Method for controlling movement of drive shaft of drive unit

Abstract

In order to determine an impact-limited movement curve in a simple manner without using an impact filter connected downstream, the invention provides that the movement curve (5) consists of a starting movement curve (5a) and a target movement curve (5b), the starting movement curve (5a) begins in a starting movement phase (pS, vS, aS) and transitions into the target movement curve (5b), and the target movement curve (5b) begins in a starting movement phase (pS, vS, aS). The target movement curve (5b) is determined from the acceleration curve starting from the initial movement phase (pA, vA, aA) and ending with the target movement phase (pZ, vZ, aZ) over a plurality of adjustment time steps k, the maximum acceleration change in each adjustment time step k corresponding to a predefined maximum impact (jmax), the acceleration curve of the target motion curve (5b) is present as a step function, the step function is created following a predefined motion limit in such a way that the area below the step function corresponds to a speed change ([delta] v) between the initial speed (vA) of the initial motion phase (pA, vA, aA) and the target speed (vZ) of the target motion phase (pZ, vZ, aZ), and ascertaining a target path by means of the ascertained target movement curve (5b), said target path passing through the target movement curve (5b), and ascertaining a point in time at which the ascertained target movement curve (5b) starts in order to reach the target position (pZ) of the target movement phase (pZ, vZ, aZ) on the basis of the target path.

Description

Technical Field

[0001] The present invention relates to a method for regulating the movement of a drive shaft of a drive, wherein the movement of the drive shaft is regulated in a predetermined regulation time step by pre-setting a desired movement value of the movement, thereby obtaining a movement phase of the movement of the drive shaft in each regulation time step, wherein a target movement phase in the form of a target position, a target velocity and a target acceleration is pre-set for the movement of the drive shaft, and starting from a starting movement phase in the form of a starting position, a starting velocity and a starting acceleration, the target movement phase is set by a movement curve while complying with predetermined movement restrictions, and wherein the desired movement value is obtained from the movement curve in each regulation time step. Background Art

[0002] The adjustment of the drive shaft of a drive is present in many applications. A drive shaft is essentially composed of a drive unit, such as an electric motor, which acts on a moving drive part of the drive in order to move the moving drive part translationally or rotationally in a desired manner. The drive shaft usually causes a movement in one direction. Of course, a plurality of drive shafts can be provided in order to move the moving drive part in a plurality of directions. Examples of applications in which drive shafts are present are cranes, robots, conveyors, machine tools, linear drives, etc., wherein this list is of course not restrictive.

[0003] Long stator linear motors are usually used as flexible conveying devices in manufacturing, processing, assembly equipment and similar equipment. Long stator linear motors are known to basically consist of a long stator in the form of a plurality of magnetic field generating units arranged one after another, such as drive coils or movable magnets, and a plurality of transport units with excitation magnets (e.g. permanent magnets, electromagnets or short-circuit windings), which move along the long stator, in which the magnetic field generating unit generates a movable electromagnetic field, which cooperates with the excitation magnets on the transport unit to move the transport unit. The drive coil can be loaded with current, for example, to generate a movable electromagnetic field. Therefore, a conveying path is formed by the long stator, along which the transport unit can move. Therefore, each transport unit can be adjusted individually and independently of each other in its movement (position, speed, acceleration). For this purpose, each magnetic field generating unit is controlled by an associated drive regulator, which can obtain a pre-set (e.g. in the form of a desired value for position or speed) for moving the transport unit from a superior device control unit.

[0004] Long-stator linear motors can be designed with one drive shaft or with multiple drive shafts. In the latter case, they are often also referred to as planar motors. In a planar motor, the magnetic field generating unit is arranged in a plane, thereby forming a planar conveying path in which the transport unit can move in two directions. In addition, the transport unit can also normally move to the planar conveying path, at least within certain limits, which constitutes a further drive shaft. Such long-stator linear motors are sufficiently known.

[0005] A common feature of all applications of drive shafts is that the movement of the drive shaft is regulated. Therefore, there is a drive regulator that regulates the movement of a drive component moved by the drive shaft in a desired manner. For the drive shaft regulation, a movement setpoint value that the drive shaft should follow can be set.

[0006] Usually, a target motion phase is given for the drive shaft, which is approached by the moving drive component, such as a determined target position on a long stator linear motor, which should be reached by the moving drive component at a determined target speed and / or target acceleration. The motion phase is understood as the motion state of the moving drive component of the drive shaft at a certain time point of the motion, i.e., position, speed, acceleration. Therefore, the drive component must be adjusted by pre-setting the desired motion value so that the target motion phase is reached starting from the initial motion phase. It is usually required to approach the target position as accurately as possible and the moving drive component is stationary at the target position, i.e., the speed and acceleration at the target position are zero.

[0007] The movement setpoint value is usually predetermined in the form of a movement curve of a movement variable, for example, in the form of a speed curve or position curve that the moving drive component should follow in order to achieve the target movement phase. The corresponding movement setpoint value to be predetermined at the current time of the drive control is then determined from the movement curve at any time of the movement, for example, a certain speed setpoint value or position setpoint value, which can be adjusted at the current time by means of the drive control. The current movement phase then occurs at any time due to the drive control.

[0008] The creation of a motion profile usually also takes into account known motion limits, such as a maximum speed or a maximum acceleration. Usually, for the motion of the drive shaft, a limit on the impact defined as the time derivative of the acceleration is predefined as a motion limit in order to reduce the mechanical load on the drive shaft due to large acceleration changes. For this purpose, a so-called impact filter that limits the acceleration change (i.e., the impact) is usually used. This impact filter is usually implemented as a low-pass filter or a mean value filter. Here, a motion profile, such as a position profile or a velocity profile, is created, and then the motion profile is adjusted in the impact filter in order to achieve impact limitation. However, this impact filter requires a lot of storage space, because multiple values ​​of the expected values ​​of the past motion must be stored in order to average. In addition, the impact filter is always related to the past, because the impact filter also processes past values. This also causes a dead time for the impact filter, because before the impact filter works normally, there must first be enough past values. This also leads to the motion profile cannot be simply switched, for example by presetting a new target motion phase.

