Drive system, trajectory planning unit and method

Abstract

The invention relates to a drive system (10), in particular a drive system for process automation, the drive system comprising: a trajectory planning unit (3), the trajectory planning unit being configured to provide a trajectory signal (xd) based on a setpoint value signal (xs); and an actuator unit (2), the actuator unit comprising an actuator element (1), in particular a valve element, the actuator unit being configured to control and / or regulate the position of the actuator element (1) based on the trajectory signal (xd). The trajectory planning unit (3) is configured to provide a trajectory signal (xd), the trajectory signal having a first signal segment (s1) and a second signal segment (s2), wherein the first signal segment (s1) has a straight-line signal course and the second signal segment (s2) has an asymptotic signal course with respect to the setpoint value signal (xs).

Description

Technical Field

[0001] The invention relates to a drive system, in particular a drive system for process automation. The drive system comprises a trajectory planning unit, which is configured to provide a trajectory signal based on a setpoint value signal. The drive system also comprises an actuator unit, which comprises an actuator element, in particular a valve element. The actuator unit is configured to control and / or adjust the position of the actuator element based on the trajectory signal.

[0002] The drive system is preferably a fluid drive system. The actuator is preferably a fluid actuator. Alternatively or additionally, the drive system may also be an electric drive system and / or the actuator may be an electric actuator.

[0003] The actuating unit comprises in particular a control and / or regulating unit which is designed to control and / or regulate the position of the actuator element based on a specified setpoint value. The trajectory signal is expediently used as a specified setpoint value for the control and / or regulating unit. The trajectory planning unit is in particular connected upstream of the control and / or regulating unit. The trajectory planning unit is expediently connected between a control unit providing the setpoint value signal and the actuating unit, in particular the control and / or regulating unit. Background Art

[0004] WO 2016 / 198109 A1 describes a fluid drive system having a path planning unit which, based on a setpoint value, provides at least one movement value for a control device and a regulating device. Summary of the invention

[0005] The object is to improve the drive system mentioned in the introduction in such a way that a path signal which can be easily parameterized is provided, by means of which a rapid and reliable regulation and / or control of the position of the actuator element is possible.

[0006] This object is achieved by a drive system according to claim 1. A trajectory planning unit of the drive system is designed to provide a trajectory signal having a first signal section and a second signal section, wherein the first signal section has a linear signal profile and the second signal section has an asymptotic signal profile with respect to the setpoint value signal.

[0007] Such a trajectory signal can be parameterized very simply. As will be explained in detail below, for the parameterization of such a trajectory signal, only two or only one parameter is preferably required in order to adapt the trajectory signal, for example, to a certain application and / or a certain execution unit. As a parameter, only a maximum speed value and / or a signal parameter of an actuator element is required, for example, for setting: at which signal value of the trajectory signal and / or at which time point, the first signal segment ends and / or the second signal segment begins. Preferably, (based on the rated value signal) not only the first signal segment but also the second signal segment is derived from these two parameters. The trajectory signal can therefore be parameterized very easily and with very little effort. Preferably, the drive system is constructed to perform parameterization automatically, for example, by automatically determining the maximum speed value within the scope of a maximum speed determination program.

[0008] Furthermore, such a trajectory signal can be used to enable rapid and at the same time reliable control and / or regulation of the actuator element. The first signal section with a linear course can be used to achieve that the actuator element is moved at the highest possible speed, in particular its own maximum speed, up to the desired setpoint value. The second signal section with an asymptotic course can ensure that the actuator element is not over-regulated beyond a predefined setpoint value and that reliable control and / or regulation is thus achieved.

[0009] Advantageous embodiments are the subject matter of the dependent claims.

[0010] The present invention also relates to a trajectory planning unit for providing a trajectory signal for controlling and / or regulating the position of an actuator element, wherein the trajectory planning unit comprises: a planning unit input for inputting a setpoint value signal; a planning unit output for outputting the trajectory signal; and a delay unit connected between the planning unit input and the planning unit output, the delay unit having an integral link. The trajectory planning unit also comprises a limiting unit connected before the integral link.

