the chassis of the lifting mechanism , and a mobile reference frame XI, YI, ZI , also Cartesian type, located at the basket , being its axes XI, YI horizontal and ZI vertical.
For the purpose of providing a solution to the problems mentioned, it is disclosed a control device for hydraulic lift equipment with at least one telescopic boom , with at least 4 degrees of freedom, comprising:

Position detection means for measuring the relative position between the elements of the mechanism. They are basically position sensors which measure the values linked to the degree of freedom of the mechanism. These data are necessary for the position analysis of the mechanism.
Control means . These are basically proportional joysticks , single axis or multi axis , mounted preferably but not limited in the basket . The control axes of joysticks correspond to the mobile reference frame XI, YI, ZI located at the basket.
Regulation and control means for operating the actuators linked to each degree of freedom. These are typically electro-hydraulic proportional flow valves and directional electric control valves.
An electronic controller or microcontroller that inputs the signals from the position detection means and the joysticks. The controller with theses input data, carries out the necessary engineering calculations for determining the theoretical position of the basket and the corresponding synchronization values for the regulation and control means , in order to perform movements of the basket or tool according to the direction of command referred to the mobile reference frame XI, YI, ZI .

The most important feature of the invention is that it allows a continuous and instantaneous interaction between direction of movement and direction of control , so that the actual direction of movement of the basket or tool at every moment exactly coincides with the actual direction of command. The control device allows moving the basket or tool in three dimensional space at the same direction that the real instantaneous operating direction of the joystick , and thus performing curvilinear paths, with or without straight sections. The trajectories performed are foreseen by the user, not dependent on operator skills.
For example it enables curvilinear movements keeping the basket or tool at constant height , according to the actual operating direction of a single joystick ,whose control axes coincide with the mobile reference frame XI-YI. By means of this single joystick, the device controls the speed and direction of the instantaneous velocity of the basket , and is able to change both parameters in the ongoing movement for performing rectilinear or curvilinear trajectories within the same movement. The operator can change the direction in the course of movement without stopping the motion.
This type of movement is achieved by inputting as reference data , the orientation of the basket in the global system xyz and its height at the instant of beginning the movement (starting from a stop), the instantaneous direction of command and dynamic coordinates of reference of the basket or tool , which change over time. During each instant of the ongoing movement, the electronic controller detects any variation of the direction of command , and based on this change of input data, it updates the reference coordinates and consequently the calculations of synchronism of the different degrees of freedom involved in the movement. This continuous and instant updating of reference coordinates together with the kinematic and dynamic calculations is what makes possible to change the direction of movement at any instant without requiring stopping the motion.
According to another feature of the invention, the control device can perform curvilinear or rectilinear raising/lowering movements in three-dimensional space , according to the direction of command , so that the actual direction of movement directly correspond to the actual operating direction of the joystick at any instant of the ongoing movement.
Such movement is achieved by means of 2 joysticks . One joystick , single axis , for the defining the speed of the basket or tool and a second joystick , dual axis, for defining the actual and instantaneous direction of the raising/lowering movement. The dual axis joystick XI, YI is the one that operated alone would perform movements at constant height . But in this case, as the movement is a combination of 2 joysticks , the electric controller changes automatically the normal functions of both , in such a way that the potentiometer of the single axis joystick defines only the speed of motion and the potentiometers of the dual axis joystick the direction in the tri-dimensional space. This way , the direction of the raising/lowering movement exactly correspond to the inclination angle of the knob of the dual axis joystick with respect to the gravity , and therefore the user can easily foresee the actual direction of motion.
According to another feature of the invention, the control device allows the operator to interact with the orientation of the basket in the course of synchronized movements , so that the basket can be simultaneously controlled according to different options previously set. This solution is disclosed below , in the Detailed Description of the Drawings.
Another feature of the control device is that it comprises a system for detecting the bending deformation of the lifting structure and consequently for improving the accuracy of linear paths of the basket/tool along the synchronized movements. The control device takes into account this deflexion avoiding an error in the analysis of position and therefore a bad performance. The elastic deformation is an indirect measurement , determined by calculation. The electronic controller calculates this deflexion by means of the information provided by the same sensors which are required for achieving the synchronization (the position detection means) and additionally by the direct or indirect measurement of the load in the basket.
Another feature of the control device is that it comprises, optionally, means for detecting the temperature of the hydraulic fluid and thereby improve the accuracy and smoothness of the synchronized movements. The electronic controller by inputting this data, readjusts accordingly the calculation values corresponding to the regulation and control means. It modifies the theoretical value of each proportional flow valve , previously calculated according to the data provided by the position detection means , the control means , and the deflexion detection system.
For aerial platform with lifting mechanisms of more than 4 degrees of freedom, a feature of the control device is that it implements a simple logic of synchronization between the different degrees of freedom which are in the same plane of movement , in order to achieve the maximum lateral or vertical reach in a rectilinear or curvilinear movement. The problem of the mechanisms with more than 2 degrees of freedom in the same plane, is that there are infinite solutions of synchronization if a kind of link between them is not established. So if a logic of synchronization between them is not defined , there is not mathematical solution.
For aerial platforms with several articulated booms, being one of them telescopic type , the logic of synchronization consist of keeping constant the angle between the basket and the boom articulating to it, during the ongoing movement, either horizontal or vertical , while there is no limitation of telescopic movement . When the telescopic movement reaches its maximum or minimum length by mechanical limitation, then the movement goes on keeping the length of the telescopic boom constant , changing the angle between the basket and the boom articulated to it . This angle, then is automatically controlled so that it tends towards 0 ° if the motion is horizontal extending , towards -90 ° if the motion is horizontal retracting , towards 90° if it is a vertical raising movement and towards - 90 º if it is a vertical lowering movement. The advantage of this logic of synchronization is allowing the maximum reach allowable by the mechanical system and its compatibility for horizontal and raising movements..
For aerial platforms with several articulated booms, being two of them telescopic type , the number of degrees of freedom can be up to seven. The logic of synchronization between the different degrees of freedom, in order to perform movements according to the actual operating direction of a joystick , is based on a smart selection of the number of degrees of freedoms involved in the movement to be performed. This method is disclosed below in the Detailed Description of the Drawings.

