Torque measurement using wireless pulse transmission

Abstract

The invention relates in particular to a sensor device (16) comprising: a stationary unit (160) having an inductor (162) and a control device (U1) which is configured to impose a pulse onto the inductor (162), and a movable unit (161), which is mounted so as to be movable relative to the stationary unit (160) and comprises a control device (U3), an inductor (163), and a sensor element (164), the control device (U3) of the movable unit (161) being configured to read out the pulse by inductive coupling of the inductors (162, 163) and to receive measurement signals from the sensor element (164).

Description

[0001] Torque measurement with wireless clock transmission

[0002] Description

[0003] The proposed solution relates in particular to a sensor device and a method for determining measurement signals.

[0004] Drive systems for electric bicycles (e.g. e-bikes or pedelecs) with at least one electric motor for the externally powered generation of an additional drive torque and thus for the provision of support power in addition to the drive power applied by muscle power are widely known.

[0005] In practice, it is common practice to make the assistance level dependent on the rider's input. This input is determined by measuring the torque currently applied to the bottom bracket spindle of the drive system by muscle power. The harder the electric bike rider pedals the pedals connected to the bottom bracket spindle, the higher the assistance level is selected to accelerate the electric bike with motor assistance. To measure the actual torque applied by muscle power, a torque sensor is typically provided on the bottom bracket spindle. This allows for direct measurement of the torque actually applied to the bottom bracket spindle, for example, based on an inverse magnetoelastic effect or using at least one strain gauge.

[0006] However, measuring the actual applied torque using a torque sensor is usually comparatively complex and costly. This also applies to other types of sensor devices with moving components.

[0007] The task is to enable measurements using a simply constructed sensor device.

[0008] This object is achieved by an object having the features of claim 1. According to this, a sensor device comprises a stationary unit with an inductance and a control device configured to impart a clock pulse to the inductance, and a movable unit movably mounted relative to the stationary unit and comprising a control device, an inductance, and a sensor element. It is provided that the control device of the movable unit is configured to read the clock pulse imparted to the inductance of the stationary unit (via the inductance of the movable unit) through an inductive coupling of the inductances and to receive measurement signals from the sensor element.

[0009] This is based on the realization that a clock pulse is regularly required for the function of the moving unit, and that components for generating such a clock pulse are typically relatively expensive and complex to manufacture, and also require installation space. With the sensor device described, it is possible to provide the control device of the moving part with a precise clock pulse, despite the relative mobility of the two units of the sensor device, and with minimal effort and relatively low manufacturing costs. The moving unit does not require its own clock generator. The inductive coupling allows wireless transmission of the clock pulse.

[0010] For example, the movable unit is mounted so it can rotate relative to the stationary unit. This allows the movable unit to be mounted directly on a shaft, for example, enabling particularly precise measurements.

[0011] The measurement signals are based, for example, on a torque acting on the sensor element and / or on a component connected (in particular, permanently) to the sensor element. Optionally, the sensor device is designed as a torque sensor for measuring torque. This allows, for example, a precise measurement of the torque applied to a pedal shaft.

[0012] The control device of the moving unit can be supplied (or capable of being supplied) with a supply voltage through the inductive coupling of the inductors. Thus, the moving unit can receive both the clock and the supply voltage via the inductive coupling of the same inductors, which thus fulfill a dual function. This further simplifies the design.

[0013] For example, the stationary unit includes a clock (optionally in the form of a quartz oscillator). The control device of the stationary unit can determine the clock based on signals from the clock. This enables a precise measurement process. Alternatively, the stationary unit can receive the clock from an external device.

[0014] The control device of the stationary unit can be configured to periodically open and close a switch, particularly in the form of a semiconductor component, to impose the clock pulse on the inductance of the stationary unit. This allows for the inductive transmission of the clock pulse in a particularly simple manner.

[0015] The control device of the moving unit is electrically connected to the inductance of the moving unit via a resistor, for example. This allows current to be limited while simultaneously enabling precise reading of the clock pulse using simple means.

[0016] Optionally, the control device of the movable unit is configured to encode the measurement signals of the sensor element using the read-out clock signal. Furthermore, the control device of the movable unit can be configured to impress the encoded measurement signals on the inductance of the movable unit. The inductances then enable both the transmission of the clock signal in one direction and the transmission of the encoded measurement signals in the other direction.

