Method for controlling an electromagnetic actuator for activating a personal protection device for a vehicle, control unit, activation device and activation unit

Abstract

Method (300) for controlling an electromagnetic actuator (114) for activating a personal protection device for a vehicle, the method (300) comprising the following steps: Reading (302) a first measurement signal (116) representing a first measured value of a current flowing through the actuator (114) when the actuator (114) is electrically conductively connected to an electrical energy source (115); Disconnecting (304) the actuator (114) from the energy source (115) using the first measurement signal (116) when the first measured value reaches a predetermined shutdown threshold (204); Receiving (306) a second measurement signal (126) representing a second measured value of a current flowing through the actuator (114) when the actuator (114) is disconnected from the energy source (115); and Reconnecting (308) the actuator (114) to the energy source (115) using the second measurement signal (126) when the second measured value reaches a predetermined switch-on threshold (206) and / or after a predetermined switch-off period (Δt) has elapsed.

Description

State of the art

[0001] The present invention relates to a method for controlling an electromagnetic actuator for activating a personal protection device for a vehicle, to a corresponding control unit, to an activation device for activating a personal protection device for a vehicle, to an activation unit and to a corresponding computer program.

[0002] Magnetic actuators used to control safety devices in vehicles can be activated by applying a voltage for a certain period of time, according to their technical specifications. To ensure that the maximum permissible current flowing through the magnetic actuators is not exceeded, the current can be regulated using electronic components. During this regulation, high power losses can be generated in the electronic components.

[0003] DE 10 2014 210 810 A1 discloses a control device for an electromagnetic actuator of a restraint device that is deactivated when a predefined threshold value of an integrated counter is reached. Once the counter reading reaches or exceeds a predefined threshold value, the actuator can be reactivated. The counter is determined by a control signal, which also supplies the current required to operate the actuator.

[0004] DE 10 2008 033 582 B3 discloses a diagnostic procedure for an electromagnetic actuator. For this diagnostic procedure, a current source is connected to the actuator, and a microcontroller detects the current flowing through the actuator, compares it with a reference value, and reports an error if discrepancies occur.

[0005] DE 10 2009 001 880 A1 discloses a power supply for an actuator in two operating states. In a second operating state, a higher supply signal level is applied to the actuator than in the first operating state. Disclosure of the invention

[0006] Against this background, the approach presented here presents a method for controlling an electromagnetic actuator to activate a personal protection device for a vehicle, a control unit that uses this method, an activation device for activating a personal protection device for a vehicle, an activation unit, and finally a corresponding computer program according to the main claims. Advantageous embodiments emerge from the respective subclaims and the following description.

[0007] The approach presented here provides a method for controlling an electromagnetic actuator to activate a personal protection device for a vehicle, the method comprising the following steps: Reading in a first measurement signal representing a first measured value of a current flowing through the actuator when the actuator is connected to an electrical energy source; Disconnecting the actuator from the energy source using the first measurement signal when the first measured value reaches a predetermined shutdown threshold; Receiving a second measurement signal representing a second measured value of a current flowing through the actuator when the actuator is disconnected from the power source; and Reconnecting the actuator to the energy source using the second measurement signal when the second measured value reaches a predetermined switch-on threshold and / or after a predetermined switch-off period has elapsed.

[0008] The electromagnetic actuator can, for example, comprise a coil and a movable element made of a magnetizable material. The coil can be designed to generate a magnetic field through a current pulse, which exerts a force on the movable element, thereby moving the movable element. A passenger protection device can be understood to be a restraint device such as an airbag, a belt tensioner, or another device in a vehicle that is suitable for increasing the safety of vehicle occupants or other road users. A vehicle can be understood to be a motor vehicle. An electrical energy source can be understood to be a battery or a capacitor, for example. In particular, the energy source can be an additional energy storage device separate from a vehicle battery. A shutdown threshold can be understood to be a maximum permitted current strength.For example, the actuator can be disconnected from the power source if the first measured value exceeds the shutdown threshold. The second measurement signal can represent a measured value of an induced current flowing through the actuator. A switch-on threshold can be understood as a minimum permissible current strength. For example, the actuator can be reconnected to the power source if the second measured value falls below the switch-on threshold.

