VEHICLE BRAKE SYSTEM AND CONTROL METHOD FOR IT

Abstract

Vehicle braking system (1), which is a braking system for a fully autonomous vehicle, comprising: a first braking device (222) configured to control a hydraulic brake pressure transmitted to a wheel cylinder; a first pressure sensor (321) configured to measure a first internal pressure of the first braking device (222);a first offset determiner (41) configured to determine that a first offset has occurred in the first pressure sensor (321) by determining that a measurement of the first pressure sensor (321) remains above a first reference pressure for more than a first reference time, characterized in that: the vehicle brake system (1) further comprises a first shut-off valve (222c) configured to allow the first internal pressure, whether present or generable by a pressure generator, to move to a brake fluid reservoir (221), wherein the first shut-off valve (222c) is further configured to open when the pressure control of the first brake device (222) is in an OFF state, and the first offset determiner (41) is further configured to determine the first offset when the pressure control of the first brake device (222) is in the OFF state.

Description

CROSS-REFERENCE TO A RELATED REGISTRATION

[0001] This application claims priority over and benefit from Korean patent application No. 10-2021-0144532, filed on October 27, 2017, the disclosure of which is incorporated herein in its entirety by reference. [Technical field]

[0002] The present invention relates to a vehicle braking system and a control method therefor, and more specifically to a vehicle braking system capable of detecting an offset of a pressure sensor in a braking system to a fully autonomous vehicle, and a control method therefor. [General state of the art]

[0003] The vehicle braking system refers to a system for slowing down or stopping a moving vehicle. A typical vehicle braking system allows or limits the rotation of wheel cylinders by controlling hydraulic brake pressure transmitted to the vehicle's wheel cylinders.

[0004] To set the target brake pressure during pressure regulation, the vehicle's braking system requires a pressure sensor. If an offset occurs in the pressure sensor and a pressure greater than the current pressure at which the sensor is input, the target brake pressure will be set lower than the actual target brake pressure, and a malfunction may occur during normal operation of the vehicle's braking system.

[0005] The conventional vehicle braking system determines that a pressure sensor offset has occurred when the pressure sensor reading is greater than or equal to a predetermined value in the non-pressure-controlled state and the unbraked state of the brake pedal. However, in a fully autonomous vehicle, where the brake pedal does not exist, it is impossible to determine the braking and non-braking states of the brake pedal. Consequently, it is impossible to detect the pressure sensor offset in the same way in a fully autonomous vehicle.

[0006] Accordingly, the development of a method for detecting an offset of a pressure sensor to a braking system for a fully autonomous vehicle can be considered.

[0007] Korean patent application No. 10-1656961 discloses a method for diagnosing a vehicle pressure sensor failure. In particular, the method for diagnosing a vehicle pressure sensor failure is disclosed for diagnosing and warning of a pressure sensor failure in a pneumatic vehicle automatic transmission.

[0008] This type of failure diagnostic procedure can only be implemented in a state where the vehicle's parking brake is engaged and the gear is in neutral, and is therefore difficult to apply to the braking system for a fully autonomous vehicle that does not include components corresponding to a brake engagement and gear position.

[0009] Korean patent application No. 10-2015-0046867 discloses a method for resetting a master cylinder pressure offset value of a vehicle brake. In particular, it discloses a method for resetting the master cylinder pressure offset value, which allows the offset value to be set even if the brake pedal switch fails.

[0010] This type of pressure offset reset method requires a master cylinder pressure reading in a state where the brake pedal is depressed and the engine is running. It therefore depends on the presence of a brake pedal. Consequently, it is limited in its application to a braking system for a fully autonomous vehicle that lacks a brake pedal. (Patent specification 1) Korean patent application no. 10-1656961 (September 12, 2016) (Patent specification 2) Korean patent application no. 10-2015-0046867 (May 4, 2015) [Revelation][Technical Problem]

[0011] One objective of the present disclosure is to provide a vehicle braking system capable of detecting an offset of a pressure sensor regardless of whether a brake pedal is provided, and a control method for this.