Brief description of the drawings.

The attached drawings show by way of non-limiting example, several embodiments of the control device of the invention. In such drawings :

Fig. 1: Schematic of the control device.
Fig. 2: Sectional view of the basket and the load detection means attached to the levelling cylinder.
Fig. 3: Plan view of the control panel , with the control means, mobile reference frame XI , YI and target direction of movement η(t).
Fig. 4: Plan, front and side view of a joystick with two control axes parallel to the mobile reference frame XIYI, and other single axis joystick for controlling the rotation of the basket during the synchronized movements by rotating the moving reference frame XI, YI about the fixed reference frame x, y, z.
Fig. 5a: Sequence of positions of a boom lift performing a continuous curvilinear movement of the basket according to the instantaneous operating direction of a single joystick , keeping constant the height and orientation of the basket with respect to the fixed reference frame xyz.
Fig. 5b : Graph referred to the movement Fig 5a , where the ordinate axis is the angle of the operating direction of the joystick with 2 control axes XIYI and the abscissa the elapsed time.
Fig. 6a: Sequence of positions of a boom lift performing a continuous curvilinear movement of the basket according to the actual operating direction of 2 joysticks , keeping the height constant . (the orientation of the basket is the orientation of its axes XI , YI with respect to the fixed reference frame xyz)
Fig. 6b : Graph referred to the movement Fig 6a , where the ordinate axis is the angle of the operating direction the joystick (dual axis XIYI ) and the abscissa the elapsed time. In this case the direction of movement η(t) is constant and aligned with the axis XI.
Fig. 6c : Graph referred to the movement Fig 6a , where the ordinate axis is the angle of rotation of the joystick (single axis) which defines the target orientation angle of the basket on the mobile reference frame and at abscissa is the elapsed time.
Fig. 7a: Sequence of positions of a boom lift performing a continuous movement along curvilinear and rectilinear paths at constant height , according to the actual operating direction of a single joysticks η(t) , so that the axis XI of the basket is automatically aligned with the direction of the movement defined by the same joystick.
Fig. 7b : Graph referred to the movement Fig 7a , where the ordinate axis is the angle of the operating direction the joystick (dual axis XIYI) and the abscissa the elapsed time. In this case the orientation of the basket is automatically aligned with the direction of movement.
Fig. 8: Sequence of positions of a boom lift performing a raising/lowering movement according to the actual operating direction of a joystick , along vertical and diagonal paths , avoiding obstructions by changing the direction of command (λy) in the course of the movement.
Fig. 9: Sequence of positions of a lift with a tool at the end tip of the boom , performing an automatic curvilinear raising/lowering movement , parallel to a curved surface.
Fig. 10a: Sequence of positions of a boom lift performing a continuous movement of the basket , avoiding a obstruction by changing the operating direction of a single joystick in the ongoing movement , and keeping constant the height and orientation of the basket with respect to the fixed reference frame xyz.
Fig. 10b : Graph referred to the movement Fig 10a , where the ordinate axis is the angle of the operating direction the joystick (dual axis XIYI ) and the abscissa the time.
Fig. 11a: Front view of a boom lift with 4 degrees of freedom performing a vertical movement assuming that the elements of the lifting mechanism are infinitely stiff.
Fig.11b: The same view as in Fig 11a , but showing the position error due to the bending deformation of the lifting mechanism.
Fig.12: The same machine as in Fig 11a , showing the error of a horizontal linear path due to the bending deformation of the lifting mechanism at the end tip of the basket δ9(t).
Fig. 13a and Fig. 13b : A boom lift with 2 articulated booms , one of which is telescopic type , (5 degrees of freedom) , and the logic of synchronization between the degrees of freedom that are in the same plane.
Fig. 14 : A boom lift with 2 telescopic booms , (7 degrees of freedom) , and a simple logic of synchronization between the degrees of freedom.
Fig. 15 : A boom lift with 2 telescopic booms , (7 degrees of freedom) ,in a rectilinear or curvilinear movement at constant height , and logic of synchronization between the degrees of freedom with the objective of achieving the maximum lateral outreach allowable by the lifting mechanism.
Fig.16 : A boom lift with 2 telescopic booms , (7 degrees of freedom) ,in a raising/lowering linear movement , and logic of synchronization between the degrees of freedom with the objective of achieving the maximum height allowable by the lifting mechanism.
Fig. 17 : Schematic of an optional solution of the control device , in which the joystick is replaced by sensors which determine the target direction of movement , and thereby enable automatic movements without operator.
Fig. 18: End tip of the boom of a hydraulic lift in which the basket has been replaced by a tool , and certain sensors for achieving automatic movements without operator.

Detailed Description of the Drawings.