[0009] The approach proposed here is based on the finding that a current flow in an electromagnetic actuator can be maintained due to the actuator's self-induction, even when the actuator is briefly disconnected from its power source. This self-induction can be used to significantly reduce the actuator's power consumption when controlling a personal protection device.

[0010] Current magnetic actuators for controlling safety devices in vehicles are primarily powered by a vehicle battery. However, since the vehicle battery can be disconnected or destroyed during an accident and thus no longer available to power an airbag control unit, for example, the airbag control unit can have its own energy storage device, which continues to supply the airbag control unit with energy for a certain period of time after the battery power is lost, enabling the activation of restraint devices such as airbags and seatbelt pretensioners. Due to their relatively high energy requirements, magnetic actuators are generally not connected to the airbag control unit's energy storage device.

[0011] The present approach now creates a method by which magnetic actuators for controlling safety devices in a vehicle can be controlled in an energy-efficient manner. This prevents a large portion of the energy in the electrical components of a control circuit from being converted into power loss in the event of activation, thus preventing it from being used to activate additional restraint devices. By reducing the power loss, it is possible to connect the magnetic actuators to an energy storage device in the control unit without significantly increasing its size. This means that even if the vehicle battery loses power, the actuators are available to activate the respective safety devices, thereby increasing occupant safety.

[0012] The method can be provided with a step of outputting an activation signal to activate the personal protection device. In a connecting step, the actuator can be connected to the power source using the activation signal. Because the actuator is de-energized when the personal protection device is deactivated, the power consumption caused by the actuator can be kept as low as possible.

[0013] It is further advantageous if, in the reconnection step, the reconnection is suppressed after a predetermined activation period of the personal protection device has elapsed. A predetermined activation period can be understood as the time period required by the personal protection device to be activated, i.e., to fully exert its protective effect. By interrupting the power supply to the actuator after activation, energy can be saved, which can then be used, if necessary, to activate additional personal protection devices or to reactivate the personal protection device.

[0014] Following the reconnection step, the steps of reading, disconnecting, receiving, and reconnecting can be performed repeatedly. The individual steps can be performed sequentially. This allows a continuous current flow through the actuator to be maintained during the activation period with minimal power consumption.

[0015] According to a further embodiment, in the disconnection step, the actuator can be disconnected from the power source if the first measured value corresponds at least to the shutdown threshold. Additionally or alternatively, in the reconnection step, the actuator can be reconnected to the power source if the second measured value corresponds at most to the startup threshold. This allows for reliable detection of a current profile in the actuator.

[0016] Furthermore, it is advantageous if the shutdown threshold represents a higher current value than the turn-on threshold. For example, the turn-on threshold current value can correspond to 25, 50, or 75 percent of the shutdown threshold current value. By making the shutdown threshold significantly higher than the turn-on threshold, control errors due to measurement fluctuations can be avoided.

[0017] The presented approach further provides a control unit for controlling an electromagnetic actuator for activating a personal protection device for a vehicle, wherein the control unit has the following features: a reading unit for reading in a first measurement signal representing a first measured value of a current flowing through the actuator when the actuator is connected to an electrical energy source; a disconnection unit for disconnecting the actuator from the energy source using the first measurement signal when the first measurement value reaches a predetermined shutdown threshold; a receiving unit for receiving a second measurement signal representing a second measured value of a current flowing through the actuator when the actuator is disconnected from the energy source; and a reconnection unit for reconnecting the actuator to the energy source using the second measurement signal when the second measured value reaches a predetermined switch-on threshold and / or after a predetermined switch-off period has elapsed.

