• 专利附录
  • 专利说明
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    • 专利摘要:
    In order to easily prevent a collision of transport units, which are moved along a conveying path of a conveyor, and / or the collision of a transport unit with a barrier and / or the crossing of a local speed limit, is determined in advance for at least a first transport unit (TEi) is whether a standstill maneuver (SMi) with predetermined kinematics can be performed for the transport unit (TEi), without causing a violation of these safety requirements. In the event of a violation of a safety requirement, the standstill maneuver is actually initiated.
    公开号:AT518354A1
    申请号:T50058/2016
    申请日:2016-02-02
    公开日:2017-09-15
    发明作者:Dipl Ing Dr Stefan Huber Msc；Ing Helmut Herzog Dipl
    申请人:Bernecker + Rainer Industrie-Elektronik Ges M B H；
    IPC主号:
    专利说明:

    Method for operating a conveyor in the form of a long stator linear motor
    The subject invention relates to a method for operating a conveyor in the form of a long-stator linear motor in which a plurality of transport units are moved along a conveyor path, wherein the movement of the transport units along the conveyor path is controlled by a predetermined set values of movement by at least one transport unit control.
    Long stator linear motors are often used as flexible conveyors in manufacturing, machining, assembly, and similar facilities. A long-stator linear motor is known to consist essentially of a long stator in the form of a plurality of successively arranged drive coils and a plurality of transport units with excitation magnets (permanent magnets or electromagnets) which are moved along the long stator by the drive coils are acted upon in accordance with an electric current. The drive coils generate a moving magnetic field which cooperates with the excitation magnets on the transport units to move the transport units. By the long stator thus a conveyor line is formed, along which the transport units can be moved. This makes it possible to regulate each transport unit individually and independently of each other in their movement (position, speed, acceleration). For this purpose, each drive coil is controlled by an associated drive coil controller, which can receive instructions for moving a transport unit (for example in the form of setpoints for position or speed) from a higher-level system control unit. It can be provided along the conveyor line and switches of Langstatorlinearmotors. Often, the long stator is also constructed in the form of conveyor segments, each conveyor segment forming part of the conveyor line and containing a number of drive coils. In most cases, a segment regulator is provided for a conveyor segment, which regulates all drive coils of the conveyor segment. The structural design of the long stator linear motor, so e.g. Of course, the design of the drive coils, the conveyor line, the transport units, the guides of the transport unit, etc., and the control concept may be different, but the basic operating principle of a Langstatorlinearmotors remains the same.
    A conveying device in the form of a long-stator linear motor can certainly become complex with a plurality of transport sections, which can be interconnected by switches. This can also be a large number of transport units are moved simultaneously. Such a conveyor thus makes high demands on the control of the movement of the individual transport units. In particular, precautions must generally be taken to ensure that individual transport units do not collide with one another during their movement.
    For example, US Pat. No. 8,863,669 B2 describes a conveying device in the form of a long-stator linear motor with a control of the movement of the transport units. Therein, the conveyor line is divided into zones, wherein a transport unit is controlled in a reference value-based zone based on a setpoint specification and is controlled in a limit-based zone by means of end position and maximum values for speed and acceleration. With limit value-based control, these specifications are converted into a motion profile with which the transport unit is moved. US 8,863,669 B2 also mentions that collisions of the transport units are to be avoided, but no comments are made as to how this is achieved.
    Likewise, along the conveyor line barriers may occur that must not be run over by a transport unit. Such barriers may be real, physical barriers, for example in the form of the end of a conveyor section, or logical barriers, for example a switch being driven by another transport unit or a conveyor segment where there is no room for another transport unit. Barriers can also be set application-related, even temporarily, by the higher-level plant control unit. Barriers may not be run over by a transport unit during operation.
    Last but not least, there may also be local speed limits along the conveyor line which must not be violated by a transport unit, for example a maximum speed in a curve in order not to exceed a maximum centrifugal force.
    It is an object of the present invention to provide a method with which a collision of transport units moved along a conveying path of a long stator linear motor and / or the collision of a transport unit with a barrier and / or the crossing of a local speed limit are prevented in a simple manner can.
    This object is achieved in that for at least one first transport unit is determined in advance, whether a standstill maneuver with predetermined kinematics can be performed for the transport unit, so that a collision of this transport unit is prevented with a preceding second transport unit or with a barrier of the conveyor line, or Exceeding a predetermined local speed limit is prevented at a location of the conveyor line by the first transport unit, or an adjustment movement of the first transport unit to a speed of a preceding second transport unit is possible, and the standstill maneuver of the first transport unit is actually initiated if at least one of these conditions violated becomes. By predicting downtime maneuvers and checking for security breaches, it is possible to ensure that a transport unit can be stopped without interfering with any other transport unit, barrier or speed limit. If a security requirement is violated, the transport unit is actually stopped.
    In a preferred embodiment, a standstill maneuver is assumed for the preceding second transport unit and it is checked whether the first transport unit comes too close to the second transport unit in the case of an assumed standstill maneuver. Normally, a standstill maneuver is carried out as quickly as possible. If a collision can be prevented during a standstill maneuver of the preceding second transport unit, it can therefore be assumed that a collision can also be prevented during normal driving maneuvers.