The following describes a control device (10) for a hydraulic lift equipment (16) (17) with a lifting mechanism with at least four degrees of freedom (α,β,γ,Lt) . The lift comprises at least a chassis (11), a turntable (12), a telescopic boom (13) and a rotating basket (9) or rotary tool (9a). In this type of machines, the elements of the lifting mechanism are usually powered by means of hydraulic actuators (7). The lift cylinder (7a) is linked to the degree of freedom(α) , the telescope cylinder (7b) (inside the telescopic boom, not showed in the drawings) is linked to the degree of freedom (Lt), the turntable motor (7c) is linked to the degree of freedom (β), and the basket/tool rotation motor (7d) is linked to the degree of freedom (γ). (Both motors are not shown in drawings)
The control device (10) comprises position detection means (1), control means (8), a detection system of bending deformations, temperature detection means (5), an electronic controller (3) and regulation and control means (6). The regulation and control means (6) are control the speed and direction of the actuating means (7) , which are usually hydraulic type. The electronic controller (3) is connected internally or externally with data unit (2) which stores the information regarding the dimensions and stiffness of the elements of the mechanical system. The software of the controller (3) is parametric , based on the information of this unit (2) , and this unit is linked to a specific model of machine (16) (16a) (17) .....
The position detection means (1) are basically sensors linked to each degree of freedom of the lifting mechanism. They are located at the elements of the lifting mechanism , for determining the magnitude of the degrees of freedom (α, β, γ , Lt , ε) , where :

(α) is the tilt angle of the telescopic boom (13) with respect to the horizontal line,
(β) angle of rotation of the turntable (12) in the plane x-y ,
(γ) the angle of rotation of the basket ( 9) or tool (9a) in the plane XI-YI with respect to the boom (13) ,
(Lt) the length of the telescopic boom (13) ,
(ε) the inclination angle of the jib (15a) with respect to gravity.

The electronic controller (3) inputs the signals of the position detection means (1), for making by computer methods the position and kinematic analysis of the mechanical system , and thus determine at each instant the velocity and coordinates of the basket/tool according to the fixed reference frame x, y, z.
The controller (3) calculates in a first stage, the coordinates of all the nodes of the lifting mechanism. This preliminary calculation does not take into account the bending deformation due the load in the basket and the variable stiffness of the elements. This is a first theoretical calculation assuming that the elements of the mechanical system are absolutely stiff.
The control means (8) located preferably at the work basket (9) are basically proportional multi-axis joysticks. The joystick (8a) is dual axis. Its two axes are aligned with the axes XI, YI of the mobile reference frame located at the basket (9). Each control axis transmits a proportional signal ( Kjx , Kjy) to the controller (3) according to the tilt angle of the knob of the joystick (λx , λy) on each axis.
The joystick (8b) is single axis. This control axis transmits a proportional signal ( Kjz) to the controller (3) according to the tilt angle of its knob.
The operation of the joystick (8a) is carried out at a certain direction defined by the angle η(t) referred to the frame of reference XI, YI . The controller (3) calculates the target direction of the movement to be performed by the basket (9) or tool (9a) according to the formula: $η (t) = \arctan (Kjy / Kjx)$
- Where η(t) is the target direction of the instantaneous velocity of the basket ,V9 (t), referred to the mobile reference frame XI-YI , at any instant of time.
The electronic controller (3) calculates the target instantaneous speed of the basket V9 (t), as : $V 9 (t) = {({Kjy}^{2} + {Kjx}^{2})}^{1 / 2}$
The detection system of bending deformations is a system for determining by computer calculation the deflexion of the lifting mechanism, taking as only input data , the direct or indirect measurement of the load in the basket , by means of the load detection means (4) , geometric data of the lifting mechanism (2 ) such as the dimensions and the inertia moments of its elements , and the information provided by the position detection means (1).
The detection system of bending deformation is described below ;
The levelling cylinder of the basket (7e) comprises a pressure transducer directly attached. This device is used as a load detecting means (4), an indirect measurement of the load at the basket. The electronic controller (3) takes as reference this data (4), just before starting a new movement, and keeps in memory this value during the whole movement. Thereby it is known the static pressure (Pr) of the levelling cylinder (7e), regardless of the pressure of the hydraulic circuit.
The load at the basket (9), by weight and workload is calculated as follows: $F 4 = \Pr * Ap * D 2 / D 1$
- where 'Ap' is the area of the cylinder (7e) and 'Pr' the static pressure inside it.
The data unit (2) storages the geometric information of the lifting mechanism , such as the area moment of inertia 'Ixi' , length 'L' , area 'A' of each element of the mechanism, i.e. booms and turntable.
As mentioned , the electronic controller (3) calculates the deflexion of the lifting mechanism, with the information provided by (2) (1) and (4). For this purpose any engineering method can be implemented , for example the method of virtual works or the direct stiffness method....
The computational method solves the system of equations: $\{Fi\} = [Ki (t)] \cdot \{δi (t)\}$
Where:

Fi is the load on the elements , including weight and workload.
δ i(t) = displacement of the nodes of the mechanism by deflexion.
Ki (t) is the stiffness of the elements at each instant of the movement. The stiffness depends on the Young's modulus 'E' , Area Moment of Inertia 'Ix', length of the elements Li (t) and for another kind of structures also the section 'A'. $Ki (t) = f (E, Ix, Li (t), A)$