[0012] Another objective of the present disclosure is to provide a vehicle braking system with improved offset sensing performance and reliability of a pressure sensor, and a control method for it.

[0013] Another objective of the present disclosure is to provide a vehicle braking system capable of normal braking even when some braking devices fail, and a control method for this. [Technical solution]

[0014] To achieve the above objectives, the vehicle braking system according to an exemplary embodiment of the present disclosure is a braking system for a fully autonomous vehicle, comprising a first braking device which includes a first shut-off valve for controlling a hydraulic brake pressure transmitted to a wheel cylinder; a first pressure sensor for measuring an internal pressure of the first braking device; and a first offset determiner for determining that an offset of the first pressure sensor has occurred when the first shut-off valve is opened, and the condition in which a measurement of the first pressure sensor exceeds a first reference pressure while being maintained for more than a first reference time.

[0015] Additionally, the vehicle braking system may further include an offset response device for transmitting an instruction and a control signal as an offset response to the first braking device when the first offset determiner determines that an offset of the first pressure sensor has occurred.

[0016] Additionally, the offset reaction device may include a feedback pressure calculator to calculate a feedback pressure of the first brake device based on an estimated internal pressure of the first brake device, after the first offset determiner has determined that an offset of the first pressure sensor has occurred.

[0017] Additionally, the feedback pressure calculator can calculate a feedback pressure of the first brake device based on an internal pressure of the first brake device estimated by a motor position sensor.

[0018] Additionally, the vehicle braking system may further include a second braking device which includes a second shut-off valve for controlling a hydraulic brake pressure that is transmitted to a wheel cylinder and for performing vehicle braking when the normal operation of the engine position sensor is impossible.

[0019] Additionally, the vehicle braking system may further include a second braking device which includes a second shut-off valve for controlling a hydraulic brake pressure transmitted to a wheel cylinder and for performing vehicle braking when an offset of the first pressure sensor occurs in a first offset determiner.

[0020] Additionally, the vehicle braking system may further include a second braking device, which includes a second shut-off valve for controlling a hydraulic brake pressure transmitted to a wheel cylinder; a second pressure sensor for measuring an internal pressure of the second braking device; and a second offset determiner for determining whether an offset of the second offset sensor has occurred.

[0021] Additionally, the second brake device can open the second relay valve to relieve residual pressure when the second shut-off valve is opened, and the condition in which a measurement of the second pressure sensor exceeds a second reference pressure for more than a second reference time is maintained, and wherein the second offset determiner can determine if an offset of the second pressure sensor has occurred after the residual pressure of the second brake device has been relieved.

[0022] Additionally, the second offset determiner can determine that an offset has occurred in the second pressure sensor when the residual pressure of the second brake device is reduced during a third reference time, and then the condition in which a measurement of the second pressure sensor exceeds a fourth reference pressure while being maintained for more than a fourth reference time.

[0023] Additionally, the second reference pressure and the fourth reference pressure can be calculated to be equal.

[0024] Additionally, the second reference time and the fourth reference time can be configured to be the same.

[0025] Additionally, the vehicle braking system may further include a fall-back switching device to switch the second pressure sensor to a fall-back state and output this information externally after the second offset determiner has determined that an offset has occurred in the second pressure sensor.

[0026] Additionally, the present disclosure provides a method for controlling a vehicle braking system, which is a method for controlling a braking system for a fully autonomous vehicle, comprising the steps (a) of measuring an internal pressure of a first braking device by a first pressure sensor; (b) of determining by a first offset determiner that an offset has occurred in the first pressure sensor when a first shut-off valve of the first pressure sensor is opened and the condition in which a measurement of the first pressure sensor exceeds a first reference pressure while being maintained for more than a first reference time; and (c) of performing vehicle braking by the second braking device.

[0027] Additionally, prior to step (c), (c0) the calculation of a feedback pressure of the first brake device based on an internal pressure of the first brake device estimated by a feedback pressure calculator from a motor position sensor can be carried out, and at step (c0) if the normal operation of the motor position sensor is impossible, step (c) can be carried out immediately.