[0009] Of course, it is also possible to generate motion profiles that are essentially limited by impact. However, generating such motion profiles is very computationally intensive. In particular, in applications such as conveyor devices in the form of long-stator linear motors with a large number of transport units to be moved, the limits of the available computing power are quickly reached. Therefore, in many applications, only simple acceleration-limited motion profiles are generated for the drive axis, which are then limited by impact in an impact filter.

[0010] In addition, there is such a problem in practice that the drive shaft adjustment is implemented discretely, that is, a new motion desired value is predetermined in a certain, predetermined adjustment time step, and the drive shaft regulator calculates the execution parameter of the drive unit for the drive shaft in each adjustment time step from the motion desired value, and uses the execution parameter to control the drive unit to adjust the current motion desired value. Here, of course, the actual value of the movement is also detected, such as the actual position and provided to the drive shaft regulator. Usually, the actual value is also detected in each adjustment time step. The execution parameter is, for example, a current or voltage that can be set on the drive coil of a long stator linear motor, or the current of the motor. It is shown that the motion desired value can only change at a discrete time point predetermined by the adjustment time step. For example, if the motion desired value is speed, this will result in a step function of a speed curve with a speed jump. These speed jumps result in large jump locations and thus large shocks in the acceleration. Therefore, it is necessary to use an impact filter to eliminate these jump locations, but this is related to the above-mentioned shortcomings. Summary of the invention

[0011] It is therefore advantageous to predetermine the movement setpoint values ​​in a discrete drive control of the drive axle in such a way that the jerk is limited and the use of jerk filters is obsolete, wherein a jerk-limited movement profile can be created as simply as possible.

[0012] This task is solved by motion curve being made up of initial motion curve and target motion curve, wherein initial motion curve starts at initial motion stage and transitions into target motion curve, and this target motion curve starts in initial motion stage and ends in target motion stage.Initial motion curve is arbitrary at this and can be assumed as known or pre-given.On multiple adjustment time steps, utilize acceleration curve to obtain target motion curve, wherein, the acceleration change in each adjustment time step is corresponding to the maximum impact of pre-given at most, so that the acceleration curve of target motion curve exists as step function, in this step function, acceleration curve is a series of acceleration values ​​discrete in time at adjustment time step k place.Therefore, possible acceleration change is between zero and the maximum impact of pre-given.Create step function when observing the motion limitation of pre-given, make the area below step function corresponding to the velocity change between the initial velocity of initial motion stage and the target velocity of target motion stage. The determined target motion profile is used to determine a target path which is traversed by the target motion profile, and based on the target path a time point (defined control time step) is determined at which the determined target motion profile is started in order to reach a target position of the target motion phase.

[0013] Thus, a target motion profile for the jerk limitation of the motion profile can be created in a simple manner purely analytically. The target motion profile ensures that the target motion phase is reached from the initial motion phase while observing the jerk limitation.

[0014] Advantageously, the target motion profile is created in that the acceleration, starting from the initial acceleration in the first acceleration section, is reduced or increased by a maximum predefined maximum impact in a plurality of adjustment time steps, and then the acceleration is reduced or increased by a maximum predefined maximum impact in a plurality of adjustment time steps in the second acceleration section until the target acceleration is reached. Alternatively, the acceleration, starting from the initial acceleration in the first acceleration section, is reduced or increased by a maximum predefined maximum impact in a plurality of adjustment time steps until a predefined minimum acceleration or maximum acceleration is reached, and then the acceleration is maintained at the minimum acceleration or maximum acceleration for a plurality of adjustment time steps in the third acceleration section, and then the acceleration is increased or reduced by a maximum predefined maximum impact in a plurality of adjustment time steps in the second acceleration section until the target acceleration is reached. This ensures a simple implementation of a target motion profile that can be easily created.

[0015] If the acceleration change in the control time step of the target motion profile corresponds to a predefined maximum jerk, if the predefined motion limitation allows an area under the step function that corresponds, in addition to a residual error, to a speed change between an initial speed of the initial motion phase and a target speed of the target motion phase, and the acceleration change changes the value of the jerk in at least one control time step of the target motion profile, wherein the value of the jerk is determined to compensate for the residual error between the area under the step function resulting from the step function and the speed change, then on the one hand, the target motion phase is approached as quickly as possible with a jerk-limited motion, and at the same time the target speed is approached precisely.

[0016] It is advantageous for accuracy if the position error between the target position resulting from the step function and the position resulting from the target motion curve is compensated by varying the acceleration change at a plurality of control time steps in the acceleration curve in order to extend or shorten the target path by the position error, wherein the area under the acceleration curve remains constant. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Refer to the following Figures 1 to 6 To explain the present invention in more detail, these figures show advantageous configurations of the present invention by way of example, schematically and non-limitingly. Here, it is shown:

[0018] Figure 1 : Drive shaft with drive shaft adjuster,

[0019] Figure 2 : Target motion curve for impact limitation,

[0020] Figure 3 : Target motion profile with impact limitation to compensate position error,

[0021] Figure 4 : a target motion profile with jerk limitation having an initial acceleration not equal to zero,

[0022] Figure 5 : drive shaft in the form of a long stator linear motor,

[0023] Figure 6 : A transport unit complex with coupled transport units. DETAILED DESCRIPTION

[0024] Figure 1A drive shaft 1 is shown with a drive unit 2, which acts on a moving drive part 3 to move it. Therefore, a movement phase (p, v, a) occurs on the moving drive part 3, where p represents the position, v represents the speed, and a represents the acceleration. The position can be an angle or a distance. Therefore, the speed can be an angular velocity or a linear velocity, and the acceleration can be an angular acceleration or a linear acceleration. The movement phase (p, v, a) should be regulated by a drive shaft regulator 4. The drive shaft regulator 4 determines the actuating variable SS, with which the drive unit 2 is controlled in order to set a predetermined movement set value BS, such as the target position of the moving drive part 3. The drive shaft regulator 4 usually also processes the actual movement value IS, such as the actual position, which is detected in the drive shaft 1, for example, based on a measuring sensor. This general structure of the drive shaft 1 is sufficiently known and does not need to be explained in more detail.