The electronic controller (3), adds the resulting displacement due to bending δi(t) , to the position coordinates of all the nodes of the lifting mechanism , previously calculated in the first stage with the data provided by the sensors (1). Thereby it is calculated the actual instantaneous position of the basket (9) with respect to the fixed reference frame x, y, z, and thus it is taken into account in the calculations of synchronizations of the different degrees of freedom involved in the ongoing motion.
According to a variant of the invention, the position detection means (1) optionally comprises in addition three distance measuring sensors , electromagnetic type. Each sensor measures the distance from a fixed point of the chassis (11) to the centre of rotation of the basket (9). With these three measurements , the electronic controller (3) calculates , by the method of triangulation , the actual instantaneous position of the basket (9) at the work space according to fixed reference frame xyz. This method of calculating the coordinates of the working basket (9) has the advantage of being based on direct measurements ,and therefore the result does not depend on the bending deformation of the lifting mechanism, neither on the conditions of the wear pads of the telescopic booms.
The electronic controller (3), after calculating the target speed and direction η(t) of the instantaneous velocity of the basket (9), and the actual position of the bended lifting mechanism, makes the necessary engineering calculations to determine the required values for the regulation and control means (6) which operate de actuators of the hydraulic system. The values of the regulation and control means for each degree of freedom are : (6a), signals for the proportional flow valve and directional valve of the lift cylinder (7a), (6b) signals for the proportional flow valve and directional valve of the telescope cylinder (7b), (6c) signal for the proportional flow valve and directional valve of the turntable (7c), and (6d) the corresponding value analogical or digital for controlling the rotation of the basket or tool (7d). The regulation values (6) calculated are the required to achieve the automatic synchronization of up to 7 degrees of freedom (α,β,γ,ε,Lt ...) , so that the basket (9) or tool (9a) moves according to the direction η(t) and speed commanded at any instant of time of the movement in course.
For achieving movements along curvilinear paths which exactly match the actual operating direction of the joystick η(t) at any instant , the electronic controller (3) detects at each instant of time (t1, t2, t3, t4 ...) changes of the direction of reference η(t) commanded , for updating the reference coordinates of the ongoing movement and the synchronization calculations which depend on the reference coordinates and direction of reference η(t) commanded.
Moreover , the controller (3) optionally corrects the calculated values (6a, 6b, 6c, 6d) according to the temperature of the hydraulic fluid in the system. This data is provided by a temperature sensor (5) located at the return to the tank of the hydraulic circuit.
A feature of the present invention is that the orientation angle (ρ) of the basket (9) or tool (9a) with respect to the fixed reference frame x, y, z , can be manually or automatically controlled in the course of the synchronized movements.
According to a first option, the control device (10) automatically controls the orientation angle the basket/tool (ρ) , synchronizing it with the other movements of the lifting mechanism, in such a way that it makes to converge during the ongoing movement, one of the axis (XI) or (YI) of the mobile reference frame located at the basket or tool , with the direction of motion η(t) at any instant. The direction of movement of the basket at its centre of rotation η(t) exactly correspond to the operating direction of a single joystick (8a) , dual axis , with respect to the mobile reference frame XI YI , at any instant. Therefore, the direction , speed and orientation angle of the basket (ρ) in a curvilinear movement at constant height is defined by a single joystick (8a) with 2 control axes parallel to the mobile reference frame.
The control device (10), with information provided by the angle sensors located at the basket and the turntable (γ) (β), automatically modifies the rotation speed of the basket (w9) with respect to the rotation speed of the turntable (w12) for keeping the basket axis (XI or YI) aligned with the direction of movement η(t).
The axis of the basket to be automatically aligned with the direction of movement η(t) is XI if the direction of command is closer to the axis XI than to YI . Similarly, the axis of the basket to be aligned with η(t) is YI , if the direction of command is closer to the axis YI than to XI .
The Fig. 7a shows a sequence of positions of a movement along curvilinear and rectilinear paths at height constant , at different instants (t0, t1, t2, t3, t4, t5 ....) , so that the axis XI of the basket is automatically aligned with the direction of movement defined by a single joystick.
The Fig. 7b shows the graph referred to this movement where the ordinate axis is the angle η(t) of the instantaneous operating direction the joystick (8a) , (dual axis XIYI ), and the abscissa the elapsed time. As can be observed , η(t) tends to be zero automatically, due to the fact that the control device makes to converge continuously the XI axis of the basket with the operating direction of motion η(t).
According to a second option, the orientation angle (ρ) of the basket or tool is controlled manually by the operator , by means of an additional joystick (8ab) which defines the actual target orientation of the basket with respect to the mobile reference frame XI,YI linked to the basket , which must be achieved in a certain increment of time. According to this option, the actual direction and speed of the curvilinear movement of the basket (at its centre of rotation) is defined by a dual axis joystick (8a) , and its actual orientation in the space , corresponds directly to the rotation of a single axis joystick (8ab).
The rotation angle (λz) of the knob (8ab), defines the target orientation; it is the exact increment of rotation degrees to which the mobile reference frame (XI, YI) of the basket or tool must converge, in a fixed and determined interval of time . Thereby the target orientation of the basket , during the ongoing movement , is easily defined and commanded by the operator , and it is achieved by the control device without relying on the operator skills. The control device (10) inputs the signal (kgj) proportional to the angle (λz) , while keeping the synchronization of the degrees of freedom involved in the rectilinear or curvilinear movement at constant height , modifying the current rotation speed of the basket (w9) with respect to the rotation speed of the turntable (w12) , in order to make converging the reference frame XI, YI of the basket into two successive instants of time.
The Fig. 6a shows a sequence of positions of a movement along a curvilinear path at height constant , at different instants (t0, t1, t2, t3 ....), where the axis XI of the basket is oriented by means of two joysticks (8a) and (8ab).
The Fig. 6b shows the graph referred to this movement where the ordinate axis, is the angle η(t) of the instantaneous operating direction the joystick (8a) , (dual axis XIYI ), and the abscissa the elapsed time.
The Fig. 6c shows the graph referred to this movement where the ordinate is the rotation angle (λz) of the joystick (8ab). As can be observed, keeping the direction of the dual axis joystick (8a) , constant and aligned with the reference axis XI (so that η(t) = 0º), and keeping the rotation angle (λz) of the single axis joystick (8ab) also constant (but different to cero), then the basket (9) traces a circular trajectory , with the axis XI of the basket tangent to the trajectory. The radius of the trajectory is proportional to the operating angle (λz) of the joystick (8ab).
Likewise, keeping the direction of the joystick (8a) constant and aligned with the axis YI (so that η(t) = 90º ) , and keeping the rotation angle (λz) also constant (but different to cero), then the basket (9) traces a circular trajectory , with the axis YI of the basket tangent to the trajectory.
Obviously , the single axis joystick (8ab) and the dual axis joystick (8a) , may be integrated together in a single joystick with 3 axes of control.
According to a third option, the orientation angle (ρ) of the basket or tool referred to the fixed reference frame xyz, is kept constant, automatically and synchronized with the others movements of the lifting mechanism. The direction and speed of the curvilinear movement of the basket, as well as its orientation in the space , is defined by only one joystick (8a) - dual axis.
The Fig. 5a, Fig. 5b, Fig. 10a, Fig. 10b illustrate this type of movement, at constant height, keeping also constant the orientation angle ( ρ) along curvilinear trajectories.
The Fig. 13a and 13b shows a boom lift comprising a lifting mechanism of 5 degrees of freedom (α,β,γ,Lt, α1), with 2 articulated booms , (13) ,(15) , being the lower one (13) telescopic type, and being (α1) the inclination angle of the boom (15) articulated with it referred to the horizontal line.
With the objective of achieving the maximum horizontal outreach along movements of basket (9) at constant height , the control device (10) synchronizes the degrees of freedom of the mechanical system implementing the following method :

