Abstract:
The invention relates to a device for monitoring the safety of a bending pole ( 22 ) in a large manipulator, whereby the arms ( 23 - 27 ) of the mast can be pivoted in relation to each other by means of a drive unit ( 34 - 38 ). The relative position of the arms of the mast in relation to the respective adjacent arm of the mast or frame of the mast ( 21 ) is measured for adjusting the position thereof. According to the invention, the positing measuring values (ε I ) of the arms of the mast are used in order to control the safety of the drive units ( 34 - 38 ) or the actuators thereof ( 80 - 84 ) in relation to a variation of predefined safety values.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention concerns a device for operating an articulated boom, more particularly a concrete placement boom, linked to a boom block, which articulated boom includes at least two boom arms which are respectively limitedly pivotable relative to the boom block or relative to an adjacent boom arm about respective horizontal articulation axes, which articulation axes are parallel to each other, by means of a preferably hydraulic operated drive unit, via a preferably remote control device including a position controller for movement of the boom with the aid of the individual actuating elements associated with the individual drive units, and with sensors associated with the individual boom arms, articulation axes and/or drive axes for the path or angle measurement for position control. The invention further concerns a large manipulator, in particular for concrete pumps, with an articulated boom linked to the boom block and with a device for operating thereof of the type described above.  
           [0003]    2. Description of the Related Art  
           [0004]    Mobile concrete pumps are conventionally operated by an operator, who is responsible not only for the control of the pump but also for the positioning of the distribution hose which is provided at the tip of the articulated boom. The operator must control multiple rotational degrees of freedom of the articulated boom via the associated drive units with movement of the articulated boom in non-structured three dimensional work space with due consideration of the boundary conditions existing at the construction site. In order to simplify the manipulation or operation in this respect, and operating device has already been proposed (DE-A-430627) in which the redundant articulated axes of the articulated boom are controllable collectively with one single control manipulation of the remote control device in any rotational position of the boom base, independent of the rotation axis thereof. Therein the articulation boom carries out an extension and retraction movement which can be observed by the operator, wherein in addition the elevation or height of the boom tip can be maintained constant. In order to make this possible, the control device includes a remote control device controllable, computer supported coordinate transformer for the drive units, via which the drive units of the articulated boom are actuated in the one main adjustment direction of the remote control device independently of the drive unit for the rotation of the boom base with accomplishment of an extension or retraction movement of the articulated boom while maintaining a predetermined height of the boom tip. In a different main adjustment direction of the remote control device the drive unit or drive unit of the rotation axis of the boom base is operable independent of the drive units of the articulated axis with carrying out a rotation movement of the articulated boom, while in a third main adjustment direction the drive units of the articulated axis are operable independently of the drive units of the rotation axis while carrying out a raising and lowering movement of the boom tip. A basic precondition for such an operation of the articulated boom is a position controller which includes among other things a sensor or sensor logic for the path or angle measurement associated with the individual boom arms, articulation axes and/or drive units. Since faults in technical systems of this type, which include not only mechanical but also electronic and hydraulic components, cannot be completely avoided, there is a need for a safety monitoring system which warns the user and when necessary takes action for safety purposes. Therein it is necessary, to recognize and evaluate the occurring problems by sensing with the objective to overcome the faults at least temporarily and to prevent undesired faulty operations and damage. A turning off of the boom and pump functions has until now been possible using an emergency turnoff switch, which is operated by the user.  
         SUMMARY OF THE INVENTION  
         [0005]    Beginning therewith, it is the task of the present invention to improve the large manipulator of the above-described type in such a manner that safety monitoring becomes possible independent of the operator.  
           [0006]    For solving this task, there is proposed the combination of characteristics as set forth in Patent claims 1, 11 and 21. Advantageous embodiments and further developments of the invention can be seen in the dependent claims.  
           [0007]    The inventive solution is based upon the realization, that the sensors for the path or angle determination, which are already present for position control, can, by taking into consideration additional criteria which occur in the case of specific failures, make possible an automatic safety monitoring. In order to accomplish this, it is proposed in accordance with the invention that the operating device includes a safety program, taking into consideration sensors for controlling the actuating elements, according to the value of predetermined safety criteria. A particularly important part of the operating device is comprised therein, that the safety program includes at least one evaluation component for output of an acoustic or optical warning signal, which alerts the operator to the occurrence of faults.  
           [0008]    According to a preferred embodiment of the invention, wherein each drive unit includes a double acting or reciprocating hydraulic cylinder, the hydraulic cylinders are acted upon with hydraulic fluid via respectively one proportional changeover valve forming the associated actuating element, and the proportional changeover valves are supplied with hydraulic fluid via a common supply line, it is proposed in accordance with the invention that the supply line is provided with a supply valve which is controllable via the safety program. Depending upon the condition of the supply valve upon occurrence of the fault, it can be switched open or closed on the basis of the evaluation of the fundamental safety criteria. The supply valve can in addition be assigned a supplemental function. For example it can be designed within the system as a simplex or half duplex operation valve for selective supplying of the boom arm valves and the support arm valves.  