[0028] Additionally, the procedure may further include the steps of (d) determining by a second offset determiner that an offset has occurred in a second pressure sensor, and (e) switching the second pressure sensor to a fall-back state by a fall-back switching device according to step (c).

[0029] Additionally, step (d) may include the steps of (d1) opening a second shut-off valve of the second pressure sensor and maintaining the state in which a measurement of the second pressure sensor exceeds a second reference pressure for more than a second reference time; (d2) reducing any residual pressure of the second pressure device during a third reference time; and (d3) determining by the second offset determiner that an offset has occurred in the second pressure sensor when the second shut-off valve is opened and maintaining the state in which a measurement of the second pressure sensor exceeds a fourth reference pressure for more than a fourth reference time. [Beneficial effects]

[0030] Among the various effects of the present disclosure, the effects that can be obtained through the technical solution described above are the following.

[0031] Firstly, the vehicle braking system according to the present disclosure is a braking system for a fully autonomous vehicle and includes a braking device, a pressure sensor for measuring the internal pressure of the braking device and an offset determiner for determining whether an offset occurs in the pressure sensor.

[0032] The offset determiner establishes that an offset has occurred in the pressure sensor when the condition in which a pressure sensor measurement exceeds a reference pressure is maintained for more than a reference time when the shut-off valve provided in the brake device is opened. Therefore, it is not necessary for the brake pedal to be depressed when the occurrence of an offset is determined.

[0033] Accordingly, the offset of the pressure sensor can be detected regardless of whether the brake pedal is present.

[0034] Additionally, the braking system includes a first braking device and a second braking device. Since the second braking device is formed in a closed-loop structure, additional pressure can be generated if the motor is driven abnormally.

[0035] In light of this point, the second offset determiner, in order to determine whether an offset occurs when the internal pressure of the second brake device is measured, reduces the residual pressure of the second brake device when an offset is suspected, and then measures the pressure of the second brake device again to determine whether an offset has occurred.

[0036] Accordingly, the offset detection performance of the pressure sensor can be further improved. Furthermore, the offset detection reliability can be increased.

[0037] Additionally, the braking system includes a primary braking device and a secondary braking device to assist in the event of failure of the primary braking device. If an offset occurs in the primary braking device, the secondary braking device can perform vehicle braking in place of the primary braking device.

[0038] Accordingly, braking by the second braking device is possible even if the normal operation of the first braking device is impaired. Normal braking of the vehicle is therefore possible even if some braking devices fail. List of characters Fig. Figure 1 is a schematic diagram illustrating the vehicle braking system according to an exemplary embodiment of the present disclosure. Fig. 2 is a schematic diagram showing a control device and a drive device that are part of the vehicle's braking system. Fig. 1 are provided, illustrated. Fig. Figure 3 is a schematic diagram illustrating a braking device located in the drive unit of the Fig. 2 is provided. Fig. 4 is a schematic diagram showing a drive device, a sensor device, and an offset determiner, which are part of the vehicle's braking system. Fig. 1 are provided, illustrated. Fig. 5 is a schematic diagram showing a sensor device, an offset determiner, and an offset reaction device that are part of the vehicle's braking system. Fig. 1 are provided, illustrated. Fig. Figure 6 is a conceptual diagram illustrating the offset determination process of a first offset determiner, which is located in the offset determiner of the Fig. 5 is included, illustrated. Fig. 7 is a conceptual diagram illustrating the offset determination process of a second offset determiner, which is located in the offset determiner of the Fig. 5 is included, illustrated. Fig. Figure 8 is a flowchart illustrating the method for controlling a vehicle propulsion system according to an exemplary embodiment of the present disclosure. Fig. 9 is a flowchart that shows specific steps S100 of the Fig. 8 illustrates. Fig. 10 is a flowchart that shows specific steps of S200. Fig. 8 illustrates. Fig. 11 is a flowchart that shows specific steps of S400. Fig. 8 illustrates. [Embodiments of the invention]

[0039] A method for controlling a vehicle braking system 1 according to an exemplary embodiment of the present disclosure is described in more detail below with reference to the drawings.

[0040] In the following description, the descriptions of some components may be omitted to clarify the features of the present disclosure.