[0017] The control device of the stationary unit can be configured to read the coded measurement signals impressed on the inductance of the movable unit through the inductive coupling of the inductances to the inductance of the stationary unit. The control device of the stationary unit can also be configured to output control signals for controlling a drive motor based on the read coded measurement signals. In this way, for example, torque-dependent drive control can be achieved using simple means.

[0018] The control device of the movable unit can be configured to read the clock by detecting zero crossings of a voltage induced in the inductance of the movable unit. This allows for a simple yet highly precise readout of the clock.

[0019] The control device of the moving unit and / or the control device of the stationary unit is / are optionally designed (each) in the form of an integrated circuit module. This allows for the use of standard components and a particularly small footprint. For example, the sensor element comprises a strain gauge. This allows for particularly robust and precise measurements with a particularly small footprint.

[0020] According to one aspect, a drive system is provided with the sensor device according to any embodiment described herein. The drive system optionally comprises a shaft, wherein the movable unit is, for example, attached to the shaft. Regarding the advantages, reference is made to the above information regarding the sensor device.

[0021] The drive system can include a drive motor controlled by control signals provided by the sensor device. This enables a sensor-controlled drive using simple means.

[0022] The shaft can be driven, for example, by the drive motor and / or by means of pedals.

[0023] According to one aspect, an electric bicycle is provided with the sensor device according to any embodiment described herein and / or the drive system according to any embodiment described herein. Regarding the advantages, reference is again made to the above information regarding the sensor device.

[0024] According to one aspect, a method for determining measurement signals is specified. The method comprises: impressing, by means of a control device of a stationary unit of a sensor device (in particular according to any embodiment described herein), a clock signal onto an inductance of the stationary unit; reading, by means of a control device of a movable unit of the sensor device that is movably mounted relative to the stationary unit and by inductively coupling the inductance of the stationary unit to an inductance of the movable unit, the clock signal impressed onto the inductance of the stationary unit; and receiving, by means of the control device of the movable unit, measurement signals from the sensor element. With regard to the advantages, reference is again made to the above information on the sensor device.

[0025] The method optionally further comprises encoding, by means of the control device of the movable unit, the received measurement signals using the read-out clock.

[0026] Furthermore, the method can comprise the following steps: impressing, by means of the control device of the movable unit, the coded measurement signals onto the inductance of the movable unit, reading, by means of the control device of the stationary unit, and by inductively coupling the inductance of the movable unit with the inductance of the stationary unit, the coded measurement signals impressed onto the inductance of the movable unit and controlling a drive motor based on the read-out coded measurement signals.

[0027] The attached figures illustrate possible embodiments of the proposed solution.

[0028] Here we show:

[0029] Figure 1 shows schematically an electric bicycle with a drive system which has a

[0030] drive motor includes;

[0031] Figure 2 shows a stationary unit and a movable unit of a

[0032] Sensor device of the drive system of the electric bicycle according to Figure 1, wherein the movable unit is attached to a shaft of the drive system and the stationary unit is attached to a frame of the electric vehicle;

[0033] Figure 3 is a circuit diagram of the stationary unit and the mobile unit according to

[0034] Figure 2; and

[0035] Figure 4 shows a method for determining measurement signals.

[0036] Figure 1 shows a variant of a proposed electric bicycle 1 with a front wheel 10 and a rear wheel 11, wherein the rear wheel 11 can be driven with electric motor assistance via at least one drive motor 13 of a drive system A of the electric bicycle 1. The drive motor 13 can transmit assistance power to the rear wheel 11 via a power transmission link, here, for example, a chain 12 (alternatively or additionally, e.g., a belt). The rear wheel 11 is rotatably mounted on a frame 18 of the electric bicycle 1.

[0037] The assistance power of the drive motor 13 is provided in addition to the drive power that a rider of the electric bicycle 1 applies by muscle power via pedals 17 of the electric bicycle 1 connected to a shaft 14, here in the form of a bottom bracket shaft. The assistance power provided by the drive motor 13, or rather its level, is controlled by an electronic control unit 15 of the drive system A. It can be provided that the assistance power provided depends on the torque applied by the rider of the electric bicycle 1 to the shaft 14. A battery, here in the form of an accumulator, of the electric vehicle provides the energy to operate the drive system A.

