SE2150567A1

SE2150567A1 - A method and a control arrangement for assisting a vehicle

Info

Publication number: SE2150567A1
Application number: SE2150567A
Authority: SE
Inventors: Christoph Ertelt; Joel Agrell; Linus Sjövall; Ninos Poli; Oscar Hällman; Rami Kraft
Original assignee: Scania Cv Ab
Priority date: 2021-05-04
Filing date: 2021-05-04
Publication date: 2022-11-05
Also published as: SE545591C2; DE102022107779A1

Abstract

A method for assisting a vehicle (100), the vehicle (100) comprising a safety critical system (134); an ignition system (136) configured to be in an ignition state, wherein the ignition state of the ignition system (136) is on or off; and a primary electrical energy source (140) for providing electric power to the safety critical system (134) when the ignition state of the ignition system (136) is off. The method comprises: providing (205; 305; 405, 409) electric power from a secondary electrical energy source (142) of the vehicle (100) to the safety critical system (134) while providing electric power from the primary electrical energy source (140) to the safety critical system (134) when the ignition state of the ignition system (136) is off and a current vehicle speed of the vehicle (100) is above a first threshold. A control arrangement (150) and a vehicle (100) including the control arrangement (150) are also disclosed.

Description

lO A METHOD AND A CONTROL ARRANGEMENT FOR ASSISTING A VEHICLE Technical field Aspects of the present invention relate to a method for assisting a vehicle comprising a safety critical system and an ignition system. Further, aspects of the present invention relate to a control arrangement for assisting a vehicle of the above-mentioned sort. Aspects of the present invention also relate to a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out a method of the above-mentioned sort, or relate to a computer-readable medium comprising instructions which, when the instructions are executed by a computer, cause the computer to carry out a method of the above-mentioned sort. Further, aspects of the present invention relate to a vehicle comprising a safety critical system and an ignition system.

Background I general, a motor vehicle, such as a vehicle with a combustion engine for driving the drive wheels of the vehicle, a hybrid vehicle having both a combustion engine and one or more electrical machines for driving the drive wheels of the vehicle or an electrical vehicle with one or more electrical machines only for driving the drive wheels of the vehicle, has an ignition system which in general includes an ignition switch. The ignition switch may for example be associated with a press button or key switch. When the ignition system is turned off when the vehicle stands still, most of the systems of the vehicle may be inactivated. However, an electrical energy source of the vehicle, such as an electric battery, may still provide electric power to some electrical systems of the vehicle, which need or should be provided with electric power to stay active when the ignition system is turned off.

Summary The inventors of the present invention have found that a motor vehicle may continue to move even if the ignition system is turned off, and that a motor vehicle may start moving although the ignition state of the ignition system is off. The reason for these situations may be mistakes made by the operator, or driver, or technical failures, for example failures in the ignition system or the parking brake system. The inventors of lO the present invention have found that these situations may be critical and dangerous, since one or more safety critical systems, for example the electronic brake system or the electric steering, during movement of the vehicle may be inactive or may not receive enough electric power to function properly because the ignition state of the ignition system is off. Thus, the inventors of the present invention have found that there may be a need for improving safety with regard to the control of the motor vehicle.

An object of the invention is to provide a solution which mitigates or solves the drawbacks and problems of conventional solutions.

The above and further objects are solved by the subject matter of the independent claims. Further advantageous embodiments of the invention can be found in the dependent claims.

According to a first aspect of the invention, the above mentioned and other objects are achieved with a method for assisting a vehicle, the vehicle comprising a safety critical system, an ignition system configured to be in an ignition state, wherein the ignition state of the ignition system is on or off, and a primary electrical energy source for providing electric power to the safety critical system when the ignition state of the ignition system is off, wherein the method comprises: o providing electric power from a secondary electrical energy source of the vehicle to the safety critical system while providing electric power from the primary electrical energy source to the safety critical system when the ignition state of the ignition system is off and a current vehicle speed of the vehicle is above a first threshold.

An advantage of the method according to the first aspect is that it is assured or at least made more certain that the safety critical system is provided with sufficient electric power when the ignition state of the ignition system is off and the vehicle is moving. Thus, by means of the method according to the first aspect, the control of the motor vehicle and the safety with regard to the control of the vehicle are improved. The safety lO improvement provided by the method according to the first aspect may be attained with an electrical energy source, or electrical energy sources, already present in the vehicle. Thus, the safety improvement may be attained without a major increase of the complexity of vehicle and/or without increasing the production costs of the vehicle.

The ignition system may comprise an ignition switch, which for example may be operated by an operator or driver.

According to an advantageous embodiment ofthe method according to the first aspect, the method comprises determining the ignition state of the ignition system. An advantage of this embodiment is that the control of the motor vehicle and the safety with regard to the control of the motor vehicle are improved.

According to a further advantageous embodiment of the method according to the first aspect, the method comprises obtaining or determining the current vehicle speed of the vehicle. An advantage of this embodiment is that the control of the motor vehicle and the safety with regard to the control of the motor vehicle are improved.

According to another advantageous embodiment of the method according to the first aspect, the method comprises comparing the obtained or determined current vehicle speed of the vehicle with the first threshold. An advantage of this embodiment is that the control of the motor vehicle and the safety with regard to the control of the motor vehicle are improved.

According to yet another advantageous embodiment of the method according to the first aspect, the method comprises interrupting the provision of electric power from the secondary electrical energy source to the safety critical system when the ignition state of the ignition system is off and the current speed of the vehicle is below a second threshold. An advantage of this embodiment is that electric power is saved, and electric power is not provided when not needed.

According to still another advantageous embodiment of the method according to the first aspect, the method comprises comparing the obtained or determined current lO vehicle speed of the vehicle with the second threshold. An advantage of this embodiment is that electric power is saved, and electric power is not provided when notneeded.

According to an advantageous embodiment ofthe method according to the first aspect, the step of providing electric power of the method comprises providing electric power to the safety critical system which comprises one or more of the group of: o a steering including electric steering; and o an electronic brake system. An advantage of this embodiment is that the control of the motor vehicle and the safety with regard to the control of the motor vehicle are improved.

According to another advantageous embodiment of the method according to the first aspect, the secondary electrical energy source comprises a first electric battery unit electrically connectable to the safety critical system via a first switch, the first switch being switchable between an open state and a closed state, wherein the method comprises controlling the first switch to provide electric power from the secondary electrical energy source to the safety critical system when the ignition state of the ignition system is off and the current vehicle speed of the vehicle is above the first threshold. An advantage of this embodiment is that the control of the motor vehicle and the safety with regard to the control of the motor vehicle are improved. Further, the safety improvement may be provided with an electrical energy source already present in the vehicle. Thus, the safety improvement may be provided without a major increase of the complexity of vehicle and without increasing the production costs of the vehicle.