[0011] The trajectory planning unit is expediently used in a drive system described here in order to provide a trajectory signal.

[0012] The present invention also relates to a method for controlling and / or adjusting the position of an actuator element of a drive system, the method comprising the following steps: providing a setpoint value signal for the position of the actuator element; providing a trajectory signal based on the setpoint value signal, wherein the trajectory signal has a first signal segment and a second signal segment, the first signal segment having a linear signal curve, and the second signal segment having an asymptotic signal curve with respect to the setpoint value signal; and controlling and / or adjusting the position of the actuator element according to the trajectory signal.

[0013] Expediently, a method for operating a drive system described here is used and / or a drive system described here is designed to operate the drive system. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In the following, exemplary embodiments are further described with reference to the accompanying drawings, wherein:

[0015] Figure 1 A schematic diagram showing a drive system;

[0016] Figure 2 A schematic diagram showing a trajectory planning unit;

[0017] Figure 3 a diagram showing the temporal course of the position of the actuator element and the temporal course of the actuation signal during a maximum speed determination procedure;

[0018] Figure 4 A diagram showing the temporal course of a trajectory signal. DETAILED DESCRIPTION

[0019] Figure 1 A drive system 10 is shown, which is used in particular for process automation.

[0020] The fluid drive system 10 comprises an actuator unit 2 having an actuator element 1 , for example a valve element. The actuator unit 2 is designed to control and / or regulate the position of the actuator element 1 based on a trajectory signal xd.

[0021] The drive system 10 is preferably a fluid drive system. The actuator 2 is preferably a fluid actuator. Alternatively or additionally, the drive system 10 may also be an electric drive system and / or the actuator 2 may be an electric actuator.

[0022] The drive system 10 further comprises a trajectory planning unit 3 which is designed to provide a trajectory signal xd based on the setpoint value signal xs. The trajectory planning unit 3 is designed to provide a trajectory signal xd which has a first signal section s1 and a second signal section s2. Figure 4 It is shown in FIG. 1 that the first signal section s1 has a straight-line signal profile and the second signal section s2 has an asymptotic signal profile with respect to the setpoint value signal xs.

[0023] Additional exemplary details are set forth below.

[0024] First, the basic structure of the drive system 10:

[0025] The drive system 10 comprises, by way of example, a control unit 14 , which is preferably a higher-level control unit, for example a programmable logic controller, ie a SPS.

[0026] The control unit 14 is designed to provide a setpoint value signal xs. The setpoint value signal xs specifies a setpoint value, in particular a setpoint position, for the actuator element 1. Preferably, the setpoint value signal comprises a temporal sequence of setpoint values. The setpoint value signal is in particular a jump signal. Preferably, the setpoint value signal comprises a signal jump from a first setpoint value to a second setpoint value, the first setpoint value defining a first position, the second setpoint value defining a second position. The setpoint value signal is in particular an electrical signal; preferably, it is an analog or digital signal.

[0027] The setpoint value signal xs is supplied to a trajectory planning unit 3 . The trajectory planning unit 3 provides a trajectory signal xd based on the setpoint value signal xs.

[0028] The trajectory signal xd is supplied to the actuator unit 2. The actuator unit 2 performs a control and / or regulation of the position of the actuator element 1 based on the trajectory signal xd. The trajectory signal xd is used in particular as a predetermined setpoint value, for example as a reference variable, for the control and / or regulation performed by the actuator unit 2. The trajectory signal xd is in particular an electrical signal; it is expediently an analog or digital signal.

[0029] By way of example, the actuator unit 2 comprises a control and / or regulating unit 15 and an actuator 16, which comprises an actuator element 1. The actuator 16 is in particular a fluid actuator. The actuator unit 2 is in particular a process valve component.