[0038] To determine a torque applied to the shaft 14, for example, a torque applied by the rider using muscle power, the drive system A comprises at least one sensor device 16 in the form of a torque sensor. Figure 2 schematically shows the exemplary design of the sensor device 16 of the electric bicycle 1. In this case, the sensor device 16 is provided on the shaft 14.

[0039] Figure 2 shows a section of the shaft 14, with the two rotatably mounted pedals 17 not shown again for the sake of simplicity. The shaft 14 is operatively connected to the power transmission link, in this case the chain 14. For this purpose, a gear (not shown in Figure 2) is attached to the shaft 14 for engagement with the chain 14. Furthermore, the drive motor 13 is operatively connected to the shaft 14 and configured to rotate the shaft 14 relative to the frame 18.

[0040] The sensor device 16 comprises a stationary unit 160 and a movable unit 161. The movable unit 161 is movable relative to the stationary unit, in this case rotatably mounted. In the present case, the stationary unit 160 is fixed relative to the frame 18, in this case attached to the frame 18. The movable unit 161 is attached to the shaft 14.

[0041] The movable unit 161 comprises, for example, (at least) one strain gauge 165. According to Figure 2, the strain gauge 165 is wound around the shaft 14, but can also be mounted in another way. If a torque is applied to the shaft 14, this leads to a torsion of the shaft 14, which can be measured by the strain gauge 165.

[0042] The stationary unit 160 and the movable unit 161 have disc-shaped sections arranged adjacent to each other.

[0043] Figure 3 illustrates further details of the stationary unit 160 and the movable unit 161.

[0044] The stationary unit 160 comprises an inductance 162 and a control device U1 configured to impart a clock pulse to the inductance 162. The movable unit 161 comprises a control device U3, an inductance 163, and a sensor element 164. It is provided that the control device U3 of the movable unit 161 is configured to read out the clock pulse electrically imparted to the inductance 162 of the stationary unit 160 by an inductive coupling of the inductances 162, 163 and thus induced by the inductive coupling in the inductance 163 of the movable unit 161.

[0045] The inductors 162, 163 are each designed in the form of an electrical coil. The inductors 162, 163 are arranged adjacent to one another, so that an alternating current in one of the inductors 162, 163 induces an alternating voltage in the other of the inductors 162, 163. In this case, the inductors 162, 163 are each arranged in the disc-shaped section of the respective unit 160, 161.

[0046] Furthermore, the control device U3 of the movable unit 161 is configured to receive measurement signals from the sensor element 164. In the example shown, the sensor element 164 comprises the strain gauge 165.

[0047] The control device U1 of the stationary unit 160 is embodied in the form of a microchip. The control device U1 of the stationary unit 160 comprises an integrated electronic circuit. The control device U1 requires a clock to function. This clock is provided (with high precision) by a clock generator Q1 of the stationary unit 160. In this case, the clock generator Q1 comprises a quartz oscillator. The clock generator Q1 has two electrical connections. Both electrical connections of the clock generator Q1 are electrically connected to a ground GND1 of the stationary unit 160 via a respective capacitor C1, C2. Furthermore, the two connections of the clock generator Q1 are electrically connected to the control device U1 of the stationary unit 160. The control device U1 of the stationary unit 160 comprises a clock determination unit Q_OSC.The clock determination unit Q_OSC is designed to set the clock generator Q1 into oscillation and to read out the frequency of this oscillation.

[0048] A switch controller SWC of the control device U1 of the stationary unit 160 is configured to output a switching signal SWD based on the read oscillation frequency. The switching signal SWD is a logical signal that alternates between the states "1" and "0," specifically at the aforementioned clock rate. The clock rate is based on the read oscillation frequency. The clock rate can correspond to the oscillation frequency or, alternatively, a multiple thereof, or vice versa. Since the clock generator outputs a precise signal, the clock rate is also temporally precise.

[0049] The switching signal SWD is applied to a switch S1 of the stationary unit 160. In this example, the switch S1 is a semiconductor component, specifically a transistor. A first terminal of the switch S1 is electrically connected to the ground GND1 of the stationary unit 160. A second terminal of the switch S1 is connected to a supply voltage VCCI of the stationary unit 160 via the inductor 162 and another capacitor C3 of the stationary unit 160. The supply voltage VCCI of the stationary unit 160 is provided by the battery of the electric bicycle 1. The capacitor C3 and the inductor 162 form an oscillating circuit. If the switch is closed, i.e., an electrically conductive connection exists between the first and second terminals of the switch S1, current flows (from the supply voltage connection VCCI) through the inductor 162 (to the ground GND1).By periodically opening and closing switch S1, a temporally varying current flows through inductance 162 of stationary unit 160, thus inducing an alternating voltage in inductance 163 of movable unit 161. This induced alternating voltage is based on the temporal pattern of the opening and closing operations of switch S1 of stationary unit 160.