According to yet another advantageous embodiment of the method according to the first aspect, the secondary electrical energy source comprises an electrical energy unit electrically connectable to the safety critical system via a DC-to-DC converter, wherein the DC-to-DC converter is configured to be in an active state or an inactive state, wherein in the active state the DC-to-DC converter is configured to convert direct current from a first voltage level to a second voltage level, wherein the method comprises controlling the DC-to-DC converter to provide electric power from the lO secondary electrical energy source to the safety critical system when the ignition state of the ignition system is off and the current vehicle speed of the vehicle is above the first threshold, and wherein the electrical energy unit comprises one or more of the group of: o a second electric battery unit; and o fuel cell unit. An advantage of this embodiment is that the control of the motor vehicle and the safety with regard to the control of the motor vehicle are improved. Further, the safety improvement may be provided with an electrical energy source already present in the vehicle. Thus, the safety improvement may be provided without a major increase of the complexity of vehicle and without increasing the production costs of the vehicle.

According to still another advantageous embodiment of the method according to the first aspect, the primary electrical energy source comprises a third electric battery unit. An advantage of this embodiment is that the control of the motor vehicle and the safety with regard to the control of the motor vehicle are improved.

According to another advantageous embodiment of the method according to the first aspect, the ignition system comprises an ignition switch, wherein the ignition state of the ignition system is on when the ignition switch is turned on, wherein the ignition state of the ignition system is off when the ignition switch is turned off or when the ignition system experiences an ignition system failure. An advantage of this embodiment is that the control of the motor vehicle and the safety with regard to the control of the motor vehicle are improved. ln unusual situations, even if the ignition switch is turned on, the ignition state of the ignition system may still be off because of the ignition system failure.

According to further advantageous embodiments of the method according to the first aspect, one or more of the first threshold and the second threshold is/are a predetermined threshold. Thus, the first threshold is a predetermined first threshold and/or the second threshold is a predetermined second threshold. An advantage of lO this embodiment is that the control of the motor vehicle and the safety with regard to the control of the motor vehicle are improved.

According to a second aspect of the invention, the above mentioned and other objects are achieved with a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method according to any one of the embodiments disclosed above or below. The advantages of the computer program according to the second aspect correspond to the above- or below-mentioned advantages of the method according to the first aspect and its embodiments.

According to a third aspect of the invention, the above mentioned and other objects are achieved with a computer-readable medium comprising instructions which, when the instructions are executed by a computer, cause the computer to carry out the method according to any one of the embodiments disclosed above or below. The advantages of the computer-readable medium according to the third aspect correspond to the above- or below-mentioned advantages of the method according to the first aspect and its embodiments.

According to an aspect of the present invention, the above-mentioned computer program and computer-readable medium are configured to implement the method and its embodiments described herein.

According to a fourth aspect of the invention, the above mentioned and other objects are achieved with a control arrangement for assisting a vehicle, the vehicle comprising a safety critical system, an ignition system configured to be in an ignition state, wherein the ignition state of the ignition system is on or off, and a primary electrical energy source for providing electric power to the safety critical system when the ignition state of the ignition system is off, wherein the control arrangement is configured to: provide electric power from a secondary electrical energy source of the vehicle to the safety critical system while providing electric power from the primary electrical lO energy source to the safety critical system when the ignition state of the ignition system is off and a current vehicle speed of the vehicle is above a first threshold.

The advantages of the control arrangement according to the fourth aspect correspond to the above- or below-mentioned advantages of the method according to the first aspect and its embodiments. lt will be appreciated that all the embodiments described for the method aspects of the invention are applicable also the control arrangement aspects the invention. Thus, all embodiments described for the method aspects of the invention may be performed by the control arrangement, which may include a control unit or a control device. As mentioned above, the control arrangement and its embodiments have advantages corresponding to the advantages mentioned above for the method and its embodiments.

According to a fifth aspect of the invention, the above mentioned and other objects are achieved with a vehicle comprising a safety critical system, an ignition system configured to be in an ignition state, wherein the ignition state of the ignition system is on or off, a primary electrical energy source for providing electric power to the safety critical system when the ignition state of the ignition system is off, and a secondary electrical energy source, and a control arrangement according to any one of the embodiments disclosed above or below.

The ignition system of the vehicle may comprise an ignition switch, which may be configured to be operated by a user, operator or driver.

According to an advantageous embodiment of the vehicle according to the fifth aspect, the ignition system comprises an ignition switch, wherein the ignition system is configured such that the ignition state of the ignition system is on when the ignition switch is turned on, and wherein the ignition system is configured such that the ignition lO state of the ignition system is off when the ignition switch is turned off or when the ignition system experiences an ignition system failure.

The above-mentioned features and embodiments of the method, the computer program, the computer-readable medium, the control arrangement and the vehicle, respectively, may be combined in various possible ways providing further advantageous embodiments.

Further advantageous embodiments of the method, the computer program, the computer-readable medium, the control arrangement and the vehicle according to the present invention and further advantages with the embodiments of the present invention emerge from the detailed description of embodiments.

Brief Description of the Drawings Embodiments of the invention will now be illustrated, for exemplary purposes, in more detail by way of embodiments and with reference to the enclosed drawings, where similar references are used for similar parts, in which: Figure 1 is a schematic view illustrating a vehicle according to the fifth aspect of the invention, in which embodiments of the present invention may be implemented; Figures 2-4 are schematic diagrams illustrating a first embodiment of the method according to the first aspect; Figures 5-7 are schematic diagrams illustrating a second embodiment of the method according to the first aspect; Figures 8-9 are schematic diagrams illustrating a third embodiment of the method according to the first aspect; Figure 10 is a flow chart illustrating aspects of the first embodiment of the method illustrated in figures 2-4; Figure 11 is a flow chart illustrating aspects of the second embodiment of the method illustrated in figures 5-7; Figure 12 is a flow chart illustrating aspects of the third embodiment of the method illustrated in figures 8-9; and lO Figure 13 is a schematic view illustrating an embodiment of the control arrangement according to the fourth aspect of the invention, in which a method according to any one of the herein described embodiments may be implemented.

