Wheel speed sensor system, vehicle including said wheel speed sensor system and method of processing wheel speed signals

The present disclosure relates to a wheel speed sensor system (1), comprising: one or more first wheel speed sensors (2a, 2b), a first application specific integrated circuit (ASIC) (4) configured to receive one or more first wheel speed signals from the one or more first wheel speed sensors (2a, 2b) and to convert the one or more first wheel speed signals to first wheel speed data, and a first electronic control unit (ECU) (6) configured to receive the first wheel speed data from the first ASIC (4) via a data link (8) between the first ECU (6) and the first ASIC (4); and one or more second wheel speed sensors (3a, 3b), a second ASIC (5) configured to receive one or more second wheel speed signals from the one or more second wheel speed sensors (3a, 3b) and to convert the one or more second wheel speed signals to second wheel speed data, and a second ECU (7) configured to receive the second wheel speed data from the second ASIC (5) via a data link (9) between the second ECU (7) and the second ASIC (5). The first ECU (6) is further configured to receive the second wheel speed data from the second ASIC (5) via a data link (13) between the first ECU (6) and the second ASIC (5), and the second ECU (7) is further configured to receive the first wheel speed data from the first ASIC (4) via a data link (14) between the second ECU (7) and the first ASIC (4). The present disclosure further relates to a vehicle including said wheel speed sensor system and to a method of processing wheel speed signals.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to German Patent Application No. 102018218837.8, filed on Nov. 5, 2018, the entire content of which is incorporated herein by reference.

The present disclosure relates primarily to a wheel speed sensor system, in particular for use in an automotive vehicle, to a vehicle including said wheel speed sensor system, and to a method of processing wheel speed signals.

Technologies related to self-driving cars, also termed autonomous or driver-less cars, play an increasingly significant role in the automotive industry. One of the most important aspects in the development of these technologies is car and passenger safety. With regard to vehicle control systems such as brake systems, a possible strategy to increase car and passenger safety includes the design of control architectures featuring redundancies so that in the case of malfunction or failure of a component one or more further components may take over the functionality of the defective component.

For example, DE102017209720A1 relates to a brake system having a redundant design including primary and secondary brake systems. Both brake systems safely decelerate the transportation vehicle and take over the function of the other brake system. The control of the safety-relevant process is based on the analysis of the signals of at least one sensor. A hardware architecture and a test mode for the hardware architecture are provided. A communications bus enables exchange of data between the primary and secondary ECUs. The at least one sensor of the hardware architecture connects to the primary ECU and to the secondary ECU. A sensor arrangement isolation circuit associated with the primary ECU and with the secondary ECU isolates the associated primary or secondary ECU from the at least one sensor.

Based on these known systems, the problem underlying the present disclosure consists in designing a wheel speed sensor system configured to compensate the failure or malfunction of system components and having a preferably simple architecture.

This problem is solved by a wheel speed sensor system and by a method of processing wheel speed signals according to the independent claims. The problem is further solved by a vehicle comprising said wheel speed sensor system. Special embodiments are described in the dependent claims.

The presently proposed wheel speed sensor system comprises:one or more first wheel speed sensors,
a first application specific integrated circuit (ASIC) configured to receive one or more first wheel speed signals from the one or more first wheel speed sensors and to convert the one or more first wheel speed signals to first wheel speed data, anda first electronic control unit (ECU) configured to receive the first wheel speed data from the first ASIC via a data link between the first ECU and the first ASIC;one or more second wheel speed sensors,a second ASIC configured to receive one or more second wheel speed signals from the one or more second wheel speed sensors and to convert the one or more second wheel speed signals to second wheel speed data, anda second ECU configured to receive the second wheel speed data from the second ASIC via a data link between the second ECU and the second ASIC.

The first ECU is further configured to receive the second wheel speed data from the second ASIC via a data link between the first ECU and the second ASIC, and the second ECU is further configured to receive the first wheel speed data from the first ASIC via a data link between the second ECU and the first ASIC.

Due to the data link between the first ECU and the second ASIC, the first ECU may receive the second wheel speed data produced by the second ASIC even if the second ECU is defective or malfunctioning. And due to the data link between the second ECU and the first ASIC, the second ECU may receive the first wheel speed data produced by the first ASIC even if the first ECU is defective or malfunctioning. In this way it is guaranteed that in the event that one of the first ECU and the second ECU is defective or malfunctioning, the other ECU may receive both the first wheel speed data produced by the first ASIC and the second wheel speed data produced by the second ASIC.