    In an implementation that is easy to implement, a standstill point or a standstill path is calculated for the first transport unit and for the second transport unit from knowledge of the kinematic implementation of the respective standstill maneuver and compared to determine whether the first transport unit and the second transport unit come too close ,
    In order to take into account stationary barriers, it is possible to check whether the first transport unit comes too close to the barrier in the event of an assumed standstill maneuver. This ensures that a transport unit can always be stopped in time for a barrier.
    The safety can be increased if a minimum distance is specified which indicates how close the transport unit of the preceding transport unit or barrier may come.
    Compliance with a speed limit can be easily controlled by checking whether the speed of the first transport unit can be reduced from a current actual speed to a limit speed limit set by the speed limit, assuming a standstill maneuver, without the first transport unit falling within the defined speed limit range gets too close. This ensures that a transport unit can always be decelerated to a specified speed without the possibility of violating a speed limit. In a simple implementation to be implemented, a speed point or a braking distance is calculated for the first transport unit from the knowledge of the kinematic implementation of the standstill maneuver, thereby determining whether the speed of the transport unit can be lowered to the limit speed before the speed limit range.
    A collision can also be prevented by an equalization maneuver if it is checked whether the speed of the first transport unit can be lowered at a standstill maneuver from a current actual speed to a speed of the second transport unit, so that between the first and second transport unit, a safety margin, the from the concrete kinematic implementation of the standstill maneuver, is complied with. This ensures that the speed of the first transport unit can always be lowered to the speed of the second transport unit without the possibility of a collision. In a simple implementation to be implemented, a speed point or an adjustment path is calculated for the first transport unit from the knowledge of the kinematic implementation of the standstill maneuver and thus determined whether the speed of the transport unit can be lowered to the speed of the second transport unit.
    The subject invention will be explained in more detail below with reference to Figures 1 to 7, which show by way of example, schematically and not by way of limitation advantageous embodiments of the invention. It shows
    1 shows an embodiment of a conveyor,
    2 shows an example of a collision avoidance according to the invention via standstill maneuvers,
    3 shows an example of a compliance with a speed limit according to the invention,
    4 shows an example of an adjustment movement according to the invention,
    Figure 5 shows the observance of a speed limit on a Angleichsbewegung, Figure 6 and 7, the treatment of points in the monitoring of security requirements and
    7 shows an implementation of a transport unit regulations with phase space limitation.
    1 shows an example of any structure of a conveyor 1 with a conveyor line 2 (indicated by the dashed line). The conveyor 1 is designed as a long stator linear motor and there are a plurality of transport units TEi, i = 1, ..., x provided, which can be moved along the conveying path 2. The conveyor line 2 is essentially defined by the long stator of the long stator linear motor 1. In the exemplary embodiment shown, a series of conveyor segments FSi, i = 1, y are provided, which define the path of the transport units TEi, that is to say the conveyor line 2. Individual conveyor sections FAi, i = 1, z of the conveyor line 2 are formed by a number of juxtaposed conveyor segments FSi. The conveyor segments FSi, and thus also the conveyor sections FAi, thereby form part of the long stator of the long-stator linear motor. The conveyor segments FSi are arranged stationary in a suitable construction and as a rule also form guide elements along which the transport unit TEi can be guided. Each conveyor section FAi comprises at least one conveyor segment FSi, usually several conveyor segments FSi. Individual conveyor sections FAi, or conveyor segments FSi of individual conveyor sections FAi (such as the conveyor segments FS1, FSm), may partially overlap along the conveyor section 2, in particular at locations of the conveyor section 2 at which a transition from a conveyor section FAi to another conveyor section FAi (such as from the conveyor section FA1 on the conveyor section FA2) takes place. It can also be provided that sections are arranged on both sides of the conveyor line 2 conveyor segments FSi. It is also possible to provide switches W, at which (depending on the conveying direction of a transport unit TEi) two conveyor sections FAi are brought together or a division into two conveyor sections FAi takes place. It is understandable that a conveyor line 2 of almost any design can thus be formed, which also need not only be in a two-dimensional plane, but can also extend in three dimensions.
    Each conveyor segment FSi comprises a number k of drive coils ASij, j = 1,..., K, where the number k does not have to be the same for each conveyor segment FSi. In FIG. 1, for the sake of clarity, only drive coils ASij of some conveyor segments FSi are shown. Each transport unit TEi comprises a number of excitation magnets EMij, j = 1,..., I, preferably on both sides (relative to the conveying direction indicated by the arrows on the transport units TEi) of the transport unit TEi. The drive coils ASij generate a moving magnetic field and act in the operation of the conveyor 1 in a known manner according to the motor principle with the excitation magnet EMij of the transport units TEi together. If the drive coils ASij are supplied with a coil current in the area of a transport unit TEi, a magnetic flux is created which, in cooperation with the excitation magnets EMij, generates a force on the transport unit TEi. Depending on the coil current, this force can be known to comprise a propulsion force-forming and a lateral force-forming force components. The propulsion force-forming force component essentially serves for the movement of the transport unit TEi and the lateral force-forming force component can be used to guide the transport unit TEi, but also to fix the path of the transport unit TEi in a switch W. In this way, each transport unit TEi individually and independently of each other along the conveying path 2 are moved by the
    Drive coils ASij are energized in the region of each transport unit TEi according to the movement to be carried out with a corresponding coil current.
