Method for operating an actuator, actuator, and control arrangement

Abstract

The invention relates to a method for actuating an actuator (1) in order to produce a permanent change in the target length of the actuator (1) in an actuator longitudinal direction (L1) by applying voltage pulses to at least two actuator segments (AS, AS1, AS2) of the actuator (1), which actuator segments are formed from an electromechanical material that is suitable for carrying out an energy-free permanent length change on the basis of a voltage pulse, or by applying voltage pulses to at least two actuator segments (AS, AS1, AS2) of the actuator (1), a first of which actuator segments is formed from an electromechanical material that is suitable for carrying out an energy-free permanent length change on the basis of a voltage pulse, and a second of which actuator segments is suitable for carrying out an energy-free decreasing length change on the basis of a voltage pulse applied to the actuating electrode (E1, E2) thereof. The invention also relates to an actuator (1) and to a control arrangement.

Description

[0001] Method for operating an actuator, actuator and positioning device

[0002] The invention relates to an actuator, an actuating device and a method for operating an actuator.

[0003] From WO2017067544A1, a method for controlling at least one section of an electromechanical element with a polycrystalline and ferroelectric or ferroelectric-piezoelectric material having a plurality of domains is known. In this method, by applying an electrical voltage in the form of at least one voltage pulse between electrodes that are in contact with the material, a portion of the domains of the material, which have different polarization directions, is converted into a state of the same polarization direction, or conversely, domains of the same polarization direction are converted into different polarization directions.

[0004] One object of the invention is to provide a method for actuating an actuator that represents an alternative to known methods of this kind. In particular, one object of the invention is to provide a method for actuating an actuator in which the actuator exhibits favorable deformation behavior.

[0005] This problem is solved by the features of claim 1. Further embodiments are specified in the dependent claims relating to it.

[0006] According to one aspect of the invention, a method for actuating an actuator to achieve a permanent, energy-free change in the desired length of the actuator in a longitudinal direction is provided, wherein the actuator has at least two actuator segments formed from an electromechanical material and arranged one behind the other in the longitudinal direction of the actuator, and actuation electrodes, wherein an actuator segment is located between each pair of actuation electrodes, and the electromechanical material of each of the at least two actuator segments is suitable and, in particular, polarized or manufactured in such a way that, due to an electrical voltage pulse applied to the actuation electrodes, it causes an energy-free, permanent change in the length of the actuator segment to which the actuation electrodes are in contact, through a polarization process or a depolarization process.which continues without the application of an electrical voltage to the same actuating electrodes, comprising: a first step (A1) with the application of an electrical voltage pulse to the actuating electrodes that are in contact with one of the actuator segments, at least one further step (A2) with a repetition of the first step for the application of a voltage pulse to the actuating electrodes that are in contact with at least one of the actuator segments, until the resulting change in length of the actuator is equal to the desired permanent change in length of the actuator to be produced without energy input or lies within a predetermined deviation from the desired permanent change in length to be produced, wherein the application of the voltage pulses to the actuating electrodes that are in contact with the respective actuator segments is time-shifted.

[0007] The method according to the invention can additionally be implemented with any other feature provided according to the invention in a combination of features described herein such that the method comprises: provision of the actuator, wherein the actuator is mounted at a first end on a base body and wherein a component to be driven is coupled to a second end of the actuator, which is coupled in the longitudinal direction of the actuator, wherein the at least two actuator segments are located between the first end and the second end, wherein the electromechanical material of each of the at least two actuator segments has a polarization state such that, due to a voltage pulse applied to actuating electrodes, a length change pulse is followed by an energy-free permanent length change of the respective actuator segment, to which the actuating electrodes are attached, caused by a polarization process or a depolarization process.which continues without the application of a voltage to the same actuating electrodes, wherein the relative motion between the base body and the component to be driven is equal to the change in length of the at least one actuator segment to which a voltage pulse is applied.

[0008] The method according to the invention can additionally be implemented with any other feature provided according to the invention in a combination of features described herein such that the application of the voltage pulses to actuating electrodes, which are located on the respective actuator segments, is time-shifted such that a voltage pulse is applied to an actuator segment only when, after a temporally preceding application of a voltage pulse, a length change pulse of the respective actuator segment caused by this voltage pulse has at least partially decayed and, in particular, has decayed to at least 50% and, in particular, to 75%.The method according to the invention can additionally be implemented with any other feature provided according to the invention in a combination of features described herein such that the actuator segment to which a voltage pulse is applied in the further step (A2) differs from the actuator segment to which a voltage pulse is applied in the temporally preceding step (A1).

[0009] The method according to the invention can additionally be implemented with any other feature provided according to the invention in a combination of features described herein such that the maximum values ​​of the voltage pulse of the first step (A1) and of the respective voltage pulse of the at least one further step (A2) are equal or differ from each other, wherein preferably the maximum value of the respective voltage pulse of the at least one further step (A2) lies within a deviation of a maximum of 50% from the maximum value of the voltage pulse in the first step (A1). Deviations of the maximum value of the respective voltage pulse of the at least one further step (A2) from the maximum value of the voltage pulse in the first step (A1) that are greater than 50% are also conceivable for certain applications.

[0010] In particular, it can be provided that the respective time offset between successive applications of voltage pulses to the actuator segments or their actuation electrodes, or between the start of each successive application, is equal to or even greater than the duration of at least one of the voltage pulses, or lies within a deviation of a maximum of 50%, in particular a maximum of 30%, and in particular 15% of the duration of one of the voltage pulses, and in particular the duration of the first voltage pulse. Generally, two successive voltage pulse applications can be carried out in such a way that they overlap in time.

[0011] In general, the entire sequence of the first step (A1) and the at least one further step (A2) of the method according to the invention can be carried out such that two successive applications of voltage pulses or several of each of two successive applications of voltage pulses take place temporally after one of the following alternatives:

[0012] (S1) The application of the second voltage pulse begins while the application of the first voltage pulse is still in progress, and in particular it may be provided that the application of the second voltage pulse begins after at least 50% and in particular at least 75% and in special cases 90% of the period in which the first voltage pulse is applied has elapsed.

[0013] (52) The application of each second voltage pulse begins at the end or substantially at the end of the application of the first voltage pulse, where ‘substantially’ is to be understood as the application of the second voltage pulse beginning within a period before or after the end of the application of the first voltage pulse which is less than 20% of the duration of the application of the first voltage pulse.

[0014] (53) The application of the second voltage pulse begins after the application of the first voltage pulse has ended, and it may be provided in particular that the period between the end of the application of the first voltage pulse and the start of the application of the second voltage pulse is more than 30% and in particular at least 50% and in special cases more than 100% of the period in which the first voltage pulse is applied.

[0015] According to a further aspect of the invention, a method for actuating an actuator to generate a permanent, energy-free target length change of the actuator in an actuator longitudinal direction is provided, wherein the actuator comprises: at least two actuator segments formed from an electromechanical material and arranged one behind the other in the actuator longitudinal direction (L), and actuation electrodes, wherein an actuator segment is arranged between each pair of actuation electrodes, wherein the electromechanical material of at least one of the actuator segments is realized according to the definition (P2) herein, and wherein the electromechanical material of at least one of the second actuator segments is realized according to the definition (P1) herein.The method comprises: a first step (B1) with the application of a first voltage pulse to the actuating electrodes of at least one of the actuator segments, thereby generating a first change in the length of the at least one first actuator segment; at least a further step (B2) with the substantially simultaneous application of a second voltage pulse to the actuating electrodes of at least one second actuator segment, which differs from the first step (B1), thereby generating a second change in the length of the at least one second actuator segment. In particular, the second change in actuator segment length can be substantially equal in magnitude and opposite in direction to the energy-free reversible length change component of the first change in actuator segment length, and can at least partially or substantially compensate for it.

[0016] The inventive method according to this aspect can additionally be implemented with any other feature provided according to the invention in a combination of features described herein such that the polarity of at least one first actuator segment generated from a preceding polarization process is identical to the polarity of the actuator segment generated from the longitudinal direction of the previous polarization process.

[0017] Polarity of at least one second actuator segment, wherein the sign of the second voltage pulse at the actuating electrodes connected to the respective second actuator segment differs from the sign of the first voltage pulse at the actuating electrodes connected to the respective first actuator segment.

[0018] Alternatively, the inventive method can be implemented according to this aspect in addition to any other feature provided according to the invention in a combination of features described herein such that the polarity of at least one first actuator segment generated from a preceding polarization process with respect to the longitudinal axis of the actuator is different from and opposite to the polarity of at least one second actuator segment, wherein the sign of the second voltage pulse at the actuating electrodes connected to the second actuator segment is identical to the sign of the first voltage pulse at the actuating electrodes connected to the first actuator segment.