While the telescopic boom (13) does not reach its minimum or maximum length, the control device (10) synchronizes the degrees of freedom (α,β,γ,Lt), keeping constant the angle (α1) of the boom (15). This section of movement is illustrated in the Fig 13a between (t0) and (t1).
Once the minimum or maximum length allowable of the telescopic boom (13) is reached due to mechanical limitation , the movement of la basket (9) goes on according to the direction of command, by means of the automatic synchronism of the degrees of freedom (α,β,γ,α1) , keeping constant the telescopic boom length (Lt), so that the angle (α1) tends towards 0 º if movement is extending out the lifting mechanism (from t1 to t2 in Fig. 10a) , or so that it tends towards -90 º if the movement is retracting the mechanism.

With the objective of achieving the maximum vertical reach along raising/lowering movements of basket (9) , the control device (10) synchronizes the degrees of freedom of the mechanical system implementing the following method :

While the telescopic boom (13) does not reach its minimum or maximum length, the control device (10) synchronizes the degrees of freedom (α,β,γ,Lt) , keeping constant the angle (α1) of the boom (15). This section of movement is illustrated in the Fig 13b between (t0) and (t1).
If the minimum or maximum length of the telescopic boom (13) is reached, the movement of la basket (9) or (9a) can go on according to the raising/lowering direction of command, by means of the synchronization of the degrees of freedom (α,β,γ,α1) , keeping constant the telescopic boom length (Lt), so that the angle (α1) tends to increase up to +90º , until both booms be aligned if it is a raising movement, or to decrease , down to a certain value between 0º and -90º, if it is a lowering movement. Once this point is reached , the lowering movement can go on by means of the automatic synchronization of (α,β,γ,Lt) , keeping (α1) constant.

The Fig. 14,15,16 shows a boom lift comprising a lifting mechanism of 7 degrees of freedom (α,β,γ,Lt,ε,α1,Lt1), with 2 telescopic booms , (13) ,(13a) and a jib (15a) , being (α1) the inclination angle of the upper telescopic boom (13a) referred to the horizontal line and (Lt1) its length.
A function switch (8d) from the control panel (8) allows to select the number of freedom that will be involved in the movement.

In a first option based on a selector switch (8d), the control device (10) performs the movement commanded , synchronizing the degrees of freedom (α,Lt,β,γ) , keeping constant the values (ε,α1,Lt1).-(see Fig. 14)
In a second option based on a selector switch (8d), the control device (10) performs the movement commanded , synchronizing the degrees of freedom (α1,Lt1,β,γ) keeping constant the values (ε, α, Lt).
In a third option based on a selector switch (8d), the control device (10) performs the movement commanded , synchronizing the degrees of freedom , (α1, α, Lt1 ,Lt , β,γ) keeping constant the angle (ε) . The control device (10), moves the end point of the lower telescopic boom (13M) according to the direction and speed of command , by means of the synchronization of the degrees of freedom (α, Lt) , and simultaneously it moves the end point of the upper telescopic boom (13N) according to the direction and speed of command , by means of the synchronization of (α1, Lt1 ,β,γ).
In a fourth option based on a selector switch (8d), if it is a movement at constant height , while the lower telescopic boom (13) does not reach the minimum or maximum length, the control device (10) synchronizes the degrees of freedom (α,β,γ,Lt) , keeping constant (α1, Lt1 , ε). Once the minimum or maximum length of the lower telescopic boom (13) is reached, the movement of la basket (9) (9a) goes on according to the direction of command, by means of the synchronization of the degrees of freedom (α1, Lt1, β,γ), keeping constant (α, Lt , ε). Once the minimum or maximum length of both telescopic booms (13) (13a) are reached , the control device combines the degrees of freedom (α,α1, β,γ) keeping constant ( Lt , Lt1, ε) so that the angle (α1) tends towards 0 º if movement is extending out the lifting mechanism, or so that the angle (α1) tends towards -90 º if the movement is retracting the mechanism.