    This basic operation of a long stator linear motor is well known, so it will not be discussed further. For the subject invention, it is also irrelevant how the transport units TEi, the conveyor segments FSi, the drive coils ASij, the excitation magnets EMij, etc. are configured constructive concrete, which is why it will not be discussed further.
    In order to control the movement of the individual transport units TEi, a transport unit controller 3 is provided, in which the setpoint values S for the movement of the transport units TEi are generated. Of course, it is equally possible to provide a plurality of transport unit controls 3, each of which may be part of the conveyor 1, e.g. a conveyor section FAi, are assigned and control the movement of the transport units TEi on this part. In addition, it is also possible to provide segment control units 4 which are assigned to a conveyor segment FSi (or else to several conveyor segments FSi or also to a part of a conveyor segment FSi) and which contain the setpoint specifications of the associated transport unit controller 3 for a transport unit TEi in coil currents for the drive coils ASij of the conveyor segment FSi, So in concrete variables, implement.
    The segment control units 4 could also be implemented in a transport unit control 3. As desired values S, positions p of the transport units TEi, or equivalently also speeds v, are specified. This means that in each clocking step n of the control for each transport unit TEi a new setpoint value S is calculated, which is adjusted by the segment control units 4. Accordingly, a suitable controller is implemented in a segment control unit 4, which converts the setpoint specification into a suitable manipulated variable, for example into a force or a coil current. The desired movement of the transport units TEi along the conveyor line 2 can also be predetermined by a conveyor control 5, in which, for example, a route calculation (eg which way should a transport unit TEi take ), A point arbitration (eg which transport unit TEi may enter a point ) , Deadlock avoidance (eg, two transport units TEi block each other ), etc., can take place to move the transport units TEi in a desired manner along the conveyor line 2, eg to realize a manufacturing, assembly, or other process. This movement specification for the transport units TEi is implemented in the transport unit control 3 in setpoint specifications for the transport units TEi.
    As such, it should be ensured in the conveyor regulation 5 that no inadmissible states occur on the conveyor line 2. This primarily comprises the avoidance of a collision of two transport units TEi on the conveyor line 2. It should also be ensured that transport units TEi do not run over uncontrolled barriers, e.g. retract uncontrolled in points W or in a conveyor segment FSi, which in turn can lead to a collision. Furthermore, compliance with speed limits for the transport units TEi can still be ensured. Compliance with these safety requirements (in particular the collision avoidance, but also the observance of speed limits) is important for a trouble-free operation of the conveyor 1.
    During ongoing operation of the conveyor 1, in particular in large conveyors 1 with very many transport units TEi and many conveyor sections FAi, but it could still occurrence that the above security requirements are violated. In order to be able to intercept such errors in this case, the invention provides that in the setpoint generation in the transport unit control 3 in each clocking step n is checked that there may be no collisions between two transport units TEi. In addition, compliance with given speed limits can also be checked for each transport unit TEi. If a risk of collision and / or the risk of exceeding a speed is detected, then the transport unit control 3 sets a corresponding action. The basic idea here is always that it must be possible at any time to stop a transport unit TEi, without the transport unit TEi colliding with another transport unit TEi, whereby there must also be no collision during the stopping process, ie during the deceleration , In this case, it is assumed according to the invention that a transport unit TEi always monitors the movement of the transport units TEk, k> i moving in the conveying direction of the transport unit TEi, with which a collision case can occur in order to monitor compliance with the security specifications. In the simplest case, this is the transport unit TEi + 1 traveling directly in front of it, it also being possible to monitor several transport units TEk moving in front of it. In particular case of switches W, it can also lead to a collision with a coming from another conveyor section FAi the conveyor section 2 transport unit TEk, which does not have to be the immediately preceding moving transport unit TEi + 1. If compliance with the safety requirements can no longer be guaranteed at a point in time for a transport unit TEi, the transport unit regulation 3 sets an action.
    An action can either be the triggering of a standstill maneuver, i. certain or all transport units TEi are stopped or performing a matching maneuver, i. the movement of a transport unit TEi is adapted to the movement of another transport unit TEk, in particular an immediately preceding TRansporteinheit TEi + 1.
    The functionality of monitoring the safety requirements is described by means of a phase space representation, which is why the safety function is also referred to as phase space limitation. The phase space is known to be a representation of the three states of a movement, namely position p, speed v and acceleration a, in a diagram. However, the phase space can also include other states, such as the jerk (time derivative of the acceleration) and / or the jerk change (two times the second derivative of the acceleration).