[0018] In this case, a control unit can be understood as an electrical device that processes sensor signals and outputs control and / or data signals depending on them. The control unit can have an interface that can be implemented in hardware and / or software. In a hardware implementation, the interfaces can, for example, be part of a so-called system ASIC, which contains a wide variety of functions of the control unit. However, it is also possible for the interfaces to be separate integrated circuits or to consist at least partially of discrete components. In a software implementation, the interfaces can be software modules that are present, for example, on a microcontroller alongside other software modules.

[0019] The disconnection unit and, alternatively or additionally, the reconnection unit can be configured to control a supply voltage switch for coupling the actuator to a supply voltage terminal. A supply voltage switch can be, for example, a high-side power amplifier. The supply voltage terminal can be connected to the power source. Such a supply voltage switch can be provided particularly cost-effectively and enables reliable power supply to the actuator.

[0020] It is also advantageous if, according to a further embodiment, the reading unit is configured to read the first measurement signal from a current measuring device for measuring a current flowing through the actuator. Additionally or alternatively, the receiving unit can be configured to receive the second measurement signal from the current measuring device. For example, the current measuring device can be connected in series with the actuator. Such a measuring arrangement can be implemented with little effort and enables precise measurement of a current flowing through the actuator.

[0021] Furthermore, the proposed approach provides an activation device for activating a personal protection device for a vehicle, the activation device having the following features: a control device according to one of the embodiments described here; an actuator; a supply voltage switch for coupling the actuator to the supply voltage connection, wherein the supply voltage switch is coupled to the disconnection unit and / or the reconnection unit of the control unit; and a current measuring device for measuring a current flowing through the actuator, wherein the current measuring device is coupled to the reading unit and / or the receiving unit of the control unit.

[0022] Such an activation device enables the activation of a personal protection device with very low power losses.

[0023] According to one embodiment, the actuator can have an inductance with a first terminal and a second terminal. The first terminal and the second terminal can be coupled to each other via a diode. A diode can, for example, be a freewheeling diode connected in parallel with the actuator. The diode can protect circuits of the control unit from voltage spikes that can occur when the actuator is switched off due to the actuator's inductance.

[0024] Furthermore, the proposed approach provides an activation unit which is designed to output an activation signal for activating the personal protection device to a control unit according to one of the embodiments described here.

[0025] Advantageously, the activation unit can be configured to control a ground potential switch for coupling the actuator to a ground potential terminal. A ground potential switch can be understood, for example, as a low-side output stage. The ground potential terminal can be connected to the power source. This allows for flexible control of the current flow through the actuator.

[0026] Also advantageous is a computer program product or computer program with program code that can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard disk memory or an optical memory and is used to carry out, implement and / or control the steps of the method according to one of the embodiments described above, in particular when the program product or program is executed on a computer or a device.

[0027] The approach presented here is explained in more detail below using the attached drawings. They show: Fig. 1 is a schematic representation of an activation device according to an embodiment of the present invention; Fig. 2 is a diagram illustrating various signal curves during the actuation of an electromagnetic actuator in a method according to an embodiment of the present invention; and Fig. 3 a flowchart of a method according to an embodiment of the present invention.

[0028] In the following description of advantageous embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and having a similar effect, whereby a repeated description of these elements is omitted.

[0029] Fig. 1 shows a schematic representation of an activation device 100 according to an embodiment of the present invention. The activation device 100 for activating a personal protection device for a vehicle comprises a control unit 102 with a read-in unit 104, a disconnection unit 106, a receiving unit 108, and a reconnection unit 110. A control circuit comprising the units 104, 106, 108, 110 can also be referred to as logic for a triggering decision. The activation device 100 further comprises a current measuring device 112, which is designed to measure a current flowing through an electromagnetic actuator 114. The actuator 114, also called an actuator, is designed to actuate a personal protection device of a vehicle (not shown here). An electrical energy source 115, here an energy storage device, is designed to provide the electrical energy required to control the actuator 114.The energy source 115 can also serve to supply energy to the control unit 102. For example, the current measuring device 112 is arranged between the actuator 114 and the energy source 115.