[0050] The frequency of this alternating voltage is read by the control device U3 of the movable unit 161. For this purpose, the control device U3 of the movable unit 161 is electrically connected to the inductance 163 of the movable unit 161 via a resistor R1 and thus receives a signal Z_DET corresponding to the induced alternating voltage. A coding element ENC of the control device U3 of the movable unit 161 receives the signal Z_DET and reads from it the clock sent by the stationary unit 160. For this purpose, the coding element ENC counts the zero crossings of the signal Z_DET. Since the control device U3 processes logical signals, the coding element ENC only receives the positive half-waves of the signal Z_DET. For this purpose, the electrical connection of the coding element ENC to the resistor R1 is connected to two diodes D2, D3, as explained in more detail below.

[0051] A capacitor C4 of the movable unit 161 is connected in parallel to the inductor 163 of the movable unit 161. A diode D1 is connected between the inductor 163 and the capacitor C4. The diode D1 allows a current to flow from a first terminal to a second terminal of the diode D1, in this case from the inductor 163 towards the capacitor C4. The diode D1 and the capacitor C4 form a rectifier, specifically a half-wave rectifier. A voltage regulator U2 is connected to the second terminal of the diode D1. The voltage regulator U2 regulates the incoming voltage to a predetermined maximum value and outputs the limited voltage as the supply voltage VCC2 of the movable unit 161. The voltage regulator U2 is also connected to the ground GND2 of the movable unit 161. The inductor 163 and the capacitor C4 are also each connected to the ground GND2 with one terminal each.

[0052] The Z_DET signal line is connected to the supply voltage VCC2 via diode D3. This diode allows current to flow toward the voltage regulator U2. The second diode D2 connects ground GND2 to the Z_DET signal line and allows current to flow toward the Z_DET signal line. Diodes D2 and D3 thus serve as contactor diodes to protect the ENC coding element from the negative half-waves of the Z_DET signal.

[0053] The coding element ENC also receives measurement signals from the sensor element 164. These measurement signals are indicative of the applied torque. The coding element ENC encodes these measurement signals in time. For example, a low frequency corresponds to a low torque and a high frequency corresponds to a high torque (or vice versa). The coding element ENC outputs the time-coded measurement signals to a switch S2 of the movable unit. In this case, the switch S2 is a semiconductor component, specifically a transistor. The switch S2 is connected in parallel to the inductor 163. Closing the switch S2 causes an increased load and thus deviations in the voltage at the inductor 162 of the stationary unit 160. The two inductors 162, 163 form a transformer. In the example shown, the inductors 162, 163 have the same number of windings.

[0054] A signal conditioning element CON of the stationary unit 160 is electrically connected to the inductance 162 of the stationary unit 160, specifically to the terminal of the inductance 162, which is connected to ground GND1 via switch S1. The signal conditioning element CON thus detects a received measurement signal TRQ_REC. The signal conditioning element CON scales the received measurement signal TRQ_REC into a predetermined voltage range. The signal conditioning element CON filters the received measurement signal TRQ_REC, specifically with a low-pass filter. This allows interference to be filtered out. A thus-generated, processed measurement signal is output by the signal conditioning element CON to a decoding element DEC of the control device U1 of the stationary unit 160. The decoding element DEC decodes the received time-coded measurement signal and, based on this, determines a measured value—in the example described, a measured value of the torque.

[0055] The control device U1 of the stationary unit 160 can control the drive motor 13 based on this measured value. The sensor device 16 can be part of the electronic control unit 15 or be communicatively connected thereto.

[0056] For temporal coding, the coding element ENC requires a temporal reference, which is also known to the stationary unit 160 so that it can determine the measured value. Typically, a quartz oscillator could be connected to a clock determination unit Q_OSC of the movable unit 161, so that the control device U3 of the movable unit 161 can also generate a correspondingly precise clock. However, such quartz oscillators are associated with increased costs and also require a more complex design. This eliminates the need for such a clock generator in the movable unit 161.