    In FIG. 2, the phase space projected onto the velocity v-position p-plane is shown for seven transport units TEi, i = 1... 7, which are located on a conveying section FAi. For example, the transport units TEi move with constant acceleration (aj = 0), but different velocities v, not equal to zero, and are at different positions p, for the sake of simplicity. The respective instantaneous position p, * and velocity vf is marked by the circles. In each clocking step n, it is now calculated in a forward-looking manner whether a standstill maneuver can be carried out for a transport unit TEi without this transport unit TEi colliding with a preceding transport unit TEk, k> i, in particular the transport unit TEi + 1 immediately preceding it. As a rule, compliance with a certain safety distance can also be checked. Everything that lies behind the transport unit TEi can thus be ignored since it can be assumed that the transport units TEi behind it carry out the same check. It is now calculated for a transport unit TEi in each cycle step n for the calculated new setpoint position p, the standstill path p, ie the path that the transport unit TEi needs to stop from the current speed v, * (v, = 0). get. The position Ρί (ν, = 0) at which the transport unit TEi comes to a halt is also referred to as a standstill point. Such a standstill maneuver is performed with a predetermined standstill acceleration a, which normally corresponds to the maximum possible acceleration amax, but should not be smaller than an acceleration with which the transport unit TEi can be delayed during a normal movement. The standstill point Ρί (ν, = 0) can be easily calculated and of course depends on how the standstill maneuver for the transport unit TEi is kinematically implemented, which can be assumed to be known.
    It should be noted at this point that the use of the setpoint values S for the phase space limitation is advantageous, since these are present anyway in the transport unit control 3. Equally, however, current actual values of the movement of the transport unit TEi could also be used for phase space limitation. Actual values must, however, be measured or calculated in some way, which is expensive. In addition, a following error monitoring can be implemented, which constantly monitors the deviation of the actual values from the setpoint values S and intervenes if this deviation becomes too great. For this reason too, the use of the setpoint values S for the phase space limitation is not a limitation. The use of setpoints or actual values is therefore considered equivalent.
    In a simple case, a standstill maneuver is performed, for example, with a constant maximum acceleration ai max and the transport unit TEi is delayed until the speed v, = 0 is reached. From the kinematic contexts it can be concluded simply that then the time Δt, until the transport unit TEi stops
    Kl follows from J-L, where v, denotes the speed at the beginning of the delay. The a. i, max v * Vj · vi
    Standstill path p, the transport unit TEi then follows from p. = -At or p. = - Depending 2 2 '^ after kinematic implementation of the standstill maneuver SMi, the calculation of the standstill path Pi can of course also be different. For example, a speed profile could be specified for the standstill maneuver SMi, with which a better approximation to the final speed ν, = 0 can be achieved. A limitation of the acceleration change may also be provided so as not to generate jerky movements of the transport unit TEi.
    Thus, as a criterion for executing a standstill maneuver SMi for a transport unit TEi in a clock step n, the inequality
    Pi * + Pi [+ M] <pj + pk are checked to avoid collision with a preceding transport unit TEk. Of course, a minimum distance M to be observed can also be provided. The minimum distance M may include a safety reserve, but it may also include the dimensions of the transport unit TEi. Likewise, the following error (ie the deviation between the desired position and the actual position of the transport unit TEi) could also be taken into account at the minimum distance M.
    Generally speaking, it is checked whether the one transport unit TEi and one preceding it transport unit TEk come too close during assumed standstill maneuvers SMi, SMk, which is e.g. can be checked via the standstill points Ρί (ν, = 0), Pk (vk = 0) or the standstill paths Pi, pk. How the transport units TEi, TEk may come after, for example, can be defined via the minimum distance M. If this is the case, a standstill maneuver SMi is triggered.
    Depending on the kinematic implementation for carrying out a standstill maneuver SMi, it may also happen that the transport unit TEi can not be stopped when the speed Vj = 0 is reached for the first time. An example of this is the implementation of a jerk filter (limitation of the permissible acceleration change) in the form of a mean value filter. This can lead to a transport unit TEi reaching the speed Vj = 0, but the movement can not be stopped at this point, but must be continued at the reverse speed. Therefore, in this case, the transport unit TEi will forcibly be moved beyond this reversal point p, (ν, = 0) the first time the speed v, = 0 is reached, and will be moved in the opposite direction at the reverse speed. The implementation of the kinematic movement of the standstill maneuver then ensures that the transport unit TEi is brought to a standstill at reverse speed. The end point p, (ν, = 0) is then reached when the speed ν, = 0 is reached again. Assuming that the phase space limitation again ensures that the rear transport unit TEi does not collide with a preceding transport unit TEk, the standstill path Pi in this case results from the minimum distance between the start position p, * of the standstill maneuver and the reversal point Ρί (ν , = 0) and end point p, (ν, = 0), ie Pi = Min {pi (Vi = 0) -pi *,
    Pi (Vi = 0) -pi *}. In the same way, in this case, the standstill point Ρί (ν, = 0) of the transport unit TEi results as a minimum from the reversal point Pi (Vi = 0) and the end point p, (Vi = 0). This is shown in Fig.2 with the transport units TE4, TE6. Otherwise, there is no difference to above in this case.
    Likewise, it is irrelevant in which direction a transport unit TEk moving in front of it moves, as indicated in FIG. 2 on the basis of the transport unit TE5 and TE6. However, this also means that the phase space limitation advantageously also takes into account transport units TEk that move in the opposite direction. The speed V, must only be considered with the correct sign, which is easily possible.