[0019] According to this aspect, the method according to the invention can additionally be implemented with any other feature provided according to the invention in a combination of features described herein such that the application of the first voltage pulse and the second voltage pulse is carried out by supplying the same control signal to the actuating electrodes of the respective first actuator segment and the actuating electrodes of the respective second actuator segment.

[0020] One object of the invention is to provide an actuator, an actuating device and an actuating system which has a favorable deformation behavior when actuated.

[0021] To solve this problem, an actuator is provided for producing a permanent target length change of the actuator in an actuator longitudinal direction when the actuator is actuated, wherein the actuator comprises: at least two actuator segments, which have an electromechanical material and are arranged one behind the other in the actuator longitudinal direction, and actuation electrodes, wherein an actuator segment is arranged between each pair of actuation electrodes, wherein the electromechanical material of at least one of the actuator segments is suitable or has a polarization state such that this electromechanical material, due to an electrical voltage pulse applied to its actuation electrodes, causes a permanent, energy-free length change of the at least one of the actuator segments, to which the same actuation electrodes are in contact, through a polarization process or a depolarization process.which persists without an applied electrical voltage to the same actuating electrodes or after the cessation of the voltage pulse applied to the same actuating electrodes, i.e., without energy, and wherein the electromechanical material of at least a second of the actuator segments is suitable or has a polarization state such that this electromechanical material, due to a voltage pulse applied to its actuating electrodes, undergoes a reversible change in length which decreases without an applied electrical voltage or after the cessation of the voltage pulse applied to the same actuating electrodes, i.e., without energy.

[0022] To solve this problem, an actuating device is further provided, comprising: an actuator with at least two actuator segments and with actuating electrodes, a presetting device, a control device which is functionally connected to the presetting device and receives a target position state for the actuator from it, and an actuator, wherein the actuator segments are arranged one behind the other in the longitudinal direction of the actuator and wherein an actuator segment is arranged between each pair of actuating electrodes, wherein the electromechanical material of each of the at least two actuator segments has a polarization state such that, due to a voltage pulse applied to actuating electrodes, a length change pulse is followed by a permanent, energy-free length change of the respective actuator segment, to which the actuating electrodes are attached, caused by a polarization process or a depolarization process.wherein the control device comprises a control command generation function and at least one control amplifier which is electrically connected to the actuator segments for applying voltage pulses, wherein the control command generation function is configured such that it derives control commands from the setpoint control states, which are transmitted by the control command generation function to each of the at least one control amplifier in order to achieve the setpoint control state of the actuator.

[0023] To solve this problem, a positioning system is further provided, comprising such a positioning device and a driven component that is coupled to the actuator and moved by the actuator. In particular, it can be provided that the actuator segments are arranged one behind the other in the longitudinal direction of the actuator, with an actuator segment arranged between each pair of actuating electrodes, wherein a first end of the actuator is configured to be mounted on a base body, and wherein the driven component is coupled to the second end of the actuator, with the at least two actuator segments located between the first end and the second end.

[0024] It is also an object of the invention to provide an actuating device with an actuator which has a favorable deformation behavior when actuated.

[0025] To solve this problem, an actuating device for operating an actuator to produce a permanent target length change of the actuator in an actuator longitudinal direction is provided, the actuating device comprising the actuator, a first control amplifier and a second control amplifier, wherein the actuator comprises: at least two actuator segments which have an electromechanical material and are arranged one behind the other in the actuator longitudinal direction, and actuation electrodes, wherein an actuator segment is arranged between each pair of actuation electrodes, wherein the electromechanical material of at least one of the first actuator segments is suitable, due to the application of a voltage pulse to the actuation electrodes which are in contact with the respective first actuator segment,to perform a permanent, energy-free length change of at least one of the first actuator segments, to which the same actuating electrodes are attached, caused by a polarization or depolarization process, which persists without an applied electrical voltage to the same actuating electrodes or after the cessation of the voltage pulse applied to the same actuating electrodes, i.e., without energy; and wherein the electromechanical material of at least one of the second actuator segments is capable of performing a reversible length change upon application of a voltage pulse to the actuating electrodes attached to the respective second actuator segment, which decreases without an applied electrical voltage or after the cessation of the voltage pulse applied to the same actuating electrodes, i.e., without energy; wherein the first control amplifier with the actuating electrodes,the actuators that are attached to each of the at least one first actuator segment, are electrically connected, wherein the first control amplifier is suitable for applying a first voltage pulse to the actuating electrodes of at least one of the first actuator segments and thereby generating a first change in the actuator segment length of the first of the actuator segments, wherein the first change in the actuator segment length is formed from the energy-free permanent length change component and from an energy-free reversible length change component preceding and exceeding the energy-free permanent length change component, wherein the second control amplifier is electrically connected to the actuating electrodes that are attached to each of the at least one second actuator segment, wherein the second control amplifier is suitableessentially simultaneously with the application of a second segment voltage pulse to the actuator electrodes of at least one of the second actuator segments by the first control amplifier, thereby generating a second change in the actuator segment length of the second actuator segment, wherein the second change in actuator segment length is equal in magnitude and opposite in direction to the energy-free reversible length change component of the first change in actuator segment length and compensates for it.

[0026] The actuator segment provided according to the invention is formed from an electromechanical material. The electromechanical material can, in particular, consist of or comprise a PZT material. Herein, PZT material is understood to mean an electromechanical ceramic material based on lead zirconate titanate, and in particular mixed crystals based on lead zirconate (PbZrO3) and lead titanate (PbTiO3).

[0027] In the actuator provided according to the invention, with at least two actuator segments, both actuator segments each have at least one deformation body with an electromechanical material and in particular a PZT material, with which the actuator segment or the deformation body changes at least one of its geometric dimensions when or as long as an electrical energy, in particular an electrical voltage, is applied to it.

[0028] According to the invention, the terms "actuator segment" and "deformation body" are to be understood as follows, unless an exception is explicitly defined herein: in every embodiment of the invention, the actuator segment comprises a deformation body made of an electromechanical material or consists of a deformation body made of an electromechanical material. The actuator provided according to the invention is formed from at least two actuator segments and actuation electrodes, wherein each actuator segment or each deformation body is located between two actuation electrodes, the two actuation electrodes being spaced apart from each other in the thickness direction of the respective actuator segment. The deformation body, and thus the actuator segment, comprises at least one deformation section made of an electromechanical material, and in particular a PZT material, with a plurality of domains, i.e., regions with unit cells of uniform dipole direction.In this context, the term "domain" refers specifically to a very small area among a multitude of very small areas, in which the polarization directions are the same or essentially the same. A deformation body or actuator segment, and especially its deformation section, may not have been subjected to a polarization process, or only partially or completely, and is therefore essentially unpolarized, partially polarized, or essentially completely polarized. In the unpolarized areas, the polarization directions of the domains are chaotically different from one another, i.e., irregularly different.This essentially unpolarized state is also referred to below as the "original state" of the deformation body or actuator segment and in particular its modification section, since the deformation body or actuator segment or its respective modification section has not yet been subjected to a polarization process.

[0029] The modification section can be a sub-area of ​​the deformation body or actuator segment, or it can be identical to the deformation body or actuator segment. Viewed in the longitudinal direction, the modification section lies within an actuating electrode that is adjacent to the deformation body or actuator segment and functions as the excitation electrode, or it overlaps at least 25% and preferably at least 50% of the area of ​​the excitation electrode that is adjacent to the respective deformation body or actuator segment.By appropriately controlling the excitation electrode, which is located on a respective first contact surface of the deformation body or actuator segment, and by applying a reference voltage to the actuating electrode, which acts as a reference electrode and is located on a respective second contact surface of the same deformation body or actuator segment, oriented opposite to the first contact surface, an electric field is generated that runs along the longitudinal direction of the deformation body.

[0030] According to the invention, the respective deformation body or actuator segment is realized according to one of the following two definitions:

[0031] (P1) Each of the at least one change section of the deformation body or actuator segment is exclusively a change section whose domains, in a start state for commissioning the deformation body or actuator segment or the actuator, are, due to a polarization process, completely or substantially completely polarized from an initial polarization state in a polarization direction that runs along the respective thickness direction and has a corresponding polarity. With a deformation body or actuator segment according to the definition (P1), only a non-permanent and reversible change in extent, and generally an increase in extent, can be realized for the period of application of an electrical voltage or electric field, which ceases upon removal of the electrical voltage or field.the electric field essentially decreases or disappears, so that the initial length of the deformation body in the direction of expansion is automatically restored or essentially restored.