[0025] It is also conceivable that the moving drive part 3 is part of multiple drive shafts 1 and that the part can therefore move in different directions, for example a transport unit in the case of a planar motor. The drive shaft regulator 4 can then regulate the movement of multiple drive shafts 1, or a drive shaft regulator 4 can be provided for each movement.

[0026] In each control time step k, wherein a predetermined time interval t is provided between two consecutive control time steps k, k+1 a , pre-set motion setpoint BS i And if necessary, detect the actual movement value IS i The drive shaft regulator 4 obtains the actuating variable SS from the actual motion value i The drive unit 2 uses the execution parameter SS i The control and thus the action on the moving drive component 3 results in a new actual movement value IS i+1 This cycle repeats until the target motion phase is reached.

[0027] Time interval t a Typically in the 100 μs range to 100 ms range, typically in the millisecond range.

[0028] The drive shaft regulator 4 is usually microprocessor-based hardware on which regulation software is executed. However, the drive shaft regulator 4 can also be implemented as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC).

[0029] The motion setpoint BS for each adjustment time step k iThe motion curve 5 is provided by the motion variables of the motion phase, such as position, velocity or acceleration. The motion curve 5 is essentially a series of values ​​of the motion variable per adjustment time step k. The motion curve 5 is, for example, a position curve with position as motion variable or a velocity curve with velocity as motion variable. The motion curve 5 is used to convert a predetermined starting motion phase (p S 、v S 、a S ) is converted into the desired target motion phase (p Z 、v Z 、a Z ). Thus, a movement phase (position, velocity, acceleration) of the moving drive element 3 occurs at each control time step during this movement. Target velocity v Z and target acceleration a Z is often equal to 0, thus approaching the determined target position p Z , at which target position the moving drive component 3 should be stationary. Of course, a target speed v not equal to 0 can also be set Z and / or target acceleration a Z In order to regulate the movement of the drive shaft 1 , in particular the movement of the drive element 3 of the drive shaft 1 , the movement curve 5 must be known.

[0030] When planning the motion curve 5, certain boundary conditions must also be observed, in particular predetermined motion limits of the motion variables. Typically, the maximum possible positive and negative accelerations a of the moving drive component 3 are max 、a min and the maximum possible positive velocity v max , and possibly also a minimum positive / negative velocity and / or a negative maximum velocity -v max is set as a movement limitation. This movement limitation can be caused by physical limitations of the drive shaft 1 or also by the application of the drive shaft 1, but is known in any case. In order to be able to dispense with a shock filter connected downstream, the shock j (as a time derivative of the acceleration) is also provided as an additional movement limitation in any case in both directions, i.e. for positive and negative accelerations, by predetermining the maximum shock ±j max It should be noted that the permissible impact j for positive and negative use max , where the permissible impact j for positive and negative directions is max The values ​​of are not necessarily the same. Therefore, the acceleration change between two consecutive adjustment time steps k, k+1 is calculated by the maximum impact j max Limit and cannot be greater than the maximum impact j max .

[0031] Positive acceleration is understood to be acceleration which increases the speed of the moving drive component 3, while negative acceleration is understood to be acceleration which decreases the speed of the moving drive component 3. This is naturally reversed when the sign of the speed changes, ie when the direction of movement changes.

[0032] The present invention assumes that there is an arbitrary initial motion phase (p S 、v S 、a S ), which initial motion phase should be converted into a predetermined target motion phase (p Z 、v Z 、a Z ).

[0033] However, due to motion constraints, the target motion phase (p Z 、v Z 、a Z ) cannot be any one at the initial movement stage (p S 、v S 、a S ) and target movement phase (p Z 、v Z 、a Z ) is achieved. Therefore, the target motion curve 5b is obtained, and the target motion curve is used to ensure the target motion phase (p Z 、v Z 、a Z ) from the initial movement stage (p A 、v A 、a A ) starts at the initial movement stage (p S 、v S 、a S ) and target movement phase (p Z 、v Z 、a Z ) is realized between. Therefore, the motion curve 5 is composed of the starting motion curve 5a, and the target motion curve 5b is connected to the starting motion curve. The starting motion curve 5a can be arbitrary and can be assumed to be predetermined. Figure 2 It is shown as an example in FIG.

[0034] Due to the discrete implementation, the acceleration value a can only be set at each control time step k of the movement profile 5 (at a predetermined time interval t a ). The acceleration profile is selected for motion planning because the jerk j can be limited in a simple manner. The acceleration change between two consecutive control time steps k, k+1 may be at most a predefined maximum jerk j max, whereby jerk limitation is already implemented. Thus, a step function with acceleration values ​​at each control time step k is obtained for the acceleration curve. The acceleration curve is a temporally discrete series of acceleration values ​​at control time step k, wherein the acceleration change between two consecutive control time steps k, k+1 is at most a predetermined maximum jerk j max .

[0035] It should be clear for understanding that the motion curve 5 for adjusting the motion is obtained by using the acceleration curve. The velocity curve (a series of discrete velocity values ​​in each adjustment time step k) is obtained by time integration from the acceleration curve, and the position curve (a series of discrete position values ​​in each control time step k) is obtained by quadratic integration. Therefore, the motion variable of the motion curve 5 can be position, velocity or acceleration. In the described embodiment, the acceleration curve is used as the motion curve 5 only for simplicity.