Detailed Description With reference to figure 1, a vehicle 100 is schematically shown. The vehicle 100 may be called a motor vehicle 100. The vehicle 100 may be a tractor or a truck, for example a heavy truck, for example provided with a trailer. The vehicle 100 comprises a powertrain 102, which in the shown embodiment comprises a combustion engine 104, for example an internal combustion engine or another combustion engine, which in a conventional manner, via a first output shaft 106 and usually via a flywheel, is connected to a gearbox 108 via a clutch 110. ln general, the combustion engine 104 comprises cylinders. ln addition to the powertrain 102 comprising a combustion engine 104, the vehicle 100 may include one or more electrical machines for driving drive wheels 114, 116, 118, 120 of the vehicle 100 and may thus for example be a so-called hybrid vehicle. The electrical machines may be provided with electric power from an electrical energy unit 168 (see figures 5 to 9), which for example may include an electric battery unit. However, instead of the powertrain 102 comprising a combustion engine 104, the vehicle 100 may include one or more electrical machines only for driving the drive wheels 114, 116, 118, 120 of the vehicle 100, whereby the vehicle 100 may be a pure electrical vehicle.

The combustion engine 104 is controlled by the engine's control system via a control device 112. Likewise, the clutch 110 and the gearbox 108 may be controlled by the engine's control system, with the help of one or more control devices (not shown). The control device 112 and/or another control device may thus be configured to control the combustion engine 104, the clutch 110, the gearbox 108, and/or any other units/devices/entities of the vehicle 100. However, in figure 1, only the units/devices/entities of the vehicle 100 useful for understanding the embodiments of the present invention are illustrated. lO lO Naturally, the powertrain 102 of the vehicle 100 may be of a different type, such as a type with a conventional automatic gearbox, a type with a hybrid driveline etc. As mentioned above, the powertrain 102 may include one or more electrical machines for driving the drive wheels 114, 116, 118, 120 of the vehicle 100, implementing a so- called hybrid drive. ln the shown embodiment, the vehicle 100 comprises four wheels 114, 116, 118, 120, but may have more wheels. The electrical machine may be arranged essentially anywhere, as long as torque is provided to one or more of the wheels 114, 116, 118, 120, for example adjacent to one or more of the wheels 114, 116, 118, 120, or along a propeller shaft 122 of the vehicle 100, for example between the gearbox 108 and the clutch 110, as is understood by a skilled person.

The vehicle 100 may comprise a propeller shaft 122 from the gearbox 108 which drives two of the wheels 114, 116 via a central gear 124, for example a conventional differential, and two drive shafts 126, 128 of the vehicle 100. The two drive shafts 126, 128 are connected to the central gear 124. The vehicle 100 may comprise a fuel tank 129 coupled to the combustion engine 104, and the combustion engine 104 may be provided with fuel from the fuel tank 129.

The vehicle 100 may comprise an exhaust gas after-treatment system 130, which also may be called an exhaust gas purification system, for treatment/purification of the exhaust gas/emissions resulting from the combustion in the combustion chamber of the combustion engine 104. The exhaust gas after-treatment system 130 may be controlled by an exhaust gas after-treatment control device 132, which may communicate with the control device 112 or another device of the engine's control system.

Further, the vehicle 100 includes a safety critical system 134, which in general is at least partly electrical, i.e. in general an at least partly electrical safety critical system 134. The safety critical system 134 is critical to the control or operation of the vehicle 100. lf the safety critical system 134 is not active when driving the vehicle 100 or when the vehicle 100 moves, the safety of vehicle 100 and of the surroundings is at risk. The safety critical system 134 may comprises one or more of the group of: a steering including electric steering (ES) and an electronic brake system (EBS). Other safety lO ll critical systems 134 are possible. The steering may be an electrohydraulic steering (EHS) or an electrohydraulic power steering (EHPS). However, in some embodiments, the steering including electric steering (ES) may exclude a hydraulic steering. The safety critical system 134 may include one or more additional systems or be indirectly or directly connected to one or more auxiliary safety critical systems, for example related to autonomous or self-driving vehicles, and/or systems supporting the ES, EBS, EHS and/or EHPS.

The vehicle 100 includes an ignition system 136. The ignition system 136 may include an ignition switch 138, which may be configured to be operated by an operator, user or driver. ln some vehicle the ignition switch 138 is associated with or may comprise a push button, a key switch or any other suitable switch. ln general, the ignition system 136 is configured to activate the main systems of vehicle 100 and possibly also accessories, such as radio, powered windows etc. ln a vehicle 100 powered by a combustion engine 104, the ignition system 136 may be configured to provide or control electric power to the starter solenoid and the engine ignition systems, such as the engine control device 112 and the ignition coil. The ignition system 136 is configured to be in an ignition state. ln the shown embodiment, the ignition state of the ignition system 136 is on when the ignition switch 138 is turned on. ln the shown embodiment, the ignition state of the ignition system 136 is off when the ignition switch 138 is turned off or when the ignition system experiences an ignition system failure. Thus, the ignition system 136 may be configured such that the ignition state of the ignition system 136 is on when the ignition switch 138 is turned on, and the ignition system 136 may be configured such that the ignition state of the ignition system 136 is off when the ignition switch 138 is turned off or when the ignition system 136 experiences an ignition system failure. ln general, ignition system failures are unusual. Thus, in unusual situations, the ignition state of the ignition system 136 may be off when the ignition system 136 experiences an ignition system failure, even if the ignition switch 138 is turned on.

Further, the vehicle 100 includes a primary electrical energy source 140 for providing electric power to the safety critical system 134 when the ignition state of the ignition system 136 is off. "Primary electrical energy source" in the context of the disclosure of lO 12 the present application means that the primary electrical energy source 140 in question is the main electrical energy source 140 that provides electric power to the safety critical system 134 when the ignition state of the ignition system 136 is off, for example when the vehicle 100 is parked. The primary electrical energy source 140 may comprise one or more electrical energy modules or units. The vehicle 100 also includes a secondary electrical energy source 142. The secondary electrical energy source 140 may comprise one or more electrical energy modules or units. The secondary electrical energy source 140 is disclosed in further detail hereinbelow.

The vehicle 100 also includes a control arrangement 150 for assisting the vehicle 100. The control arrangement 150 may be configured to provide electric power to the safety critical system 134 of the vehicle 100 or to control the electric power provision or supply to the safety critical system 134 of vehicle 100. More specifically, the control arrangement 150 is configured to provide electric power from the secondary electrical energy source 142 of the vehicle 100 to the safety critical system 134 while providing electric power from the primary electrical energy source 140 to the safety critical system 134 when the ignition state ofthe ignition system 136 is off and a current vehicle speed of the vehicle 100 is above a first threshold. Thus, the control arrangement 150 may be configured to provide electric power at the same time from both the primary electrical energy source 140 and the secondary electrical energy source 142 to the safety critical system 134 when the ignition state of the ignition system 136 is off and a current vehicle speed of the vehicle 100 is above the first threshold. The control arrangement 150 is disclosed in further detail herein below. Further, the control arrangement 150 may be configured to interrupt the provision of electric power from the secondary electrical energy source 142 to the safety critical system 134 when the ignition state of the ignition system 136 is off and the current speed of the vehicle 100 is below a second threshold.

