Abstract:
The invention relates to a drive control means, in particular for controlling a windscreen wiper drive of a motor vehicle, having a first interface and a second interface, wherein, after receiving control information via the first interface, the drive control means is arranged to configure itself in a master role and to output control information via the second interface in order to control a further drive control means.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to a drive control means, in particular for controlling a windscreen wiper drive of a motor vehicle. 
         [0002]    Motor vehicles have windscreen wipers in order to clear moisture and dirt from the window panes of the motor vehicle. A windscreen wiper comprises a drive, a wiper arm and a wiper blade. The drive transmits an oscillating movement to the wiper arm, which guides the wiper blade across the window pane. Windscreens of passenger cars are normally equipped with two adjacent wipers. In order to avoid a mechanical connection between the wiper arms of both windscreen wipers, each windscreen wiper can have its own drive associated therewith, wherein the drives are synchronized in order to prevent a collision of the wiper arms or respectively the wiper blades and in order to maintain a predetermined sequence of movement of the windscreen wipers. Each of the drives comprises a control means associated therewith. Depending upon the configuration of the entire windshield wiper system, one of the control means in the role of the “master” defines the movement to be performed by both of the wiper arms and transmits certain items of movement information to the other control means, which in the role of the “slave” follows this lead. Both control means furthermore control the drives associated with them. 
         [0003]    The aim of the invention is to provide a drive control means, which allows for a dynamic association of the roles in a two wiper system. 
       SUMMARY OF THE INVENTION 
       [0004]    According to the invention, a drive control means comprises a first and a second interface, in particular to control a windscreen wiper drive of a motor vehicle. If the drive control means receives control information via the first interface, said means configures itself in the master role and outputs control information via the second interface. If, on the other hand, the drive control means receives only data via the second interface, said means can then configure itself in the slave role. Two such drive control means, the respective second interfaces of which are connected to one another, are located in a control system for two windscreen wipers of a motor vehicle. 
         [0005]    In order to equip or provide a motor vehicle with windscreen wiper systems or replacement parts, it is consequently no longer required to differentiate between different drive control means. Management, storage and production costs can therefore be saved. Moreover, it is readily possible to change an existing distribution of the master or slave roles onto two drive control means by removing the connection of the control module to the first interface of one of the drive control means and connecting it instead to the first interface of the other drive control means. 
         [0006]    The drive control means can configure itself as slave in the event that no control information could be received via the first interface over a predetermined period of time. As a result, a configuration of a plurality of drive control means as master in a system, which can lead to operational malfunctions, is unlikely. The configuration as master or as slave can be reversed by control information being received via the first interface, which if need be triggers a new configuration of the drive control means, parallel to an operation in the respective role. This increases a configuration speed and allows the drive control means to be more easily managed. 
         [0007]    The drive control means can be configured to exchange control information, which comprises a target position and an actual position of a drive that is connected to one of the drive control means, via the second interface. In so doing, the drive control means configured as master can transmit a target position and receive an actual position. A collision detection can, for example, be implemented using this information if one of the wiper arms meets resistance and continues operation at a reduced speed or stops. The drive control means configured as master can resolve such a collision by allowing one or both of the drives to run in a predetermined sequence and at a predetermined speed in a suitable direction. 
         [0008]    The drive control means can access at least two stored characteristic curves and in a configuration in the master role control the drive according to a first characteristic curve and in a configuration in the slave role according to a second characteristic curve. The characteristic curves define a temporal course of a movement of the drive or respectively the wiper arm. A characteristic course of movement of a drive connected to the drive control means can therefore vary depending upon whether said drive control means is configured as master or as slave. This allows for an interaction in the course of movement of the drives to change by reconfiguring the master and slave roles. In addition, a communication complexity between two drive control means is minimized by the local processing of characteristic curves. 
         [0009]    The drive control means can be arranged to configure itself as slave in cases of doubt, for instance after receiving control information via the first as well as the second interface. Mechanical and data collisions can thereby be avoided if both drive control means try to assume the master role. 
         [0010]    If the drive control means does not receive any control information via one of the interfaces thereof over a predetermined period of time, said means can bring a drive associated therewith into a park position. If an error occurs, said means can prevent the drive from remaining in a position where it disrupts the operational dependability of the motor vehicle or where it represents a potential obstacle for the second drive. 
         [0011]    According to a further aspect, the invention comprises a method for controlling two drives, with which a drive control means is associated in each case. A first drive control means receives control information via a first interface and thereupon outputs control information to a second drive control means via the second interface thereof. Each drive control means controls a drive associated therewith. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The invention is now explained in detail while making reference to the accompanying figures, in which 
           [0013]      FIG. 1  shows a control system for windscreen wipers of a motor vehicle; 
           [0014]      FIGS. 2   a  and  2   b  show windscreen wiper arrangements to be operated by means of the control system from  FIG. 1 ; 
           [0015]      FIG. 3  shows a characteristic curve diagram comprising wiper characteristic curves of the drives of the control system from  FIG. 1 ; and 
           [0016]      FIG. 4  shows a method for controlling the control system from  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0017]      FIG. 1  shows a control system  100  for windscreen wipers in a motor vehicle  105 . The control system  100  comprises a control module  110 , a first drive control means  115  and a second drive control means  120 . A first drive  125  is associated with the first drive control means  115  and a second drive  130  is associated with the second drive control means  120 . The first drive  125  operates a first wiper arm  135  and the second drive  130  operates a second wiper arm  140 . Said first drive control means  115  comprises a first interface  145  and a second interface  150 . Said second drive control means  120  comprises a first interface  155  and a second interface  160 . The control module  110  is connected to a first interface  145  of said first drive control means  115  by means of a first connection  165 . A second connection  170  runs from the second interface  150  of said first drive control means  115  to the second interface  160  of said second drive control means  120 . 