[0036] Figure 2 An arbitrary, known starting motion curve 5a (dotted line, in which the starting motion phase (p S 、v S 、a S )) and the target motion curve 5b. In this embodiment, the target motion phase (p Z 、v Z 、a Z ) through the target position p Z Given, at this target position, the target velocity v Z and target acceleration a Z In this example, the target motion curve 5b describes the deceleration (ie negative acceleration) of the moving drive component 3, wherein the target motion curve 5b can however also include positive accelerations. The target motion curve 5b is preferably implemented as a curve for the initial motion phase (p A 、v A 、a A ) and reach the target movement phase (p Z 、v Z 、a Z ), so that the target motion curve 5b can therefore start as late as possible. This has the effect, for example, that the acceleration change in the target motion curve 5b should correspond as much as possible to the maximum impact j max However, the target movement profile 5 b can also correspond to other specifications, such as other movement limitations, acceleration changes only every nth (n>1) control time step k, etc.

[0037] The target motion curve 5b should be used to change the initial position p A Change to the target position p Z , the initial velocity v AChange to target speed v Z And the initial acceleration a A Change to target acceleration a Z , i.e., when the target motion curve 5b is implemented using the drive shaft regulator 4, a target motion phase (p Z 、v Z 、a Z ). Because the initial movement phase (p A 、v A 、a A ) and the starting motion curve 5a can also be arbitrary and must comply with predetermined motion constraints, so the target motion curve 5b must be determined in order to convert the initial motion phase (p A 、v A 、a A ) is converted into the target motion phase (p Z 、v Z 、a Z ).

[0038] In order to explain the determination of the target motion curve 5 b, it is assumed for the sake of simplicity that before the target motion curve 5 b, the moving drive element 3 moves with a constant positive initial velocity v not equal to 0. A motion, and the initial acceleration is therefore a A is equal to 0.

[0039] Figure 2 The acceleration curve of the target motion curve 5b is shown. The resulting velocity and position curve are known to be obtained as the time integral of the acceleration curve and are Figure 2 Not shown.

[0040] In the described embodiment, the currently known initial velocity v A Reduce to target speed v Z = 0 and reach the target position p at the same time Z Therefore, the speed of the moving drive component 3 can be changed to the target speed v by the acceleration presetting in a plurality of control time steps k. Z , where the maximum permissible acceleration change in each control time step k corresponds to the predefined maximum impact j max , in order to comply with the shock limits.

[0041] In the exemplary embodiment shown, the moving drive element 3 is first decelerated, which takes place in a plurality of control time steps k. In this case, the acceleration a is reduced in each control time step k, wherein the acceleration change in each control time step k corresponds at most to a predetermined maximum impact j. max , until the predetermined minimum acceleration a is reached min .

[0042] From a certain point in time (control time step k), the acceleration must be increased again in order to reach the target acceleration a again in a number of control time steps k, taking into account the jerk limitation. Z = 0. The acceleration cannot be less than the minimum acceleration a min , which can give a number of control time steps k, in which the minimum acceleration a min Further deceleration (such as in Figure 2 ). It is therefore also possible that even the minimum acceleration a is not reached. min Thus, the maximum possible (ie the shortest possible in terms of time) deceleration of the moving drive part 3 is achieved while observing the jerk limit.

[0043] Generally speaking, this means that in the acceleration curve of the target motion curve 5b, the acceleration a increases from the initial acceleration a to A Assume that in a first acceleration segment 7a the acceleration is reduced or A increased in a plurality of control time steps k, wherein the acceleration change corresponds at most to a predefined maximum jerk j max In the subsequent second acceleration segment 7 b , the acceleration a is increased or decreased in a plurality of control time steps k, wherein the acceleration change corresponds at most to a predetermined maximum impact j max , until the target acceleration a is reached Z In this case, a triangular step function is generated as the acceleration curve. However, a third acceleration segment 7c can be generated between the first acceleration segment 7a and the second acceleration segment 7b, in which a predetermined minimum acceleration a is reached. min or maximum acceleration a max This acceleration is then maintained for a plurality of control time steps k. In this case, a trapezoidal step function is produced as the acceleration curve.

[0044] Since the adjustment time step k and the predetermined maximum impact j max The acceleration limit at a min , a max Of course, the remaining steps R1 and R2 in the step function of the acceleration curve cannot change with the maximum possible acceleration (maximum impact j max ) implementation, such as in Figure 2 However, these remaining step lengths R1, R2 can be easily determined.

[0045] For example, adjust the number of time steps k by Given, so that the initial acceleration a A When using the predetermined maximum impact j max The predetermined minimum acceleration a is reached min The remaining step length R1 is thus The remaining step R2 can be obtained similarly.

[0046] The number i of control time steps k in the first acceleration segment 7 a and in the second acceleration segment 7 b can therefore be determined in a simple manner.

[0047] As is known, the area under the acceleration curve corresponds to the velocity. For the target motion curve 5b, the area under the acceleration curve corresponds to the velocity v A To target speed v Z The speed change Δv, that is, according to Figure 2 The speed reduction achieved in the described exemplary embodiment is therefore the area under the acceleration curve must correspond to the speed change Δv in order to reach the predefined target speed v Z . This provides the information for planning to achieve the target speed v Z The first criterion for the target motion curve 5b.

[0048] It is not important to calculate the area under the step function of the acceleration curve. This area is mainly determined by the change in the minimum acceleration a min or maximum acceleration a max The number of adjustment time steps k of the third acceleration section 7c is affected. min or maximum acceleration a max The more adjustment time steps k are, the larger the area becomes and thus the greater the speed change Δv achieved with the target motion curve 5b. min , we can simply use the maximum impact j max The area can also be influenced by selecting a number of acceleration changes in the control time step k. In principle, the area can be influenced between zero and a predetermined maximum impact j max Freely select acceleration changes.