With reference to figures 2 to 4, a first embodiment of the method according to the first aspect is schematically illustrated. Further, aspects of the vehicle 100 and the control arrangement 150 are also schematically illustrated. More specifically, the electric power supply to the safety critical system 134 according to the first embodiment of the method is illustrated in figures 2 to 4. With reference to figure 2, the vehicle 100 lO 13 includes a safety critical system 134 which may be any one of the safety critical systems mentioned above. The vehicle 100 includes a primary electrical energy source 140 for providing electric power to the safety critical system 134 when the ignition state of the ignition system 136 is off. The primary electrical energy source 140 may include a third electric battery unit 160, which may be called a power battery unit (or service battery unit) and may be a 24 V battery unit, for example for tractors and buses, or a 12 V battery unit, for example for cars. Other voltage levels are possible.

With reference to figure 2, the vehicle 100 includes a secondary electrical energy source 142, which in the shown embodiment includes a first electric battery unit 162 electrically connectable to the safety critical system 134 via a first switch 164. The first switch 164 is switchable between an open state and a closed state. The first electric battery unit 162 may be a 24 V battery unit, for example for tractors and buses, or a 12 V battery unit, for example for cars. Other voltage levels are possible. For example, the control arrangement 150 may be configured to control the first switch 164, for example via a printed circuit board, PCB. ln the shown embodiment, the first electric battery unit 162 is an electric starting battery unit for starting the engine 104 of the vehicle 100, for example when the switch 164 is closed upon activation of the starter motor of the vehicle 100. More specifically, in the shown embodiment, the first electric battery unit 162 is electrically connected in parallel with the third electric battery unit 160. lt may be defined that the first switch 164, or breaker, is situated between the first electric battery unit 162 and one pole of the third electric battery unit 160, which makes it possible to disconnect the first electric battery unit 162 from the safety critical system 134, for example when the engine 104 of the vehicle 100 is switched off.

With reference to figure 2, in the shown embodiment, when the ignition state of the ignition system 136 is on, and the vehicle 100 and/or engine 104 is running, electric power is provided from/via the unit 166 to the safety critical system 134 as indicated by the arrows in figure 2. lf the vehicle 100 is a hybrid vehicle, the unit 166 may be an electric generator (or alternator) or a DC-to-DC converter. lf the vehicle 100 includes a combustion engine 104 only and no electrical machines for driving the drive wheels, the unit 166 is an electric generator only. lO 14 With reference to figure 3, when the ignition state of the ignition system 136 is off, electric power is provided from the primary electrical energy source 140 to the safety critical system 134, as indicated by the arrows in figure 3. However, the electric power provided from the primary electrical energy source 140 to the safety critical system 134 may not be sufficient for the safety critical system 134 to operate properly. This may not be critical if the vehicle 100 stands still. However, if the ignition switch 138 is turned off by mistake and thus forces the ignition state ofthe ignition system 136 to be off, or if the ignition state of the ignition system 136 is off because of an ignition system failure, and the vehicle 100 is still moving, safety is put at risk.

With reference to figure 4, the above-mentioned risk situation is addressed by the first embodiment of the method by controlling and closing the first switch 164 and providing electric power from the secondary electrical energy source 142 of the vehicle 100 to the safety critical system 134 while providing electric power from the primary electrical energy source 140 to the safety critical system 134, as indicated by the arrows in figure 4, when the ignition state of the ignition system 136 is off and a current vehicle speed of the vehicle 100 is above a first threshold. Thus, according to the first embodiment of the method, electric power is provided from both the primary electrical energy source 140 and the secondary electrical energy source 142 to the safety critical system 134 at the same time when the ignition state of the ignition system 136 is off and the current vehicle speed of the vehicle 100 is above the first threshold, whereby sufficient electric power to the safety critical system 134 for proper operation of the safety critical system 134 when the vehicle 100 moves is assured or at least made more certain.

With reference to figures 5 to 7, a second embodiment of the method according to the first aspect is schematically illustrated. Further, aspects of the vehicle 100 and the control arrangement 150 are also schematically illustrated. More specifically, the electric power supply to the safety critical system 134 according to the second embodiment of the method is illustrated in figures 5 to 7. With reference to figure 5, the vehicle 100 includes a safety critical system 134 which may be any one of the safety critical systems mentioned above. The vehicle 100 includes a primary electrical energy source 140 for providing electric power to the safety critical system 134 when the ignition state of the ignition system 136 is off. As mentioned above, the primary lO electrical energy source 140 may include the third electric battery unit 160, which may be called a power battery unit (or service battery unit) and may, for example, be a 12 V or a 24 V battery unit.

With reference to figure 5, the vehicle 100 includes a secondary electrical energy source 142, which in the shown embodiment includes an electrical energy unit 168 electrically connectable to the safety critical system 134 via a DC-to-DC converter 170 (or DC/DC converter). The electrical energy unit 168 comprises one or more of the group of: a second electric battery unit and fuel cell unit. The second electric battery unit may include one or more lithium-ion (or Li-ion) batteries, but other electric batteries are possible. The second electric battery unit may be a high voltage battery unit. The fuel cell may include one or more fuel cells. Fuel cells are known to the skilled person and thus not discussed in further detail. The electrical energy unit 168 of the secondary electrical energy source 142 may be the main electrical energy source for driving the drive wheels 114, 116, 118, 120 of the vehicle 100. The vehicle 100 illustrated in figures 5 to 7 may be a pure electric vehicle including only electrical machines for driving the drive wheels 114, 116, 118, 120 of the vehicle 100. Then, only the electrical energy unit 168 is provided. The vehicle 100 illustrated in figures 5 to 7 may be a hybrid vehicle including both the electrical energy unit 168 and a combustion engine 104.