[0032] (P2) Each of the at least one change section of the deformation body or actuator segment is exclusively a change section whose domains in a start state for commissioning the deformation body or actuator segment or the actuator are preferably not polarized or only partially polarized, i.e., generally polarized by a polarization process from the original polarization state to a proportion of >0% and <100% and preferably to a proportion between 10% and 90% in a polarization direction that runs along the respective thickness direction, whereby a voltage pulse applied to corresponding electrodes in the thickness direction causes an energy-free permanent orIrreversible length change of the deformation body or actuator segment occurs in the thickness direction, which persists as long as no voltage is applied to the same actuation electrodes, whereby prior to the permanent length change of the deformation body due to the application of the voltage pulse or with the application of the voltage pulse, a temporally impulsive increase or impulsive overshoot of the length of the deformation body occurs above the subsequently established permanent length or length change of the deformation body, i.e. an initial length change pulse.The temporal profile of the initial length-change impulse, or the impulsive increase or overshoot in the length of the deformed body, takes the form of a unipolar impulse with a sudden rise and fall. This unipolar impulse increases, in particular, with or immediately after the application of the voltage pulse and then falls until the permanent or irreversible length change of the deformed body occurs. The duration of the unipolar length-change impulse can be calculated by multiplying the duration of the voltage pulse by a factor in the range between 0.75 and 10, specifically between 1.0 and 5, or between 1.0 and 2.5, or specifically between 1.0 and 1.5.

[0033] Herein, "hard PZT material" refers to a material realized according to definition (P1). Herein, "soft PZT material" refers to a material realized according to definition (P2). A deformation body of an actuator segment according to definition (P1) is also referred to as "hard" herein, and a deformation body of an actuator segment according to definition (P2) is also referred to as "soft" herein.

[0034] In the case of deformation bodies or actuator segments of an actuator unit according to the invention, the direction of expansion runs essentially in the longitudinal direction of the respective deformation body, both in the case of a deformation body or actuator segment according to (P1) and in the case of a deformation body or actuator segment according to (P2).

[0035] To achieve state (P1), a remanent polarization of the at least one changing section of the deformation body or actuator segment is produced under the influence of a constant electric field before the commissioning of the at least one changing section of the deformation body.

[0036] In this context, the deformation body or actuator segment according to the definition (P1) is also understood as a deformation body made of a fully polarized material.

[0037] An actuator segment or deformation body according to (P1) thus undergoes an expansion in the longitudinal direction of the respective actuator segment or deformation body by applying an electrical voltage or voltage pulse to the actuating electrodes that are in contact with the respective actuator segment or deformation body, whereby this expansion only occurs as long as the voltage or voltage pulse is applied at a substantially constant rate and returns completely or substantially completely when the voltage is removed, and is therefore reversible. In contrast, a deformation body or actuator segment according to the definition (P2) can be subjected to appropriate control, i.e.,By applying a single voltage pulse or several electrical voltage pulses to the actuating electrodes that are in contact with the respective actuator segment or deformation body, a change in the expansion of the actuator segment or deformation body to which the same actuating electrodes are in contact is generated, which persists without the application of a voltage, i.e., even after the removal of the electrical voltage, and is therefore remanent or irreversible and is therefore also referred to as "permanent".Therefore, the electromechanical material of a deformation body or actuator segment, as defined in (P2), on which actuation electrodes are arranged opposite its direction of deformation or expansion, is suitable for inducing a polarization or depolarization process and a resulting permanent change in length without energy input, based on at least one voltage pulse applied to the actuation electrodes. Here, "permanent change in length without energy input" is understood to mean a change in length that persists as long as no voltage or voltage pulse is applied to the same actuation electrodes after the at least one voltage pulse.

[0038] With regard to the actuator segment or a deformation body according to the definition (P2), it is also conceivable that the domains of the modification section have a degree of polarization of 0% (completely unpolarized) or a degree of polarization of 100% (completely polarized), although limitations regarding the expansion directions or the corresponding expansion magnitude must then be accepted. Thus, with a degree of polarization of 0% or essentially 0%, at least initially only a remanent increase in expansion can be achieved by applying corresponding voltage pulses, whereas with a degree of polarization of 100% or essentially 100%, initially only a remanent decrease or reduction in expansion can be realized by applying corresponding voltage pulses.In particular, an actuator segment or its deformation body according to the definition (P2) can be realized such that a proportion greater than 0% and less than 100%, and in particular a proportion between 1% and 99%, and especially preferably a proportion between 10% and 90%, of the domains of the actuator segment or its deformation body are polarized from an initial polarization state in a polarization direction running along the respective longitudinal direction for the commissioning of the deformation body due to a polarization process. In general, a "proportion greater than 0% and less than 100%" can be understood here to mean, in particular, a proportion greater than 1% and less than 99%, and specifically a proportion greater than 0.1% and less than 99.9%.Herein, the actuator segment or deformation body according to the definition (P2) is also understood as an actuator segment or deformation body made of a not fully polarized material that is capable of inducing a permanent or remanent relevant change in length solely on the basis of at least one voltage pulse of a magnitude relevant to the specific case. This means that the permanent relevant change in length persists even when no voltage is applied to the deformation body after the at least one voltage pulse. The relevant change in length is preferably considered here to be a change in length in the respective longitudinal direction of the deformation body with a magnitude of 0.1% of the longitudinal length of the actuator segment or deformation body at a voltage applied to the deformation body that is, for example, below 200 V.Alternatively or additionally, the change in length in the respective longitudinal direction of the actuator segment or deformation body may preferably be greater than 0.1 nanometers. For short, this material is also referred to herein as a polarized material suitable for undergoing a permanent change in length due to a voltage pulse.

[0039] An actuator segment or deformation body according to the definition (P2) is controlled by applying an electrical voltage in the form of at least one voltage pulse with a defined amplitude and duration. This results in a permanent or remanent change in the degree of polarization of the changing section, depending on the amplitude and duration of the voltage pulse, for a controlled permanent change in the expansion of the changing section or its actuator segment or deformation body, even without the presence of an electrical voltage, i.e., even after the previously applied voltage has been reduced to zero.

[0040] It can be advantageous for the amplitude of the voltage pulses to be dimensioned for a defined increase in the extent of the change section of the electromechanical material along the longitudinal direction or direction of expansion such that a resulting electric field strength between adjacent electrodes is positive and between >0 and 300% of the coercive field strength, and preferably between 50% and 240% of the coercive field strength. The corresponding amplitude can be smaller the longer the duration and / or the greater the number of applied voltage pulses, and conversely, the corresponding amplitude can be larger the shorter the duration and / or the greater the number of applied voltage pulses.Coercive field strength refers to the field strength sufficient to align most or all of the dipole moments of the domains of a ferroelectric material in the direction of the electric field (saturation polarization). There are positive and negative coercive field strengths, which are equal in magnitude for most soft piezoceramics. If the magnitude of the electric field in a ferroelectric deformation body, initially polarized in the positive thickness direction, is reduced in the direction of the negative coercive field strength (negative voltage along the original polarization direction), the dipole moments of the domains of the ferroelectric material, or at least most of them, align along a direction opposite to the original polarization direction and thus opposite to the original orientation of the ferroelectric domains.

[0041] Furthermore, it can be advantageous for the amplitude of the voltage pulses to be dimensioned for a defined decrease in the extent of the change section of the electromechanical material along the direction of expansion V such that the resulting electric field strength between adjacent electrodes is negative and between greater than 0% and less than or equal to 240% of the coercive field strength, and preferably between greater than 0% and less than or equal to 120% of the coercive field strength. Here, too, the corresponding amplitude can be smaller the longer the duration and / or the greater the number of applied voltage pulses, and conversely, the corresponding amplitude can be larger the shorter the duration and / or the number of applied voltage pulses.

[0042] The embodiments of the method according to the invention influence the following effects, which result from applying a voltage pulse to an actuator segment or a deformation body according to the definition (P2) to achieve a permanent change in length of the actuator segment or deformation body: By applying a voltage pulse to an actuator segment or a deformation body according to the definition (P2), the change in length of the actuator segment or deformation body initially overshoots the length that exists as the permanent or remanent length of the actuator segment or deformation body after the application of the voltage pulse.As an example, Figure 1 shows a functional representation with the upper part of the diagram showing the time course of a voltage pulse applied to an actuator segment or a deformation body, and the lower part showing the time course of a change in length of the actuator segment or deformation body caused by this voltage pulse. The voltage pulse causes two components of the change in length of the actuator segment or deformation body, which add up to a resultant change in length of the actuator segment or deformation body.