[0049] However, due to the discretization of the acceleration a in the adjustment time step k, the area generated under the acceleration curve may not correspond exactly to the desired speed change Δv, but rather a certain error may occur and the target speed v may not be reached exactly. Z If all acceleration changes are at a predetermined maximum impact j maxThis is the case, in particular, when a Δj occurs. This error occurs directly as a difference between the determined area and the desired change in speed Δv and can therefore be determined simply. To compensate for this error, the acceleration change is changed by a value Δj in at least one control time step k of the target motion curve 5b, so that the area under the acceleration curve corresponds to the desired change in speed Δv. Of course, the predefined motion limits must be observed here, and in particular, the predefined maximum impact j must not be violated. max and the maximum acceleration a max or minimum acceleration a min The determination of this value Δj can be carried out in a simple manner, since its influence on the area under the acceleration curve can be determined directly.

[0050] exist Figure 2 For example, the first acceleration change after the third acceleration interval 7c does not have a maximum impact j max In this embodiment, the remaining acceleration change is again carried out with the maximum impact j max Therefore, the area under the acceleration curve becomes larger.

[0051] Therefore, the target motion curve 5b can be obtained to achieve the change from the initial speed v A To target speed v Z The desired speed change Δv.

[0052] If the maximum impact j is used to determine the target motion curve 5b max , it is ensured that the speed change Δv occurs as quickly as possible while observing the movement restrictions, ie with the fewest possible control time steps k.

[0053] However, not only should the target speed v be reached Z , and the target position p should be reached Z The question therefore arises as to when the target motion curve 5b must be started, e.g. Figure 2 As shown in FIG. 5 , the target position p is generated at the end of the target motion curve 5 b. Z Therefore, when the moving drive component 3 moves with the target motion curve 5b, a target path is additionally determined using the target motion curve 5b determined for achieving the speed change Δv, which is traversed when executing the determined target motion curve 5b. Z The second standard of movement.

[0054] It is also unimportant to determine the target path covered by the previously determined target motion profile 5 b , since the target path results as the time integral of the velocity profile generated by the target motion profile 5 b or as the quadratic time integral of the acceleration profile of the target motion profile 5 b .

[0055] Therefore, the current position of the moving drive element 3 must be checked. If the current position corresponds to the target position p Z and the target path, the target motion curve 5b must be turned on in order to generate the desired target position p using the target motion curve 5b Z The time point for the start of the target movement curve 5b can thus be determined.

[0056] Here, too, errors are expected due to the discretization. In particular, given the target position p Z The difference from the target path will not correspond exactly to the position that the moving drive element 3 would occupy in the adjustment time step k when executing the motion profile 5. As a result, the target motion profile 5b will start too early or too late, and the target position p Z will not be generated accurately. If the target position p Z If the requirements are not too high, this error can be accepted. However, if the target position p should be approached as accurately as possible Z , then this error can also be compensated.

[0057] Here again, the solution consists in changing the acceleration change in the acceleration curve of the target motion curve 5b by the value Δj in a plurality of control time steps k. However, the area under the acceleration curve must not be changed in order to achieve the target speed v Z Of course, here again the predefined movement limits must be observed, in particular the predefined maximum impact j must not be violated. max and minimum acceleration a min or maximum acceleration a max This is Figure 3 The goal is to achieve the same speed change Δv by the value Δj at a number of adjustment time steps k, but with a change in time, so that the target position p is reached exactly Z The error is compensated. Therefore, the speed change Δv caused by the target motion curve 5b is prolonged or shortened as required.

[0058] The determination of this value Δj can be carried out in a simple manner, since its influence on the area under the acceleration curve and thus on the target path can be determined directly.

[0059] Figure 3An exemplary embodiment for position correction is shown. In this exemplary embodiment, the acceleration change is reduced by the value Δj in the first control time step k in the first acceleration segment 7a. Therefore, the acceleration change no longer corresponds to the maximum impact j max Other acceleration changes are based on the maximum impact j max occurs (but can occur with smaller acceleration changes). Therefore, the initial velocity v A The speed decreases more slowly and the target path is extended. However, this will reduce the area under the acceleration curve. In order to counteract this reduction, in this embodiment, the acceleration change is also reduced by the value Δj in the first adjustment time step k in the second acceleration section 7b in order to compensate for the smaller area. The other acceleration changes are again based on the maximum impact j max occurs (but can also occur with smaller acceleration changes). Therefore, the initial velocity v A It is immediately apparent that there are a number of possibilities for intervening in the acceleration change of the acceleration curve in order to extend or shorten the target path without changing the area under the acceleration curve.

[0060] As already mentioned, the target motion curve 5b does not necessarily have to be set at an initial acceleration a. A = 0 initial movement stage (p A 、v A 、a A ). Generally speaking, the initial acceleration a A Any value can be used (within the given movement limit a max 、a min This is for example in Figure 4 However, this does not change the basic process described above.

[0061] In this embodiment, the target motion curve 5b is a curve with an initial acceleration a. A >0 and known to occur during the initial movement phase (p A 、v A 、a A ) in the initial velocity v A The target motion curve 5b is the same as the above Figure 2 Therefore, from the initial movement stage (p A 、v A 、a A ) is decisive, and this area should correspond to the area from the initial velocity v A To target speed v ZThe target motion curve 5b can be used to determine the target path, from which it can be determined when (or at which adjustment time step k) the target motion curve 5b must start. Z or at target speed v Z and the target position p Z The above errors in can also be compensated in the same way.

[0062] The target motion curve 5b does not necessarily have to change the speed from the initial speed v A Reduce to target speed v Z (eg zero), but the target motion curve 5b can also be set to increase the speed. Therefore, the target motion curve 5b can also be limited to the area of ​​positive acceleration.