[0030] The control and / or regulating unit 15 is expediently designed as a control head, a positioner head and / or a positioner. The control and / or regulating unit 15 is expediently arranged on the actuator 16, in particular mounted thereon and has, for example, a mechanical interface with which the control and / or regulating unit 15 is fixed to the actuator 16.

[0031] The control and / or regulating unit 15 is expediently designed to provide, based on the trajectory signal xd and / or the setpoint value signal xs, preferably a fluidic, in particular pneumatic or hydraulic control signal as. The control signal as is supplied to the actuator 16 in order to cause an actuation, in particular a position change, of the actuator element 1. The control and / or regulating unit 15 expediently comprises an electrofluidic, in particular an electropneumatic, converter for generating the control signal as.

[0032] The control and / or regulating unit 15 is designed to actuate the actuator 16 with the actuation signal as, so that the actuator element 1 assumes the position specified by the trajectory signal xd.

[0033] The actuator 16 preferably comprises a valve, in particular a process valve. The actuator element 1 is exemplarily a valve element of a valve. The actuator 16 preferably also comprises a fluid valve drive. The fluid valve drive comprises at least one pressure chamber that can be loaded with a control signal in order to put the actuator element 1, in particular the valve element, into motion.

[0034] For example, the control signal as enables the actuator element 1, in particular the valve element, to be moved to a first position corresponding to a first setpoint value, such as a closed position, and / or to a second position corresponding to a second setpoint value, such as an open position. Preferably, the actuator element 1 can also be moved to one or more other positions.

[0035] The actuator unit 2 expediently comprises a sensor unit, for example a position sensor, by means of which the position of the actuator element 1 can be determined. The control and / or regulating unit 15 expediently is designed to carry out a regulation of the position of the actuator element 1 taking into account a sensor signal from the sensor unit. For example, the control and / or regulating unit 15 takes into account the sensor signal, in particular the detected position of the actuator element 1, as a feedback variable in the position control of the actuator element 1. The control and / or regulating unit 15 uses the trajectory signal xd, in particular as a reference variable and expediently forms a difference between the trajectory signal xd and the feedback variable within the scope of the regulation to be carried out in order to determine a control deviation and to provide an actuation signal as based on the determined control deviation, in particular to provide the actuation signal as in such a way that the control deviation is minimized.

[0036] Alternatively, the control and / or regulating unit 15 can also be designed to carry out no regulation based on the trajectory signal xd, but only pure control, ie a so-called “open loop” control without feedback.

[0037] The trajectory planning unit 3 can be provided as a separate unit by way of example. Alternatively, the trajectory planning unit 3 can also be integrated in one unit together with the control and / or regulation unit 15, for example in a control head, in a position regulator head and / or in a positioner. In addition, the trajectory planning unit 3 can be integrated in the control unit 14.

[0038] The trajectory planning unit 3 and in particular the trajectory signal xd generated by the trajectory planning unit 3 will be discussed in more detail below.

[0039] Figure 4 An exemplary time course of the trajectory signal xd is shown. The time t is plotted on the horizontal axis. The signal value of the trajectory signal xd is plotted on the vertical axis. The trajectory signal xd has, by way of example, a generally monotonous, in particular strictly monotonous signal trend. By way of example, the trajectory signal xd extends monotonically, in particular strictly monotonically, from an initial value xs0 to a setpoint xs1 predetermined by the setpoint signal xs. In addition, the trajectory signal may also extend monotonically, in particular strictly monotonically, in a decreasing manner, in particular if a jump downward and / or less than xs0 is predetermined by the setpoint signal xs, then the trajectory signal then extends monotonically, in particular strictly monotonically, in a decreasing manner. The trajectory signal xd and / or its first-order derivative is preferably continuous, in particular via the transition between the total first signal segment s1, the total second signal segment s2 and / or the first signal segment s1 and the second signal segment s2. The trajectory signal xs preferably does not have an overshoot beyond the setpoint xs1.