           [0009]    Preferably the safety program can include various evaluation components, which individually or in combination address  
           [0010]    the condition of the switching of the supply valve,  
           [0011]    the presence or absence of control input via the remote control,  
           [0012]    control deviations with reference to the path or angle, which are greater than predetermined threshold values,  
           [0013]    the speed of path or angle control deviations which are greater than the predetermined threshold valves, and  
           [0014]    angular velocities which are greater than predetermined threshold valves.  
           [0015]    Further, pressure sensors can be provided on the piston side and rod side ends of the drive unit which is in the form of a hydraulic cylinder, wherein the safety program or protocol includes an evaluation component responsive to the output data of the pressure sensors.  
           [0016]    An aspect of the invention is a large manipulator with the above-described characteristics of a boom operating device with safety features.  
           [0017]    The inventive features can also be defined in process terms, in that for the safety monitoring of an articulated boom in a large manipulator, in which the boom arms of the articulated boom are pivotable relative to each other by means of a drive unit and the relative position of the boom arms relative to the boom block or to an adjacent boom arm are continuously monitored for position control, it is the position measuring values of the boom arms that are used for safety control of the actuating elements in accordance with a deviation from predetermined safety threshold values. In particular, a warning signal can be triggered upon exceeding the safety threshold values. If the drive units for the boom arms are driven hydraulically using hydraulic fluid, it has been found to be particularly advantageous, that upon a deviation from the predetermined safety threshold values the supply of hydraulic fluid is switched off or, depending upon circumstances, switched to the drive units. In particular in the case of stationary operation with switched off hydraulic fluid supply, the hydraulic fluid supply and therewith also the position control is switched on when the angle velocity is not zero and a predetermined deviation threshold is not exceeded. The term “stationary operation” is herein intended to mean pump operation without movement of the articulated boom. The low angular velocity indicates, as the evaluation criteria, a small leak in the hydraulic system or an actuating element or drive unit with a small defect, wherein in an emergency operation still a controlled return guidance of the articulated boom in a safe transport position with assistance of the position controller is possible. If however the predetermined angular velocity threshold is exceeded, then the hydraulic oil supply and therewith also the position control remains switched off. The operator must then secure the articulated mast on-site or take measures for transporting.  
           [0018]    A similar situation occurs when in the movement operation the speed or velocity of the control deviation exceeds a predetermined threshold. In this situation, in the case of turned-on hydraulic fluids supply, the hydraulic fluid supply and therewith also the position control are switched off. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    In the following the invention will be described in greater detail on the basis of a illustrative embodiment shown in schematic manner in the figure. There is shown  
         [0020]    [0020]FIG. 1 a side view of a mobile concrete pump with collapsed articulated boom;  
         [0021]    [0021]FIG. 2 a mobile concrete pump according to FIG. 1 with articulated boom in working position;  
         [0022]    [0022]FIG. 3 a flow diagram of a device for operating the articulated mast with safety monitoring;  
         [0023]    [0023]FIG. 4 a flow diagram of an axis-based safety protocol. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0024]    The mobile concrete pump  10  includes a transport vehicle  11 , a thick matter pump  12  in the form of for example a two cylinder piston pump as well as a concrete placement boom  14  rotatable about a vehicle-fixed vertical axis  13  as carrier for a concrete distribution line  16 . Via the concrete distribution line  16  fluid concrete, which is introduced continuously into a supply container  17  during concretizing, is conveyed to a concretizing location  18  located distant from the location of the vehicle  11 .  
         [0025]    The placement boom  14  is comprised of a boom block  21  rotatable about the vertical axis  13  via a hydraulic rotation drive  19  and an articulated boom  22  which is continuously adjustable to various reaches r and height differentials h between the vehicle  11  and the concretization location  18 . The articulated boom  22  is comprised in the illustrated embodiment of five articulated boom arms  22  through  27  connected to each other, which are pivotable about axes  28  to  32  running parallel to each other and at right angles to the vertical axis  13  of the placement boom  21 . The articulation angle ε 1  through ε 5  (FIG. 2) of the articulated linkages formed by the articulated axes  28  to  32  and their orientation or arrangement relative to each other is so determined relative to each other that the placement boom  14 , as can be seen from FIG. 1, following multiple folding, is collapsible to a space-saving transport configuration upon the vehicle  11 . By an activation of drive units  34  to  38 , which are individually associated with the articulation axes  28  to  32 , the articulated boom  22  can be unfolded to various distances r and/or height differentials h between the concretizing location  18  and the vehicle location (FIG. 2).  