    In Figure 2 is still a barrier B still shown. This is, for example, the entry area of a switch W, which may only be overrun when the switch W is released for a transport unit TEi, e.g. by a higher-level conveyor control 5. The standstill path Pb of a barrier B can be regarded as zero and the current position pB * of the barrier thus corresponds to a standstill point pB (v = 0), wherein the position pB * of the barrier is of course a predetermined position. Thus, for example, the above inequality can again be used for the check, that is, ρ; * + ρ; [+ M] <pB * in order to avoid a collision with the barrier, again considering a minimum distance M.
    It is therefore assumed for the collision monitoring of Phasenraumlimitierung of an extreme case in which it is assumed that a transport unit TEk, k> i a standstill maneuver SMk according to a predetermined kinematic motion, e.g. with maximum possible acceleration amax, executes or that there is a barrier B on the conveyor line 2, which must not be run over. In this case, it must be ensured that a transport unit TEi moved on the conveyor line 2 in the conveying direction behind it can be stopped with a predetermined standstill maneuver SMi without a collision with the preceding transport unit TEk or the barrier B coming. This ensures that the transport units TEi of the conveyor 1 can be stopped at any time without causing a collision, or that the two transport units TEi, TEk or the transport unit TEI and the barrier B do not come too close.
    If, during operation, the previously calculated standstill points Ρί (ν, = 0) and Pk (Vk = 0) of two transport units TEi, TEk, possibly taking into account a reversal point p 'and end point p "as described above, or the precalculated standstill point Ρί (ν, = 0) of a transport unit TEi and the standstill point pB (v = 0) come too close to a barrier B, possibly taking into account a minimum distance M, then a standstill maneuver SMi is performed for the transport unit TEi. The check of the condition "come too close" can be done in a suitable manner, for example with the above inequalities. Of such a standstill maneuver SMi, the other transport units TEi of the conveyor 1 need not yet be directly affected, i. These can initially continue the movement normally. However, such a standstill maneuver SMi can also force transport units TEi traveling behind to execute a standstill maneuver SMi. The triggering of a standstill maneuver SMi can also be regarded as a fault, which causes the standstill of a conveyor section FAi or the entire conveyor 1.
    To monitor a speed limit is also assumed by a standstill maneuver SMi a transport unit TEi and it is proactively checked in each clock step, whether the speed v, a transport unit TEi with a standstill maneuver SMi safely from a current actual speed v, * to that by the speed limit (indicated 3) predetermined limit speed vG, for example, in a region of the conveyor section FAi on which the transport unit TEi is currently being moved, can be lowered, as shown in Figure 3. The part of the standstill maneuver SMi until reaching the limit speed vG is referred to as braking distance ε. The braking distance ε, can be calculated again from the known concrete kinematic implementation of the standstill maneuver SMi. If, for example, a deceleration of the transport unit TEi with a constant maximum acceleration ai max is assumed as an example, then the braking distance results
    , This can be for the
    Transport unit TEi are checked in each clock step n for a given speed limit, whether the inequality
    holds, where pG indicates the predetermined position of the speed limit on the conveyor sections FAi and pf the current position of the transport unit TEi. In this case, as described above, in turn, a certain minimum distance M can be specified. If the above condition for a transport unit TEi can not be complied with, a standstill maneuver SMi for stopping the transport unit TEi is triggered for the transport unit TEi, which in turn may constitute a fault in the operation of the conveyor 1. As already explained above, this can also trigger a standstill maneuver SMi in the case of the transport units TEi traveling behind, as soon as the phase space limitation for these transport units TEi responds.
    Alternatively, a speed position Pi (Vi = vG) could also be calculated and it can be checked whether the speed position Pi (Vi = vG) and the predetermined position pG come too close to the speed limit, which in turn can be defined over the minimum distance.
    However, a local speed limit does not have to be defined statically, but it can also be provided that the local speed limit is dynamically switched on and off, for example via the conveyor control 5 or in a fixed time pattern. To deal with such dynamic speed limits, this can initially be considered static and monitored by the Phasenraumlimitierung. However, if it is clear or known that for a transport unit TEi the speed limit will not be up until leaving the speed limit range then the speed limit for the transport unit TEi may be ignored.
    It is also conceivable that a speed limit is defined only for one, or even several, specific transport unit TEi. Thus, for example, it would also be possible to make a speed limit dependent on the state, for example of the load, of the transport unit TEi. With a high load, for example, a speed limit can apply in a curve, whereas an empty transport unit TEi need not be subject to this speed limit.
    However, it may be provided for certain transport units TEi to adjust the movement of the transport unit TEi without immediately having to carry out a complete standstill maneuver SMi, that is, to ν, = 0, in the event of a conflict. For example, only one destination position can be defined for a transport unit TEi, wherein the route to the destination position can be flexibly specified by the transport unit controller 3, e.g. in the form of a specific speed profile while maintaining maximum values for the speed and acceleration, and possibly also for the jerk or jerk change. Thus, the transport unit controller 3, in which normally the phase space limitation will also be implemented, can change the movement of the transport unit TEi while maintaining the target position in order to avoid a complete standstill maneuver SMi. The Phasenraumlimitierung can perform a Angleichsbewegung so that the security requirements are met. This case may occur, for example, when the immediately preceding transport unit TEi + 1 is traveling in the same direction but at a lower speed vi + i than the transport unit TEi at speed v ,. This would inevitably lead to the fact that the phase space limitation eventually addresses, because the two transport units TEi, TEi + 1 come too close at some point. In this case, the transport unit TEi would be stopped with a standstill maneuver SMi, although a simple speed adjustment of the transport unit TEi would be sufficient.