[0057] The control device U3 of the movable unit 161 further comprises an integrated clock determination unit RC_OSC, which, however, has a precision that is insufficient to allow the temporal coding of the measurement signals. The control device U3 can correct the clock signal of the integrated clock determination unit RC_OSC based on the clock received from the stationary unit 160. Alternatively, the control device U3 does not use the (inaccurate) clock signal of the integrated clock determination unit RC_OSC for the temporal coding of the measurement signal at all, but instead simply counts the clock pulses in the signal Z_DET, for example. The (inaccurate) clock signal of the integrated clock determination unit RC_OSC is used here to operate the control device U3.

[0058] The clock signal is transmitted from the stationary unit 160 to the movable unit 161 via inductors 162 and 163, and the coded measurement signal is transmitted in the opposite direction. Furthermore, the movable unit 161 receives the supply voltage VCC2 for operating the movable unit 161 via inductors 162 and 163.

[0059] It should be noted that, for illustrative purposes, Figure 3 does not show all the elements of the stationary unit 160 and the movable unit 161, and the stationary unit 160 and the movable unit 161 may include additional components. Ground GND1 of the stationary unit 160 is galvanically isolated from ground GND2 of the movable unit 161. Resistor R1 protects against excessive currents.

[0060] Figure 4 shows a method for determining measurement signals, specifically for determining torque in an electric bicycle. The method is carried out, for example, by the sensor device 16 described above and comprises the following steps.

[0061] Step S1: Impressing, by means of a control device U1 of a stationary unit 160 of a sensor device 16, a clock signal onto an inductance 162 of the stationary unit 160.

[0062] Step S2: Reading out, by means of a control device U3 of a movable unit 161 of the sensor device 16, which is mounted movably relative to the stationary unit 160, and by an inductive coupling of the inductance 162 of the stationary unit 160 with an inductance 163 of the movable unit 161, the clock impressed on the inductance 162 of the stationary unit 160.

[0063] Step S3: Receiving, by means of the control device U3 of the movable unit 161, measurement signals from the sensor element 164. Step S3 can be performed before or after step S1 and / or step S2.

[0064] Step S4: Encoding, by means of the control device U3 of the movable unit 161, the received measurement signals using the read-out clock.

[0065] Step S5: Impressing, by means of the control device U3 of the movable unit 161, the coded measurement signals onto the inductance 163 of the movable unit 161.

[0066] Step S6: Reading out, by means of the control device U1 of the stationary unit 160, and by the inductive coupling of the inductance 163 of the movable unit 161 with the inductance 162 of the stationary unit 160, the coded measurement signals impressed on the inductance 163 of the movable unit 161.

[0067] Step S7: Controlling a drive motor 13 based on the read-out coded measurement signals.

[0068] Steps S1-S7 can be repeated continuously. List of reference symbols

[0069] electric bike

[0070] 10 front wheel

[0071] 11 Rear wheel

[0072] 12 chain

[0073] drive motor

[0074] 14 Wave

[0075] 15 electronic control unit

[0076] 16 Sensor device

[0077] 160 inpatient units

[0078] 161 movable unit

[0079] 162, 163 Inductance

[0080] 164 sensor element

[0081] 165 strain gauges

[0082] 17 Pedal

[0083] 18 frames

[0084] drive system

[0085] C1-C4 capacitor

[0086] CON signal conditioning element

[0087] D1-D3 diode

[0088] DEC decoding element

[0089] ENC coding element

[0090] GND1. GND2 Ground

[0091] Q1 clock generator

[0092] Q_OSC clock determination unit

[0093] RC_OSC clock determination unit

[0094] R1 resistor

[0095] S1 , S2 switch swc switch control

[0096] SWD switching signal TRQ_REC received measuring signal U1 , U3 control device U2 voltage regulator

[0097] VCCI , VCC2 supply voltage

[0098] Z DET Signal

Claims

Claims 1. Sensor device (16), comprising: a stationary unit (160) with an inductance (162) and a control device (U1) which is designed to impress a clock pulse on the inductance (162), and a movable unit (161) which is mounted so as to be movable relative to the stationary unit (160) and has a control device (U3), an inductance (163) and a sensor element (164), wherein the control device (U3) of the movable unit (161) is designed to read out the clock pulse impressed on the inductance (162) of the stationary unit (160) by an inductive coupling of the inductances (162, 163) and to receive measurement signals from the sensor element (164).

