Abstract:
In a method for controlling a pedal- and motor-driven bicycle, the motor in the vehicle being able to assist the driver at least in a pushing operation, the movement or state variable of the pedal is compared with a threshold value in the pushing operation, and the driving of the vehicle is modified at least briefly as a function of the exceeding or not attaining of this threshold value.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method and a device for controlling a motor of a pedal- and motor-operated vehicle. 
     2. Description of the Related Art 
     Over the past few years, the use of bicycles equipped both with a muscle-powered and a motor-powered drive has been increasing. So-called electric bicycles such as E-bikes or Pedelec are equipped with a drive system which uses pedals as well as an installed motor. Depending on the development of the electric bike, the motor may provide the sole drive during conventional use or also only a supporting component of the locomotion that supports the driver in the pedal operation. 
     In addition, the installed motor may also support the driver when the bike is being pushed. In this case, no operation of the pedals by the driver is provided, so that it may be necessary to set a special support mode at the electric bicycle. 
     To use the motor as pushing aid, it is therefore possible to set the desired support via an appropriate adjustment in the HMI or the control unit of the electric bicycle, for example. The (pushing) driver will then be able to move the vehicle without much exertion because the motor of the electric bicycle moves the electric bike virtually by itself in the walking direction, without any pedal operation by the driver being necessary. This has the advantage that the driver finds it much easier to move the electric bicycle across ramps (for baby carriages) provided with steps along the side or in the middle. However, it should not be overlooked that the pedals, which are fixedly coupled to the motor and rotate along, are located at the level of the legs of the (pushing) driver. Because the driver in this (or a similar) situation may possibly not be fully aware of the rotating pedals, the legs can easily be injured by the pedals, particularly since the motor continues to drive the pedals. 
     Furthermore, a danger potential also exists in case of a sudden obstacle that the pedals may encounter, e.g., a stair step or a stone, since such an obstruction hampers safe pushing. 
     BRIEF SUMMARY OF THE INVENTION 
     A method as well as a control device for a pedal- and motor-driven vehicle such as a bicycle is described by the present invention. The motor in the vehicle is able to assist the driver at least in a pushing operation. The core of the present invention concerns the option of controlling this automatic driving of the motor in a pushing operation under certain circumstances, by modifying it at least briefly, such as reducing or stopping it completely. 
     This has the advantage that the driver while pushing does indeed obtain some assistance by the motor-supported drive on the one hand, but will not be injured as a result of sudden resistance of the pedal rotation by uncontrolled driving. 
     According to the present invention, the movement or the state of at least one pedal is detected in order to avoid such undesired driving. The drive or the drive output of the motor is then at least briefly varied or reduced as a function of this movement or state. 
     In one development of the invention, the pedal motion is detected as a function of the applied torque, the (rotational) speed or the acceleration/deceleration behavior of the pedals, the revolutions per minute and/or the force that is acting on the pedals. 
     In an advantageous manner, the movement or state variable of the at least one pedal is compared with a threshold value in order to modify the driving of the vehicle at least briefly as a function of the exceeding or not attaining of this threshold value. For example, it is provided that the drive output of the motor is reduced or the motor even switched off completely in a sudden deceleration of the pedal movement or a detected counteracting force that occurs when the pedals strike an obstacle. 
     Optionally, it may also be provided that the motor or the driving is interrupted only briefly, whereupon the movement or the state of the pedals is checked again following a certain time interval. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically shows the design of a device according to the present invention. 
         FIG. 2  shows a flow chart which illustrates one possible realization of the control method of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As already explained in the introduction, the present invention is used in pedal- and motor-driven vehicles such as electric bikes, in which pushing assistance is provided by the motor in the form of a support mode, and the pedals and the motor are linked to each other. To monitor the pedal movement or the state of the pedals, a control device  100  is provided, which, for instance, may be accommodated in an HMI (human-machine interface) or in a separate control unit. As illustrated in  FIG. 1 , a processing unit  110  is provided in this control unit  100 , which is connected to at least one sensor  130  on the one side, and optionally, to a memory  120 . Starting from the sensor variable, e.g., a torque  135  detected by a torque sensor  130 , processing unit  110  is able to carry out a comparison with a stored threshold value SWDreh. Depending on the result, motor  160  may subsequently be actuated in that, for example, the drive torque or the entire drive output is reduced either in part or completely. Instead of torque  135  of the pedals, it is also possible to use a suitable sensor  140  to monitor the (rotational) speed, the revolutions per minute or the acceleration of the pedals. Using these variables  145  as well, it is possible to detect whether the pedals are encountering an obstacle and are braked abruptly. Finally, the use of a force sensor  150  is another option, which detects force  155  that is acting on the pedals when they strike an obstacle in a direct manner. Such force sensors  150  are already provided in some electric bikes for estimating the actuation of the pedals by the driver, and consequently for estimating the degree of driving support provided by the motor. A corresponding threshold value for each of the detected variables is of course able to be stored in memory  120  and called up. 
     One possible sequence of the monitoring or control method of the present invention is illustrated in  FIG. 2 . In this context it may be provided that the algorithm is started automatically when the support or pushing mode is initiated. As an alternative, however, this may be preceded by another check step, which checks whether the speed of the vehicle is below a predefined threshold, e.g., a threshold that corresponds to a typical pushing behavior. Conceivable, for example, is a threshold of 4 to 6 km/h. This check is to prevent an unintended interruption of the drive during a conventional driving operation. 
     After the algorithm is started, it may be checked in a first optional step  200  whether the bicycle is moving at all. If the bicycle is stationary, the algorithm can be interrupted. In this case, however, it must be assumed that the support or push mode is switched off as well. In the following step  210 , a variable is then detected that characterizes the movement of the pedals or the state of the pedal movement. As explained already, this movement is detectable by recording torque  135 , (rotational) speed  145 , the revolutions per minute, the acceleration or force  155  acting on the pedals. In order to detect a change in movement, e.g., due to the pedals hitting an obstacle (such as a stair, stone, calf or leg), it is checked in next step  220  whether the detected variable is experiencing an abrupt change. This is realized in the current step in that it is checked whether the variable exceeds a threshold value or has dropped below such a threshold value. For example, an abrupt deceleration makes it possible to detect the obstacle or obstruction in the pedal movement. When the torque is taken into consideration, the fact that the pedal has hit an obstacle may be detected by an increase in the variable. In this context, a threshold value that is greater than zero may possibly be selected, in order to disregard smaller obstacles. In general, however, a threshold value that differs from zero or from a value that differs only slightly from zero, for example, may be used for this check. In the event that this threshold value is not exceeded, i.e., it is determined that the pedals are moving freely or the obstruction is of no particular significance, the algorithm will be ended. In the other case, motor  160 , which supplies the thrust for the push assistance, is actuated in step  230 . In so doing, the motor output may be deactivated in a stepwise manner, using a flank, or reduced immediately or switched off completely. 
     In steps  210  and  220 , the detection of more than one variable and the comparison with the corresponding threshold values is able to be implemented as well in an alternative development. This has the advantage that because of the detection of two independent values, the precision in detecting an obstruction of the pedals, and thus in determining the intervention in the motor control, is increased. 
     When executing the algorithm in  FIG. 2 , it may alternatively also be provided that a loop to step  200  or  210  takes place from step  220 , or following the actuation of the motor in step  230 .