If it is a raising/lowering movement , while the lower telescopic boom (13) does not reach the minimum/maximum length, the control device (10) synchronizes the degrees of freedom (α, Lt , β,γ) , keeping constant the angle (α1, Lt1 , ε) . If the minimum or maximum length of the lower telescopic boom (13) is reached, the control device (10) synchronizes (α1, Lt1 β,γ) , keeping constant (α,Lt , ε) until the minimum/maximum length of the upper telescopic boom (13a) is reached. If the minimum/maximum length of both telescopic booms are reached, then the control device (10) synchronizes (α,α1,β,γ) keeping constant (Lt , Lt1 ε) until the angle (α1) reaches the value of 0º. Once this point is reached, the raising/lowering movement goes on synchronizing (Lt1 ,α1,β,γ) , keeping constant (α, Lt ε) .
According to an alternative mode of implementing the invention, the joysticks (8a, 8b, 8ab), instead of being located at the basket (9) of the lift equipment , can be located at the chassis (11) or in any other place of the fixed frame of reference xyz , even as wireless remote control , without changing any of the characteristics of the invention mentioned above. In this case , the axes if the joystick (8a) , wherever it is , can still be referred to the axes of the mobile reference system linked to the tool (9a).
According to an alternative mode the invention , the control device enables fully automatic movements without operator , joystick or programming requirements.
For lift equipment without basket , which incorporates a tool (9 a) at the end tip of the boom , such as an automatic paint spray gun (or blasting nozzles , grit blasting turbines , inspection sensor etc..) , the control device enables automatic movements along curvilinear paths , keeping the tool parallel to the curved surfaces to be treated , keeping also constant the distance to the target surface and the speed of the tool.
For defining a direction of movement without using joysticks , the control device (10) comprises 3 distance sensors (8s) which measure the distance from a plane of the tool (9a) to the closest surface in front of it. The difference of these three measurements allows defining a direction of movement parallel to the curved surface , which replaces the direction of a joystick . Thereby it is possible to perform automatic raising/lowering movements or movements at constant height along curvilinear or rectilinear surfaces . With these 3 distance sensors (8s) , together with the sensors of the position detection means (1) linked to the degrees of freedom of the lifting mechanism , the control device (10) achieves keeping constant the speed of the tool and its distance to the surfaces , by means of the automatic synchronization of the degrees of freedom of the lifting mechanism. This automatic synchronization is achieved by the control device (10) as it has been disclosed above in the description of the invention .

Claims

Direction and speed control device (10) , for telescopic or articulated hydraulic lift equipment with lifting mechanism of at least four degrees of freedom. The degrees of freedom comprise at least; Boom tilting (α), extension/retraction of telescopic boom (Lt), rotation of turntable (β) about its vertical axis and rotation of basket (9) or tool (the 9a) (γ) about its vertical axis ZI.
The control device (10) comprises:
- position detection means (1) which are basically sensors linked to each degree of freedom of the lifting mechanism.

- regulation and control means (6) which are mainly electro-hydraulic proportional flow valves and directional control valves,

- actuating means (7) which are basically cylinders and motors generally hydraulic type,

- an electronic controller (3),

- and control means (8) or joysticks, one of which (8a) comprises at least 2 control axes parallel to the axes of a mobile Cartesian reference frame XI YI located preferably at the basket (9) or tool (9a).
The control device (10) is characterized in that it enables a continuous and instantaneous interaction , between actual direction of motion and actual direction of joystick in accordance with the 3 following sections:

- It enables moving the basket (9) or alternative tool (9a) at an instantaneous velocity V9 (t) whose direction, at its centre of rotation, matches exactly the instantaneous operating direction η(t) of a single joystick (8a) referred to its 2 control axes XI YI, being able to change the direction of command η(t) in the ongoing movement , in order to perform curvilinear or partially rectilinear trajectories which correspond directly to the real direction of command at any instant , keeping all the time the basket (9) or tool (the 9th) at constant height, in such away that its orientation angle (ρ) with respect to the fixed reference frame x, y, z , can be modified manually or automatically during the course of the movement.

- It allows raising/lowering the basket (9) or tool (9a) at a defined instantaneous velocity so that the speed is proportional to inclination angle a joystick (8b) , and the direction of movement matches exactly the actual inclination angle (λy) o (λx) of another joystick (8a) with respect to its vertical axis ZI, or the direction resulting from the combination of both values, being able to change in the ongoing movement , the directions (λy) or (λx) for performing raising/lowering curvilinear trajectories, with or without vertical or diagonal sections , which correspond directly to the actual direction of command.