2. Sensor device (16) according to claim 1, characterized in that the movable unit (161) is rotatably mounted relative to the stationary unit (160).

3. Sensor device (16) according to claim 1 or 2, characterized in that the sensor device (16) is designed in the form of a torque sensor for measuring a torque and the measuring signals are based on a torque acting on the sensor element (164) and / or on a component connected thereto.

4. Sensor device (16) according to one of the preceding claims, characterized in that the control device (U3) of the movable unit (161) is supplied with a supply voltage (VCC2) by the inductive coupling of the inductors (162, 163).

5. Sensor device (16) according to one of the preceding claims, characterized in that the stationary unit (160) comprises a clock generator (Q1) in the form of a quartz oscillator, wherein the control device (U1) of the stationary unit (160) determines the clock on the basis of signals from the clock generator (Q1).

6. Sensor device (16) according to one of the preceding claims, characterized in that the control device (U1) of the stationary unit (160) is designed to periodically open and close a switch (S1) in order to impose the clock on the inductance (162) of the stationary unit (160).

7. Sensor device (16) according to one of the preceding claims, characterized in that the control device (U3) of the movable unit (161) is electrically connected to the inductance (163) of the movable unit (161) via a resistor (R1).

8. Sensor device (16) according to one of the preceding claims, characterized in that the control device (U3) of the movable unit (161) is configured to encode the measurement signals of the sensor element (164) using the read-out clock and to impress the encoded measurement signals on the inductance (163) of the movable unit (161).

9. Sensor device (16) according to claim 8, characterized in that the control device (U1) of the stationary unit (160) is configured to read out the coded measurement signals impressed on the inductance (163) of the movable unit (161) by the inductive coupling of the inductances (162, 163) to the inductance (162) of the stationary unit (160) and to output control signals for controlling a drive motor (13) based on the coded measurement signals read out.

10. Sensor device (16) according to one of the preceding claims, characterized in that the control device (U3) of the movable unit (161) is designed to read the clock by detecting zero crossings of a voltage induced in the inductance (163) of the movable unit (161).

11. Sensor device (16) according to one of the preceding claims, characterized in that the control device (U1, U3) of the movable unit (161) and / or the stationary unit (160) is designed in the form of an integrated circuit module.

12. Sensor device (16) according to one of the preceding claims, characterized in that the sensor element (164) comprises a strain gauge.

13. Drive system (A) comprising a shaft (14) and a sensor device (16) according to one of the preceding claims, wherein the movable unit (161) is attached to the shaft (14).

14. Drive system (A) according to claim 13, characterized by a drive motor (13) controlled by control signals provided by the sensor device (16).

15. Drive system (A) according to claim 14, characterized in that the shaft (14) can be driven by the drive motor (13) and / or by means of pedals (17).

16. Electric bicycle (1) with a sensor device (16) according to one of claims 1 to 12 and / or a drive system (A) according to one of claims 13 to 15.

17. A method for determining measurement signals, comprising: Impressing (S1), by means of a control device (U1) of a stationary unit (160) a sensor device (16), a clock to an inductance (162) of the stationary unit (160), Reading (S2), by means of a control device (U3) of a movable unit (161) of the sensor device (16) which is mounted movably relative to the stationary unit (160) and by an inductive coupling of the inductance (162) of the stationary unit (160) with an inductance (163) of the movable unit (161), the clock pulse impressed on the inductance (162) of the stationary unit (160) and Receiving (S3), by means of the control device (U3) of the movable unit (161), measurement signals from the sensor element (164).

18. The method of claim 17, further comprising: Coding (S4), by means of the control device (U3) of the movable unit (161), the received measurement signals using the read-out clock.

19. The method of claim 18, further comprising: Impressing (S5), by means of the control device (U3) of the movable unit (161), the coded measuring signals onto the inductance (163) of the movable unit (161), Reading (S6), by means of the control device (U1) of the stationary unit (160), and by the inductive coupling of the inductance (163) of the movable unit (161) with the inductance (162) of the stationary unit (160), the Inductance (163) of the movable unit (161) impressed coded measuring signals and Controlling (S7) a drive motor (13) based on the read-out coded measurement signals.

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