[0030] The reading unit 104 is configured to read a first measurement signal 116 from the current measuring device 112. The first measurement signal 116 represents a measured value of a current flowing through the actuator 114 when the actuator 114 is electrically conductively connected to the energy source 115. The isolating unit 106 is configured to receive the first measurement signal 116 from the reading unit 104 and, using the first measurement signal 116, to provide an isolating signal 118 when the measured value of the current flowing through the switched-on actuator 114 reaches a predetermined shutdown threshold. The shutdown threshold can be stored, for example, in the control unit 102.Depending on the embodiment, the separation unit 106 is alternatively or additionally implemented with a time control which serves to provide the separation signal 118 after a predetermined switch-off period has elapsed, during which the actuator 114 must at least be switched off before it can be switched on again.

[0031] The activation device 100 is further configured with a supply voltage switch 120, here a high-side output stage, which is contacted with a supply voltage terminal 121. For example, the supply voltage switch 120 is arranged between the energy source 115 and the current measuring device 112, with the supply voltage terminal 121 being fed by the energy source 115.

[0032] The supply voltage switch 120 serves to control a current flow between the energy source 115 and the actuator 114. For this purpose, the supply voltage switch 120 is designed to receive the disconnect signal 118 from the disconnect unit 106 and, in response to receiving the disconnect signal 118, to disconnect the energy source 115 from the actuator 114.

[0033] Due to self-induction of the actuator 114, an induction current continues to flow through the actuator 114 when the supply voltage switch 120 is open. According to this exemplary embodiment, the activation device 100 comprises a diode 122, for example a freewheeling diode, which electrically conductively connects a first terminal 123 to a second terminal 124 of the actuator 114 and serves to avoid voltage peaks in the switched-off state of the actuator 114 as a result of self-induction.

[0034] The current measuring device 112 is configured to output a second measurement signal 126 while the actuator 114 is switched off. The second measurement signal 126 thus represents a measured value of the current induced by the actuator 114. The receiving unit 108 is configured to receive the second measurement signal 126 and transmit it to the reconnection unit 110. The reconnection unit 110 is configured to send a reconnection signal 128 to the supply voltage switch 120 using the second measurement signal 126, provided that the measured value represented by the second measurement signal 126 reaches a predetermined switch-on threshold, which, like the switch-off threshold, can be stored in the control unit 102. Accordingly, the supply voltage switch 120 is configured to restore the electrical connection between the energy source 115 and the actuator 114 using the reconnection signal 128.As a result, the current applied to actuator 114 increases again. If the current measuring device 112 now determines that the shutdown threshold has been reached again, the supply voltage switch 120 can be controlled once again via the read-in unit 104 and the disconnection unit 106 in the manner described above to disconnect the energy source 115 from the actuator 114 again.

[0035] In addition, Fig. 1 shows an activation unit 130. The activation unit 130 is designed to provide an activation signal 132 representing a triggering decision in the event of activation of the personal protection device, for example in the event of an imminent collision of the vehicle. For this purpose, the activation unit 130 can be coupled, for example, to corresponding environmental and acceleration sensors of the vehicle. The activation unit 130 can alternatively be implemented as a component of the control unit 102. A connection unit 134 of the control unit 102 is designed to generate a connection signal 136 using the activation signal 132 and to provide it to the supply voltage switch 120. The supply voltage switch 120 is designed to apply a supply voltage to the actuator 114 for the first time using the connection signal 136.The actuator 114 is then controlled in the manner described above in order to activate the personal protection device in the most energy-efficient way possible.

[0036] According to this exemplary embodiment, the activation unit 130 is configured to additionally control a ground potential switch 141, which is contacted with a ground potential terminal 142. Likewise, the energy source 115 is connected to the ground potential terminal 142. The ground potential switch 140 is configured to couple the actuator 114 to the ground potential terminal 142.