[0041] In this specification, the components are assigned to the different reference numbers even in different exemplary embodiments, and the overlapping descriptions for them are omitted.

[0042] The accompanying drawings are provided only to facilitate understanding of the exemplary embodiments disclosed in this specification, and the technical ideas disclosed in this specification are not limited by the accompanying drawings.

[0043] Singular expressions include plural expressions unless the context dictates otherwise.

[0044] The vehicle braking system 1 is described below according to an exemplary embodiment of the present disclosure with reference to the Fig. 1 to Fig. 5 described.

[0045] The vehicle braking system 1 according to the present disclosure is a system for slowing down or stopping the speed of a vehicle in motion, and relates in particular to a braking system for a fully autonomous vehicle in which a brake pedal can be omitted.

[0046] The vehicle's braking system 1 allows or limits the rotation of wheel cylinders by controlling a hydraulic brake pressure transmitted to the wheel cylinders of the wheels 2. In this case, the current pressure must be measured in order to set the target brake pressure at the time of pressure adjustment. A detailed description of this procedure is provided below.

[0047] The vehicle braking system 1 includes a control device 10, a drive device 20, a sensor device 30 and an offset determiner 40 as well as an offset reaction device 50.

[0048] The control device 10 controls each component of the drive device 20. For this purpose, the control device 10 is electrically connected to the drive device 20.

[0049] In the illustrated exemplary embodiment, the control device 10 includes a motor control device 11 and a brake device control device 12, and the drive device 20 includes a motor 21 and a brake device 22. Additionally, the motor control device 11 and the brake device control device 12 are electrically connected to the motor 21 and the brake device 22.

[0050] The engine control unit 11 and the brake control unit 12 each control the engine 21 and the brake system 22, respectively, so that the vehicle can travel at a target speed. The engine control unit 11 and the brake system control unit 12 compare the current speed and the target speed of the vehicle and accelerate or decelerate the vehicle accordingly.

[0051] In this case, the braking device 22 can reduce the vehicle's speed by allowing or restricting the rotation of the vehicle's wheels 2.

[0052] The brake device 22 controls a hydraulic brake pressure that is transmitted to the wheel cylinders. Accordingly, the alternating movement of the wheel cylinder can be induced. As a result, it is possible to allow or restrict the rotation of the vehicle wheels 2.

[0053] The brake device 22 includes a brake fluid reservoir 221, a first brake device 222 and a second brake device 223.

[0054] The brake fluid reservoir 221 has a space formed within it in which the brake fluid is received.

[0055] The first brake device 222 mainly controls the amount of brake fluid supplied to the wheel cylinders.

[0056] The first brake device 222 is connected to the brake fluid reservoir 221 to obtain brake fluid from the brake fluid reservoir 221. In this case, the required internal pressure of the first brake device 222 can be changed according to the target brake fluid supply quantity of the first brake device 222.

[0057] The internal pressure of the first brake device 222 can be determined according to the open / closed state of a flow control valve 222a, a first relay valve 222b and a first shut-off valve 222c provided in the first brake device 222.

[0058] For example, when the first shut-off valve 222c is opened, the entire pressure is moved to the brake fluid reservoir 221 even when the pressure generator is operated, and therefore the internal pressure of the first brake device 222 does not exceed a certain pressure.

[0059] Whether the first shut-off valve 222c opens can be determined by measuring the excitation current of the first shut-off valve 222c. When the first shut-off valve 222c opens, the current flowing through the first shut-off valve 222c does not exceed a predetermined current value. In an exemplary embodiment, the excitation current of the first shut-off valve 222c does not exceed 100 mA when the first shut-off valve 222c opens.

[0060] If the normal operation of the first braking device 222 is difficult, braking of the vehicle can be carried out by the second braking device 223.

[0061] The second brake device 223 assists in regulating the amount of brake fluid supplied to the wheel cylinder of the first brake device 222. Accordingly, normal braking of the vehicle is possible even if the first brake device 222 fails.

[0062] In the illustrated exemplary embodiment, the second brake device 223 is formed as a redundancy circuit with respect to the first brake device 222.