Preferably, the data link between the second ASIC and the first ECU is configured as a direct data link between the second ASIC and the first ECU. For example, the data link between the second ASIC and the first ECU may comprise a cable or an optical fiber having a first end and a second end. The first end of this cable or optical fiber connecting the second ASIC with the first ECU may then be received in an output connector of the second ASIC, and the second end of this cable or optical fiber connecting the second ASIC with the first ECU may then be received in an input connector of the first ECU.

Similarly, the data link between the first ASIC and the second ECU is preferably configured as a direct data link between the first ASIC and the second ECU. For example, the data link between the first ASIC and the second ECU may comprise a cable or an optical fiber having a first end and a second end. The first end of this cable or optical fiber connecting the first ASIC with the second ECU may then be received in an output connector of the first ASIC, and the second end of this cable or optical fiber connecting the first ASIC with the second ECU may then be received in an input connector of the second ECU.

The first ECU typically comprises a programmable processing unit such as a microprocessor or a field programmable gate array (FPGA). Similarly, the second ECU typically comprises a programmable processing unit such as a microprocessor or an FPGA.

Converting the one or more first wheel speed signals to the first wheel speed data in the first ASIC typically includes converting the one or more first wheel speed signals to a data format which is readable by the first ECU. To that end, the first ASIC may include an analogue to digital converter for digitizing the one or more first wheel speed signals. For example, the first ASIC being configured to convert the one or more first wheel speed signals to the first wheel speed data may include the first ASIC being configured to convert the one or more first wheel speed signals to one or more first pulse-width-modulated (PWM) signals.

Similarly, converting the one or more second wheel speed signals to the second wheel speed data in the second ASIC typically includes converting the one or more second wheel speed signals to a data format which is readable by the second ECU. To that end, the second ASIC may include an analogue to digital converter for digitizing the one or more second wheel speed signals. For example, the second ASIC being configured to convert the one or more second wheel speed signals to the second wheel speed data may include the second ASIC being configured to convert the one or more second wheel speed signals to one or more second pulse-width-modulated (PWM) signals.

The one or more first wheel speed sensors typically include one or more magnetic or optical sensors configured to produce the one or more first wheel speed signals indicative of the rotational speed of one or more rotating or rotatable components such as one or more vehicle wheels. Similarly, the one or more second wheel speed sensors typically include one or more magnetic or optical sensors configured to produce the one or more second wheel speed signals indicative of the rotational speed of one or more rotating or rotatable components such as one or more vehicle wheels.

The wheel speed sensor system may further comprise at least one controllable device. The at least one controllable device may comprise at least one electric motor. For example, the at least one electric motor may be configured to drive a hydraulic piston for producing a hydraulic brake pressure. However, it is likewise conceivable that the controllable device comprises one or more electric switches or one or more electrically controllable valves, for example.

The first ECU may be configured to process the first wheel speed data and the second wheel speed data received by the first ECU to produce control data. The first ECU may then further be configured to control the at least one controllable device based on the control data produced by the first ECU. Similarly, the second ECU may be configured to process the first wheel speed data and the second wheel speed data received by the second ECU to produce the control data. The second ECU may then further be configured to control the at least one controllable device based on the control data produced by the second ECU. Again, this symmetry in the control architecture ensures that control of the controllable device is guaranteed even in the event that one of the first ECU and the second ECU is defective or malfunctioning.

The first ECU may be configured to determine whether the second ECU is defective. And if the first ECU determines that the second ECU is defective, the first ECU may further be configured to control the controllable device based on the control data produced by the first ECU. Similarly, the second ECU may be configured to determine whether the first ECU is defective. And if the second ECU determines that the first ECU is defective, the second ECU may further be configured to control the controllable device based on the control data produced by the second ECU.

The first ECU may further be configured to transmit the first wheel speed data received by the first ECU to the second ECU via a bidirectional data link between the first ECU and the second ECU. Similarly, the second ECU may be configured to transmit the second wheel speed data received by the second ECU to the first ECU via said bidirectional data link between the first ECU and the second ECU. Preferably, said bidirectional data link is configured as a direct data link between the first ECU and the second ECU. For example, the bidirectional data link may comprise a cable or an optical fiber having a first end and a second end. The first end of this cable or optical fiber connecting the first ECU with the second ECU may then be received in a connector or port of the first ECU, and the second end of this cable or optical fiber connecting the first ECU with the second ECU may then be received in a connector or port of the second ECU.

In a standard mode of operation when both the first ECU and the second ECU are operational, the first ECU may be configured to receive the second wheel speed data from the second ECU via said bidirectional data link between the first ECU and the second ECU. The first ECU may then be configured to operate as a master ECU. When the first ECU operates as the master ECU the first ECU is configured to control the controllable device based on the control data produced by the first ECU.