With reference to figure 5, the DC-to-DC converter 170 is configured to be in an active state or an inactive state. ln the active state, the DC-to-DC converter 170 is configured to convert direct current, which originates from the electrical energy unit 168, from a first voltage level to a second voltage level. Thus, the DC-to-DC converter 170 has a high voltage side 172 and a low voltage side 174. For a tractor or bus, the DC-to-DC converter 170 may be configured to convert direct current from 650 V to 24 V. For a car, the DC-to-DC converter 170 may be configured to convert direct current from 400 V to 12 V. Other voltage levels are possible. The electrical energy unit 168 may be indirectly connected to the high voltage side 172 of the DC-to-DC converter 170 via a junction box 176 or directly electrically connected to the high voltage side 172 of the DC-to-DC converter 170. Thus, it is to be understood that the junction box 176 in alternative embodiments may be excluded. Further, the electrical energy unit 168 may be electrically connected to the high voltage side 172 of the DC-to-DC converter 170 lO 16 via one or more second switches 177. Each second switch 177 is switchable between an open state and a closed state.

With reference to figure 5, a battery management unit (BMU) 178 may be provided. The battery management unit 178 may be directly or indirectly connected to one or more of the electrical energy unit 168, the DC-to-DC converter 170 and the second switch 177. The battery management unit 178 may be configured to communicate with or to control one or more of the electrical energy unit 168, the DC-to-DC converter 170 and the second switch 177. For example, the control arrangement 150 may be directly or indirectly connected to one or more of the DC-to-DC converter 170, the battery management unit 178 and one or more auxiliary safety critical system 180 of the vehicle 100. The control arrangement 150 may be directly connected to the electrical energy unit 168 (see figure 5) or indirectly connected to the electrical energy unit 168 via the battery management unit 178. The control arrangement 150 may be configured to communicate with or to control the electrical energy unit 168 directly (see figure 5) or via the battery management unit 178. The control arrangement 150 may be configured to communicate with or to control the DC-to-DC converter 170. The auxiliary safety critical system 180 may be a system, for example at least party electrical, which supports the safety critical system 134. The control arrangement 150 may be configured to communicate with or to control the auxiliary safety critical system 180.

With reference to figure 5, in the shown embodiment, when the ignition state of the ignition system 136 is on, and the vehicle 100 and/or engine 104 is running, electric power is provided from the electrical energy unit 168 to the safety critical system 134 via the active DC-to-DC converter 170, as indicated by the arrows in figure 5. lf needed, for example in overload situations, when the ignition state of the ignition system 136 is on, electric power may be provided from both the electrical energy unit 168 and the primary electrical energy source 140, as indicated by the arrows in figure 5.

With reference to figure 6, when the ignition state of the ignition system 136 is off, electric power is provided from the primary electrical energy source 140 to the safety critical system 134, as indicated by the arrows in figure 6, while the DC-to-DC converter 170 is inactive, whereby no electric power is provided from the electrical energy unit lO 17 168 to the safety critical system 134. However, the electric power provided from the primary electrical energy source 140 to the safety critical system 134 may not be sufficient for the safety critical system 134 to operate properly. This may not be critical 100 if the vehicle stands still. However, if the ignition switch 138 is turned off by mistake and thus forces the ignition state of the ignition system 136 to be off, or if the ignition state of the ignition system 136 is off because of an ignition system failure, and the vehicle 100 is still moving, safety is put at risk.

With reference to figure 7, the above-mentioned risk situation is addressed by the second embodiment of the method by controlling the DC-to-DC converter 170, more specifically by activating the DC-to-DC converter 170, i.e. switching the DC-to-DC converter 170 to its active state, to provide electric power from the secondary electrical energy source 142, in the shown embodiment from the electrical energy unit 168, to the safety critical system 134 while providing electric power from the primary electrical energy source 140 to the safety critical system 134, as indicated by the arrows in figure 7, when the ignition state of the ignition system 136 is off and the current vehicle speed of the vehicle 100 is above the first threshold. Thus, according to the second embodiment of the method, electric power is provided from both the primary electrical energy source 140 and the secondary electrical energy source 142 to the safety critical system 134 at the same time when the ignition state of the ignition system 136 is off and the current vehicle speed of the vehicle 100 is above the first threshold, whereby sufficient electric power to the safety critical system 134 for the safety critical system 134 to operate properly when the vehicle move is assured or at least made more certain.

When activating the DC-to-DC converter 170 to provide electric power from the secondary electrical energy source 142 to the safety critical system 134 when the ignition state of the ignition system 136 is off and the current vehicle speed of the vehicle 100 is above the first threshold, the control arrangement 150 may be configured to communicate with, for example to send a wake-up signal to, the auxiliary safety critical system 180 for supporting the safety critical system 134. When the ignition state of the ignition system 136 is off and the current vehicle speed of the vehicle 100 is above the first threshold, also the auxiliary safety critical system 180 may be provided lO 18 with electric power from the primary electrical energy source 140 and/or the secondary electrical energy source 142.

With reference to figures 8 and 9, a third embodiment of the method according to the first aspect is schematically illustrated. Further, aspects of the vehicle 100 and the control arrangement 150 are also schematically illustrated. More specifically, the electric power supply to the safety critical system 134 according to the third embodiment of the method is illustrated in figures 8 and 9. The third embodiment essentially corresponds to the second embodiment, and therefore the common features are not described in detail again for the third embodiment.

The additional feature of the third embodiment of figures 8 and 9 in relation to the second embodiment of figures 5 to 7 is that the secondary electrical energy source 142 also includes a first electric battery unit 162 disclosed in connection with figures 2 to 4. When the ignition state of the ignition system 136 is off and the current vehicle speed of the vehicle 100 is above the first threshold, the DC-to-DC converter 170 can be activated, for example by the control arrangement 150, while the first switch 164 can be closed, whereby electric power can be provided from both the electrical energy unit 168 and from the first electric battery unit 162 to the safety critical system 134 while providing electric power from the primary electrical energy source 140 to the safety critical system 134, as indicated by the arrows in figure 9, when the ignition state of the ignition system 136 is off and the current vehicle speed of the vehicle 100 is above the first threshold. Thus, according to the third embodiment of the method, electric power is provided from both the primary electrical energy source 140 and the secondary electrical energy source 142, which includes the electrical energy unit 168 and from the first electric battery unit 162, to the safety critical system 134 at the same time when the ignition state of the ignition system 136 is off and the current vehicle speed of the vehicle 100 is above the first threshold, whereby sufficient electric power to the safety critical system 134 is made more certain.