- The continuous and instantaneous interaction between actual direction of movement and actual direction of joystick η(t), (or the correlation between the instantaneous velocity of the basket (9) or tool (9a) with the operation of the joystick) , is performed synchronizing automatically the degrees of freedom of the lifting mechanism. The automatic synchronization is achieved by means of the regulation and control means (6) , so that their values are calculated by the electronic controller (3), which detects at each instant of time changes of the operating direction η(t) , and consequently it updates the coordinates of reference of the movement in course , the synchronism calculations , and the corresponding values of the regulation and control means (6) , taking into account in the position analysis, the bending deformation of the lifting mechanism in order of improve the accuracy of trajectories.
Direction and speed control device according to claim 1 characterized in that the orientation angle (ρ) of the basket (9) or tool (9a), during movements along curvilinear or rectilinear paths at constant height , depends on a predefined option of control, according to the following cases:
- Option 1 : the control device (10) automatically controls the orientation angle of the basket (ρ) referred to fixed frame of reference x, y, z, keeping automatic synchronization with the others movements of the lifting mechanism, in such a way that some of the axes of the reference frame linked to the basket or tool, (XI or YI), converges automatically with the direction of movement η(t) at any instant. The instantaneous direction of movement of the basket at its centre of rotation η(t) , exactly corresponds to the instantaneous operating direction of the joystick (8a) referred to its 2 Cartesian axes XI YI. Therefore , the speed and direction of the curvilinear movement of the basket, as well as its orientation in the space is defined and controlled by only one joystick (8a) of 2 axes of control.

- Option 2 : The orientation angle of the basket or tool (ρ) is controlled manually, by means of an additional control axis (8ab) which defines the actual target orientation of the basket with respect to the mobile reference frame XI,YL linked to the basket , which must be achieved in a certain increment of time. According to this option, the actual direction and speed of the curvilinear movement of the basket is defined by a dual axis joystick (8a) , and its actual orientation at the space by means of a single axis joystick (8ab) in such a way that the direction and orientation of the basket/tool correspond directly to the direction and orientation of command . The rotation angle (λz) of the knob (8ab), defines the real target orientation; it is the exact increment of rotation degrees to which the mobile reference frame (XI , YI) of the basket or tool must converge, in a fixed and determined interval of time , thereby without relying on the operator skills.

- Option 3 : The orientation angle of the basket (ρ) referred to the fixed frame of reference xyz, is kept constant during the course the movement, automatically and synchronized with the others movements of the lifting mechanism. The direction and speed of the curvilinear movement of the basket/tool , as well as its orientation at the space , is defined by only one joystick (8a) dual axis.
Direction and speed control device, according to claims 1 ,2 characterized in that the automatic orientation of the basket (9) or tool (9a) towards the direction of movement η(t) of its centre of rotation , is performed aligning its local reference axis XI with the actual operating direction of the joystick η(t) , if the direction of movement commanded is closer to the axis XI than to the axis YI.
Similarly the basket (9) or tool (9a) is oriented aligning its local reference axis YI with the actual operating direction of the joystick η(t) , if the direction of movement commanded is closer to the axis YI than to the axis XI.
Direction and speed control device, according to claims 1 ,2 3, characterized in that if the joysticks (8a) and (8ab) are located at the same basket (9), if the direction of the dual axis joystick (8a) is kept constant and aligned with the reference axis XI (so that η(t) = 0º) , and the rotation angle (λz) of the single axis joystick (8ab) is also kept constant, then the basket (9) traces a circular trajectory , with the axis XI of the basket tangent to the trajectory. The radius of the trajectory is proportional to the operating angle (λz) of the joystick (8ab).
Likewise, keeping the direction of the joystick (8a) constant and aligned with the axis YI ( η(t) = 90º ) , and keeping the rotation angle (λz) also constant, then the basket (9) traces a circular trajectory , with the axis YI of the basket tangent to the trajectory.
Direction and speed control device according to anyone of the previous claims , for lift hydraulic equipment with lifting mechanism of at least 5 degrees of freedom (α,β,γ,Lt, α1) , comprising at least 2 articulated booms being one of them (13) telescopic type, being (α1) the inclination angle of the other boom (15) articulated with it referred to the horizontal line , characterized in that the electronic controller (3) implements the following logic of synchronism along a movement at constant height:
While the telescopic boom (13) does not reach its minimum or maximum length, the control device (10) synchronizes the degrees of freedom (α,β,γ,Lt) , keeping constant the angle (α1) of the other boom (15). Once the minimum or maximum length of the telescopic boom (13) is reached, the movement of la basket (9) or (9a) goes on according to the actual direction of command, by means of the automatic synchronism of the degrees of freedom (α,β,γ,α1) ,

keeping constant the telescopic boom length (Lt), in such a way that the angle (α1) tends towards 0 º if movement is extending out the lifting mechanism, or so that the angle (α1) tends towards -90 º if the movement is retracting the mechanism.
Direction and speed control device according to anyone of the previous claims , for lift hydraulic equipment with lifting mechanism of at least 5 degrees of freedom (α,β,γ,Lt, α1), comprising at least 2 articulated booms being one of them (13) telescopic, and being (α1) the inclination angle of the other boom (15) articulated with it with respect to gravity , characterized in that the electronic controller (3) implements the following logic of synchronism along a vertical movement or raising/lowering curvilinear movement :
While the telescopic boom (13) does not reach its minimum or maximum length, the control device (10) synchronizes the degrees of freedom (α,β,γ,Lt) , keeping constant the angle (α1) of the other boom (15). If the minimum or maximum length of the telescopic boom (13) is reached, the movement of la basket (9) or (9a) goes on according to the actual raising/lowering direction of command, by means of the synchronization of the degrees of freedom (α,β,γ,α1) , keeping constant the length of the telescopic boom (Lt), in such a way that the angle (α1) tends to increase up to +90º , until both booms are aligned if it is a raising movement, or to decrease , down to a certain value between 0º to -90º, if it is a lowering movement. Once this point is reached , the lowering movement can go on by means of the automatic synchronization of (α,β,γ,Lt) , keeping (α1) constant.
Direction and speed control device according to anyone of the previous claims , for lift hydraulic equipment with lifting mechanism of 6 or 7 degrees of freedom (α,α1,β,γ, Lt, Lt1) and optionally (ε) for a jib , comprising at least 2 telescopic booms articulating with each other , being (α1) the inclination angle of the upper telescopic boom (13a) referred to the horizontal line and (Lt1) its length , characterized in that the electronic controller (3) implements the following logic of synchronism along a curvilinear movement of the basket (9) (9a) , with or without rectilinear sections , which corresponds exactly to the actual operating direction of the joystick (8a) or (8b) at any instant:
- According to a first option based on a selector switch (8d), the control device (10) performs the movement commanded , synchronizing the degrees of freedom (α,Lt,β,γ ) , keeping constant the values (ε,α1,Lt1).