[0043] (F1) A first component is a piezoelectric length change component, which is an energy-free, reversible length change component with a relatively short-term length change of the actuator segment or deformation body and whose magnitude significantly exceeds the length change of the actuator segment or deformation body resulting from (F2). The voltage pulse can have a duration between 50 ms and 150 ms, preferably between 70 ms and 120 ms, wherein the rise and fall times at the edges of the voltage pulses can be between 5 ms and 20 ms, preferably between 8 ms and 12 ms. The magnitude of the length change or length increase of the actuator segment or deformation body depends on the magnitude and duration of the applied voltage pulse.Furthermore, the amount of length change or length increase of the actuator segment or deformation body depends on the current degree of polarization of the electromechanical material according to (P2). The greater the degree of polarization, i.e., the more domains are already aligned, the greater the deviation or overshoot of the length change of the actuator segment or deformation body beyond the specified permanent length according to (F2).

[0044] (F2) A second component, following the piezoelectric length change component (F1), is a ferroelectric length change component. This component is a permanent, energy-free length change component, meaning it causes a lasting or remanent length change of the actuator segment or deformation body after the applied voltage pulse has decayed or ceased or been removed. As illustrated in Figure 1, the ferroelectric component causes an increase in the length of the actuator segment or deformation body, each increase resulting from a change in the orientation of domains due to the applied voltage pulse. The length change is essentially proportional to the number of domains that have undergone repolarization and thus reorientation due to the voltage pulse. The length change of component (F2) occurs in the same direction as the length change of component (F1).The component (F1) precedes and exceeds the energy-free permanent length change component (F2), and is therefore greater in magnitude than the magnitude of the length change component (F2). Between the formation of the length change component (F1) and the achievement of the desired permanent length change of the actuator segment or deformation body, a creep process of the actuator segment or deformation body occurs during or within the formation of the length change component (F2). This creep process, starting with the relatively large initial length change of the actuator segment or deformation body (here: length increase) and a subsequent partial length change of the actuator segment or deformation body that is inversely proportional to its sign (here: length decrease), causes a further length change of the deformation body in the direction of the inverse length change due to the length change component (F1).This further change in length of the actuator segment or deformation body during the creep process is relatively small compared to the length change component (F1). The creep process, or rather the formation of the length change component (F2), lasts longer than the formation of the length change component (F1), in particular by a factor of at least 2 and specifically by a factor of at least 3. The relatively short-term piezoelectric length change component (F1) can exceed the ferroelectric length change component (F2) by a factor of more than 2.

[0045] Since the total length change of the actuator segment or deformation body due to length change component (F1) is significantly greater than that due to length change component (F2), and can, for example, be more than twice as large, length change component (F1) is also referred to here as "overshoot." Because, in the given application, the length change caused by component (F2) is the permanent length change of the actuator segment or deformation body that is to be achieved or is desired by applying the voltage pulse, overshoot in the formation of length change component (F1) is generally detrimental. Component (F1) is larger the greater the applied voltage and the greater the degree of polarization of the material according to (P2).

[0046] One disadvantage of the occurrence of the length change component (F1) is, for example, unwanted movements of a driven component that is moved by the actuator. This can lead to exceeding a tolerance range for the permissible movements of a driven component.

[0047] Another disadvantage of the occurrence of the length change component (F1) is unwanted dynamic effects in the movements of a component driven by the actuator.

[0048] Such adverse dynamic effects can be compensated for by ensuring that the at least one voltage pulse applied to an actuator segment or deformation body according to definition (P2) to achieve a permanent change in the length of the actuator segment or deformation body is S-shaped. In particular, the rise and fall phases of the trapezoidal voltage pulse can be S-shaped. This S-shape, or rounding of the initial and final phases of the voltage pulse, can be achieved using a polynomial of at least the fourth degree or by a sinusoidal contour. In both cases, the derivatives of the voltage signal, and thus the position signal as well as its first and second derivatives (velocity and acceleration), are continuously differentiable, i.e., they exhibit no discontinuities, thereby reducing dynamic effects (see Figure 7).

[0049] The change in length of the actuator caused by the creep process can be compensated by an additional compensation voltage pulse, which is smaller in value or amplitude than the at least one voltage pulse applied for the permanent change in length of the actuator segment or deformation body, and which is inversely proportional to this voltage pulse with respect to its sign, i.e., has a sign opposite to that of the voltage pulse applied for the permanent change in length of the actuator segment or deformation body.

[0050] In particular, the magnitude of each additional compensation voltage pulse is less than 50% of the magnitude of the voltage pulse applied to achieve the permanent length change of the actuator segment or deformation body. The duration of each additional compensation voltage pulse can be specified depending on the application.

[0051] The actuator segment provided according to the invention can be used particularly advantageously for movements of the actuator in the nanometer range.

[0052] In this context, "orientation" with respect to a surface, and in particular a surface, refers to the normal to that surface. If the surface in question is not flat but, for example, curved, the normal to a flat surface of the same size can be used to determine the surface normal, provided that the normal to the flat surface exhibits the smallest overall deviation relative to the curved surface.

[0053] Unless explicitly defined otherwise, the values ​​mentioned in the embodiments of the method according to the invention are in any case to be understood as a range of values, the limit of which is defined by the deviation of + / - 10% from the respective value mentioned.

[0054] The term “essentially” in relation to a feature or value shall be understood in particular to mean that the feature or value contains a deviation of 20% and specifically of 10% from the feature or its geometric property or from the value specified.

[0055] The following describes embodiments of the invention with reference to the accompanying figures. The figures show:

[0056] Figure 1 shows a functional representation with a time course of a voltage pulse applied to an actuator segment in the upper part of the functional representation and the time course of a change in length of the actuator segment caused by this voltage pulse, with a ferroelectric length change component and a preceding piezoelectric length change component in the lower part of the functional representation.

[0057] Figure 2 shows an embodiment of an actuator with two actuator segments for carrying out the respective method according to the invention.

[0058] Figure 3A shows a schematic representation of an embodiment of an actuator for applying a first embodiment of the method according to the invention, wherein the actuator has four actuator segments, each comprising a soft electromechanical material, which have an identical polarity with respect to the longitudinal direction.

[0059] Figure 3B on the left shows a first functional representation with four diagrams showing temporally offset voltage pulses with the same sign in their respective time courses, whereby each voltage pulse controls one of the four actuator segments of the actuator shown in Figure 3A; the middle figure shows a second functional representation with four diagrams showing length changes in their respective time courses, each of which is executed by one of the four actuator segments of the actuator shown in Figure 3A due to the control according to the first functional representation; and the right figure shows a third functional representation with a diagram showing the sum or superposition of the length changes of the four actuator segments according to Figure 3A in their time courses and thus of the actuator.

[0060] Figure 4A shows a schematic representation of an embodiment of an actuator for applying a second embodiment of the method according to the invention, wherein the actuator has a first actuator segment made of a soft electromechanical material and a second actuator segment made of a hard electromechanical material, wherein the actuator segments are arranged one behind the other in a longitudinal direction of the actuator and have the same polarity with respect to the longitudinal direction.

[0061] Figure 4B on the left shows a first functional representation with two diagrams showing opposing voltage pulses with different signs over time, each controlling one of the two actuator segments of the actuator shown in Figure 4A; the middle figure shows a second functional representation with two diagrams showing length changes over time, each resulting from the control of one of the two actuator segments of the actuator shown in Figure 4A according to the first functional representation; and the right figure shows a third functional representation with a diagram showing the sum or superposition of the length changes of the two actuator segments according to Figure 4A over time, and thus of the actuator.

[0062] Figure 5A shows a schematic representation of an embodiment of an actuator for applying the second embodiment of the method according to the invention, wherein the actuator has a first actuator segment made of a soft electromechanical material and a second actuator segment made of a hard electromechanical material, wherein the actuator segments are arranged one behind the other in a longitudinal direction of the actuator and have the same polarity with respect to the longitudinal direction;

[0063] Figure 5B on the left shows a first functional representation with two diagrams showing different but identical (positive) voltage pulses over time, each controlling one of the two actuator segments of the actuator shown in Figure 5A; the middle figure shows a second functional representation with two diagrams showing length changes over time, each executing one of the two actuator segments of the actuator shown in Figure 5A as a result of the control according to the first functional representation; and the right figure shows a third functional representation with a diagram showing the sum or superposition of the length changes of the two actuator segments according to Figure 5A over time, and thus of the actuator, where the voltage pulses have the same (positive) sign.

