Method for operating a control unit for a parking brake system

Abstract

The invention relates to a method for operating a control unit (10) for a parking brake system having a parking brake and a first microcontroller and a second microcontroller (1a) for controlling the parking brake. According to the method, the first microcontroller and the second microcontroller (1a, 1b) are tested one after the other when the system is switched on. The rated operation of the system is started after the end of the test. For this purpose, the second microcontroller (1b) is activated for controlling the parking brake, and the first microcontroller (1a) is deactivated as redundancy. In the event of a failure in the second microcontroller (1b), a transition from a setpoint operation into an unsetpoint operation in which the first microcontroller (1a) assumes the control function of the second microcontroller (1b) is made. During the nominal operation, operation-related data is transmitted from the second microcontroller (1b) to the first microcontroller (1a), such that the operation-related data can be used by the first microcontroller (1a) in the event of a fault.

Description

Technical Field

[0001] The invention relates to a method for operating a control unit for a parking brake system. The invention further relates to a computer program product designed to implement the method. The invention also relates to a control unit that is set up or programmed to carry out the method or the computer program product. Finally, the invention relates to a parking brake system having such a control unit. Background Art

[0002] Motor vehicles typically have at least one parking brake, with which the rolling of the motor vehicle can be prevented. For this purpose, the parking brake, also known as parking brake, can be adjusted between a position in which the parking brake locks at least one wheel of the motor vehicle and another position in which the parking brake releases the lock. In order to adjust and thus actuate the parking brake, the motor vehicle usually has a control unit.

[0003] In the event of a fault or failure of the controller, it is desirable that the parking brake can still be actuated. It is conceivable to configure such a controller redundantly. Parking brake systems are therefore known, which include a controller with two microcontrollers for controlling the parking brake. This ensures that in the event of a single fault in one of the two microcontrollers, the parking brake can still be actuated by the other microcontroller.

[0004] Such a system is described, for example, in DE 10 2017 222 484 A1.

[0005] It has proven to be problematic that the two microcontrollers cooperate with one another in nominal operation in such a way that, in the event of a fault in the active microcontroller, the previously inactive microcontroller can assume the functions of the active microcontroller. For this purpose, the necessary and constantly required data balancing of the considerable amounts of data between the two microcontrollers in nominal operation has proven to be very complex in practice and can also limit the effective power of the controller having two microcontrollers to a not insignificant degree in nominal operation, i.e., fault-free operation. Summary of the invention

[0006] It is therefore the object of the present invention to provide an improved method for operating a control unit having two microcontrollers for a parking brake system which solves the aforementioned problems.

[0007] This object is achieved by the subject matter of the independent claims. Preferred embodiments are the subject matter of the dependent claims.

[0008] The basic idea of ​​the invention is therefore that in the nominal operating state of the control unit, only those data that are actually relevant to the operation and are therefore necessary for a seamless switchover from the nominal active microcontroller to the previously inactive redundant microcontroller in the event of a fault are continuously balanced between the two microcontrollers, i.e. between the active and the inactive but redundant microcontroller. In contrast, less operationally relevant or even operationally irrelevant data are balanced only when the control unit or the parking brake system using the control unit is switched on, i.e. started, and optionally after the end of operation, i.e. when the control unit or the parking brake system is switched off. In this way, the data load during the data exchange between the two microcontrollers in the nominal operation of the control unit can be significantly reduced without adversely affecting or even preventing a smooth transfer of control from the microcontroller that was active before the fault occurred to the previously redundant, inactive microcontroller.

[0009] The method according to the present invention is used to operate a controller for a parking brake system, which has a parking brake, a first microcontroller and a second microcontroller, a first electronic circuit arrangement structure and a second electronic circuit arrangement structure, and a first H-bridge and a second H-bridge for controlling the parking brake. According to the method, the first microcontroller and the second microcontroller are tested one after another when the system is switched on. After the test is completed, the rated operation of the system is started. For this purpose, the second microcontroller is activated for controlling the parking brake, and the first microcontroller is deactivated as a redundancy, so that the first microcontroller does not operate the servomotor. When a fault occurs in the second microcontroller, the rated operation is switched to the non-rated operation, in which the first microcontroller assumes the control function of the second microcontroller for controlling the parking brake. During the rated operation, the operation-related data are continuously transferred from the second microcontroller to the first microcontroller, so that the operation-related data can be used by the first microcontroller in the event of a fault. In this way, when the control is switched from the second microcontroller to the first microcontroller, other faults are suppressed. Ideally, such faults are completely avoided. The method according to the invention can be implemented as a computer program product in the control unit or in its two microcontrollers.