[0040] The trajectory signal xd is expediently a jump response to a jump of the setpoint value signal xs. By way of example, the setpoint value signal xs jumps to the signal value xs1 at time t0, expediently from the signal value xs0, for example from the signal value xs=0, to the signal value xs1.

[0041] The trajectory signal xd comprises the two signal segments s1 and s2. The two signal segments s1, s2 are consecutive signal segments in time which do not overlap in time. Advantageously, these signal segments S1 and S2 also do not overlap in terms of their signal values.

[0042] The first signal segment s1 has a straight-line signal profile, and therefore in particular has a constant slope. The first signal segment s1 is expediently composed exclusively of a straight-line signal profile. The first signal segment s1 preferably starts at the signal value xs0, wherein the jump of the setpoint value signal xs also starts from this signal value xs0.

[0043] The second signal section s2 has an asymptotic signal profile with respect to the signal value xs1. By way of example, the second signal section has a limited increasing signal profile. Expediently, the second signal section s2 consists exclusively of an asymptotic signal profile.

[0044] By way of example, the second signal segment s2 directly adjoins the first signal segment s1. The transition U from the first signal segment s1 to the second signal segment s2 is preferably continuous. Preferably, the transition U from the first signal segment s1 to the second signal segment s2 is also continuous in terms of a first-order derivative. The trajectory signal xd therefore has no kink at the transition U from the first signal segment s1 to the second signal segment s2; the slope of the segment start of the second signal segment s2 is preferably identical to the slope of the first signal segment s1. By way of example, the slope of the second signal segment s2 decreases starting from the segment start.

[0045] The parameterization of the trajectory signal xd will be discussed in more detail below.

[0046] The trajectory planning unit 3 is configured to provide a linear signal trend based on the maximum speed value vmax of the actuator element 1. The maximum speed value vmax is preferably a value determined in advance. The maximum speed value vmax is in particular the value of the determined maximum movement speed, wherein the actuator element 1 can move from a first position, such as a first end position (Endlage) and / or a closed position of the valve unit to a second position, such as a second end position and / or an open position of the valve unit at this maximum movement speed. The trajectory planning unit 3 is in particular configured to provide a linear signal trend with the same slope as the maximum speed value vmax of the actuator element 1. The first signal segment s1 starts, for example, with the same value as the value of the setpoint value signal xs, wherein the jump in the setpoint value signal xs is carried out based on this. For example, the first signal segment s1 starts with a signal value xs0 and then increases with a constant slope until the transition U.

[0047] As will be explained further below, the trajectory planning unit 3 expediently has a first maximum speed value vmax1 and a second maximum speed value vmax2 and is designed to selectively provide the first signal segment s1 with the same slope as the first maximum speed value vmax1 or with the same slope as the second maximum speed value vmax2, depending on the direction in which the setpoint value signal xs moves (i.e., increases or decreases). Preferably, the first maximum speed value vmax1 and the second maximum speed value vmax2 differ in their own signs and / or their own values.

[0048] The trajectory planning unit 3 is preferably configured to provide the trajectory signal xd, in particular the first signal segment s1 and / or the second signal segment s2, based on a time constant T. The time constant T is in particular a time constant that describes the time behavior of a delay element, in particular a time behavior of a first-order delay element. The time constant T preferably specifies the ratio of the difference between the setpoint value signal xs and the trajectory signal xd to the slope of the trajectory signal xd. The drive system 10, in particular the trajectory planning unit 3, is preferably configured to provide the time constant T based on the maximum speed value vmax. The drive system 10, in particular the trajectory planning unit 3, is also preferably configured to provide the time constant T based on the setpoint value signal xs. The trajectory planning unit 3 is preferably configured to provide different time constants T for different setpoint values ​​or setpoint value jumps of the setpoint value signal xs. If a change to a first setpoint value is specified by the setpoint value signal xs, then, for example, a different time constant is calculated than in the case of a change to a second change different from the first setpoint value being specified by the setpoint value signal xs.