[0037] According to one embodiment, actuator 114 is designed like an electromagnet, i.e., with a coil. When actuator 114 is activated, a current pulse generates a magnetic field in the coil. This magnetic field exerts a force on a magnetizable material, which then moves in the magnetic field. This movement can, for example, release a holding device, triggering a mechanically stressed safety device in the vehicle. The coil of the electromagnet can be connected in parallel with freewheeling diode 122.

[0038] After the control unit 102 has made an activation decision based on sensor data, both the high-side output stage 120 and the low-side output stage 141 are controlled. Logic located on the high side, which may include units 104, 106, 108, 110, 134, is configured to control the high-side output stage 120 when various start conditions, such as "triggering decision made" or "measured current less than the maximum permitted current," are met. These start conditions may vary depending on the embodiment.

[0039] This initiates an inductive current flow through actuator 114. The current currently present is determined using a current measuring device 112, also referred to above as a current measuring device. When a maximum current is reached, this is reported to the logic, which then switches off the high-side output stage 120 again. Due to the inductance and the freewheeling diode 122 in the actuator, which can alternatively be arranged in the control unit 102, the current flow through actuator 114 is maintained. In this operating mode, no energy is drawn from the energy storage device 115 of the control unit 102. When the current falls below a current threshold or after a defined time has elapsed, the high-side output stage 120 is switched on again by the logic, so that actuator 114 again draws power from the energy storage device 115 until the switch-off current threshold is reached again. The sequence can now begin again.

[0040] After the activation time defined for each actuator type has elapsed, the triggering decision for the high-side power stage 120 is canceled. Due to the logic, the high-side power stage 120 is no longer switched on even if the current falls below the threshold, as shown below using Fig. 2. The current drops to zero due to the inductance, the freewheeling diode 122, and the still-open low-side output stage 141. When current stops flowing, the trigger decision for the low-side output stage 141 is also canceled.

[0041] In this way, only as much energy is drawn from the energy storage device 115 as the actuator 114 needs to activate the safety device. The resulting losses are minimal, since very little energy is converted into heat. Thus, the system has sufficient energy available to activate other restraint devices.

[0042] Due to the very efficient use of the energy stored in the energy storage device 115, it is possible to use a correspondingly smaller energy storage device to control the actuator 114. This can save manufacturing costs.

[0043] Fig. Figure 2 shows a diagram illustrating various signal curves during the control of an electromagnetic actuator in a method according to an embodiment of the present invention. The respective x-axes of the signal curves are arranged one above the other and assigned a time t. The method is, for example, a method as described below with reference to Fig. 3 is described in more detail.

[0044] The control of the actuator begins at a time t0, at which a first trigger signal 200 is generated, which triggers a trigger decision to trigger a low-side output stage, such as a ground potential switch, as described in Fig. 1. The level of the first trigger signal 200 increases abruptly from zero to a constant value.

[0045] At a time t1 following time t0, a second trigger signal 202 is generated, which triggers a trigger decision for triggering a high-side output stage, such as a supply voltage switch, as described by Fig. 1. For example, the second trigger signal 202 is a signal derived from Fig. 1 described activation signal.

[0046] Between time t1 and a time t2 following time t1, the connection signal 136 is present to connect the actuator to the power source for the first time via the high-side output stage. During a period between times t1 and t2, a current flow 204 through the actuator rises sharply until it reaches a maximum current threshold 205, also called the shutdown threshold, at time t2. When the maximum current threshold 205 is reached, the actuator is shut down. The level of the connection signal 136 drops abruptly to zero.

[0047] In response to reaching the maximum current threshold 205, the second measurement signal 126 is generated at time t2 as an output signal for a current measurement in the actuator in order to measure an induced current flowing through the switched-off actuator. A level of the second measurement signal 126 is constant during a period between time t2 and a time t3 following time t2. During this period, the current waveform 204 gradually decreases until it reaches a minimum current threshold 206, also called the switch-on threshold, at time t3. In response to reaching the minimum current threshold 206, the level of the second measurement signal 126 drops abruptly to zero and remains at zero until a time t4 following time t3.