[0063] The second brake device 223 is connected to the brake fluid reservoir 221 and the first brake device 222 to receive brake fluid from at least one of the brake fluid reservoirs 221 and the first brake device 222. In this case, the required internal pressure of the first brake device 223 can be changed according to the target brake fluid supply quantity of the second brake device 223.

[0064] In the illustrated exemplary embodiment, the second brake device 223 includes a pressure relief valve 223a, a second relay valve 222b, and a second shut-off valve 222c, which are formed from a normally closed (NC) valve. The internal pressure of the second brake device 223 can be determined according to the open / closed state of the pressure relief valve 223a, the second relay valve 222b, and the second shut-off valve 222c.

[0065] For example, when the second shut-off valve 222c is opened, the entire pressure is moved to the brake fluid reservoir 221 even when the pressure generator is operated, and therefore the internal pressure of the first brake device 222 does not exceed a certain pressure.

[0066] Whether the second shut-off valve 222c opens or not can be determined by measuring the current through the second shut-off valve 222c. When the second shut-off valve 222c opens, the current flowing through it does not exceed a predetermined current value. In an exemplary embodiment, the excitation current of the second shut-off valve 222c does not exceed 100 mA when the second shut-off valve 222c opens.

[0067] Data relating to the operating state of the drive device 20 are collected by the sensor device 30. For this purpose, the sensor device 30 is electrically connected to the motor 21 and the brake device 22.

[0068] In the illustrated exemplary embodiment, the sensor device 30 includes a motor position sensor (MPS) 31 and a pressure sensor 32.

[0069] The motor position sensor 31 collects data related to the operating state of the motor 21. In particular, data is collected about the operating state of the motor 21, which is responsible for pressure generation. For this purpose, the motor position sensor 31 is electrically connected to the motor 21.

[0070] The pressure sensor 32 collects pressure data from the brake device 22.

[0071] Pressure sensor 32 provides current pressure data required to calculate the target brake pressure when the pressure of the brake device 22 is set. If an offset is generated in pressure sensor 32 and a pressure greater than the current pressure to pressure sensor 32 is applied, the target brake pressure will be set lower than the current target brake pressure, which may cause errors during the normal operation of the vehicle brake system 1.

[0072] The pressure sensor 32 includes a first pressure sensor 321 and a second pressure sensor 322. The first pressure sensor 321 and the second pressure sensor 322 are electrically connected to the first brake device 222 and the second brake device 223 such that the internal pressures of the first brake device 222 and the second brake device 222 are measured.

[0073] Although the first pressure sensor 321 and the second pressure sensor 322 have similar structures and functions, there are differences in some structures.

[0074] If the first shut-off valve 222c at the first pressure sensor 321 is opened in a state where the pressure control of the first brake device 222 is in an OFF state, there is less probability of abnormal pressure building up. This is due to the fact that pressure is transferred back to the brake fluid reservoir 221 while the first shut-off valve 222c is open in a state where the pressure control of the first brake device 222 is in an OFF state.

[0075] The second pressure sensor 322 is formed in a closed-loop structure. As described above, the pressure valve 223a of the second brake device 223 is also designed as a normally closed valve. Accordingly, abnormal pressure can be generated in the second brake device 223 due to opposing electromotive forces or faulty control of the pressure generator. Therefore, when measuring the second pressure sensor 322, it is necessary to take the abnormal pressure of the second brake device 223 into account.

[0076] Due to the above-mentioned difference, there is also a difference in the procedure for determining the occurrence of an offset between the first pressure sensor 321 and the second pressure sensor 322.

[0077] The offset determiner 40 determines whether an offset occurs between the first pressure sensor 321 and the second pressure sensor 322.

[0078] In the illustrated exemplary embodiment, the offset determiner 40 includes a first offset determiner 41 and a second offset determiner 42. The first offset determiner 41 and the second offset determiner 42 determine whether an offset occurs in the first pressure sensor 321 and the second pressure sensor 322, respectively.

[0079] The first offset determiner 41 includes a first control state determiner 411, which is connected to the first pressure sensor 321 to conduct current, and determines the pressure control state of the first brake device 222.