[0010] In a preferred embodiment of the method according to the invention, a switchover from nominal operation to non-nominal operation also occurs in the event of a fault in the second electronic circuit arrangement.

[0011] Expediently, in non-rated operation and in the event of a fault in the second electronic circuit arrangement, the first microcontroller also controls the first H-bridge and also the second H-bridge via the first electronic circuit arrangement of the controller.

[0012] Particularly preferably, in nominal operation the second microcontroller actuates the first H-bridge and also the second H-bridge via the second electronic circuit arrangement of the controller.

[0013] In a further preferred embodiment, the first microcontroller is tested before the second microcontroller is tested in terms of time. This means that after the controller is switched on or initialized, the second microcontroller provided for the rated operation undergoes a functional test second. In this respect, the first electronic circuit arrangement for controlling the two H-bridges cooperating with the first microcontroller, by means of which the servomotor of the parking brake is controlled in turn, can also undergo a functional test. Thereafter, the second microcontroller provided for the rated operation (which then controls the parking brake in the rated operation after the performed test) undergoes a functional test. Correspondingly, the second electronic circuit arrangement for controlling the two H-bridges cooperating with the second microcontroller, by means of which the servomotor of the parking brake is controlled, can undergo a functional test.

[0014] Particularly preferably, in rated operation, operation-independent data are not permanently or periodically transferred from the second microcontroller to the first microcontroller. In this way, overloading of the data connection between the two microcontrollers can be at least suppressed during operation. Such overloading is ideally completely avoided.

[0015] According to an advantageous development of the method according to the invention, after the operation is completed, data not relevant to the operation, i.e. data which are not transmitted between the two microcontrollers during the nominal operation, are transmitted from the second microcontroller for controlling the parking brake to the first microcontroller. In this way, it is ensured that the two microcontrollers are synchronized the next time the parking brake system is switched on.

[0016] Particularly preferably, in order to avoid data losses or synchronization problems during the shutdown process, operation-related data can also be transferred from the microcontroller controlling the parking brake to the other microcontroller after the operation has ended.

[0017] The invention further relates to a computer program product comprising instructions which can be read by a control unit, so that the control unit carries out the method according to the invention when executing the computer program product described above.

[0018] The present invention further relates to a controller for a parking brake system of a motor vehicle. The controller comprises a first H-bridge and a second H-bridge for optionally controlling a servomotor of the parking brake system, as well as a first electronic circuit arrangement for controlling the two H-bridges and a second electronic circuit arrangement for controlling the two H-bridges. In addition, the controller comprises a first microcontroller for controlling the first circuit arrangement and a second microcontroller for controlling the second circuit arrangement. The two microcontrollers are connected to each other in a data transmission or data transmission capable manner. According to the present invention, the controller is set up or programmed to execute the method according to the present invention described above, so that the advantages of the method according to the present invention explained above are transferred to the controller according to the present invention. The method according to the present invention can be implemented as a computer program product in the controller according to the present invention or in its two microcontrollers.

[0019] The invention further relates to a parking brake system for a motor vehicle. The parking brake system according to the invention comprises a parking brake with an actuator for locking the wheels of the motor vehicle and a servomotor for adjusting the actuator. The parking brake system also comprises a control according to the invention for controlling the servomotor, so that the advantages explained above of the method according to the invention are also transferred to the parking brake system according to the invention.

[0020] Further important features and advantages of the invention are revealed in the dependent claims, in the drawings and in the associated description of the figures based on the drawings.

[0021] It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination but also in other combinations or alone, without departing from the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Preferred exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0023] Schematically respectively:

[0024] Figure 1 A diagram showing an exemplary illustration of the structure of a controller according to the present invention is shown, Figure 2a -d shows a diagram which explains the method according to the invention by way of example. DETAILED DESCRIPTION

[0025] Figure 1The structure of a control unit 10 for a parking brake system of a motor vehicle (not shown) is shown by way of example in a schematic diagram. The parking brake system comprises a parking brake having two actuators (not shown) for locking the wheels of the motor vehicle and two servomotors 20a, 20b for adjusting the two actuators. The servomotors 20a, 20b can be controlled and thus adjusted by means of the control unit 10, which in turn results in an adjustment of the actuators (not shown) which are drive-connected to the servomotors 20a, 20b. The control unit 10 comprises a first H-bridge and a second H-bridge 11a, 11b for selectively controlling the two servomotors 20a, 20b. The two H-bridges 11a, 11b can have power amplifiers for controllably driving the servomotors 20a, 20b in a known manner.