         [0018]    The control module  110  is a part of an electrical system of the motor vehicle  105  and communicates at regular intervals with the first drive control means  115 . In so doing, information is exchanged irrespective of which operating state the first drive  125  and the second drive  130  assume. The items of information exchanged can include configuration, status and operating parameters. The first connection  165  can be part of a LIN bus. On the basis of information transmitted by the control module  110  via the first interface  145 , for example items of control information, said first drive control means  115  recognizes that it is to be configured as master. Said first drive control means  115  thereupon controls the drive  125  associated therewith according to the information, which it receives via the first interface  145  thereof and sends via the second interface  150  thereof and the second connection  170  corresponding information to the second interface  160  of the second drive control means  120 . Said second drive control means  120 , the first interface  155  of which is not connected to any communication partner, recognizes by the absence of information via the first interface  155  thereof that it is to configure itself as slave. Said second drive control means thereupon evaluates information received via the second interface  160  thereof and controls the drive  130  associated therewith according to the information that has been received. The second connection  170  can, for example, be a Carline connection. 
         [0019]    The drives  125  and  130  are direct current motors, which act on the wiper arms  135  and  140  by means of a gear mechanism. Sensors (not depicted) are attached to the drives or to the gear mechanisms in order to determine an actual movement or an absolute position of the wiper arms  135  or  140 . The drive control means  115  and  120  are connected to these sensors and actuate said drives  125  or respectively  130  as a function of the information received from the sensors and via the interfaces  145  or respectively  160 . Said drive control means  115  and  120  comprise in each case H-bridges (not depicted) for selecting a rotational direction of said drives  125  and  130 . Said drive control means  115  and  120  can be designed as integral parts of said drives  125  or respectively  130 . 
         [0020]      FIGS. 2   a  and  2   b  show two different windscreen wiper arrangements  200  of a motor vehicle for controlling by means of the control system  100  from  FIG. 1 . The stylized views of  FIGS. 2 and 2   a  ensue from the interior of the motor vehicle  105 . The windscreen wiper arrangement  200  comprises in each case a windscreen  205  of the motor vehicle  105  and in each case two windscreen wipers  210 - 225 . Each windscreen wiper  210 - 225  comprises in each case a drive such as the drives  125 ,  130  in  FIG. 1 , a wiper arm such as the wiper arms  135 ,  140  from  FIG. 1  and a wiper blade (without reference numeral). 
         [0021]    In  FIG. 2   a , a right windscreen wiper  210  and a left windscreen wiper  215  are arranged to run in opposite directions, i.e. when the left windscreen wiper  210  is moved counterclockwise, the right windscreen wiper is then moved clockwise and vice versa. In a resting position depicted, that windscreen wiper  210 ,  215 , which is associated with a driver&#39;s side of the motor vehicle  105 , is staggered with the windscreen wiper  215 ,  210 , which is assigned to a passenger side of said motor vehicle  105 , in such a way that the driver&#39;s side windscreen wiper  210 ,  215  can also then be moved if the passenger&#39;s side windscreen wiper  215 ,  210  remains in the resting position thereof. In so doing, said driver&#39;s side windscreen wiper is assigned to the first drive control means  115 , which is configured as master, so that an operation of said driver&#39;s side windscreen wiper  210 ,  215  is not dependent upon the operability of the drive control means  115 ,  120 , which is configured as slave, or the windscreen wiper  215 ,  210  associated therewith. Depending upon whether the motor vehicle  105  is driven from the right or left side, the left widescreen wiper  210  or the right windscreen wiper  215  is connected to the first drive control means  115  which is configured as master. Park positions for each windscreen wiper  210 ,  215  are selected in such a way that vision through the wind screen  205  is obstructed as little as possible for an occupant of the motor vehicle  105  and at the same time a movement of the respective other windscreen wiper  210 ,  215  is possible without collision. This is the case for each windscreen wiper  210 ,  215  at both ends of the pivoting movement thereof. 