[0080] In the first offset determiner 41, the pressure control of the first brake device 222 is in an OFF state, and if the measurement of the first pressure sensor 321 exceeds a predetermined pressure value while the first shut-off valve 222c is open, it is determined that an offset has occurred in the first pressure sensor 321.

[0081] The second offset determiner 42 includes a second control state determiner 412, which is connected to the second pressure sensor 322 to conduct current and determines the pressure control state of the second brake device 223.

[0082] If the second offset determiner 42 determines that an offset has occurred, the reduction of the abnormal pressure in the second brake device 223 must precede this. The second offset determiner 42 determines that an offset has occurred in the second pressure sensor 322 if the pressure control of the second brake device 223 is activated even after the residual pressure in the second brake device 223 has been reduced and the second shut-off valve 222c is opened.

[0083] Accordingly, the offset detection performance of the second pressure sensor 322 can be further improved, and the offset detection reliability can be further increased.

[0084] A more detailed description of the offset generation determination process of the offset determiner 40 is provided below.

[0085] When the offset determiner 40 determines that an offset of the first pressure sensor 321 or the second pressure sensor 322 has occurred, the offset response device 50 transmits an instruction and a control signal as an offset response to brake devices 222, 223 corresponding to the pressure sensor 32 in which the offset has occurred.

[0086] The offset reaction device 50 is connected to the pressure sensor 32 and the offset determiner 40 in terms of energy, in order to receive an offset generation signal from the offset determiner 40 and to transmit a reaction instruction and a control signal to the pressure sensor 32.

[0087] In the illustrated exemplary embodiment, the offset reaction device 50 includes a feedback pressure calculator 51 and a fall-back switching device 52.

[0088] The feedback pressure calculator 51 calculates the feedback pressure of the brake device based on the estimated internal pressure of the brake device.

[0089] In an exemplary embodiment, the feedback pressure calculator 51 calculates the feedback pressure of the brake device based on the internal pressure value of the brake device, which is estimated by the motor position sensor 31.

[0090] Once it has been determined that an offset of the pressure sensor 32 has occurred, the fall-back switching device 52 converts the pressure sensor 32, in which the offset occurred, to a fall-back state and outputs this information. The fall-back switching device 52 can, for example, alert the driver to the fall-back state by means of a visual or an audible signal.

[0091] In an exemplary embodiment, the pressure of the first brake device 222 is controlled by the feedback pressure derived from the feedback pressure computer 51 when an offset has occurred in the first pressure sensor 321. If, in the exemplary embodiment described above, normal operation of the motor position sensor 31 is impossible, the second brake device 223 performs the vehicle braking.

[0092] In another exemplary embodiment, if an offset occurs in the first pressure sensor 321, the offset reaction device 50 immediately switches the vehicle braking power, which is the subject of the second braking device 223.

[0093] In yet another exemplary embodiment, the fall-back switching device 52 switches the second pressure sensor 322 to a fall-back state when an offset has occurred in the second pressure sensor 322, and outputs this information externally.

[0094] Each component of the vehicle brake system 1 has been described above. The offset determination process of the pressure sensor 32, which is included in the vehicle brake system 1, is described below with reference to the Fig. 6 to Fig. 7 described.

[0095] Fig. Figure 6 illustrates a process in which the first offset determiner 41 determines whether an offset has occurred in the first pressure sensor 321.

[0096] The first offset determiner 41 can determine that the input or release determiner of the brake pedal is not required, and if the pressure control of the first brake device 222 is in an OFF state, it can be determined that no pressure is applied.

[0097] Determining the offset occurrence of the first pressure sensor 321 is based on the assumption that the pressure control of the first brake device 222 is in an OFF state, and that the first shut-off valve 222c is in an open state.

[0098] A point in time at which the measurement of the first pressure sensor 321 exceeds a first reference pressure (P1) is designated as t = t0. Thereafter, if the condition in which the measurement of the first pressure sensor 321 exceeds the first reference pressure (P1) is maintained even after t = t1, the first offset determiner 41 determines that an offset has occurred in the first pressure sensor 321.