With reference to figure 8, in some embodiments, the control arrangement 150 may be configured to check if the electric power from the electrical energy unit 168, via the DC- to-DC converter 170, and from the primary electrical energy source 140 to the safety lO 19 critical system 134, as indicated by the arrows in figure 8, is sufficient before closing the first switch 164, i.e. before providing electric power from the first electric battery unit 162 to the safety critical system 134. Thus, if the electric power from the electrical energy unit 168, via the DC-to-DC converter 170, and the primary electrical energy source 140 to the safety critical system 134 is sufficient, the first switch 164 is kept open, as indicated in figure 8. lf the electric power from the electrical energy unit 168, via the DC-to-DC converter 170, and from the primary electrical energy source 140 to the safety critical system 134 is insufficient, the first switch 164 is closed, as indicated in figure 9, whereby electric power is also provided from the first electric battery unit 162 to the safety critical system 134.

With reference to the embodiments shown above, the secondary electrical energy source 142 may be an electrical energy source already present in the vehicle 100 and used for the general operation of the vehicle 100. However, an additional electrical energy source may be added to the vehicle and form the secondary electrical energy source, wherein the additional electrical energy source is not used in the vehicle for other operation purposes.

Each of the first electric battery unit 162, second electric battery unit and the third electric battery unit 160 mentioned above or below may comprise one or more electric batteries interconnected, for example connected in series, to one another in various manners known to the skilled person.

The first embodiment of the method for assisting a vehicle 100 is further illustrated by reference to the schematic flow chart in figure 10. The method according to the first embodiment comprises: o determining 201 the ignition state of the ignition system 136; o if the ignition state of the ignition system is off, obtaining or determining 202 the current vehicle speed of the vehicle 100. For example, the vehicle 100 may be standing still, for example being parked, and then starting to move because of mistakes made by the driver or because of technical failures in the parking brake system. The vehicle 100 may for example be standing still in a downhill slope lO before moving. Alternatively, the vehicle 100 may be moving, and then the ignition state of the ignition system 136 is switched off, for example because of mistakes made by the driver, for example by turning off the ignition switch 138 by mistake, or because of technical failures, for example failures in the ignition system; comparing 203 the obtained or determined current vehicle speed with the first threshold. For example, the first threshold may be 5 km/h. However, other values of the first threshold are possible; if the current vehicle speed is above the first threshold, controlling 204 the first switch 164, for example closing 204 the first switch 164 and keeping the first switch 164 closed, and thus providing 205 electric power from the secondary electrical energy source 142 (the first electric battery unit 162 in the embodiment shown in figures 2 to 4) of the vehicle 100 to the safety critical system 134 while providing electric power from the primary electrical energy source 140 to the safety critical system 134 when the ignition state of the ignition system 136 is off and the current vehicle speed of the vehicle 100 is above the first threshold; determining 206 the ignition state of the ignition system 136; if the ignition state of the ignition system is off, obtaining or determining 207 the current vehicle speed of the vehicle 100; comparing 208 the obtained or determined current vehicle speed with the second threshold. For example, the second threshold may be 4 km/h. However, other values of the second threshold are possible; and if the current vehicle speed is below the second threshold, interrupting 209 the provision of electric power from the secondary electrical energy source 142 (the first electric battery unit 162 in the embodiment shown in figures 2 to 4) to the safety critical system 134 by controlling the first switch, for example opening the first switch 164 and keeping the first switch 164 open.

With reference to figure 11, the second embodiment of the method for assisting a vehicle 100 is further illustrated by way of a schematic flow chart. The method according to the second embodiment comprises: o determining 301 the ignition state of the ignition system 136; lO 21 if the ignition state of the ignition system is off, obtaining or determining 302 the current vehicle speed of the vehicle 100; comparing 303 the obtained or determined current vehicle speed with the first threshold; if the current vehicle speed of is above the first threshold, controlling 304 the DC-to-DC converter 170, for example activating 304 the DC-to-DC converter 170 and keeping the DC-to-DC converter 170 in the active state, and thus providing 305 electric power from the secondary electrical energy source 142 (the electrical energy unit 168 in the embodiment shown in figures 5 to 7) of the vehicle 100 to the safety critical system 134 while providing electric power from the primary electrical energy source 140 to the safety critical system 134 when the ignition state of the ignition system 136 is off and the current vehicle speed of the vehicle 100 is above the first threshold; determining 306 the ignition state of the ignition system 136; if the ignition state of the ignition system is off, obtaining or determining 307 the current vehicle speed of the vehicle 100; comparing 308 the obtained or determined current vehicle speed with the second threshold; and if the current vehicle speed of is below the second threshold, interrupting 309 the provision of electric power from the secondary electrical energy source 142 (the electrical energy unit 168 in the embodiment shown in figures 5 to 7) to the safety critical system 134 by controlling the DC-to-DC converter 170, for example inactivating the DC-to-DC converter 170 and keeping the DC-to-DC converter 170 in the inactive state, With reference to figure 12, the third embodiment of the method is further illustrated by way of a schematic flow chart. The method according to the third embodiment comprises: o determining 401 the ignition state of the ignition system 136; o if the ignition state of the ignition system is off, obtaining or determining 402 the current vehicle speed of the vehicle 100; lO 22 comparing 403 the obtained or determined current vehicle speed with the first threshold; if the current vehicle speed of is above the first threshold, controlling 404 the DC-to-DC converter 170, for example activating 404 the DC-to-DC converter 170 and keeping the DC-to-DC converter 170 in the active state, and thus providing 405 electric power from the secondary electrical energy source 142 (the electrical energy unit 168 in the embodiment shown in figures 8 to 9) of the vehicle 100 to the safety critical system 134 while providing electric power from the primary electrical energy source 140 to the safety critical system 134 when the ignition state of the ignition system 136 is off and the current vehicle speed of the vehicle 100 is above the first threshold; checking 406 if the electric power from the electrical energy unit 168, via the DC-to-DC converter 170, and from the primary electrical energy source 140 to the safety critical system 134 is sufficient; if the electric power from the electrical energy unit 168, via the DC-to-DC converter 170, and from the primary electrical energy source 140 is sufficient, keeping 407 the first switch 164 open; if the electric power from the electrical energy unit 168, via the DC-to-DC converter 170, and the primary electrical energy source 140 is insufficient, controlling 408 the first switch 164 by closing 408 the first switch 164, and thus providing 409 electric power from the first electric battery unit 162 to the safety critical system 134 while providing electric power from the electrical energy unit 168 and the primary electrical energy source 140 to the safety critical system 134 when the ignition state of the ignition system 136 is off and the current vehicle speed of the vehicle 100 is above the first threshold; determining 410 the ignition state of the ignition system 136; if the ignition state of the ignition system is off, obtaining or determining 411 the current vehicle speed of the vehicle 100; comparing 412 the obtained or determined current vehicle speed with the second threshold; and if the current vehicle speed of is below the second threshold, interrupting 413 the provision of electric power from the secondary electrical energy source 142 lO 23 (the electrical energy unit 168, and possibly the first electric battery unit 162 in the shown embodiment in figures 8 and 9) to the safety critical system 134 by controlling the DC-to-DC converter 170, for example inactivating the DC-to-DC converter 170 and keeping the DC-to-DC converter 170 in the inactive state and possibly by controlling the first switch, for example opening the first switch 164 and keeping the first switch 164 open.