The wheel speed sensor system may further comprise a control area network (CAN) BUS. The first ECU and the second ECU may then be configured to exchange at least one of the first wheel speed data, the second wheel speed data and the control data via this CAN BUS. That is, the first ECU may be configured to transmit at least one of the first wheel speed data, the second wheel speed data and the control data to the second ECU via this CAN BUS. Similarly, the second ECU may be configured to transmit at least one of the first wheel speed data, the second wheel speed data and the control data to the first ECU via this CAN BUS.

The wheel speed sensor system may further comprise a first printed circuit board (PCB) and a second PCB separate from the first PCB. The first ASIC and the first ECU may both be disposed on the first PCB. And the second ASIC and the second ECU may both be disposed on the second PCB. Arranging the first ASIC and the first ECU and the second ASIC and the second ECU on separate PCBs may further increase the robustness of the wheel speed sensor system against possible failures occurring on one of the two PCBs.

A vehicle comprising the above-described wheel speed sensor system may further comprise a first axle as well as a first left wheel and a first right wheel coupled to the first axle at opposite ends of the first axle. And the vehicle may further comprise a second axle as well as a second left wheel and a second right wheel coupled to the second axle at opposite ends of the second axle.

The above-mentioned one or more first wheel speed sensors may include a first left wheel speed sensor disposed on or at the first left wheel. The first wheel speed sensor may be configured to produce a first left wheel speed signal indicative of a speed of the first left wheel. And the one or more first wheel speed sensors may include a first right wheel speed sensor disposed on or at the first right wheel. The first right wheel speed sensor may be configured to produce a first right wheel speed signal indicative of a speed of the first right wheel.

The above-mentioned one or more second wheel speed sensors may include a second left wheel speed sensor disposed on or at the second left wheel. The second left wheel speed sensor may be configured to produce a second left wheel speed signal indicative of a speed of the second left wheel. And the one or more second wheel speed sensors may include a second right wheel speed sensor disposed on or at the second right wheel. The second right wheel speed sensor may be configured to produce a second right wheel speed signal indicative of a speed of the second right wheel.

The presently proposed method of processing wheel speed signals comprises:transmitting one or more first wheel speed signals from one or more first wheel speed sensors to a first ASIC,converting the one or more first wheel speed signals to first wheel speed data using the first ASIC, andtransmitting the first wheel speed data from the first ASIC to a first ECU via a data link between the first ASIC and the first ECU, and transmitting the first wheel speed data from the first ASIC to a second ECU via a data link between the first ASIC and the second ECU;transmitting one or more second wheel speed signals from one or more second wheel speed sensors to a second ASIC,converting the one or more second wheel speed signals to first wheel speed data using the second ASIC, andtransmitting the second wheel speed data from the second ASIC to the second ECU via a data link between the second ASIC and the second ECU, and transmitting the second wheel speed data from the second ASIC to the first ECU via a data link between the second ASIC and the first ECU.

The method may comprise:processing the first wheel speed data and the second wheel speed data received by the first ECU to produce control data, andcontrolling at least one controllable device based on the control data produced by the first ECU; orprocessing the first wheel speed data and the second wheel speed data received by the second ECU to produce the control data, andcontrolling the at least one controllable device based on the control data produced by the second ECU.

The method may comprise determining whether the second ECU is defective, and, if it is determined that the second ECU is defective, controlling the controllable device based on the control data produced by the first ECU.

The method may comprise determining whether the first ECU is defective, and, if it is determined that the first ECU is defective, controlling the controllable device based on the control data produced by the second ECU.

The method may comprise transmitting the first wheel speed data received by the first ECU from the first ECU to the second ECU via a bidirectional data link between the first ECU and the second ECU. Additionally or alternatively, the method may comprise transmitting the second wheel speed data received by the second ECU from the second ECU to the first ECU via said bidirectional data link between the first ECU and the second ECU.

When both the first ECU and the second ECU are operational, the method may comprise transmitting the second wheel speed data received by the second ECU from the second ECU to the first ECU via the bidirectional data link between the first ECU and the second ECU. The method may then further include the step of controlling the controllable device based on the control data produced by the first ECU based on the first wheel speed data received by the first ECU via the data link between the first ASIC and the first ECU and based on the second wheel speed data received by the first ECU via the bidirectional data link between the first ECU and the second ECU.