[0049] By way of example, the trajectory planning unit 3 is designed to determine the time constant based on the maximum speed value vmax and on the setpoint value signal xs and expediently also on the signal parameter a, and more specifically by way of example determines the time constant as follows:

[0050] T = (1-a)xs / vmax.

[0051] For “xs”, in this case, in particular the value of the setpoint value signal xs is used, to which the setpoint value signal xs changes, that is, for example, Figure 4 In the example, xs1.

[0052] By means of the signal parameter a, it can be defined at which signal value of the trajectory signal xd the transition U from the first signal segment s1 to the second signal segment s2 is performed. By way of example, the signal parameter a is between 0 and 1. By way of example, the signal parameter a specifies at which portion (Anteil) of the signal value change to be performed of the trajectory signal xd the transition U is located, i.e., on the signal value axis (i.e., the vertical axis), how large is the portion of the first signal segment s1 for the sum of the first and second signal segments s1 and s2. By way of example, the trajectory signal undergoes a signal value change from 0 to xs1. By means of the parameter a, it can now be set at which portion of the difference between 0 and xs1 the transition U from the first signal segment s1 to the second signal segment s2 should be performed. If the trajectory signal xd = a xs1, the transition U is performed. Preferably, the parameter a is greater than 0.5, in particular greater than 0.7, preferably greater than 0.8 and / or expediently less than 0.9. Expediently, the parameter a is selectable, in particular adjustable by a user.

[0053] The signal value of the trajectory signal xd at which the transition U takes place is also designated as x*. The associated time at which the transition U takes place is also designated as t*.

[0054] Therefore, the signal parameter a can be used to set at which signal value x* and / or at which time t* the first signal segment s1 ends and / or at which signal value x* and / or at which time t* the second signal segment s2 begins. Preferably, the signal parameter a, the signal value x* and / or the time t* can be input into the trajectory planning unit 3 via a user interface. The trajectory planning unit 3 is configured to provide a trajectory signal xd based on the signal parameter a.

[0055] It will be discussed below how this maximum speed value vmax can be determined.

[0056] The drive system 10 is expediently designed to carry out a maximum speed determination procedure, in which the actuator element 1 is set in motion in order to determine a maximum speed value vmax of the actuator element 1. Preferably, the drive system 10 is designed to carry out the maximum speed determination procedure outside of normal operation of the drive system 10, in particular before normal operation, i.e., for example, during an initialization phase.

[0057] An exemplary maximum speed determination procedure should be referred to below. Figure 3 To further elaborate. Figure 3 Two diagrams are shown: an upper diagram in which the control signal as is plotted over the time t, and a lower diagram in which the position x of the actuator element 1 is plotted over the time t.

[0058] The drive system 10 is designed, for example, to move the actuator element 1 from a first position x1 to a second position x2 and, expediently, from the second position x2 to the first position x1 during a maximum speed determination procedure. The first position x1 and / or the second position x2 are, for example, each an end position of the actuator element 1. The drive system 10 is designed to determine a maximum speed value vmax based on the movement of the actuator element 1, for example, using the above-mentioned sensor unit, in particular a position sensor. By way of example, the drive system 10 is designed to determine a first maximum speed value vmax1 based on the movement of the actuator element 1 from the first position x1 to the second position x2, and to determine a second maximum speed value vmax2 based on the movement of the actuator element 1 from the second position x2 to the first position x1.

[0059] Figure 3 The upper diagram of shows an exemplary control of the actuator 16 during the maximum speed determination process. First, the control signal as is provided with a first signal value as1. At the time point t11, the signal value of the control signal as is changed from as1 to as2. Exemplarily, a jump is made, in particular an upward jump, from as1 to as2. The control signal as is then maintained at as2. At the time point t21, the signal value of the control signal as is changed from as2 to as1. Exemplarily, a jump is made, in particular a downward jump, from as2 to as1. Exemplarily, the signal value as2 is the maximum possible signal value of the control signal as and / or the signal value as1 is the minimum possible signal value of the control signal as.