[0048] At time t3, the reconnection signal 128 is generated to reconnect the actuator to the power source. The level of the reconnection signal 128 remains constant during a period between times t3 and t4. During this period, energy is drawn from the power source. Alternatively, the reconnection signal 128 is generated after a predetermined time period Δt has elapsed, which here corresponds to a time interval between times t2 and t3. When the reconnection signal 128 is present, the current waveform 204 rises significantly faster than it previously fell, until it reaches the maximum current threshold 205 again at time t4. When the maximum current threshold 205 is reached at time t4, the level of the reconnection signal 128 drops abruptly to zero. The actuator is thereby disconnected from the power source. At the same time, the level of the second measurement signal 126 rises abruptly again.In turn, the induction current flowing through the actuator is measured.

[0049] Furthermore, Fig. 2 shows the signal curves at subsequent times t6 to t13, which follow times t0 to t5. The signal curves between times t6, t7, between times t8, t9, between times t10, t11, and between times t12, t13 correspond to the signal curves described above using the example of the period between times t4, t5. The signal curves between times t5, t6, between times t7, t8, between times t9, t10, and between times t11, t12, however, correspond to the signal curves described above using the example of the period between times t3, t4.

[0050] At a time when Fig. 2, for example, lies between times t12 and t13, the personal protection device is fully activated. At this time, the level of the second trigger signal 202 drops abruptly to zero. This suppresses a renewed output of the reconnection signal 128 following time t12. Thus, the current waveform 204 continues to fall below the minimum current threshold 206 even after reaching the minimum current threshold 206 at time t13.

[0051] At a time tn following time t13, the level of the first trigger signal 200 also drops abruptly to zero. The current waveform 204 has also dropped to zero at time tn.

[0052] Fig. 3 shows a flowchart of a method 300 according to an embodiment of the present invention. The method 300 for controlling an electromagnetic actuator to activate a personal protection device for a vehicle is carried out, for example, by the units of a control unit, as described with reference to Fig. 1 and Fig.2. In a step 302, a first measurement signal is read in, which represents a first measured value of a current flowing through the actuator when the actuator is connected to an electrical energy source. Following step 302, in a further step 304, the actuator is disconnected from the energy source using the first measurement signal when the first measured value reaches a predetermined switch-off threshold. According to one embodiment, the actuator is disconnected when the first measured value corresponds at least to the switch-off threshold. In a step 306, a second measurement signal is now received, which represents a second measured value of a current flowing through the actuator when the actuator is disconnected from the energy source. When the second measured value reaches a predetermined switch-on threshold, the actuator is reconnected to the energy source in a step 308 using the second measurement signal.In addition or alternatively to reaching the activation threshold, the actuator is reconnected after a predetermined deactivation period has elapsed. According to a further embodiment, the actuator is reconnected when the second measured value corresponds at most to the activation threshold.

[0053] Steps 302, 304, 306, and 308 can be repeated consecutively until a predetermined activation period of the personal protection device has elapsed. For example, after the activation period has elapsed, reconnection of the actuator to the power source is suppressed in step 308.

[0054] The exemplary embodiments described and shown in the figures are selected only as examples. Different exemplary embodiments can be combined with one another in their entirety or with regard to individual features. Furthermore, one exemplary embodiment can be supplemented by features of another exemplary embodiment.

[0055] Furthermore, the process steps presented here can be repeated and carried out in a different order than that described.

[0056] If an embodiment includes an “and / or” link between a first feature and a second feature, this should be read as meaning that the embodiment according to one embodiment includes both the first feature and the second feature and according to another embodiment includes either only the first feature or only the second feature.