[0063] The present invention can be implemented as follows. The movement of the drive shaft 1 starts from a predetermined initial movement phase (p S 、v S 、a S ) starts with a desired or predefined initial motion profile 5a. The initial motion profile 5a provides the drive axle controller 4 with a motion setpoint value BS in each control time step k. k In each control time step k, the motion phase occurring in the next control time step k+1 is determined, for example, in which the movement is carried out with the maximum impact j max Continue or, if known, start from the initial motion curve 5a. The motion phase in the next adjustment time step k+1 is used as the initial motion phase (p A 、v A 、a A ) and on this basis, the target motion curve 5b is obtained, and the initial velocity v is caused by the target motion curve A and target speed v Z The target path is determined from the determined target motion curve 5b. If the target path is less than the difference between the target position pz and the current position in the control time step k, the target motion curve 5b is initiated in the current or at the latest in the next control time step k+1, thereby determining the time point for the start of the target motion curve 5b. Otherwise, the start motion curve 5a is continued. This constitutes the online determination of the target motion curve 5b.

[0064] Therefore, it can also be that the initial movement phase (p S 、v S 、a S ) and initial movement phase (p A 、v A 、a A )coincide.

[0065] However, it is of course also possible to determine the target movement curve 5 b for a predefined starting movement curve 5 a offline, ie in advance before the movement is carried out.

[0066] If the acceleration in the starting motion profile 5a is zero for a certain period of time, i.e. the speed cannot be changed, then the target motion profile 5b has to be calculated only once for this speed as long as the acceleration remains zero, since the target motion profile 5b cannot be changed (at least as long as no new target motion phase (p) is predefined). S 、v S 、a S )).

[0067] Likewise, the initial movement profile 5a can be planned with the aid of the acceleration profile while observing the predefined movement limits, wherein the acceleration change between two consecutive control time steps k, k+1 is at most a predefined maximum jerk j max , whereby impact limitation has already been implemented. This can be done in such a way that the speed change or position change should be implemented as quickly as possible through the initial motion curve 5a. Therefore, it can be provided that the predetermined maximum impact j max The acceleration in the acceleration profile of the initial motion profile 5a is changed. For a motion with a constant velocity, the acceleration is simply set to zero, but the previously acting acceleration can only be reduced by a predetermined maximum impact. Acceleration changes greater than a predetermined maximum impact j must be prohibited. max .

[0068] A significant advantage when determining the motion curve 5 or the target motion curve 5b of the motion curve 5 according to the invention is that no knowledge of the past is required. The memory requirement for determining the impact-limited motion curve 5 is thus significantly reduced. There is also no dead time as in the impact filter.

[0069] In each adjustment time step k, the target motion curve 5b can be obtained as the initial motion phase (p A 、v A 、a A ). The target path can be obtained from the target motion curve 5b. If the target path is smaller than the moving drive component 3 and the target position p Z The current distance (or the target path is less than the target position p Z and the current position), the target motion curve 5b must start, thereby determining the time point for the start of the target motion curve 5b. In this case, the target position p may be exceeded. Z , but this can be compensated by compensating for the position errors that occur. It is also conceivable to determine the movement phase in the next control time step k+1, for example in which the movement is calculated with the maximum impact jmax Then, the calculated motion phase in the next adjustment time step k+1 can be used as the initial motion phase (p A 、v A 、a A ), so as to determine the target motion curve 5b and the target path on this basis. If the determined target path is smaller than the moving drive component 3 and the target position p Z The current distance (or if the target path is less than the target position p Z and the current position), the target motion curve 5b determined is started in the current adjustment time step k. This ensures that the moving drive unit 3 does not completely reach the target position p Z However, the resulting position errors can be compensated as described above.

[0070] Another advantage is that the target movement phase (p) can be changed even during the movement of the drive shaft 1. S 、v S 、a S When determining the target movement curve 5b, the changed target movement phase (p S 、v S 、a S ). Therefore, the target motion phase (p S 、v S 、a S ) to respond to new pre-sets.

[0071] Not lastly, the determination of the target motion curve 5 b according to the invention also ensures a linear complexity of the calculations. If the number of control time steps increases, the complexity of the calculations increases linearly with the increase in the control time steps. The linear complexity is produced in particular by the fact that the required calculations are reduced to the determination of the area under the step function and no numerical mathematical methods or optimizations (usually solved iteratively) are required.

[0072] The motion curve 5, in particular the target motion curve 5b and, if necessary, the starting motion curve 5a, is predetermined by the device control device 6. The device control device 6 is used to control the device 10 that implements the drive axis 1. The motion curve 5 for the drive axis 1 is created on the device control device 6. The device control device 6 is a computer with corresponding software for creating the motion curve 5. The drive axis regulator 4 can also be integrated in the device control device 6.

[0073] As mentioned at the outset, the drive shaft 1 can be embodied, for example, in a long-stator linear motor (also called a planar motor). Figure 5For example, a long stator linear motor is shown as an embodiment of the device 10. The long stator linear motor consists of a stator 11, on which magnetic field generating units 12 for generating a magnetic field are arranged side by side, such as drive coils or movable magnets (in Figure 5 In the figure, only some magnetic field generating units are shown for clarity. A plurality of n transport units Tn move along the stator 11. An excitation magnet assembly 13, such as a permanent magnet, is arranged on each transport unit Tn (at Figure 5 , for the sake of clarity, only the excitation magnet assembly is shown on the transport unit T1). The magnetic field generated by the magnetic field generating unit 12 acts together with the excitation magnetic field generated by the excitation magnet assembly 13 to move the transport unit Tn. Therefore, the drive shaft 1 is composed of a magnetic field generating unit 12 (or a certain number of magnetic field generating units) as a drive unit 2, which acts on the transport unit Tn as a moving drive component 3 to move it. Here, due to this movement, the other magnetic field generating units 12 always act together with the transport unit Tn. In order to generate a magnetic field, the magnetic field generating unit 12 is controlled by the drive shaft regulator 4 through the execution variable SS, for example, in order to apply a coil voltage to a certain magnetic field generating unit 12 in order to generate a magnetic field. The movement setpoint value BS for the drive shaft regulator 4 is derived from the movement curve 5 of the predetermined movement of the transport unit Tn. Similarly, the drive shaft regulator 4 obtains the actual variable IS of the movement of the transport unit Tn, for example, the actual position on the stator 11 is obtained by a position sensor (not shown). In this way, the movement of the conveying unit Tn on the stator 11 can be planned and executed individually and independently of each other. In a planar motor, the drive shaft 1 forms the direction of movement on the stator 11 .