[0060] Figure 3 The lower diagram of shows the movement of the actuator element 1 caused by the above-described actuation of the actuator 16. The actuator element 1 is initially in position x1. At time t11, the actuator element 1 begins to move in the direction of position x2. At time t12, the actuator element 1 reaches position x2. At time t21, the actuator element 1 begins to move in the direction of the first position x1 and at time t22, the actuator element 1 reaches the first position x1. The slope between t11 and t12 corresponds, by way of example, to the first maximum speed value vmax1 and the slope between t21 and t22 corresponds, expediently, to the second maximum speed value vmax2.

[0061] According to the configuration explained above, the drive system 10 is configured to execute a maximum speed determination procedure in order to determine the maximum speed value. Alternatively or additionally, the drive system 10 can also be configured to determine the maximum speed value in normal operation, to estimate the maximum speed value, for example based on position values ​​and / or speed values ​​determined in normal operation.

[0062] The drive system 10 is preferably configured to repeatedly determine the maximum speed value vmax. In this way, it is possible to detect how or whether the maximum speed value vmax changes. The drive system 10 is preferably configured to perform a diagnosis based on one or more maximum speed values ​​and in particular to determine wear. Preferably, the diagnosis is performed on a remotely arranged server, in particular a cloud server.

[0063] Reference Figure 2 An exemplary embodiment of the trajectory planning unit 3 will be discussed in more detail below.

[0064] The trajectory planning unit 3 has a planning unit input 6 for inputting a setpoint value signal xs and a planning unit output for outputting a trajectory signal xd.

[0065] By way of example, the trajectory planning unit 3 comprises a delay unit which is connected between a planning unit input 6 and a planning unit output 7. This results in a signal path from the planning unit input 6 via the delay unit to the planning unit output 7. By means of the signal processing carried out in the delay unit, a trajectory signal xd is generated from the supplied setpoint value signal xs. This trajectory signal xd, in particular both the first signal section s1 and also the second signal section s2, is therefore provided when using the delay unit.

[0066] The delay unit is designed in particular to provide the trajectory signal with a slope that depends on the difference between the trajectory signal xd and the setpoint value signal xs. In particular, the delay unit is designed to provide the trajectory signal xd with a slope that is proportional to the difference between the trajectory signal xd and the setpoint value signal xs. Preferably, the delay unit is designed to provide the trajectory signal xd with a greater slope in the case of a greater difference between the trajectory signal xd and the setpoint value signal xs and to provide the trajectory signal xd with a smaller slope in the case of a smaller difference.

[0067] The trajectory planning unit 3 expediently further comprises a limiting element 4, which is used to limit the slope of the trajectory signal xd. The limiting element 4 is expediently connected between a planning unit input 6 and a planning unit output 7. By limiting the slope of the trajectory signal xd by the limiting element 4, a first signal section S1 with a straight signal curve is obtained.

[0068] By way of example, the delay unit comprises a transmission element 8. The transmission element 8 is a transmission element of a first-order delay element (also known as a PT1 element).

[0069] The transmission elements 8 include, by way of example, a proportional element 9, an integral element 11 and a subtractive element 12. The transmission elements 8 are connected in series between the planning unit input 6 and the planning unit output 7. A feedback path 18 extends from the planning unit output 7 to the subtractive element 12.

[0070] The limiting element 4 is connected in series to the transmission element 8. By way of example, the limiting element 4 is connected before the integral element 11 and expediently after the proportional element 9.

[0071] The setpoint value signal xs is supplied via the planning unit input 6 to a subtraction unit 12 which forms the difference between the setpoint value signal xs and the trajectory signal xd. This difference is supplied to a proportional element 9 which scales the difference by multiplying it by a factor 1 / T. The scaled difference is supplied to the input of the limiting element 4.