[0064] Figure 6A shows a schematic representation of an embodiment of an actuator for applying the second embodiment of the method according to the invention, wherein the actuator has a first actuator segment made of a soft electromechanical material and a second actuator segment made of a hard electromechanical material, and wherein the actuator segments are controlled by a single control amplifier, wherein the actuator segments are arranged one behind the other in a longitudinal direction of the actuator and have the same polarity with respect to the longitudinal direction;

[0065] Figure 6B on the left shows a first functional representation with two diagrams showing essentially identical voltage pulses with the same (positive) sign over time, each controlling one of the two actuator segments of the actuator shown in Figure 6A; the middle figure shows a second functional representation with two diagrams showing length changes over time, each executing one of the two actuator segments of the actuator shown in Figure 6A as a result of the control according to the first functional representation; and the right figure shows a third functional representation with a diagram showing the sum or superposition of the length changes of the two actuator segments according to Figure 6A over time, and thus of the actuator, where the voltage pulses have the same (positive) sign.

[0066] According to the invention, a method for actuating an actuator 1 to produce a permanent or fixed change in the desired length of the actuator 1 in a longitudinal direction L is provided. The embodiments of the method according to the invention use an actuator 1 formed from at least two actuator segments AS or AS1, AS2, each with a deformation body D or D1, D2 and actuation electrodes E. Each deformation body D or D1, D2 comprises an electromechanical material according to the definition (P1) or the definition (P2). Each actuator segment AS1, AS2 is formed from two end surfaces AE1, AE2 and a circumferential surface AU, wherein the end surfaces AE1, AE2 are opposite to each other with respect to the longitudinal direction L of the actuator 1, and wherein the circumferential surface AU of the respective actuator segment AS1, AS2 extends between the end surfaces AE1, AE2. In the sequence of at least two

[0067] Actuator segments AS1, AS2 of actuator 1 are each a first actuator segment AS1 and a second actuator segment AS2 located one behind the other in the actuator longitudinal direction L and arranged such that a second end surface AE2 of the respective first actuator segment AS is facing the first end surface AE1 of the respective second actuator segment AS.

[0068] The actuator 1 can also have more than two actuator segments AS, wherein the actuator segments AS, as described with reference to the actuator segments AS1 , AS2, are located one behind the other in the actuator longitudinal direction L and wherein end surfaces AE1 , AE2 of different directly adjacent actuator segments AS are facing each other.

[0069] In general, it is provided that at least one first actuation electrode E is located on the first end surface AE1 of each actuator segment AS, and at least one second actuation electrode E is located on the second end surface AE2 of each actuator segment AS. Each actuator segment AS is made of an electromechanical material and is designed such that, when a corresponding voltage or voltage profile is applied to the actuation electrodes located on a respective actuator segment AS, the length of the respective actuator segment can be changed in its longitudinal direction LA.

[0070] The embodiment of an actuator 1 shown in Figure 2, with a first end 1a and a second end 1b, specifically comprises a first actuator segment AS1 with a first end surface AE11, on which a first actuating electrode E11 is located, and a second end surface AE12, on which a second actuating electrode E12 is located. Similarly, the second actuator segment AS2 has a first end surface AE21, on which a first actuating electrode E21 is located, and a second end surface AE22, on which a second actuating electrode E22 is located. The first end surfaces AE11 and AE21 of the actuator segments, and the second end surfaces AE12 and AE22 of the actuator segments, respectively, lie in the longitudinal direction L of the actuator segment. ÄThe actuator segments are spaced apart along their respective lengths and are oriented in opposite directions, with their longitudinal direction LA running along the actuator's longitudinal direction L. The first and second actuator segments AS1 and AS2 are positioned one behind the other along the actuator's longitudinal direction L and are arranged such that the second end face AE2 of the first actuator segment AS1 faces the first end face AE1 of the second actuator segment AS2. The first end 1a and the second end 1b form the ends of actuator 1, spaced apart along the actuator's longitudinal direction L and oriented in opposite directions with respect to the actuator's longitudinal direction L.

[0071] Alternatively, the actuator can also be configured such that, unlike the illustration in Figure 2, there is not two electrodes E, E' between each pair of adjacent actuator segments AS or between all actuator segments AS, but only one electrode E', which is connected to both one actuator segment and the second actuator segment of the two actuator segments AS. This embodiment of actuator 1 is shown schematically in Figures 3A, 4A, 5A, and 6A. According to the invention, an actuating device is also provided, comprising a presetting device, a control device functionally connected to the presetting device and receiving a target position from it, and an actuator according to one of the embodiments described herein.The actuator can thus have at least one actuator segment AS with an electromechanical material according to (P1), or at least one actuator segment AS with an electromechanical material according to (P2), or several actuator segments AS partly with an electromechanical material according to (P1) and partly with an electromechanical material according to (P2). The control device has a single control amplifier electrically connected to the actuation electrodes E of the at least one actuator segment AS, or several control amplifiers, each electrically connected to the actuation electrodes E of the actuator segments AS of actuator 1, and optionally a control command generation function that determines control commands in a predetermined manner, based on specifications, or based on determination criteria.In the case of using at least one control amplifier, this is functionally connected to the actuator segments AS of actuator 1. The control commands include, in particular, the identification or selection of the at least one actuator segment AS to which a voltage pulse is to be applied and, optionally, at least one of the following criteria: for each selected actuator segment AS, in particular depending on the electromechanical material (P1) or (P2) of the respective actuator segment AS, the number of voltage pulses to be applied, the size or amplitude of the voltage pulse to be applied, the shape or time course of the voltage pulse to be applied. Determination criteria for identifying the respective control command can be application-specific criteria, such as...technical criteria, or optimization criteria for maintaining the accuracy of achieving the target set state or the change behavior of the actuator segment AS to be controlled, particularly with regard to maintaining the accuracy of achieving the target set state.

[0072] The control device is configured such that the control command generation function transmits the at least one control command to the at least one control amplifier, which, based on the control command, determines at least one voltage pulse to the actuating electrodes E of the respective actuator segment AS to be controlled. If the control device has a single control amplifier, this single control amplifier is electrically connected to two actuating electrodes E or a pair of actuating electrodes E per actuator segment AS, with at least one actuating electrode E of the pair of actuating electrodes E being connected to the end faces AE1, AE2 of a respective actuator segment AS.The actuator can also have two or more control amplifiers, each of which is electrically connected, analogously, to at least one pair of actuation electrodes E per actuator segment AS, with one actuation electrode E1, E2 of each pair of actuation electrodes E1, E2 being connected to the end faces AE1, AE2 of a respective actuator segment AS. In particular, at least one actuation electrode E, which is electrically connected to different control amplifiers, is connected to each of the end faces AE1, AE2 of different actuator segments AS.It may also be provided that one of the two actuation electrodes attached to an actuator segment is an actuation electrode for applying the voltage pulse or the voltage, and that another of the electrodes attached to an actuator segment is a common electrode through which a reference voltage is applied to other actuator segments or to all other actuator segments.

[0073] A movement or change in shape of the respective embodiment of the actuator 1, or at least of an actuator segment thereof, due to a voltage pulse applied to each actuator segment, causes a change in the actual position state of a component driven by the actuator 1 and coupled to the actuator 1. To execute a movement or change in shape of the respective embodiment of the actuator 1, the input device sends target positions of the actuator to the control device, which has a control command generation function and at least one control amplifier, which is electrically connected either individually or to actuation electrodes attached to actuator segments. The input device can be configured to generate the target positions independently or automatically, or to receive them from an application system that is functionally connected to the control device.The application system can have an input device, for example, with the option of manual input of at least one target position or functional reception of a target position. The control device's control command generation function determines control commands from the target positions, which are transmitted by the control command generation function to each of the at least one control amplifier. The at least one control amplifier determines control signals in the form of voltage pulses from the control commands for each of the at least one pair of actuation electrodes E, in order to cause a deformation of the respective actuator segment AS and thus of actuator 1. The deformation of actuator 1, in turn, causes a change in the actual position and, in particular, a movement of the component driven by actuator 1 according to the target position.The control device, and in particular the control command generation function or the at least one control amplifier, can in particular have a compensation function that is suitable or configured such that a first voltage pulse is applied to actuation electrodes E1, E2 of at least one of the first actuator segments AS with an electromechanical material according to (P2) and, optionally simultaneously, a second voltage pulse is applied to actuation electrodes E1, E2 of at least one of the second actuator segments AS with an electromechanical material according to (P1) such that a short-term first length change component of at least one first actuator segment AS is at least partially or to at least 50% compensated. Alternatively or additionally, the compensation function can be suitable or configured to implement the various steps of the embodiments of the method according to the invention.The compensation function can also be configured in such a way that, in the case that a first voltage pulse is applied to at least one of the first actuator segments AS with an electromechanical material according to (P2) on actuating electrodes E1, E2, the aforementioned second voltage pulse is applied to at least one of the second actuator segments AS with an electromechanical material according to (P1).