[0074] Due to the fact that the transport units Tn can be moved individually and independently of one another on the stator 11, it is known to provide for collision avoidance. Collision avoidance serves to prevent undesired collisions between two transport units Tn or between a transport unit Tn and another part of the device 10, for example a processing station arranged on the transport device. Such collision avoidance can be found, for example, in EP 3202612A1. During this collision avoidance, it is continuously checked whether the transport unit TN can carry out a stationary maneuver or an adjustment maneuver with a change of movement with a predetermined mobility without the risk of a collision with a transport unit moving in front or with a stationary part of the device 10. Such a stationary maneuver or adjustment maneuver therefore constitutes a motion profile 5 which can be planned as described above. Target motion phase (p Z 、v Z 、a Z ) During stationary operation, Z =a Z = 0. Any desired target movement phase (p Z 、v Z 、aZ ). Static maneuvers or adjustment maneuvers should usually be performed as quickly as possible, i.e. with the smallest possible target path. For this reason, the minimum acceleration a is also set for such maneuvers. min Defined as a movement restriction so that the transport unit Tn can be delayed as quickly as possible.

[0075] The determination of the target motion curve 5b according to the invention without a shock filter connected downstream is particularly advantageous for such stationary maneuvers or adjustment maneuvers for collision avoidance. The fact that no dead time occurs when creating the target motion curve 5b (as in the case of a shock filter) makes it possible, among other things, to reduce the required safety distance between adjacent transport units Tn on the stator 11. The transport units Tn can thus be moved closer to one another, which increases the transport volume of the transport units Tn per unit time, which is helpful in particular in transport applications.

[0076] In some applications, a plurality of transport units Tn also form a transport unit complex 14, such as in Figure 5 1, 2. However, it is not mandatory that the transport units Tn of the transport unit complex 14 are directly adjacent to each other, but other transport units can also move between them. Of course, it is also advantageous in such a transport unit complex 14 that the transport units Tn can be moved closer to each other one after another.

[0077] The transport units Tn in the transport unit complex 14 move in coordination with one another, so that the movements of the transport units Tn in the transport unit complex 14 are no longer independent of one another. For example, the distance between two transport units Tn in the transport unit complex 14 should remain constant.

[0078] How the movements are coordinated is not important here. For example, one transport unit Tn in the transport unit complex 14 can serve as the master of a predetermined movement, which the other transport units Tn in the transport unit complex 14 follow.

[0079] The two transport units Tn in the transport unit complex 14 can also be mechanically coupled, as in Figure 6 , for example, by means of a connection 15 between coupling points 16 on the transport units Tn. A coordinated movement can require, for example, that the distance between the coupling points 16 (for example, the Euclidean distance in space) remains the same during the movement. A coordinated movement can also require that the forces exerted by the two transport units Tn via the coupling points 16 on the connection 15 remain the same.

[0080] Movement restrictions, in particular maximum acceleration a, which must be observed, are predefined for each transport unit Tn. max and minimum acceleration a minThis does not pose a problem for the independent movement of the transport unit Tn. However, due to the coupled movement of the transport unit Tn in the transport unit complex 14, this can lead to difficulties, in particular during braking maneuvers, such as standstill maneuvers or maneuvers for collision avoidance, which are carried out with the greatest possible acceleration, since coordinated movement must be maintained at the same time. Such difficulties often occur in curved sections of the stator 11.

[0081] For example, if the transport unit complex 14 moves into a curved section of the stator 11, the movement of the transport units Tn in the transport unit complex 14 continues to be coordinated. For example, the distance between two transport units Tn continues to be maintained. However, it may happen that the coordinated movement with the predefined movement limits cannot be followed. For example, the coordinated movement may require that the transport units Tn of the transport unit complex 14 must move at a speed greater than the minimum acceleration a. min Negative acceleration braking or braking with a speed greater than the maximum acceleration a max The acceleration is accelerated in order to maintain the coordinated motion. However, this is not possible due to the predefined motion restrictions.

[0082] To solve this problem, in addition to the defined first acceleration limit, a second acceleration limit is assigned to the transport units Tn of the transport unit complex 14. The second acceleration limit is greater in magnitude than the first acceleration limit, i.e., a negative acceleration and / or a positive acceleration greater in magnitude than the first acceleration limit. Thus, the transport units Tn in the transport unit complex 14 have the possibility to use the second acceleration limit for movement, if necessary, in order to maintain the coordinated movement of the transport units Tn within the transport unit complex 14.

[0083] The first acceleration limit and the second acceleration limit can be configured by a user, for example. However, it is also conceivable that these acceleration limits are set by the drive axle regulator 4 or the machine control device 6, for example, based on knowledge of the application.

[0084] For example, a transport unit T1 of a transport unit group 14 performs a braking maneuver with a predetermined maximum deceleration according to the presetting of the movement limitation with the first acceleration limitation. Due to the coordinated movement, another transport unit T2 of the transport unit complex 14 must follow. If this second transport unit is also braked only with the first acceleration limitation, this second transport unit will no longer have the opportunity to simultaneously change the distance between the two transport units T1, T2. Since the second acceleration limitation is greater than the first acceleration limitation, the second transport unit T2 has this possibility.