The embodiments of the method according to the first aspect may also be called a method for providing electric power to a safety critical system 134 of a vehicle 100 or a method for controlling the electric power provision or supply to a safety critical system 134 of a vehicle 100.

One or more of the first threshold and the second threshold mentioned above or below may be a predetermined threshold. Thus, the above- or below-mentioned first threshold may be a predetermined first threshold, and the above- or below-mentioned second threshold may be a predetermined second threshold.

Unless disclosed otherwise, it should be noted that the method steps illustrated in figures 10 to 12 and described herein do not necessarily have to be executed in the order illustrated in figures 10 to 12. The steps may essentially be executed in any suitable order. Further, one or more steps may be excluded or added without departing from the scope of the appended claims. For example, in some embodiments, the step of obtaining or determining 202, 302, 403 the current vehicle speed of the vehicle 100 and the step of comparing 203, 303, 403 the obtained or determined current vehicle speed with the first threshold may be performed before the step of determining 201, 301, 401 the ignition state of the ignition system 136. For example, by means of this embodiment, the DC-to-DC converter 170 may remain active (without being turned off and then turned on again) when the ignition state of the ignition system 136 is switched to off. Further, in some embodiments, the step of obtaining or determining 207, 307, 411 the current vehicle speed of the vehicle 100 and the step of comparing 208, 308, 412 the obtained or determined current vehicle speed with the second threshold may be performed before the step of determining 206, 306, 410 the ignition state of the ignition system 136. The step of obtaining or determining 202, 302, 403 the current lO 24 vehicle speed of the vehicle 100 and the step of comparing 203, 303, 403 the obtained or determined current vehicle speed with the first threshold may be performed continuously.

With reference to figure 1, the shown control arrangement 150 may include an ignition state determining unit 152 for determining the ignition state of the ignition system 136 to perform the determining steps 201, 206, 301, 306, 401, 410 in figures 10 to 12. The ignition state determining unit 152 may be directly or indirectly connected to the ignition system 136 and may be configured to directly or indirectly communicate with the ignition system 136.

The shown control arrangement 150 may include a vehicle speed unit 154 for obtaining or determining the current vehicle speed of the vehicle 100 to perform the steps 202, 207, 302, 307, 402, 411 in figures 10 to 12. The vehicle speed unit 154 may be directly or indirectly connected to a vehicle speed sensor 144 of the vehicle 100 (see figure 1) and configured to directly or indirectly communicate with the speed sensor 144 to obtain the current vehicle speed. Alternatively, the vehicle speed unit 154 per se may be configured to determine the current vehicle speed, for example by including a vehicle speed sensor.

The shown control arrangement 150 may include a comparison unit 156 for comparing the obtained or determined current vehicle speed of the vehicle 100 with the first threshold to perform the comparison steps 203, 303, 403 in figures 10 to 12. The comparison unit 156 may also be configured to compare the obtained or determined current vehicle speed of the vehicle 100 with the second threshold to perform the comparison steps 208, 308, 412 in figures 10 to 12. The comparison unit 156 may be directly or indirectly connected to the vehicle speed unit 154 and may be configured to directly or indirectly communicate with the vehicle speed unit 154.

The shown control arrangement 150 may include an interruption unit 158 for interrupting or blocking the provision of electric power from the secondary electrical energy source 142 to the safety critical system 134 when the ignition state of the ignition system 136 is off and the current speed of the vehicle 100 is below the second lO threshold to perform the interruption steps 209, 309, 413 in figures 10 to 12. The interruption unit 158 may be directly or indirectly connected to the comparison unit 156 and may be configured to directly or indirectly communicate with the comparison unit 156. The interruption unit 158 may be directly or indirectly connected to the secondary electrical energy source 142, and possibly also to the primary electrical energy source 140.

The control arrangement 150 may be directly or indirectly connected to and communicate with the engine's control system, for example the control device 112.

Figure 13 shows in schematic representation a control arrangement 150, which may include a control unit 500, which may correspond to or may include one or more of the above-mentioned units 152, 154, 156, 158 of the control arrangement 150. The control unit 500 may comprise a computing unit 501, which can be constituted by essentially any suitable type of processor or microcomputer, for example a circuit for digital signal processing (Digital Signal Processor, DSP), or a circuit having a predetermined specific function (Application Specific Integrated Circuit, ASIC). The computing unit 501 is connected to a memory unit 502 arranged in the control unit 500. The memory unit 502 provides the computing unit 501 with, for example, the stored program code and/or the stored data which the computing unit 501 requires to be able to perform computations. The computing unit 501 is also arranged to store partial or final results of computations in the memory unit 502. ln addition, the control unit 500 may be provided with devices 511, 512, 513, 514 for receiving and transmitting input and output signals. These input and output signals can contain waveforms, impulses, or other attributes which, by means of the devices 511, 513 for the reception of input signals, can be detected as information and can be converted into signals which can be processed by the computing unit 501. These signals are then made available to the computing unit 501. The devices 512, 514 for the transmission of output signals are arranged to convert signals received from the computing unit 501 in order to create output signals by, for example, modulating the signals, which can be transmitted to other parts of and/or systems in the vehicle 100. lO 26 Each of the connections to the devices for receiving and transmitting input and output signals can be constituted by one or more of a cable; a data bus, such as a CAN bus (Controller Area Network bus), a MOST bus (Media Orientated Systems Transport bus), or some other bus configuration; or by a wireless connection.

Control systems in modern vehicles commonly comprise communication bus systems consisting of one or more communication buses for linking a plurality of electronic control units (ECU's), or controllers, and various components located on the vehicle. Such a control system can comprise a large number of control units and/or control arrangements and the responsibility for a specific function can be divided amongst more than one control unit. Vehicles of the shown type thus often comprise significantly more control units or control arrangements than are shown in figure 1, which is well known to the person skilled in the art within this technical field. Alternatively or in addition thereto, the embodiments of the present invention may be implemented wholly or partially in one or more other control units already present in the vehicle.