    The equalizing motion will be described with reference to FIG. Here, the transport unit TEi moves at a speed v, which is greater than the speed vk of a preceding transport unit TEk. It is assumed again from a standstill maneuver SMi, which is calculated in advance, the standstill maneuver SMi does not stop the transport unit TEi in this case, that is delayed to the final speed ν, = 0, but is aligned with the speed vk a preceding moving transport unit TEk. The standstill maneuver SMi is again after a predetermined kinematic movement. For example, in a simple case, the standstill maneuver SMi again takes place with a constant maximum acceleration ai max. For the adjustment movement, it is preferable to implement a kinematic movement which ensures as smooth as possible an adjustment movement, as indicated in FIG.
    First (analogously to the calculation of the braking distance ε,) according to the concrete kinematic implementation of the standstill maneuver SMi the Angleichsweg γ, calculated, which is required to the transport unit TEi according to the kinematic implementation of Angleichsbewegung of the speed v, to the speed vk of a preceding Decelerate transport unit TEk. In the same way, a speed position Pi (Vi = vk) could again be calculated and used for the check.
    Now, preferably, two conditions are satisfied by the phase space limitation. On the one hand, the two transport units TEi, TEk should not come so close to one another during an adjustment movement that a standstill maneuver SMi as described with reference to FIG. 1 is triggered by the phase space limitation. This is indicated in Figure 4 by the position p, 'and the starting position pk * of the transport unit TEk at the time when the transport unit TEi reaches the speed vk. Therefore, a safety distance S is predetermined, which is at least to be complied with after performing the Angleichsbewegung between the two transport units TEi, TEk, so that the transport unit TEi is not stopped. Likewise, the safety distance S should be so large that in case of a delay of the preceding transport unit TEk with an acceleration which is greater than the acceleration for decelerating the transport unit TEi (ie the two transport units TEi, TEk come closer when decelerating) triggering a Standstill movement SMi to stop the transport unit TEi is prevented. The safety distance S can be determined from the knowledge of the kinematic implementations of the movements of the transport units TEi, TEk.
    Thus, an adjustment motion can be triggered, for example, if the condition
    is injured. This can ensure that an adjustment movement can be performed without the phase space limitation triggering a standstill maneuver SMi for stopping the transport unit TEi. The adjustment movement can be implemented in the transport unit control 3 in an advantageous embodiment, for example, simply by setting a new maximum speed v, = vk for the transport unit TEi.
    If the equalizing motion is implemented kinematically differently than a standstill maneuver for stopping the transport unit TEi, e.g. because a gentle approach to the target speed vk is sought, another potential for improvement can be used. It is assumed that the preceding transporting unit TEk executes a standstill maneuver SMk during the equalizing movement. In this case, for the transport unit TEi, the smooth adjustment movement would first be performed until the phase space limitation intervenes and the transport unit TEi stops with a standstill maneuver SMi. If the transport unit TEi had already executed a standstill maneuver SMi, this would have come to a standstill earlier, whereby instead of the equalization movement at a later time equal
    Standstill maneuver SMi could be executed. Thus, the conveyor 1 would possibly later go into an unwanted error state, which may be sufficient to resolve potential conflict situation along the conveyor line 2 by itself, before intervening the Phasenraumlimitierung.
    Thus, a locally defined speed limit can be treated with an equalizing motion, as described with reference to FIG. If a speed limit to the speed vG is provided on the conveyor line 2, then an adjustment movement with the equalization path γ is carried out, for example, if the condition
    get hurt. Again, a minimum distance M and / or a safety distance S can be taken into account. After the speed limit, the speed of the transport unit TEi can, if necessary, be increased again, for example, by the specification in the transport unit control 3, as indicated in Figure 5.
    Switches W can also be treated with the above concepts, as described with reference to FIGS. 6 and 7. A switch W is assigned a conflict zone K within which only one standstill point Pi (Vi = 0) of a single transport unit TEi may be located, since otherwise a collision between transport units TEi in the switch area may occur in the case of standstill maneuvers SMi. For turnout treatment, in turn, the standstill maneuvers SMi of the transport units TEi are calculated and evaluated in a forward-looking manner.
    6 shows from the perspective of the conveying direction of the transport unit TE1 diverging points W1, W2, W3 with the associated conflict zones K1, K2, K3, where the transport unit TEi each between several conveyor sections FA1, FA2, FA3, FA4 of the conveyor section 2 can choose , A transport unit TE2 with the same conveying direction as the transport unit TE1 but on a conveyor section FA2 on which the transport unit TE1 is not to be moved can be ignored because no collision can occur. However, a transport unit TE3 with the opposite direction of movement is treated as if it were located on the same conveyor section FA1 as the transport unit TE1. In addition, in the case of standstill maneuvers SMi, only one of the two transport units TE1, TE3 is permitted to enter the conflict zone K2 of the switch W2, which is assigned to the two conveyor sections FA1, FA2. Otherwise, the phase space limitation described above ensures that the two transport units TE1, TE3 do not collide on the conveyor section FA1.