[0026] In addition, the controller 10 follows Figure 1 The controller 10 comprises a first electronic circuit arrangement 12a for controlling the two H-bridges 11a, 11b and a second electronic circuit arrangement 12b for controlling the two H-bridges 11a, 11b. In addition, the controller 10 comprises a first microcontroller 1a for controlling the first circuit arrangement 12a and a second microcontroller 1b for controlling the second circuit arrangement 12b.

[0027] The method according to the invention can be implemented in the control unit 10, which is described below according to Figure 2a-2d Flowchart illustration of the.

[0028] According to the method, in measure a), the first microcontroller and the second microcontroller 1a, 1b are tested one after another when the control unit 10 is switched on. In the example, the first microcontroller 1a is tested before the second microcontroller 1b in terms of time. During the testing of the two microcontrollers 1a, 1b, the two H bridges 11a, 11b of the control unit 10 are also tested.

[0029] For this reason, Figure 2a As shown in , first the first circuit arrangement 12a is activated and the second circuit arrangement 12b is deactivated. In this configuration, the two H-bridges 11a, 11b are tested by means of the first microcontroller 1a, which controls the two H-bridges 11a, 11b via the first circuit arrangement 12a.

[0030] Afterwards, if Figure 2b , the first circuit arrangement 12a is deactivated and the second circuit arrangement 12b is activated. In this configuration, the two H-bridges 11a, 11b are tested by means of a second microcontroller 1b, which is controlled by the second circuit arrangement 12b and tests the two H-bridges 11a, 11b in this way.

[0031] Then, the controller 10 starts Figure 2c . During the rated operation, in measure b) of the method, the second microcontroller 1b remains activated for controlling the two servomotors 20a, 20b, whereas the first microcontroller 1a remains inactive as a redundant unit for controlling the two servomotors 20a, 20b. In this case, the second microcontroller 1b controls the two H-bridges 11a, 11b via the second circuit arrangement 12b.

[0032] During nominal operation, the operation-related data updated in the memory of the second microcontroller 1b are transferred from the second microcontroller 1b to the first microcontroller 1a after the update has been completed (see Figure 2c ), so that the operation-related data are available to the first microcontroller 1a in the event of a fault. In contrast, in nominal operation, data that are not relevant to the operation of the controller 10 or the parking brake are not transmitted from the second microcontroller 1b to the first microcontroller 1a. Therefore, no unnecessary data load is generated when transmitting data between the two microcontrollers 1a, 1b.

[0033] In the event of a fault in the second microcontroller 1b, Figure 2d As shown in the figure, in measure c) of the method, a switch is made from rated operation to non-rated operation, in which the first microcontroller 1a assumes the control functions of the second microcontroller 1b. Due to the synchronization of the operation-related data between the two microcontrollers 1a, 1b in rated operation, this transfer can be realized without the need for further data exchange. The first microcontroller 1a now controls the two H bridges 11a, 11b via two circuit arrangements 12a, 12b. In this way, it is ensured that despite the functional failure that occurs in the second microcontroller 1b, the servomotor 10 of the parking brake continues to be controlled - ideally without being noticed by the user of the controller 10.

[0034] In a typically occurring scenario in which no fault occurs in the second microcontroller 1b during rated operation, there is no need to switch to non-rated operation, and after the operation of the controller 10 or the parking brake system has ended, operation-independent data can be transferred from the second microcontroller 1b to the first microcontroller 1a in measure d).

[0035] After the operation has been completed, for reasons of safety, the operation-relevant data, preferably all operation-relevant data, can also be transferred again from the second microcontroller 1 b which controls the servomotors 20 a , 20 b to the first microcontroller 1 a .

[0036] In a variant of the method according to the invention, a switchover from nominal operation to non-nominal operation also occurs when a fault occurs in the second electronic circuit arrangement 12 b.