FIG.1shows an automotive vehicle100including a front axle20, a rear axle30, a front left wheel20a, a front right wheel20b, a rear left wheel30aand a rear right wheel30b. The wheels20a,20bare mounted on opposing ends of the front axle20, and the wheels30a,30bare mounted on opposing ends of the rear axle30. The vehicle100further includes a wheel speed sensor system1comprising a front left wheel speed sensor (WSS)2adisposed at the front left wheel20a, a front right WSS2bdisposed at the front right wheel20b, a rear left WSS3adisposed at the rear left wheel30a, and a rear right WSS3bdisposed at the rear right wheel30b. Each of the wheel speed sensors2a,2b,3a,3bmay comprise a magnetic sensor or an optical sensor, for example.

The wheel speed sensor system1further comprises a first printed circuit board (PCB)16, a second PCB17separate from the first PCB16and at least one controllable device10. The controllable device10may include an electric motor, an electric switch or a controllable valve, for example. For instance, the controllable device10may be configured to influence or to control a hydraulic pressure in one or more brake cylinders for braking the wheels20a,20b,30a,30b. The wheel speed sensors2a,2bare in communication with the first PCB16via communication lines21a,21b, and the wheel speed sensors3a,3bare in communication with the first PCB17via communication lines31a,31b. The controllable device10is in communication with the PCBs16,17via communication lines11,12. And the PCBs16,17are in communication with one another via data links13,14and via a bidirectional data link15. Moreover, each of the PCBs16,17is in communication with a controller area network (CAN) BUS18of the vehicle100so that the PCBs16,17may furthermore communicate with one another via the CAN BUS18.

A more detailed illustration of the wheel speed sensor system1is depicted inFIG.2, wherein the same features shown inFIGS.1and2are designated with the same reference signs inFIGS.1and2.FIG.2shows that the first PCB16comprises a first application specific integrated circuit (ASIC)4and a first electronic control unit (ECU)6, and that the second PCB17comprises a second ASIC5and a second ECU7. The first ECU6and the second ECU7may include one or more microprocessors or one or more field programmable field arrays (FPGAs), for example.

The front left WSS2aand the front right WSS2bare configured to produce wheel speed signals indicative of a rotational speed of the front left wheel20aand of the front right wheel20b, respectively, and to transmit these wheel speed signals to an input of the first ASIC4via the communication lines21a,21b. The first ASIC4is configured to receive the wheel speed signals from the WSSs2a,2band to convert them to first wheel speed data. The first wheel speed data have a format which is readable by the first ECU6and by the second ECU7. To that end, the first ASIC4may include an analogue to digital converter, for example. For instance, the first wheel speed data produced by the first ASIC4may include one or more pulse width modulated (PWM) signals. The first ASIC4is configured to transmit the first wheel speed data to the first ECU5via a data link8connecting the first ASIC4with the first ECU5. Additionally, the first ASIC4is configured to transmit the first wheel speed data to the second ECU7via the data link14connecting the first ASIC4with the second ECU7. For example, the data link14connecting the first ASIC4with the second ECU7may be configured as a cable or as an optical fiber that directly links an output connector or output port, for example a low voltage output connector or a low voltage output port, of the first ASIC4with an input connector or input port of the second ECU7.

Similarly, the rear left WSS3aand the rear right WSS3bare configured to produce wheel speed signals indicative of a rotational speed of the rear left wheel30aand of the rear right wheel30b, respectively, and to transmit these wheel speed signals to an input of the second ASIC5via the communication lines31a,31b. The second ASIC5is configured to receive the wheel speed signals from the WSSs3a,3band to convert them to second wheel speed data. The second wheel speed data have a format which is readable by the first ECU6and by the second ECU7. To that end, the second ASIC5may include an analogue to digital converter, for example. For instance, the second wheel speed data produced by the second ASIC5may include one or more pulse width modulated (PWM) signals. The second ASIC5is configured to transmit the second wheel speed data to the second ECU7via a data link9connecting the second ASIC5with the second ECU7. Additionally, the second ASIC5is configured to transmit the second wheel speed data to the first ECU6via the data link13connecting the second ASIC5with the first ECU6. For example, the data link13connecting the second ASIC5with the first ECU6may be configured as a cable or as an optical fiber that directly links an output connector or output port, for example a low voltage output connector or a low voltage output port, of the second ASIC5with an input connector or input port of the first ECU6.

Moreover, the first ECU6is in communication with the second ECU7via the bidirectional data link15and via the CAN BUS18. Again, the bidirectional data link15connecting the first ECU6with the second ECU7may be configured as a cable or as an optical fiber that directly links an output connector or output port of the first ECU6with an input connector or input port of the second ECU7. That is, the first ECU6may transmit the first wheel speed data received by the first ECU6to the second ECU7via the bidirectional data link15and/or via the CAN BUS18. Similarly, the second ECU7may transmit the second wheel speed data received by the second ECU7to the first ECU6via the bidirectional data link15and/or via the CAN BUS18.