[0085] However, this concept of the second acceleration limitation for the transport units Tn in the transport unit complex 14 is independent of how the movement profiles of the transport units Tn are planned or created.

[0086] Therefore, an advantageous method can be derived for a long-stator linear motor in order to control a transport unit complex 14 having a plurality of transport units Tn, the movements of which are coordinated with one another:

[0087] The transport units Tn of the transport unit complex 14 are each assigned a first acceleration limit, with which the maximum possible positive and / or negative first acceleration of the movement of the transport unit is determined. The transport units Tn of the transport unit complex 14 are each assigned a second acceleration limit, with which the maximum possible positive and / or negative second acceleration of the movement of the transport unit is determined, wherein the positive and / or negative second acceleration is greater in magnitude than the positive and / or negative first acceleration. The transport units Tn in the transport unit complex 14 use the first acceleration limit for their movement. If this does not allow coordinated movement of the transport units Tn, at least one transport unit Tn of the transport unit complex 14 uses the second acceleration limit.

Claims

1. A method for regulating the movement of a drive shaft (1) of a drive, wherein the movement of the drive shaft (1) is regulated with a predetermined regulation time step k by presetting a movement setpoint value (BS) for the movement, whereby a movement phase (p, v, a) of the movement of the drive shaft (1) is obtained in each regulation time step k, wherein a target position (p Z ), target speed (v Z ) and target acceleration (a Z ) in the form of target movement phase (p Z 、v Z 、a Z ) and from the starting position (p S )、Starting speed (v S ) and initial acceleration (a S ) in the form of the initial movement phase (p S 、v S 、a S ) is set based on the movement profile (5) while observing the predefined movement constraints. Z 、v Z 、a Z ), and wherein the desired motion value (BS) is obtained from the motion curve (5) in each adjustment time step k, It is characterized in that The motion curve (5) is composed of a starting motion curve (5a) and a target motion curve (5b), wherein the starting motion curve (5a) is S 、v S 、a S ) and transitions into the target motion profile (5b), which begins with an initial motion phase (p A 、v A 、a A ) and starts with the target motion phase (p Z 、v Z 、a Z )Finish, The target motion profile (5b) is determined using an acceleration profile over a plurality of control time steps k, wherein the acceleration change in each control time step k corresponds at most to a predetermined maximum impact (j max ), so that the acceleration curve of the target motion curve (5b) exists as a step function, in which the acceleration curve is a temporally discrete series of acceleration values ​​at an adjustment time step k, The step function is created while observing the predefined movement limits, so that the area under the step function corresponds to the initial movement phase (p A 、v A 、a A ) of the initial velocity (v A ) and the target motion phase (p Z 、v Z 、a Z ) of the target speed (v Z ), and A target path is obtained using the obtained target motion curve (5b), the target path passes through the target motion curve (5b), and a time point is obtained according to the target path, at which the obtained target motion curve (5b) starts, so as to reach the target motion phase (p Z 、v Z 、a Z ) of the target position (p Z ).

2. The method according to claim 1, characterized in that The acceleration in the acceleration curve increases from the initial acceleration (a) in the first acceleration section (7a) to A ) is used to reduce or increase the maximum predetermined maximum impact (j) in a plurality of control time steps k. max ), then the acceleration in the second acceleration section (7b) is increased or decreased by the maximum of the predetermined maximum impact (j max ), until the target acceleration (a A ).

3. The method according to claim 1, characterized in that: The acceleration is increased from the initial acceleration (a A ) is used to reduce or increase the maximum predetermined maximum impact (j) in a plurality of control time steps k. max ), until the predetermined minimum acceleration (a min ) or maximum acceleration (a max ), then the acceleration is maintained at the minimum acceleration (a) for a plurality of adjustment time steps k in the third acceleration section (7c). min ) or maximum acceleration (a max ), and then the acceleration is increased or decreased in a second acceleration section (7b) by a maximum of the predetermined maximum impact (j max ), until the target acceleration (a A ).

4. The method according to any one of claims 1 to 3, characterized in that If the predefined movement limitation allows that the area under the step function corresponds to the initial movement phase (p A 、v A 、a A ) of the initial velocity (v A ) and the target motion phase (p Z 、v Z 、a Z ) of the target speed (v Z ), the acceleration change in the control time step k of the acceleration curve corresponds to the predetermined maximum impact (j max ), and the speed change changes the impact value (Δj) in at least one adjustment time step k of the acceleration curve, wherein the impact value (Δj) is determined in order to compensate for the residual error between the area under the step function and the speed change (Δv) resulting from the step function.

5. The method according to any one of claims 1 to 4, characterized in that Compensation of the target position (p) generated by the step function Z ) and a position error resulting from the target motion curve (5b) by varying the acceleration change at a plurality of adjustment time steps k in the acceleration curve so as to extend or shorten the target path by the position error, wherein the area under the acceleration curve remains unchanged.

6. The method according to any one of claims 1 to 5, characterized in that In each adjustment time step k of the starting motion curve (5a), the current motion phase (p, v, a) is used as the initial motion phase (p A 、v A 、a A ), and using the initial motion phase (p A 、v A 、a A ) to obtain the target motion curve (5b) and the target path, and if the target position (p Z ) and the initial position (p A ) is smaller than the target path, the target motion curve (5b) is triggered in the next adjustment time step k+1.

7. The method according to any one of claims 1 to 5, characterized in that In each adjustment time step k of the starting motion curve (5a), the motion phase (p, v, a) of the next adjustment time step k+1 after the current adjustment time step k is used as the initial motion phase (p A 、v A 、a A ), and using the initial motion phase (p A 、v A 、a A ) to obtain the target motion curve (5b) and the target path, and if the target position (p Z ) and the initial position (p A ) is smaller than the target path, the target motion curve (5b) is triggered in the current adjustment time step k.

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