- According to a second option based on a selector switch (8d), the control device (10) performs the movement commanded , synchronizing the degrees of freedom (α1,Lt1,β,γ) keeping constant the values (ε, α, Lt).

- According to a third option based on a selector switch (8d), the control device (10) performs the movement commanded , synchronizing the degrees of freedom , (α1, α, Lt1 ,Lt , β,γ) keeping constant the angle (ε) . The control device (10), moves the end point of the lower telescopic boom (13M) according to the direction and speed of command , by means of the synchronization of the degrees of freedom (α, Lt ) , and simultaneously it moves the end point of the upper telescopic boom (13N) according to the direction and speed of command , by means of the synchronization of (α1, Lt1 ,β,γ).

- According to a fourth option based on a selector switch (8d), if it is a movement at constant height , while the lower telescopic boom (13) does not reach the minimum or maximum length, the control device (10) synchronizes the degrees of freedom (α,β,γ,Lt) , keeping constant (α1, Lt1 , ε). Once the minimum or maximum length of the lower telescopic boom (13) is reached, the movement of la basket (9) (9a) goes on according to the direction of command, by means of the synchronization of the degrees of freedom (α1, Lt1, β,γ), keeping constant (α , Lt , ε). Once the minimum or maximum length of both telescopic booms (13) (13a) are reached , the control device combines the degrees of freedom (α,α1, β,γ) keeping constant ( Lt , Lt1, ε) in such a way that the angle (α1) tends towards 0 º if movement is extending out the lifting mechanism, or so that the angle (α1) tends towards -90 º if the movement is retracting the mechanism.
If it is a raising/lowering movement , while the lower telescopic boom (13) does not reach the minimum/maximum length, the control device (10) synchronizes the degrees of freedom (α, Lt , β,γ) , keeping constant the angle (α1, Lt1 , ε) . If the minimum or maximum length of the lower telescopic boom (13) is reached, the control device (10) synchronizes (α1, Lt1 β,γ) , keeping constant (α,Lt , ε) until the minimum/maximum length of the upper telescopic boom (13a) is reached. If the minimum/maximum length of both telescopic booms are reached, then the control device (10) synchronizes (α,α1,β,γ) keeping constant (Lt , Lt1 ε) until the angle (α1) reaches the value 0º (horizontal). Once this point is reached, the raising/lowering movement goes on synchronizing (Lt1 ,α1,β,γ) , keeping constant (α, Lt ε) .
Direction and speed control device according to the previous claims , characterized in that optionally it comprises between 1 and 3 distance sensors (8s) which measure the distance from a plane of the tool (9a) to the closest surface in front of it , with the objective of calculating and defining a direction of movement , parallel to the curved surface , which replaces the operating direction of the joystick and thus enabling the control device (10) to perform automatic raising/lowering movements or movements at constant height along curvilinear or rectilinear surfaces without operator, automatically and without programming requirements . With the information of these distance sensors (8s) , together with the signals of the sensors of the position detection means (1) which are linked to the degrees of freedom of the lifting mechanism , the control device (10) is able to keep exactly constant the speed of the tool (9a) and its distance to the curved surfaces , by means of the automatic synchronization of the degrees of freedom of the lifting mechanism involved in the movement. This automatic synchronization is achieved thanks to the right definition of the values of the regulation and control means (6) , which are calculated by the electronic controller (3) taking into account the position and kinematic analysis as well as the bending deformation of the lifting mechanism.
Direction and speed control device according to the previous claims , characterized in that optionally it comprises a temperature detection means (5), which input to the microcontroller (3) the information concerning the hydraulic fluid temperature of the actuating system . The microcontroller (3) corrects , according to this input, the synchronization signals of the regulation and control means (6) for improving the smoothness of movements and accuracy of trajectories.
Direction and speed control device according to the previous claims , characterized in that the position detection means (1) optionally , in addition comprise three electromagnetic distance sensors which measure the distance from three fixed points located at the chassis ( 11) to centre of rotation of the basket (9). By reading these three measurements, the electronic controller (3) calculates by the triangulation method , the position of the basket (9) in the fixed reference frame xyz at any instant, regardless of the bending deformation of the lifting mechanism , and it uses this data to calculate the outputs for the regulation means (6) , in order to accurately synchronize the degrees of freedom of the lifting mechanism.
Direction and speed control device according to the previous claims , characterized in that optionally the single axis joystick (8ab) and the dual axis joystick (8a), may be integrated together in a single joystick with 3 axes of control.
Direction and speed control device according to the previous claims, characterized in that it comprises a system for determining the bending deflection of the lifting mechanism, that consist of the engineering calculation of the displacements due to bending of the nodes of the lifting mechanism , carried out by the electronic controller (3) , which takes as only input data , the direct or indirect measurement of the load (4) in the basket, data from a unit (2) which contains information about the stiffness properties and dimensions of the elements of the lifting mechanism, and the relative position between them according to the information given by the position detection means (1) .