The first ECU6is configured to process the first wheel speed data and the second wheel speed data received by the first ECU6to produce control data and to control the controllable device10based on these control data. For example, the first ECU6may be configured to compare the wheel speed of one or more of the wheels20a,20b,30a,30bwith a target wheel speed value and to transmit one or more control signals to the controllable device10via the communication line11, wherein the one or more control signals are based on the wheel speed of one or more of the wheels20a,20b,30a,30band based on the target wheel speed value. For instance, the first ECU6may be configured to determine that the wheel speed of one or more of the wheels20a,20b,30a,30bis above the target wheel speed value and to transmit a control signal to the controllable device10that prompts the controllable device10to decelerate one or more of the wheels20a,20b,30a,30buntil their wheel speed reaches the target wheel speed value.

Similarly, the second ECU7is configured to process the first wheel speed data and the second wheel speed data received by the second ECU7to produce control data and to control the controllable device10based on these control data. For example, the second ECU7may be configured to compare the wheel speed of one or more of the wheels20a,20b,30a,30bwith a target wheel speed value and to transmit one or more control signals to the controllable device10via the communication line12, wherein the one or more control signals are based on the wheel speed of one or more of the wheels20a,20b,30a,30band based on the target wheel speed value. For instance, the second ECU7may be configured to determine that the wheel speed of one or more of the wheels20a,20b,30a,30bis above the target wheel speed value and to transmit a control signal to the controllable device10that prompts the controllable device10to decelerate one or more of the wheels20a,20b,30a,30buntil their wheel speed reaches the target wheel speed value.

In the following, different modes of operation of the wheel speed sensor system1are described. Both the first ECU6and the second ECU7are configured to determine if the other ECU is operational or malfunctioning. For example, as long as the first ECU6is operational it may continually transmit a first status signal to the second ECU7, for example via the bidirectional data link15or via the CAN BUS18. Once the second ECU7no longer receives the first status signal from the first ECU6, the second ECU7may determine that the first ECU6is no longer operational or that the first ECU6is malfunctioning. Similarly, as long as the second ECU7is operational it may continually transmit a second status signal to the first ECU6, for example via the bidirectional data link15or via the CAN BUS18. Once the first ECU6no longer receives the second status signal from the second ECU7, the first ECU6may determine that the second ECU7is no longer operational or that the second ECU7is malfunctioning.

In a standard mode of operation of the wheel speed sensor system1in which both the first ECU6and the second ECU7are operational, the first ECU6receives the first wheel speed data produced by the first ASIC4via the data link8between the first ASIC4and the first ECU6, and receives the second wheel speed data produced by the second ASIC5via the data link9between the second ASIC5and the second ECU7and via the bidirectional data link15between the second ECU7and the first ECU6. In the standard mode of operation, the first ECU6operates as the master control unit meaning that the first ECU6produces the control data or control signals for controlling the controllable device10and transmits the control data or control signals produced by the first ECU6to the controllable device via the data link11between the first ECU6and the controllable device10. It is understood that due to the symmetry of the architecture of the wheel speed sensor system1the role of the first ECU6and of the second ECU7in the standard mode of operation could be reversed. In other words, it is conceivable that in the standard mode of operation the second ECU7could operate as the master control unit instead of the first ECU6.

In a first failure mode of the wheel speed sensor system1in which the first ECU6is operational and the second ECU7is not operational or malfunctioning, the first ECU6receives the first wheel speed data produced by the first ASIC4via the data link8between the first ASIC4and the first ECU6, and receives the second wheel speed data produced by the second ASIC5via the data link13directly connecting the second ASIC5with the first ECU6. In the first failure mode, the first ECU6operates as the master control unit, as described above with reference to the standard mode of operation.

In a second failure mode of the wheel speed sensor system1in which the second ECU7is operational and the first ECU6is not operational or malfunctioning, the second ECU7receives the first wheel speed data produced by the first ASIC4via the data link14directly connecting the first ASIC4with the second ECU7, and receives the second wheel speed data produced by the second ASIC5via the data link9between the second ASIC5and the second ECU7. In the second failure mode, the second ECU7operates as the master control unit meaning that the second ECU7produces the control data or control signals for controlling the controllable device10and transmits the control data or control signals produced by the second ECU7to the controllable device via the data link12between the second ECU7and the controllable device10.