         [0022]    The windscreen wiper arrangement  200  in  FIG. 2   b  comprises a left windscreen wiper  220  and a right windscreen wiper  225 , which vary in the position of their axes of rotation and their resting positions from the windscreen wipers  210  and  215  of  FIG. 2   a . The windscreen wipers  220  and  225  operate concurrently, i.e. they move substantially synchronously to each other with regard to their clockwise or counterclockwise direction of rotation. The position of the left windscreen wiper  220  already establishes the association thereof to the driver&#39;s side of the motor vehicle  105  because the portion of the windscreen  205  that is swept by said left windscreen wiper  220  corresponds to an optimal viewing window for a driver of the motor vehicle  105 . An unswept first remaining portion of the windscreen  205  lies in the region of the center of said windscreen  205 . The right windscreen wiper  225  is situated on the passenger&#39;s side of the motor vehicle  105 , wherein an unswept second remaining portion of said windscreen  205  in the upper right corner thereof presents less of a problem for a passenger in the vehicle. The left windscreen wiper  220  is associated with the first drive control means  115  in  FIG. 1 , which is configured as master. Park positions also result here as previously described in reference to  FIG. 2   b.    
         [0023]      FIG. 3  shows a characteristic curve diagram  300  for drives  125  and  130  of the control system  100  from  FIG. 1 . Time is plotted in the horizontal direction and an angle of rotation N of the windscreen wipers  210 ,  215  of the windscreen wiper arrangement  200  in  FIG. 2   a  or respectively of the wiper arms  135  and  140  of the control system  100  in  FIG. 1  is plotted in a vertical direction. The angles of rotation correspond to deflections from resting positions and are specified as amounts. A first wiper characteristic curve  310  corresponds to the left windscreen wiper  210  in  FIG. 2   a , which is controlled by means of the first drive  125  of the first drive control means  115 , which is configured as master. A second wiper characteristic curve  320  corresponds to the right windscreen wiper  215 , which is controlled by means of the second drive  130  of the second drive control means  120 , which is configured as slave. 
         [0024]    At a point in time T 0 , the angles of rotation N of the two wiper characteristic curves  310  and  320  are likewise 0. In a region between T 0  and T 1 , the angle of rotation N of the second wiper characteristic curve  320  initially increases faster than that of the first wiper characteristic curve  310  up until the point in time T 1  where both wiper characteristic curves  310  and  320  reach the maximum angle of rotation N max . In like fashion, both of said wiper characteristic curves  310  and  320  return again to 0 between T 1  and T 2 . That means that said first wiper characteristic curve initially drops before said second wiper characteristic curve  320  drops. 
         [0025]    The reason why the course of the first wiper characteristic curve  310  and the second wiper characteristic curve  320  do not match is based on the fact that the left windscreen wiper  210  in  FIG. 2   a  has to be deflected by a certain amount before the right windscreen wiper  215  can be deflected without colliding with said left windscreen wiper  210 . Said windscreen wipers  210  and  215  have achieved their maximum deflection N max  if said left windscreen wiper  210  is maximally deflected in a counterclockwise direction and said right windscreen wiper  215  is maximally deflected in a clockwise direction. From this location a return movement of said windscreen wipers  210  and  215  proceeds accordingly, i.e. said right windscreen wiper  215  runs ahead of said left windscreen wiper  210  with regard to the angle of rotation thereof in order to facilitate a collision-free movement. 
         [0026]      FIG. 4  shows a method for controlling the drives  125  or respectively  130 , which is to be carried out on the first drive control means  115  or respectively on the second drive control means  120  from  FIG. 1 . The method comprises the steps  405  to  450 . 
         [0027]    The method  400  is located in the starting state in step  405 . In step  410  a timer is started in order to monitor a passing of a predetermined period of time. Control information is subsequently received in step  415  via the first interface  145  or respectively  155 . A check is subsequently made in step  420  to determine whether control information is actually present. If this is the case, further items of control information are outputted via the second interface  150  or respectively  160  in the following step  425 . In step  430 , that drive  125 ,  130 , which is associated with the drive control means in which the method  400  is executed, is controlled in accordance with the control information which was received via the first interface  145  or respectively  155 . Further items of control information are thereupon received via the first interface  145  or respectively  155  and the method returns back to step  425 . 
         [0028]    If, however, it is determined in step  420  that no items of control information are present, a check is then made in step  440  to determine whether the timer has run down in the meantime. If this is not the case, the method continues with step  415  and receives further items of control information. Otherwise control information is received via the second interface  150  or respectively  160  in step  445 . The drive  125 ,  130 , which is associated with the drive control means  115 ,  120  in which the method  400  is executed, is subsequently controlled in step  450  according to the control information received via said interface  150  or respectively  160 . Thereafter the method  400  returns to step  445 . 
         [0029]    The first infinite loop over the steps  425 ,  430  and  435  corresponds to a configuration of a drive control means  115  or  120  as master; whereas the second infinite loop over the steps  445  and  450  corresponds to a configuration as slave. 
         [0030]    Other sequences are likewise possible, in particular those, which allow the infinite loops to be broken out of within the scope of a reconfiguration. To meet this end, steps for receiving data via the first interface and for checking received control information, said steps being analogous to steps  410 - 440 , are run through within the loops. Additional procedural steps are, for example, possible within the scope of a collision resolution, an emergency operational sequence in the event that the individual components of the windscreen wiper system malfunction or within the scope of a method for moving into a park position.