[0074] According to the invention, an actuating system is also provided, comprising an embodiment of the actuating device described herein and the component to be driven by the actuator 1. The first end 1a may be configured for arrangement or mounting on a base body, and the component to be driven may be coupled to or attached to the second end 1b, being movable relative to the base body. When the actuator 1 is actuated by applying at least one voltage pulse, the component to be driven moves relative to the base body in accordance with the time-dependent change in length of the at least one actuator segment AS. The first end 1a and the first end 1b may, in particular, each be an outer end of the actuator 1.

[0075] A first embodiment of the inventive method for producing a permanent, energy-free change in the desired length of the actuator 1 in the longitudinal direction L provides that at least two actuator segments AS of the actuator 1 are actuated, each of which has an electromechanical material that is suitable and, in particular, polarized in such a way as to produce, on the basis of a voltage pulse applied to the actuating electrodes E of each actuator segment AS of the actuator 1, an energy-free permanent or remanent change in length of the actuator 1 caused by a polarization process or a depolarization process, which corresponds to an increase or decrease in length of the actuator 1, wherein the change in length continues even after the application or cessation or removal of the voltage pulse and thus without the application of an electrical voltage to the same actuating electrodes E.The actuator segments AS are thus each formed from an electromechanical material according to the definition (P2).

[0076] An example illustrating this first embodiment of the method according to the invention, using an actuator 1 with four actuator segments AS11, AS12, AS13, AS14, is shown in Figures 3A and 3B. Generally, the first embodiment of the method is applied to an actuator 1 with at least two actuator segments AS or AS11, AS12, AS13, AS14, at least one actuation electrode E is located on each of the oppositely located end faces of these segments, wherein the actuator segments AS or AS11, AS12, AS13, AS14 are arranged one behind the other in the longitudinal direction L of the actuator.

[0077] The first embodiment of the inventive method for producing a predetermined permanent target length change of the actuator 1 in the actuator longitudinal direction L comprises, in particular, the following steps: a first step (A1) with the application of a voltage pulse to the actuating electrodes E, which are located at each of the end faces opposite to each other with respect to the actuator longitudinal direction L of one of the actuator segments AS or AS11, AS12, AS13, AS14; at least one further step (A2) with a repetition of the first step (A1), i.e., the application of a voltage pulse to the actuating electrodes E, which are located at at least one of the actuator segments AS or AS12, AS13, AS14.AS11, AS12, AS13, AS14 are applied until the resulting change in length of the actuator (1) equals the desired permanent change in length of the actuator (1) or is within a specified deviation from the desired permanent change in length, wherein the application of the voltage pulses to the actuation electrodes E, which are connected to the respective actuator segment AS or AS11, AS12, AS13, AS14, is time-shifted.

[0078] The middle illustration of Figure 3B, and also the lower functional diagram of Figure 1, show that the temporal course of the length change of an actuator segment AS or AS11, AS12, AS13, AS14 due to the application of a voltage pulse to the actuation electrodes E, which are located on the respective actuator segment AS or AS11, AS12, AS13, AS14 (see upper functional diagram of Figure 1), consists of an energy-free permanent or remanent length change component L D and results from a length change component Lz that precedes and exceeds the energy-free permanent length change component and decreases without energy.

[0079] By applying at least one voltage pulse to the actuating electrodes E, which are located on each actuator segment AS or AS11, AS12, AS13, AS14 of a number n of deformation bodies or actuator segments of the actuator 1 (as can be seen from the left-hand figure of Fig. 3B), a detrimental "overshooting" of the length of the entire actuator 1 is reduced compared to applying a voltage pulse to the actuating electrodes E of an actuator consisting of only a single actuator segment, provided that only a single voltage pulse is applied to the actuating electrodes E of the single actuator segment, the magnitude of which is equal to, or greater or less than, the magnitude of the aforementioned voltage pulses applied to the actuating electrodes E of the multiple actuator segments. This factor can, in particular, be equal to the number n of actuator segments of the actuator 1.This is achieved by applying at least one voltage pulse of lower magnitude to the actuating electrodes E, each of which is connected to one of the several actuator segments AS or AS11, AS12, AS13, AS14. Likewise, at least one voltage pulse of higher magnitude can be applied to the actuating electrodes E, each of which is connected to one of the several actuator segments AS or AS11, AS12, AS13, AS14. Preferably, at least one voltage pulse of the same magnitude is applied to the actuating electrodes E, each of which is connected to one of the several actuator segments AS or AS11, AS12, AS13, AS14. If the length of the individual actuator segments AS or AS11, AS12, AS13, AS14 in the last case is smaller by a factor of n than the length of the individual actuator segment in the second case, the same permanent or remanent length change fraction LD results for the compared actuators. In the first case, or...In the second case, a smaller or larger, permanent or remanent length change fraction LD results for the actuators being compared. The first case, in particular, can be advantageous for improving the position resolution of an actuator consisting of several actuator segments AS11, AS12, AS13, AS14 compared to an actuator consisting of a single actuator segment AS.

[0080] In principle, a voltage pulse can be applied to the actuating electrodes E on the same actuator segment AS, or it can be applied to the actuating electrodes E on different actuator segments AS, and in particular, sequentially. The repetition of the first step, i.e., each subsequent step, can thus be achieved by applying a voltage pulse to the actuating electrode E of the first actuator segment AS used for the first step (A1), or to the actuating electrodes E of at least one further actuator segment AS. The same applies, if applicable, starting from each subsequent step.

[0081] In particular, the repetition of the first step A1, i.e., each subsequent step, by applying a voltage pulse to the actuating electrodes E, which are connected to a further actuator segment AS, can be provided, for example, as often as necessary until either the number of applications of a voltage pulse to the actuating electrodes E, which are connected to each actuator segment AS, is equal to the number of actuator segments AS of the actuator 1, wherein the voltage pulses are such that they cause the permanent target length change of the actuator 1 to be produced, or until the caused length change of the actuator 1 is equal to the permanent target length change of the actuator 1 to be produced.

[0082] The number of repetitions can be determined according to one of the following two alternatives:

[0083] (W1) The number of repetitions is provided such that the number of applications of a voltage pulse to the actuating electrodes E, which are applied to an actuator segment AS, is equal to the number of actuator segments AS of the actuator 1 which are used or intended to be used in the method, wherein each voltage pulse causes a previously known or previously determined change in length (i.e., increase or decrease in length) of the respective actuating actuator segment, and wherein the voltage pulses are applied successively to each of the actuating electrodes E, which are applied to each of the actuator segments AS of the actuator 1, thereby causing the desired permanent change in length of the actuator 1.

[0084] (W2) The number of repetitions is provided such that the applications of a voltage pulse to the actuating electrodes E, which are located on individual actuator segments AS and in particular on a subset of all actuator segments AS, take place until the resulting change in length of actuator 1 is equal to the permanent target change in length of actuator 1.

[0085] Another embodiment of the inventive method for actuating an actuator 1 to generate an energy-free permanent or remanent target length change of the actuator 1 in an actuator longitudinal direction L, which is described below with reference to Figures 4A and 4B, uses an actuator 1 which has: at least one first of the actuator segments AS of the actuator A, which is realized according to the definition (P2) and in particular with a soft electromechanical material and especially with a soft PZT material and is thus suitable for generating, by applying a voltage pulse to actuating electrodes E which are in contact with the respective first of the actuator segments AS, an energy-free permanent or remanent change of the target length of the actuator 1 caused by a polarization process or a depolarization process.to perform a permanent change in length which persists without applying a voltage to the same actuation electrodes E, and at least a second of the actuator segments AS of the actuator A, which according to the definition (P1) and in particular with a hard electromechanical material and specifically with a hard PZT material and is thus suitable to perform an energy-free or non-permanent or reversible change in length due to a voltage pulse applied to its actuation electrodes E.