    FIG. 7 shows points W1, W2 merging with one another from the perspective of the conveying direction of the transport unit TE1 with the associated conflict zones K1, K2, where transport units TEi from a plurality of conveyor sections FA1, FA2, FA3 are brought together onto a conveyor section. A transport unit TE3 on a different conveyor section FA3 than the transport unit TE1 and with a conveying direction opposite to the transport unit TE1 can be ignored since a collision can occur. A transport unit TE4, which moves on the same conveyor section FA1 as the transport unit TE1, but with opposite conveying direction must be taken into account. If, for example, move the transport unit TE4 on the switch W1 on the same conveyor section FA1 on which the transport unit TE1 is on the way, then engages the phase space limitation described above. If the transport unit TE4 is to move on the switch W1 on another conveyor section FA2, then only one of the two transport units TE1, TE4 is assigned to the two conveyor sections FA1, FA2 in the case of a standstill maneuver SM1, SM4 into the conflict zone K1 of the switch W1 retract. A transport unit TE2, which moves in the same direction of movement as the transport unit TE1 but on another conveyor section FA2, must also be taken into account when the two conveyor sections FA1, FA2 are merged at a switch W1. In this case, only one of the two transport units TE1, TE2 may enter in the case of a standstill maneuver SM1, SM2 in the conflict zone K1 of the switch W1, the two conveyor sections FA1, FA2 is assigned.
    The treatment of switches W1, W2, W3, as described above, can be treated, for example, by setting barriers B for certain transport units TEi. If collisions can occur between two transport unit TEi in the switch area or in a conflict zone K of a switch W in the case of standstill maneuvers SMi, then a barrier B can be set for one of the transport units TEi involved, whereby the normal phase space limitation ensures that this transport unit TEi does not overrun the barrier B. The barrier B can be removed again if the collision risk no longer exists. Thus, no other mechanisms of phase space limitation are required for switches, as described above. It is only necessary to implement a program logic which performs the setting and canceling of the temporary barriers B according to the above conditions.
    Of course, the phase space limitation can also use the knowledge related to the conveyor line 2. For example, there may be conveyor sections FAi where no standstill maneuvers SMi can occur. An example of this is a conveyor section FAi in which a mechanical coupling with a robot acts, because the robot performs work on a workpiece on a transport unit TEi. In this case, for example, an adjustment movement could be delayed because it does not have to be expected that a preceding transport unit TEk will execute a standstill maneuver SMk in such a conveyor section FAi.
    Similarly, the phase space limitation could use knowledge of a higher level conveyor scheme 5, with route calculation, point arbitration, deadlock avoidance, control of temporary barriers, etc. Assuming that the phase space limitation causes a standstill maneuver SMi (also as an adjustment movement) for a transport unit TEi due to a set temporary barrier B, it knows that this barrier B certainly opens in the sufficiently near future. Then the phase space limitation of this standstill maneuver SMi could also avoid. An example of this could be the control of the access of a transport unit TEi to a conveyor segment FSi by means of temporary barriers B. The access of a transport unit TEi is regulated in a forward-looking manner, for example in the conveyor control 5. The phase space limitation prevents the passage of the barrier B. The set barrier B could now also pass to the phase space limitation the information as to when the barrier is safely removed, e.g. because a preceding transport unit TEk will have safely left the conveyor segment FSi. Thus, the phase space limitation for a transport unit TEi may cause a standstill SMi despite set barrier B later, because it is clear that a preceding transport unit TEk have left the conveyor segment FSi before the transport unit TEi enters the conveyor segment FSi with the standstill maneuver ( and thus no barrier B would be set anymore).
    Similarly, assumptions about the planned or performed movement of other transport units TEi could help improve various phase space limitation interventions. If, for example, it is certain that the transport unit TEk will accelerate sufficiently in FIG. 4, then this could be taken as the reason for the phase space limitation not to initiate the matching maneuver at all.
    In a simplified embodiment could also be provided for a transport unit TEi compliance with the safety specifications on the standstill maneuver SMi not to check in each clock step, but at longer intervals, for example, only every x-th clock step xn.
    The implementation of the monitoring of the security specifications can be done, for example, as shown schematically in Figure 8. Here, it is assumed that the phase space limitation 10 is implemented in a transport unit control 3. The transport unit control 3 either receives directly set values S for moving a transport unit TEi, for example from a higher-level conveyor control 5, or receives a destination Z for the movement, for example in the form of a target speed or a target position. If a target Z is specified, then a movement profile unit 11 can also be provided in the transport unit controller 3, which converts the target Z into target values S of the movement, for example in the form of a speed profile. These alternative possibilities are indicated in Fig.8 by the switch S1. The setpoint S is used to drive the drive coils ASij, e.g. via a segment control unit 4, used.
    However, the setpoint value S is also used in a phase space limitation 10 in order to monitor compliance with the safety specifications for a transport unit TEi as described above. For this purpose, it is assumed that the phase space limitation 10 has all the information necessary therefor, such as, for example, knowledge of the movement of preceding transport units TEk, local speed limits, barriers, etc. If the phase space limitation 10 is due to the setpoint value S, the phase space limitation 10 intervenes and initiates a standstill maneuver SMi for the transport unit TEi. For this purpose, the phase space limitation 10 predefines the setpoint values S (SMi) for the standstill maneuver SMi. This is indicated by the switch S2 in Fig.8. The standstill maneuver SMi can, as described, lead to the stopping of the transport unit TEi, or can also be implemented as an adjustment movement.