Claims

[1] Method (300) for controlling an electromagnetic actuator (114) for activating a personal protection device for a vehicle, the method (300) comprising the following steps: Reading (302) a first measurement signal (116) representing a first measured value of a current flowing through the actuator (114) when the actuator (114) is electrically conductively connected to an electrical energy source (115); Disconnecting (304) the actuator (114) from the energy source (115) using the first measurement signal (116) when the first measured value reaches a predetermined shutdown threshold (204); Receiving (306) a second measurement signal (126) representing a second measured value of a current flowing through the actuator (114) when the actuator (114) is disconnected from the energy source (115); and Reconnecting (308) the actuator (114) to the energy source (115) using the second measurement signal (126) when the second measured value reaches a predetermined switch-on threshold (206) and / or after a predetermined switch-off period (Δt) has elapsed. [2] Method (300) according to claim 1, characterized in that an induction current through the actuator (114) is detected as the second measurement signal. [3] Method (300) according to claim 1 or 2, characterized by a step of outputting an activation signal (132) for activating the personal protection device, wherein in a step of connecting the actuator (114) is connected to the energy source (115) using the activation signal (132). [4] Method (300) according to one of the preceding claims, characterized by that in the reconnection step (308) the reconnection is suppressed after a predetermined activation period of the personal protection device has elapsed. [5] Method (300) according to one of the preceding claims, characterized by that following the step of reconnecting (308), the steps of reading (302), disconnecting (304), receiving (306) and reconnecting (308) are repeatedly carried out. [6] Method (300) according to one of the preceding claims, characterized by that in the step of disconnecting (304) the actuator (114) is disconnected from the energy source (115) if the first measured value corresponds at least to the switch-off threshold (205), and / or in the step of reconnecting (308) the actuator (114) is reconnected to the energy source (115) if the second measured value corresponds at most to the switch-on threshold (206). [7] Method (300) according to one of the preceding claims, characterized by that the switch-off threshold (205) represents a higher current value than the switch-on threshold (206). [8] Control unit (102) for controlling an electromagnetic actuator (114) for activating a personal protection device for a vehicle, the control unit (102) having the following features: a reading unit (104) for reading in and / or receiving a first measurement signal (116) of a current measuring device (112) (see original claim 9), which represents a first measured value of a current flowing through the actuator (114) when the actuator (114) is connected to an electrical energy source (115); a disconnection unit (106) for disconnecting the actuator (114) from the energy source (115) using the first measurement signal (116) when the first measurement value reaches a predetermined shutdown threshold (205); a receiving unit (108) for receiving a second measurement signal (126) representing a second measured value of a current flowing through the actuator (114) when the actuator (114) is disconnected from the energy source (115); and a reconnection unit (110) for reconnecting the actuator (114) to the energy source (115) using the second measurement signal (126) when the second measured value reaches a predetermined switch-on threshold (206) and / or after a predetermined switch-off period (Δt) has elapsed. [9] Control device (102) according to claim 8, characterized by that the separation unit (106) and / or the reconnection unit (110) is designed to control a supply voltage switch (120) for coupling the actuator (114) to a supply voltage terminal (121). [10] Activation device (100) for activating a personal protection device for a vehicle, the activation device (100) having the following features: a control device (102) according to one of claims 8 or 9; an actuator (114); a supply voltage switch (120) for coupling the actuator (114) to the supply voltage connection (121), wherein the supply voltage switch (120) is coupled to the disconnection unit (106) and / or the reconnection unit (110) of the control unit (102); and a current measuring device (112) for measuring a current flowing through the actuator (114), wherein the current measuring device (112) is coupled to the reading unit (104) and / or the receiving unit (108) of the control unit (102). [11] Activation device (100) according to claim 10, characterized by that the actuator (114) has an inductance with a first terminal (123) and a second terminal (124), wherein the first terminal (123) and the second terminal (124) are coupled to one another via a diode (122). [12] Activation unit (130) which is designed to output an activation signal (132) for activating the personal protection device to a control unit (102) according to one of claims 8 or 9. [13] Activation unit (130) according to claim 12, characterized by that the activation unit (130) is designed to control a ground potential switch (141) for coupling the actuator (114) to a ground potential terminal (142). [14] Computer program configured to perform all steps of a method (300) according to any one of claims 1 to 7. [15] A machine-readable storage medium having stored thereon a computer program according to claim 14.

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