[0086] An example illustrating this further embodiment of the method according to the invention with a corresponding actuator 1 is shown in Figures 4A and 4B. The actuator 1 according to Figure 4A has a first actuator segment AS21 and a second actuator segment AS22. In the representation of Figure 4A, the first actuator segment AS21, which is lower in Figure 4A, has an electromechanical material according to the definition (P2), and the second actuator segment AS22, which is upper in Figure 4A, has an electromechanical material according to the definition (P1). The actuator segments AS21 and AS22 are arranged one behind the other in the longitudinal direction L of the actuator. The polarity of both actuator segments AS21 and AS22 is identical with respect to the longitudinal direction L of the actuator.

[0087] In general, the actuator 1, which is used in the further embodiment of the method according to the invention as shown in Figure 4A, can have one or both of the following features (K1), (K2):

[0088] (K1) at least one actuator segment AS each with an electromechanical material according to the definition (P1),

[0089] (K2) at least one actuator segment AS each with an electromechanical material according to the definition (P2).

[0090] This further embodiment of the method according to the invention comprises the following steps: a first step (B1) with the application of a first voltage pulse to the actuating electrodes E of at least one first of the actuator segments AS21, AS22 and thereby generating a first change in the actuator segment length of the at least one first actuator segment AS21, AS22, wherein the first change in the actuator segment length is formed from the energy-free permanent length change component LD and from an energy-free regressive length change component Lz preceding and exceeding the energy-free permanent length change component; at least one further step (B2) with the substantially simultaneous application of a second voltage pulse to the actuating electrodes E of at least one second actuator segment AS21, which differs from the first method step (B1).AS22 and thereby generating a second change in the actuator segment length of at least one second actuator segment AS21, AS22. The middle illustration of Figure 4B shows that the second change in actuator segment length can be essentially equal in magnitude and opposite in direction to the energy-free decaying length change component Lz of the first change in actuator segment length, and essentially compensates for it.

[0091] The left-hand side of Figure 4B shows, in the lower section, the time course of the first voltage pulse applied to the actuating electrodes E connected to the first actuator segment AS21, and in the upper section, the time course of the second voltage pulse applied to the actuating electrodes E connected to the second actuator segment AS22. The first and second voltage pulses occur simultaneously or substantially simultaneously and are oppositely directed or have different signs. Furthermore, they can have the same or substantially the same maximum magnitude.Typically, the maximum voltage values ​​differ because hard PZT ceramics have lower amplification properties than soft PZT ceramics, especially if at least one actuator segment with a hard PZT ceramic has approximately the same length as at least one actuator segment with a soft PZT ceramic. In particular, the voltage pulses can be axially symmetrical about the time axis.

[0092] The middle section of Figure 4B shows, in the lower part, the time course of the first length change of the first actuator segment AS21 and, in the upper part, the time course of the second length change of the second actuator segment AS22. The second change in the length of the second actuator segment AS22 is defined by a relatively short-term length change component. Since, according to Figure 4A, the polarity of actuator segments AS21 and AS22 is the same in the longitudinal direction L of the actuator, and the voltage pulses applied to actuator segments AS21 and AS22 have opposite signs, the resulting short-term length changes of actuator segments AS21 and AS22 essentially cancel each other out. This is illustrated in the right-hand section of Figure 4B, which shows the time course of the resulting length change LD of the entire actuator 1.

[0093] In contrast to the foregoing, Figures 5A and 5B illustrate an embodiment of the method according to the invention using an actuator 1 in which the polarity of the first actuator segment AS21 and the polarity of the second actuator segment AS22 differ with respect to the actuator's longitudinal direction L. As the left-hand figure of Figure 5B shows, the voltage pulses applied to the two actuator segments AS21 and AS22 have the same sign. The right-hand figure of Figure 5B shows that this causes a second length change component of the respective second actuator segment AS22, which partially or completely compensates for the short-term first length change component of the respective first actuator segment AS21.

[0094] The illustrations of the method according to the invention in Figures 4 and 5 also show actuators, each having two control amplifiers.

[0095] Figures 6A and 6B illustrate a method according to the invention that can be carried out with an actuator comprising only one control amplifier. Figures 6A and 6B show that the polarity of the first actuator segment AS1 and the polarity of the second actuator segment AS2 are different with respect to the actuator longitudinal direction L. The first and second voltage pulses are generated by applying the same control signal to the electrodes of the first actuator segment AS and the electrodes of the second actuator segment AS.In the third section of Figure 6B, viewed from the left side, it is shown that this causes a second length change component of the respective second actuator segment AS22, as also shown in Figures 4B and 5B, which partially or completely compensates for the short-term first length change component of the respective first actuator segment AS21. Reference numeral list.

[0096] 1 actuator

[0097] 1a End

[0098] 1b End

[0099] AE1 first end face of an actuator segment AS

[0100] AE2 second end face of an actuator segment AS

[0101] AS actuator segment

[0102] AS1 first actuator segment

[0103] AS2 second actuator segment

[0104] AS11, AS12, AS13, AS14 actuator segment

[0105] AS21, AS22 actuator segment

[0106] D Deformation body

[0107] D1 first deformation body

[0108] D2 second deformation body

[0109] E Actuating electrode

[0110] E11 first actuation electrode of the first actuator segment

[0111] E12 second actuation electrode of the second actuator segment

[0112] E21 first actuation electrode of the first actuator segment

[0113] E22 second actuation electrode of the second actuator segment

[0114] L actuator longitudinal direction

[0115] L A Actuator segment longitudinal direction

[0116] L D a permanently or persistently changing length component that requires no energy

[0117] L z Energy-free decreasing component of length change

Claims

Claims 1. Method for actuating an actuator (1) to achieve a permanent, energy-free change in the desired length of the actuator (1) in an actuator longitudinal direction (L1), wherein the actuator (1) comprises: at least two actuator segments (AS, AS11, AS12, AS13, AS14), each comprising an electromechanical material and arranged one behind the other in the actuator longitudinal direction (L), and actuation electrodes (E), wherein an actuator segment is located between each pair of actuation electrodes, wherein the electromechanical material of each of the at least two actuator segments (AS, AS11, AS12, AS13, AS14) is suitable or has a polarization state such that, as a result of a voltage pulse applied to actuation electrodes (E), it causes a permanent, energy-free change in the length of the actuator segment on which the actuation electrodes are located. concerns, executes,which continues without applying a voltage to the same actuating electrodes (E), comprising: a first step (A1) with the application of a voltage pulse to actuating electrodes (E) of one of the actuator segments (AS, AS11, AS12, AS13, AS14), at least one further step (A2) with a repetition of the first step (A1) of the application of a voltage pulse to the actuating electrodes that are applied to at least one of the actuator segments (AS, AS11, AS12, AS13, AS14) until the resulting change in length of the actuator (1) is equal to the desired permanent change in length of the actuator (1) without energy input or is within a predetermined deviation from the desired permanent change in length, wherein the application of the voltage pulses to actuating electrodes that are applied to the respective actuator segments (AS, AS11, AS12, AS13, AS14) are to be addressed, with each event occurring at a different time.

2. The method according to claim 1, wherein the method comprises: Provision of the actuator (1), wherein the actuator (1) is mounted at a first end (1a) on a base body and wherein a component to be driven is coupled to a second end (1b) of the actuator (1) in the longitudinal direction (L1) of the actuator, wherein between The first end (1a) and the second end (1b) are located at least two actuator segments (AS, AS11, AS12, AS13, AS14), wherein the electromechanical material of each of the at least two actuator segments (AS, AS11, AS12, AS13, AS14) has a polarization state such that, due to a voltage pulse applied to actuating electrodes (E), a length change pulse is followed by a permanent, energy-free length change of the respective actuator segment, to which the actuating electrodes are attached, caused by a polarization process or a depolarization process, which continues without the application of a voltage to the same actuating electrodes (E), wherein the relative motion between the base body and the component to be driven is equal to the length change of the at least one actuator segment to which a voltage pulse is applied.

3. Method according to claim 1 or 2, wherein the application of the voltage pulses to actuating electrodes, which are located on the respective actuator segments (AS, AS11 , AS12, AS13, AS14), is time-shifted such that a voltage pulse is applied to an actuator segment (AS, AS11 , AS12, AS13, AS14) only when, after a previous application of a voltage pulse, a length change pulse of the respective actuator segment (AS, AS11 , AS12, AS13, AS14) resulting from this voltage pulse has at least partially decayed and, in particular, has decayed to at least 50% and, in particular, to 75%.

4. Method according to one of the preceding claims, wherein the actuator segment (AS, AS11 , AS12, AS13, AS14) to which a voltage pulse is applied in the further step (A2) differs from the actuator segment (AS, AS11 , AS12, AS13, AS14) to which a voltage pulse is applied in the respective temporally preceding step (A1).