    权利要求:
    Claims (11)
    [1]
    claims
    1. A method for operating a conveyor (1) in the form of a Langstatorlinearmotors in which a plurality of transport units (TEi) along a conveying path (2) are moved, wherein the movement of the transport units (TEi) along the conveying path (2) by a default of Reference values (S) of the movement by at least one transport unit control (3) is controlled, characterized in that for at least one first transport unit (TEi) is determined in advance, whether for the transport unit (TEi) a standstill maneuver (SMi) can be performed with predetermined kinematics such that a) a collision of this transport unit (TEi) with a preceding second transport unit (TEk) or with a barrier (B) of the conveyor line (2) is prevented, or b) the exceeding of a predetermined local speed limit (vG) at one location (pG) of the conveyor line (2) by the first transport unit (TEi) is prevented, or c) an A equal movement of the first transport unit (TEi) to a speed (vk *) of a preceding second transport unit (TEk) is possible, and that the standstill maneuver (SMi) of the first transport unit (TEi) is actually initiated if at least one of these conditions is violated.
    [2]
    2. The method according to claim 1, characterized in that for the preceding moving second transport unit (TEk) a standstill maneuver (SMk) is accepted and it is checked whether the first transport unit (TEi) at an assumed standstill maneuver (SMi) of the second transport unit (TEk ) comes too close.
    [3]
    3. The method according to claim 2, characterized in that for the first transport unit (TEi) and for the second transport unit (TEk) from the knowledge of the kinematic implementation of the respective standstill maneuver (SMi, SMk) each have a standstill point (Pi (Vi = 0) , pk (vk = 0)) or a standstill path (p ,, pk) are calculated and compared to determine whether the first transport unit (TEi) and the second transport unit (TEk) are getting too close.
    [4]
    4. The method according to claim 1, characterized in that it is checked whether the first transport unit (TEi) in an assumed standstill maneuver (SMi) of the barrier (B) comes too close.
    [5]
    5. The method according to any one of claims 2 to 4, characterized in that a minimum distance (M) is specified, which indicates how close the transport unit (TEi) of the preceding moving transport unit (TEk) or the barrier (B) may come.
    [6]
    6. The method according to claim 1, characterized in that it is checked whether the speed (v,) of the first transport unit (TEi) at an assumed standstill maneuver (SMi) of a current actual speed (v, *) to a predetermined speed limit by the limit speed (vG) can be lowered without the first transport unit (TEi) comes too close to the defined range of the speed limit.
    [7]
    7. The method according to claim 6, characterized in that for the first transport unit (TEi) from the knowledge of the kinematic implementation of the standstill maneuver (SMi) a speed point (pi (Vi = vG)) or a braking distance (ε,) is calculated and thus determining whether the speed (v,) of the transport unit (TEi) can be lowered to the limit speed (vG) before the speed limit range.
    [8]
    8. The method according to claim 6 or 7, characterized in that a minimum distance (M) is specified, which indicates how close the transport unit (TEi) may come to the region of the speed limit.
    [9]
    9. The method according to claim 1, characterized in that it is checked whether the speed (v,) of the first transport unit (TEi) in an assumed standstill maneuver (SMi) of a current actual speed (v, *) to a speed (vk) of second transport unit (TEk) can be lowered, so that between the first transport unit (TEi) and second transport unit (TEk) a safety distance (S), which results from the concrete kinematic implementation of the standstill maneuver (SMi) is met.
    [10]
    10. The method according to claim 9, characterized in that for the first transport unit (TEi) from the knowledge of the kinematic implementation of the standstill maneuver (SMi) a speed point (pi (Vi = vG)) or an Angleichsweg (γ,) is calculated and thus it is determined whether the speed (v,) of the first transport unit (TEi) can be lowered to the speed (vk) of the second transport unit (TEk).
    [11]
    11. The method according to claim 9 or 10, characterized in that in addition to the safety distance (S) a minimum distance to be observed (M) is taken into account.
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    同族专利:
    公开号 | 公开日
    CA2956747A1|2017-08-02|
    EP3202612B1|2020-06-17|
    AT518354B1|2018-06-15|
    US10220862B2|2019-03-05|
    US20170217460A1|2017-08-03|
    EP3202612A1|2017-08-09|
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    ATA50058/2016A|AT518354B1|2016-02-02|2016-02-02|Method for operating a conveyor in the form of a long stator linear motor|ATA50058/2016A| AT518354B1|2016-02-02|2016-02-02|Method for operating a conveyor in the form of a long stator linear motor|
    EP17152998.5A| EP3202612B1|2016-02-02|2017-01-25|Method for operating a conveying device in the form of a long stator linear motor|
    CA2956747A| CA2956747A1|2016-02-02|2017-01-31|Method for operating a transport assembly in the form of a linear stator linear motor|
    US15/422,055| US10220862B2|2016-02-02|2017-02-01|Method for operating a transport assembly in the form of a linear stator linear motor|
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