[0072] The limiting link 4 has at least one threshold value and is configured to output the signal value present at the input end at its own output end if the signal value (especially in numerical value) present at the input end is less than the threshold value, and to output the threshold value if the signal value (especially in numerical value) present at the input end is greater than or equal to the threshold value. Preferably, the limiting link 4 has an upper threshold value and a lower threshold value and is configured to output the upper threshold value at its own output end if the signal value present at the input end is greater than or equal to the threshold value; output the signal value present at the input end if the signal value present at the input end is less than the upper threshold value and greater than the lower threshold value; and output the lower threshold value if the signal value present at the input end is less than or equal to the lower threshold value.

[0073] The output signal of the limiting element 4 is supplied to an integrating element 11 which integrates the output signal and outputs the result of the integration as a trajectory signal xd.

[0074] According to a configuration (not shown in the figures), the trajectory planning unit 3 expediently also has a dead time component. Expediently, dead times that occur in the drive system 10 during the startup phase are taken into account in the trajectory planning via the dead time component.

[0075] Additional exemplary details shall be set forth below.

[0076] The trajectory planning unit 3 is used in particular to provide a prescribed setpoint value for a position control loop of a fluid drive system. The trajectory planning unit 3 corresponds appropriately to a PT1 link, to which the limiting link 4 has been added. The parameterization of the trajectory planning unit 3 takes into account the dynamics of the system to be regulated. The required dynamic characteristic value is the following maximum speed value (also referred to as the maximum movement speed (Verfahrgeschwindigkeit)), which can be simply determined in an initialization phase or can also be estimated online, i.e. during operation, and can thus be adaptively adapted. Suitably, the trajectory planning unit 3 adapts the maximum speed value during operation, in particular performs adaptive trajectory planning.

[0077] Furthermore, downtimes which typically occur in fluid systems during the startup phase can also be easily taken into account in trajectory planning.

[0078] By means of this trajectory planning, the drive system is operated in a guaranteed manner with regard to variable limitation at the beginning, that is, during the first signal segment s1. Static friction effects can thereby be compensated to the maximum extent. In addition, a time-optimal trajectory is obtained (the drive system is operated at maximum speed). In order to avoid overshooting of the drive system, a second signal segment s2, a "soft landing" phase, is defined, which brings the system to the setpoint value without overshooting. In particular, by suitable selection of the signal parameter a, it can be ensured that no overshooting occurs.

[0079] The target trajectory is reached at the maximum speed vmax (during the first signal segment s1) up to the predeterminable position x and then automatically transitions to the transition region (ab t>t*). In the transition region (during the second signal segment s2, also called "soft landing"), the trajectory planning unit behaves like a conventional PT1 element. This transition from the first signal segment s1, the saturation region, to the second signal segment s2, the so-called soft landing region (at t=t*) is (mathematically) smooth.

[0080] In particular, the trajectory planning unit 3 , which is implemented in particular as a modified PT1 element, can therefore be parameterized accordingly and a very simple, time-optimal trajectory planning adapted to the system behavior can be provided and overshooting can also be avoided.

[0081] The movement of the actuator element 1 during the upward and downward movement is expediently linear; that is to say it has a constant speed.

[0082] By knowing the maximum movement speed for opening and closing, ie the maximum speed value vmax, the trajectory signal can therefore be determined in such a way that, on the one hand, the maximum movement speed is taken into account and, on the other hand, overshooting is avoided.

[0083] The trajectory planning unit 3 is expediently implemented as a first-order delay element (PT1 element), in which the signal (ie, the speed or the slope) is limited at the input of the integrator. With such a trajectory planning unit 3, the trajectory signal xd can be generated so that it is limited in speed up to a certain, predeterminable position, resulting in a first signal section.