Here and in this document, units are often described as being provided for performing steps of the method according to embodiments of the invention. This also includes that the units are designed to and/or configured to perform these method steps.

The units 152, 154, 156, 158 of the control arrangement 150 are in figure 1 illustrated as separate units. These units 152, 154, 156, 158 may, however, be logically separated but physically implemented in the same unit, or can be both logically and physically arranged together. These units 152, 154, 156, 158 may for example correspond to groups of instructions, which can be in the form of programming code, that are input into, and are utilized by a processor/computing unit 501 (see figure 13) when the units are active and/or are utilized for performing its method step.

The control arrangement 150, which may include one or more control units 500, e.g. a device or a control device, according to embodiments of the present invention may be arranged to perform all of the method steps mentioned above, in the claims, and in connection with the herein described embodiments. The control arrangement 150 is associated with the above described advantages for each respective embodiment. lO 27 According to the second aspect of the invention, a computer program 503 (see figure 13) is provided, comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method according to one or more of the embodiments disc|osed above.

According to the third aspect of the invention, a computer-readable medium is provided, comprising instructions which, when the instructions are executed by a computer, cause the computer to carry out the method according to one or more of the embodiments disc|osed above.

The person skilled in the art will appreciate that a the herein described embodiments of the method according to the first aspect may be implemented in a computer program, which, when it is executed in a computer, instructs the computer to execute the method. The computer program is usually constituted by a computer program product 403 stored on a non-transitory/non-volatile digital storage medium, in which the computer program is incorporated in the computer-readable medium of the computer program product. The computer-readable medium comprises a suitable memory, such as, for example: ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), Flash memory, EEPROM (Electrically Erasable PROM), a hard disk unit, etc.

The present invention is not limited to the above described embodiments. lnstead, the present invention relates to, and encompasses all different embodiments being included within the scope of the independent claims.

Claims

1. A method for assisting a vehicle (100), the vehicle (100) comprising a safety critical system (134), an ignition system (136) configured to be in an ignition state, wherein the ignition state of the ignition system (136) is on or off, and a primary electrical energy source (140) for providing electric power to the safety critical system (134) when the ignition state of the ignition system (136) is off, wherein the method comprises: o providing (205; 305; 405, 409) electric powerfrom a secondary electrical energy source (142) of the vehicle (100) to the safety critical system (134) while providing electric power from the primary electrical energy source (140) to the safety critical system (134) when the ignition state of the ignition system (136) is off and a current vehicle speed of the vehicle (100) is above a first threshold.

2. A method according to claim 1, wherein the method comprises determining (201, 206; 301, 306; 401, 410) the ignition state of the ignition system (136).

3. A method according to claim 1 or 2, wherein the method comprises obtaining or determining (202, 207; 302, 307; 402, 411) the current vehicle speed of the vehicle (100).

4. A method according to any one of the claims 1 to 3, wherein the method comprises comparing (203; 303; 403) the obtained or determined current vehicle speed of the vehicle (100) with the first threshold.

5. A method according to any one of the claims 1 to 4, wherein the method comprises interrupting (209; 309; 409) the provision of electric power from the secondary electrical energy source (142) to the safety critical system (134) when the ignition state of the ignition system (136) is off and the current speed of the vehicle (100) is below a second threshold. lO

6. A method according to claim 5, wherein the method comprises comparing (208; 308; 412) the obtained or determined current vehicle speed of the vehicle (100) with the second threshold.

7. A method according to any one of the claims 1 to 6, wherein the step of providing electric power (205; 305; 405, 409) of the method comprises providing electric power to the safety critical system (134) which comprises one or more of the group of: o a steering including electric steering; and o an electronic brake system.

8. A method according to any one of the claims 1 to 7, wherein the secondary electrical energy source (142) comprises a first electric battery unit (162) electrically connectable to the safety critical system (134) via a first switch (164), the first switch (164) being switchable between an open state and a closed state, and wherein the method comprises controlling (204; 408) the first switch (164) to provide electric power from the secondary electrical energy source (142) to the safety critical system (134) when the ignition state of the ignition system (136) is off and the current vehicle speed of the vehicle (100) is above the first threshold.

9. A method according to any one of the claims 1 to 8, wherein the secondary electrical energy source (142) comprises an electrical energy unit (168) electrically connectable to the safety critical system (134) via a DC-to-DC converter (170), wherein the DC-to-DC converter (170) is configured to be in an active state or an inactive state, wherein in the active state the DC-to-DC converter (170) is configured to convert direct current from a first voltage level to a second voltage level, wherein the method comprises controlling (304; 404) the DC-to-DC converter (170) to provide electric power from the secondary electrical energy source (142) to the safety critical system (134) when the ignition state of the ignition system (136) is off and the current vehicle speed of the vehicle (100) is above the first threshold, and wherein the electrical energy unit (168) comprises one or more of the group of: o a second electric battery unit; and lO o fuel cell unit.

10. A method according to any one of the claims 1 to 9, wherein the primary electrical energy source (140) comprises a third electric battery unit (160).

11. A method according to any one of the claims 1 to 10, wherein ignition system (136) comprises an ignition switch (138), wherein the ignition state of the ignition system (136) is on when the ignition switch (138) is turned on, and wherein the ignition state of the ignition system (136) is off when the ignition switch (138) is turned off or when the ignition system (136) experiences an ignition system failure.

12. A computer program (503) comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method according to any one of the claims1 to

13. A computer-readable medium comprising instructions which, when the instructions are executed by a computer, cause the computer to carry out the method according to any one of the claims 1 to

14. A control arrangement (150) for assisting a vehicle (100), the vehicle (100) comprising a safety critical system (134), an ignition system (136) configured to be in an ignition state, wherein the ignition state of the ignition system (136) is on or off, and a primary electrical energy source (140) for providing electric power to the safety critical system (134) when the ignition state of the ignition system (136) is off, wherein the control arrangement (150) is configured to: provide electric power from a secondary electrical energy source (142) of the vehicle (100) to the safety critical system (134) while providing electric power from the primary electrical energy source (140) to the safety critical system (134) when the ignition state of the ignition system (136) is off and a current vehicle speed of the vehicle (100) is above a first threshold. lO

15. A vehicle (100) comprising a safety critical system (134), an ignition system (136) configured to be in an ignition state, wherein the ignition state of the ignition system (136) is on or off, a primary electrical energy source (140) for providing electric power to the safety critical system (134) when the ignition state of the ignition system (136) is off, and a secondary electrical energy source (142), and a control arrangement (150) as claimed in claim 14.