5. Method according to one of the preceding claims, wherein the maximum values ​​of the voltage pulse of the first step (A1 ) and of the respective voltage pulse of the at least one further step (A2) are equal or the maximum value of the respective voltage pulse of the at least one further step (A2) is within a deviation of a maximum of 50% from the maximum value of the voltage pulse in the first step (A1 ).

6. Method according to one of the preceding claims, wherein the maximum values ​​of the voltage pulse of the first step (A1) and of the respective voltage pulse in at least one further step (A2) are different from each other.

7. Method according to one of the preceding claims, wherein the respective time offset between successive applications of the actuator segments (AS, AS11 , AS12, AS13, AS14) is equal to the duration of a voltage pulse or is within a deviation of a maximum of 50% of the duration of one of the voltage pulses.

8. Method for actuating an actuator (1) to generate a permanent, energy-free change in the desired length of the actuator (1) in an actuator longitudinal direction (L), wherein the actuator (1) comprises: at least two actuator segments (AS, AS21, AS22) made of an electromechanical material, arranged one behind the other in the actuator longitudinal direction (L), and actuation electrodes (E), wherein an actuator segment (AS, AS21, AS22) is arranged between each pair of actuation electrodes (E), wherein the electromechanical material of at least one of the actuator segments (AS, AS21, AS22) is suitable or polarized in such a way as to cause, due to a voltage pulse applied to its actuation electrodes (E), a permanent, energy-free change in length of the at least one of the actuator segments (AS, AS21, AS22) caused by a polarization process or a depolarization process. to which the same actuating electrodes (E) are located,which persists without the application of a voltage to the same actuating electrodes (E), and wherein the electromechanical material of at least one second of the actuator segments (AS, AS21, AS22) is suitable to perform an energy-free change in length after the cessation of a voltage pulse applied to its actuating electrodes (E), comprising the method: a first step (B1) with the application of a first voltage pulse to the actuating electrodes (E) of the at least one first of the actuator segments (AS, AS21, AS22) and thereby generating a first change in the actuator segment length of the at least one first actuator segment (AS, AS21, AS22), wherein the first change in the actuator segment length consists of the energy-free permanent length change component (L, D ) and from a length change component that precedes and exceeds the energy-free permanent length change component (L) z) is formed, at least one further step (B2) with an essentially simultaneous application of a second voltage pulse to the actuation electrodes (E) of the at least one second actuator segment (AS, AS21, AS22) which is different from the first process step (B1), thereby generating a second change in the actuator segment length of the at least one second actuator segment (AS, AS21, AS22), wherein the second change in the actuator segment length is in the opposite direction to the energy-free decreasing length change component (L) z ) the first change in actuator segment length and at least partially compensates for it.

9. Method according to claim 8, wherein the polarity of at least one first actuator segment (AS, AS21, AS22) and the polarity of at least one second actuator segment (AS, AS21, AS22) is identical with respect to the actuator longitudinal direction (L), wherein the sign of the second voltage pulse at the actuating electrodes located at the respective second actuator segment is different from the sign of the first voltage pulse at the actuating electrodes located at the respective first actuator segment.

10. Method according to claim 8, wherein the polarity of at least one first actuator segment (AS, AS21, AS22) and the polarity of at least one second actuator segment (AS, AS21, AS22) is different with respect to the actuator longitudinal direction (L), wherein the sign of the second voltage pulse at the actuating electrodes connected to the respective second actuator segment is identical to the sign of the first voltage pulse at the actuating electrodes connected to the respective first actuator segment.

11. Method according to claim 1 0, wherein the first voltage pulse and the second voltage pulse are each supplied by supplying the same control signal to the actuation electrodes of the respective first actuator segment (AS, AS21 , AS22) and the actuation electrodes of the respective second actuator segment (AS, AS21 , AS22).

12. Actuator (1) for producing a permanent target length change of the actuator (1) in an actuator longitudinal direction (L) upon actuation of the actuator (1), wherein the actuator (1) comprises: at least two actuator segments (AS, AS21, AS22) comprising an electromechanical material and arranged one behind the other in the actuator longitudinal direction, and actuation electrodes (E), wherein an actuator segment (AS, AS21, AS22) is arranged between each pair of actuation electrodes (E), wherein the electromechanical material of at least one of the actuator segments (AS, AS21, AS22) is suitable or has a polarization state such that, due to a voltage pulse applied to its actuation electrodes (E), this electromechanical material causes a permanent, energy-free length change of the at least one of the actuator segments by means of a polarization process or a depolarization process. (AS, AS21, AS22),to be carried out on which the same actuating electrodes (E) are applied, which continues without the application of a voltage to the same actuating electrodes (E), and wherein the electromechanical material of at least a second of the actuator segments (AS, AS21, AS22) is suitable or has a polarization state such that this electromechanical material undergoes a change in length without energy when a voltage pulse applied to its actuating electrodes (E) is removed.

13. Actuating device comprising: an actuator (1) with at least two actuator segments (AS, AS11, AS12, AS13, AS14) and with actuating electrodes (E), a presetting device, a control device functionally connected to the presetting device and receiving a target position state for the actuator (1) from it, and an actuator, wherein the actuator segments are arranged one behind the other in the longitudinal direction of the actuator and wherein an actuator segment (AS, AS11, AS12, AS13, AS14) is arranged between each pair of actuating electrodes (E), wherein the electromechanical material of each of the at least two actuator segments (AS, AS11, AS12, AS13, ASM) has a polarization state such that, due to a voltage pulse applied to actuating electrodes (E), a length change pulse is followed by a permanent, energy-free length change of the respective actuator segment to which the actuating electrodes are attached, caused by a polarization process or a depolarization process, wherein the control device has a control command generation function and at least one control amplifier which is electrically connected to the actuator segments (AS, AS21, AS22) for the application of voltage pulses, wherein the control command generation function is configured such that it determines control commands from the target control states, which are transmitted by the control command generation function to each of the at least one control amplifier in order to achieve the target control state of the actuator (1).

14. Actuating system comprising an actuating device according to claim 13 and a driven component coupled to the actuator (1 ) and moved by the actuator.

15. Actuating device for actuating an actuator (1) to produce a permanent target length change of the actuator (1) in an actuator longitudinal direction (L), the actuating device comprising the actuator (1), a first control amplifier and a second control amplifier, wherein the actuator (1) comprises: at least two actuator segments (AS, AS21, AS22) having an electromechanical material and arranged one behind the other in the actuator longitudinal direction (L), and actuating electrodes (E), wherein an actuator segment (AS, AS21, AS22) is arranged between each pair of actuating electrodes (E), wherein the electromechanical material of at least one of the first actuator segments (AS, AS21, AS22) is suitable, due to the application of a voltage pulse to the actuating electrodes that are in contact with the respective first actuator segment,to carry out a permanent, energy-free length change of at least one of the actuator segments (AS, AS21, AS22), to which the same actuating electrodes (E) are attached, caused by a polarization process or a depolarization process, which persists without applying a voltage to the same actuating electrodes (E), and wherein the electromechanical material of at least one of the second actuator segments (AS, AS21, AS22) is suitable for performing a non-energy-dependent change in length after the application of a voltage pulse to the actuating electrodes located on the respective second actuator segment ceases, wherein the first control amplifier is electrically connected to the actuating electrodes (E) located on each of the at least one first actuator segment (AS, AS21, AS22), wherein the first control amplifier is suitable for applying a first voltage pulse to the actuating electrodes (E) of at least one of the first actuator segments (AS, AS21, AS22) and thereby generating a first change in the actuator segment length of the respective first of the actuator segments (AS, AS21, AS22), wherein the first change in the actuator segment length consists of the non-energy-dependent length change component (L) D) and from a length change component preceding and exceeding the energy-free permanent length change component (L) z) is formed, wherein the second control amplifier is electrically connected to the actuation electrodes (E) that are applied to each of the at least one second actuator segment (AS, AS21, AS22), wherein the second control amplifier is suitable to apply a second voltage pulse to the actuation electrodes (E) of at least one of the second actuator segments (AS, AS21, AS22) essentially simultaneously with the application of the voltage to the at least one first actuator segment (AS, AS21, AS22) by the first control amplifier, thereby generating a second change in the actuator segment length of the respective second of the actuator segments (AS, AS21, AS22), wherein the second change in actuator segment length is equal in magnitude and opposite in direction to the energy-free reversible length change component (L). z ) the first change in actuator segment length and compensates for it.

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