         [0026]    The remote control device  50  includes in the illustrated embodiment a remote control element  60  in the form of a control lever, which can be moved in three main directions back and forth with output of control signals  64 . The control signals are transmitted along a radio wave transmission path  68  to a radio receiver  70  integrated in the vehicle, the output of which receiver is connected to a micro-controller  74  via a bus system  72  in the form of, for example, a CAN-bus. The micro-controller  74  includes a software module  76 ,  77  which interprets the control signals  64  received from the remote control device  50 , transforms and translates these via a position controller  92  and a subsequent arranged signal provider  94  into operating signals for the drive units  34  through  36 . The operation or actuation of the drive units  34  through  36  occurs via the actuator elements  80  through  84  which are in the form of proportional changeover valves, which are connected with their outlet lines  86 ,  87  to the piston side and rod side of the drive units  34  through  38  which are in the form of double acting hydraulic cylinders. The drive unit  19  for the boom block  21  is in the form of a hydraulic rotation drive, which is controlled via the actuating element  85 .  
         [0027]    Subsequent to the interpretation routine  76  is a software module in the form of a coordinate transformer  77 , of which it is the main task to transform the incoming control signal interpreted as cylinder coordinates φ,r,h into predetermined clock pulses into angle signals φ,ε I  for the rotation and tilt or inclination axis  13 ,  28  through  32 , wherein the drive units of the redundant articulated axis  28  to  32  of the articulated mast  22  are respectively operable or drivable according to the value of a predetermined path-tilt-characteristic. Each articulation axis  28  to  32  is so controlled using software within the coordinate transformer  77  that the articulated linkages move harmonically relative to each other as a function of path and time. The control of the redundant degrees of freedom of the articulated linkages occurs thus according to a preprogrammed strategy, with which the self collision with adjacent boom arms  23  through  27  can be precluded during the course of movement. For increasing precision it is, besides this, possible to make use of correction data stored in the memory for compensation of a load-dependent deformation. The angular changes achieved in this manner in the coordinate transformer  77  are compared in the position controller  92  with the intended values provided by the angle provider or controller  96  and converted via the signal provider  94  into actuation signals U ε for the drive units  19 ,  34  through  38 .  
         [0028]    Besides control via the coordinate provider  64 , which interprets the incoming data as cylinder coordinates and appropriately translates them (see DE-A-4306127), the individual drive units  19 ,  34  through  36  can also be controlled directly via the control element  60  and the associated actuation elements  66  through  76 .  
         [0029]    A feature of the device shown in FIG. 3 is comprised therein, that the micro-controller  74  of the control device includes an evaluation and safety program  100  responsive to the output data of the sensor  96  for controlling the actuating elements  80  through  84  in the form of proportional changeover valves depending upon the magnitude of the predetermined safety criteria. The actuating elements are acted upon with hydraulic pressure via pump  102  and a supply line  104 . An on/off supply valve  106  is located in the supply line  104 , which can be in the form of, for example, a simplex or half duplex operation valve, via which selectively also the chassis support leg hydraulics of the mobile concrete pump  10  is supplied. In the area of the supply valve  106  there is located an emergency shutoff switch  108 , via which the operator can in an emergency interrupt the supply of hydraulic fluid along supply line  104 . As described in greater detail below on the basis of FIG. 4, the evaluation and safety program  100  also acts via signal lines  110 ,  112  on the supply valve  106 . Besides this, in the case of a fault, the safety program can initiate an acoustic or optical signal device  114 . In the safety program  100  the measurement data of the angle provider  96  are evaluated, just as in the position controller  92 , on the basis of defined safety criteria and translated into control signals for the supply valve  106 , the warning signal emitter  114  and the signal provider  94  for controlling the actuating elements  80  through  84 .  
         [0030]    The safety monitoring in the evaluation and safety program  100  occurs with reference to the axes. By way of example and on the basis of the flow diagram shown in FIG. 4 the monitoring logic of an articulation axis is explained.  