Claims

1. A drive system (10), the drive system comprising: a trajectory planning unit (3) which is designed to provide a trajectory signal (xd) based on the setpoint value signal (xs); and an actuator unit (2), comprising an actuator element (1), the actuator unit being designed to control and / or regulate the position of the actuator element (1) based on the trajectory signal (xd), in, The trajectory planning unit (3) is designed to provide the trajectory signal (xd), the trajectory signal having a first signal section (s1) and a second signal section (s2), wherein the first signal section (s1) has a linear signal profile and the second signal section (s2) has an asymptotic signal profile with respect to the setpoint value signal (xs), wherein the trajectory planning unit (3) comprises: a planning unit input (6), the planning unit input being used to input the setpoint value signal (xs); a planning unit output (7), the planning unit output being used to output the trajectory signal (xd); a delay unit connected between the planning unit input (6) and the planning unit output (8); and a limiting element (4), wherein the delay unit comprises an integral element (11), a proportional element (9) and a subtractive element (12), and wherein the subtractive element (12), the proportional element (9), the limiting element (4) and the integral element (11) are connected in series, wherein the limiting element (4) is connected before the integral element (11).

2. The drive system (10) according to claim 1, wherein the drive system (10) is a fluid drive system and the actuator (2) is a fluid actuator.

3. The drive system (10) according to claim 1, wherein the trajectory planning unit (3) is designed to provide a linear signal curve based on a maximum speed value of the actuator element (1).

4. The drive system (10) according to claim 3, wherein the trajectory planning unit (3) is designed to provide a linear signal curve with a slope based on a maximum speed value of the actuator element (1).

5. The drive system (10) according to claim 4, wherein the drive system (10) is designed to provide a time constant (T) based on the maximum speed value and to provide the trajectory signal (xd) based on the time constant (T). 6 . The drive system ( 10 ) according to claim 5 , wherein the drive system is designed to provide the time constant (T) also on the basis of the setpoint value signal (xs).

7. A drive system (10) according to any one of claims 3 to 6, wherein the drive system (10) is configured to perform a maximum speed determination procedure, wherein the actuator element (1) is set in motion in order to determine a maximum speed value.

8. A drive system (10) according to claim 1 or 2, wherein the trajectory planning unit (3) is constructed to provide the trajectory signal (xd) based on signal parameters, wherein the signal parameters can be used to set: at which signal value (x*) and / or at which time point (t*) the first signal segment (s1) ends and / or at which signal value (x*) and / or at which time point (t*) the second signal segment (s2) begins. 9 . The drive system ( 10 ) according to claim 8 , wherein the trajectory planning unit ( 3 ) is designed to provide the second signal section ( s2 ) directly after the first signal section ( s1 ).

10. The drive system (10) according to claim 9, wherein the trajectory planning unit (3) is designed to provide a trajectory signal (xd) having a transition from the first signal segment (s1) to the second signal segment (s2) which is continuous in terms of a first-order derivative.

11. The drive system (10) according to claim 10, wherein the trajectory planning unit (3) comprises the limiting link (4), and the limiting link is used to limit the slope of the trajectory signal (xd).

12. The drive system (10) according to claim 1, wherein the delay unit comprises a transfer link (8) of a first-order delay link.

13. The drive system (10) according to claim 1, wherein the drive system (10) is a drive system for process automation.

14. The drive system (10) according to claim 1, wherein the actuator element (1) is a valve element.

15. The drive system (10) according to claim 4, wherein the trajectory planning unit (3) is designed to provide a linear signal curve based on a maximum speed value of the actuator element (1) with the same slope as the maximum speed value.

16. A drive system (10) according to claim 5, wherein the drive system (10) is constructed to provide a time constant (T) based on a maximum speed value / the maximum speed value and to provide the first signal segment and / or the second signal segment (s2) based on the time constant (T).

17. Method for controlling and / or regulating the position of the actuator element (1) of the drive system (10) according to claim 1, the method comprising the following steps: Providing the setpoint value signal (xs) for the position of the actuator element (1); Providing the trajectory signal (xd) based on the setpoint value signal (xs) by using the trajectory planning unit (3); The position of the actuator element (1) is controlled and / or regulated as a function of the trajectory signal (xd).

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