[0037] Expediently, in non-rated operation and in the event of a fault in the second electronic circuit arrangement 12 b , the first microcontroller 1 a also controls the first H-bridge 11 a and also the second H-bridge 11 b via the first electronic circuit arrangement 12 a of the controller 10 .

Claims

1. A method for operating a control unit (10) for a parking brake system, the parking brake system having a parking brake and a first and a second microcontroller (1a, 1b), a first and a second electronic circuit arrangement (12, 12b), and a first and a second H-bridge (11a, 11b) for controlling a first servomotor (20a, 20b) of the parking brake, - according to the method, the first microcontroller and the second microcontroller (1a, 1b) are tested successively when the control unit (10) is switched on, - according to the method, after the test has been completed, the rated operation of the controller (10) is started and for this purpose the second microcontroller (1b) is activated for controlling the servomotors (20a, 20b) and the first microcontroller (1a) is deactivated as a redundancy, - according to the method, when a fault occurs in the second microcontroller (1b), the rated operation is switched to a non-rated operation, in which the first microcontroller (1a) assumes control of the servomotors (20a, 20b) by the second microcontroller (1b), According to the method, during the nominal operation only operation-relevant data are transmitted from the second microcontroller (1b) to the first microcontroller (1a), so that in the event of a fault, the operation-relevant data are available to the first microcontroller (1a).

2. The method according to claim 1, It is characterized in that In the event of a fault in the second electronic circuit arrangement (12b), a switch is also made from the nominal operation to the non-nominal operation.

3. The method according to claim 1 or 2, It is characterized in that In the non-rated operation and in the event of a fault in the second electronic circuit arrangement (12b), the first microcontroller (1a) controls the first H-bridge (11a) and also the second H-bridge (11b) via the first electronic circuit arrangement (12a) of the controller (10).

4. The method according to any one of claims 1 to 3, It is characterized in that In the rated operation, the second microcontroller (1b) controls the first H-bridge (11a) and also the second H-bridge (11b) via a second electronic circuit arrangement (12b) of the controller (10).

5. The method according to any one of the preceding claims, It is characterized in that The first microcontroller (1a) is tested chronologically before the second microcontroller (1b) is tested.

6. The method according to any one of the preceding claims, It is characterized in that After carrying out the test, the first electronic circuit arrangement (12a) is switched to an inactive state so that it does not actuate the servomotors (20a, 20b).

7. The method according to any one of the preceding claims, It is characterized in that During nominal operation of the control unit (10), no operation-independent data are transmitted from the microcontroller (1b) controlling the servomotors (20a, 20b) of the parking brake to the other microcontroller (1a).

8. The method according to any one of the preceding claims, It is characterized in that After the end of the nominal operation of the control unit (10), operation-independent data, preferably all operation-independent data, are transmitted from the microcontroller (1b) controlling the servomotors (20a, 20b) of the parking brake to the other microcontroller (1a).

9. The method according to any one of the preceding claims, It is characterized in that After the rated operation of the control unit (10) has been completed, all operation-relevant data are transmitted from the microcontroller (1b) controlling the parking brake to the other microcontrollers (1a).

10. Computer program products, It comprises instructions which can be read by a controller (10) so that the controller (10) carries out a method according to any one of the preceding claims when executing the computer program product.

11. A controller (10) for a parking brake system of a motor vehicle, the controller comprising: - a first H-bridge and a second H-bridge (11a, 11b) for selectively controlling servomotors (20a, 20b) of the parking brake system, a first electronic circuit arrangement (12a) for controlling the first H-bridge (11a) and a second electronic circuit arrangement (12b) for controlling the second H-bridge (11a), a first microcontroller (1a) for controlling the first circuit arrangement (12a) and a second microcontroller (1b) for controlling the second circuit arrangement (12b), wherein: The two microcontrollers (1a, 1b) are connected to one another for data transmission or for data transmission capability. - wherein the controller (10) is set up / programmed to carry out the method according to any one of claims 1 to 9 and / or to implement the computer program product according to claim 10.

12. The controller according to claim 11, It is characterized in that During operation, the controller (10) executes the computer program product according to claim 6.

13. A parking brake system for a motor vehicle, the parking brake system comprising: - a parking brake comprising at least one actuator for locking the wheels of the motor vehicle and at least one servomotor (20a, 20b) for adjusting the at least one actuator, - A controller (10) according to claim 11 or 12, for controlling the at least one servomotor (20a, 20b).

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