         [0031]    The safety routine  100 ′ according to FIG. 4 includes evaluation components (safety criteria) for the following values:  
         [0032]    Input Values (Comparison Values)  
               ɛ        (   t   )       =            measured                 angle                 ɛ                                of                 the                                selected                                articulation                 axis                                at                                           time                 t                     ɛ   soll          (   t   )       =            intended                                value                 of                 the                 concerned                                angle                   Δɛ        (   t   )       =                ɛ   intended          (   t   )       -     ɛ        (   t   )                     =            control                                deviation                 at                 time                 t                   Δɛ   g     =            adjustable                                threshold                 value                                therefore                   V   ɛ     =            (       ɛ        (   t   )       -         ɛ        (     t   -     Δ                 t       )       /   Δ                   t                     =            angular                                velocity                 at                 time                 t                   V     ɛ   g       =            adjustable                                threshold                 value                                therefore                   (     for                                example                 0.3        °   /   s       )                     V   Δɛ     =            (       Δɛ        (   t   )       -         Δɛ        (     t   -     Δ                 t       )       /   Δ                   t                     =            change                 velocity                 of                                the                 control                 deviation                 at                                time                 t                   V     Δɛ   g       =            adjustable                 threshold                 value                 therefore                   F   ɛ     =            travel                                allowance                                for                                angle                 ɛ                 =            0        :                   angle                                ɛ                 maintaining                 ≠            0        :                   angle                 ɛ                                changing                   (   moving   )                     SV   =            control                 supply                   valve                             (     intended                 condition     )                                =            1        :                   hydraulic                                fluid                 sent                 to                 control                 elements                   (     releasing                 boom     )                            at                 the                 same                                time          :                     axis                 is                                controlled                 or                 blocked                 =            0        :                   hydraulic                 fluid                                blocked                                to                                control                 elements                          at                                the                 same                 time        :                   axis                 is                 not                 controlled                                or                 blocked                                 
 
         [0033]    Outvalues (Set Values)  
               SV   =            driving                 the                 supply                 valve                   (     intended                 condition     )                                  U   ɛ     =            control                 value                 for                 the                 actuating                 element                                for                                axis                                           ɛ                 S   =            warning                 signal                 at                                the                 signal                                  provider                             (       for                 example                 horn     ,   light     )                   =            1        :                   leakage                 warning                 =            2        :                   defect                 warning                 sensor        /        actuator                   RA   =            control                 internal                 error                 or                 failure                                cell                                         (     control                                deviation                 limit                 for                                  Δɛ   u                                  or                 as                                the                 case                 may                 be                                  V     Δɛ   g                                    is                 exceeded     )     .                                 
 
         [0034]    The axis-specific safety program  100 ′ is carried out in real time in predetermined time intervals. In the main branch there is sequentially checked the operating condition of the supply valve SV, the condition of the failure cell RA and the drive or extension input F ε . If in the main branch no impermissible deviations of the angular velocity V ε  and the control deviation Δε from the respective threshold value is determined, then the system is controllable, so that no error announcement is made (no reaction). If in contrast a threshold value is exceeded in the values V ε  or as the case may be Δε, then this is assumed to have the meaning of a significant defect, which can lead to a switching off of the axis movement (U ε =0) and to a blockage of the supply valve (SV=0). At the same time there is produced a defect warning sensor/actuator (S=2) via the signal device  114 . This setting or position has the same effect as an emergency cutoff, which gives the operator opportunity to find the source of the problem and to remedy the same or to bring the articulated boom into the transport position according to FIG. 1 using manual operation.  
         [0035]    The left branch of the safety program  100 ′ is run primarily in the stationary condition, when for example concrete is being extruded without movement of the articulated mast. In this case the supply valve  106  is closed (SV=0) and the position controller  92  is switched off. Nevertheless the angular velocity V ε  of the concerned axis is being continuously monitored by comparison with the associated threshold value V ε     g   . If a small change occurs, then the supply valve  106  is engaged (SV=1) and therewith the position control  92  is engaged. In the case of a large leakage (“no”-branch) the supply valve  106  and the position control  92  remain switched off. In both cases a leakage warning (S=1) is produced, which in the first case makes possible an emergency operation for controlled return of the articulated boom into a safe transport position with aid of the position controller. In the latter case the boom hydraulic is without pressure, so that only a recovery, however no operation of the articulated boom, is possible.  
         [0036]    The right branch in the flow diagram of the safety program  100 ′ shows the evaluation of safety criteria during the moving operation (F ε ≠0). The control value to the actuating element is in this case first U ε ≠0. It is sequentially checked whether the control deviation Δε and the change velocity of the control deviation V Δε  exceeds the respective threshold value. If this is not the case, then error-free normal operation must be occurring (no reaction). If at least one of the thresholds is exceeded, then the control value U ε  for the concerned actuating element is set to zero and the control internal error cell RA=1.  
         [0037]    Appropriate safety routines are carried out in real time operation for all axes of the system.  
         [0038]    In summary the following can be concluded: The invention concerns a device for monitoring the safety of an articulated boom  22  of a large manipulator, in which the mast arms  23  through  27  of the articulated boom  22  are pivotable relative to each other respectively via a drive unit  34  through  38 , wherein the relative position of the boom arms relative to the respective adjacent boom arm or mast block  21  is measured for position control. In accordance with the invention the position measured values ε I  of the boom arms are used for safety control of the drive unit  34  through  38  or as the case may be their actuation elements  80  through  84  depending upon the value of their deviation from the preset safety threshold values.