[0099] If a time from t = t0 to t = t1 is a first reference time, the first reference time can be changed according to the operating state of the vehicle braking system 1.

[0100] In an exemplary embodiment, the first reference pressure (P1) is 15 bar, and the first reference time is 1 s.

[0101] In summary, the first offset determiner 41 does not require whether the brake pedal is depressed when the first pressure sensor 321 determines that an offset has occurred. Accordingly, the offset of the pressure sensor 321 can be detected regardless of whether the brake pedal is deployed.

[0102] The process by which the second offset determiner 42 determines whether an offset has occurred in the second pressure sensor 322 is described below with reference to Fig. 7 described.

[0103] Similar to the first offset determiner 41, the offset determiner 42 also does not require an input or release determiner of the brake pedal, and determining the occurrence of the first offset by the second pressure sensor 322, and determining the occurrence of the offset by the second pressure sensor 322, requires that the pressure control of the second brake device 223 is in an OFF state, and the second shut-off valve 222c is in an open state.

[0104] A time point at which the measurement of the second pressure sensor 322 exceeds a second reference pressure (P2) is designated as t = t0. Thereafter, if the condition in which the measurement of the second pressure sensor 322 exceeds the second reference pressure (P2) is maintained even after t = t2, the second offset determiner 42 determines that it suspects the occurrence of an offset of the second pressure sensor 322.

[0105] The second offset determiner 42 reduces the internal residual pressure of the second brake device 223 until t = t3 is reached, when the occurrence of the offset of the second pressure sensor 322 is suspected. In this case, the residual pressure of the second brake device 223 can be reduced while the pressure valve 223a and the second relay valve 223b are opened.

[0106] Then, if the condition in which the measurement of the second pressure sensor 322 exceeds a fourth reference pressure is maintained even after reaching t = t4, it is determined that an offset has occurred in the second pressure sensor 322.

[0107] If the time from t = t0 to t = t2, the time from t = t2 to t = t3 and the time from t = t3 to t = t4 are each designated as the second, third and fourth reference time, the second, third and fourth reference time can be changed according to the operating state of the vehicle braking system 1.

[0108] In one exemplary embodiment, the second and fourth reference pressures can be set to be the same. For example, both the second and fourth reference pressures can be set to 15 bar.

[0109] In another exemplary embodiment, each of the second, third, and fourth reference times can be set the same. For example, the second, third, and fourth reference times can all be set to 1 second.

[0110] As described above, the vehicle braking system 1 has been described according to an exemplary embodiment of the present disclosure. The method for controlling the vehicle braking system 1 is described below with reference to the Fig. 8 to Fig. 11 described.

[0111] The method for controlling the vehicle braking system 1 according to an exemplary embodiment of the present disclosure includes the steps of determining whether an offset of the first pressure sensor 321 has occurred (S100), reacting to the occurrence of the offset of the first pressure sensor 321 (S200), performing vehicle braking by the second braking device 223 (S300), determining whether an offset of the second pressure sensor 322 has occurred (S400) and reacting to the occurrence of the offset of the second pressure sensor 322 (S500).

[0112] First, the step (S100) of determining whether an offset of the first pressure sensor 321 has occurred is described.

[0113] The step (S100) of determining whether an offset of the first pressure sensor 321 has occurred includes the steps of measuring the internal pressure of the first brake device 222 by the first pressure sensor 321 (S110) and determining that an offset has occurred in the first pressure sensor 321 (S120).

[0114] After step (S110) of measuring the internal pressure of the first brake device 222 by the first pressure sensor 321, if the condition in which the measurement of the first pressure sensor 431 exceeds a first reference pressure is maintained for more than a first reference time while the first shut-off valve 222c of the first pressure sensor is open, step (S120) of determining that an offset has occurred in the first pressure sensor 321 is carried out.

[0115] Conversely, if the first shut-off valve 222c of the first pressure sensor 321 is not in an open state, or if the state in which the measurement of the first pressure sensor 321 exceeds the first reference pressure for more than the first reference time is not maintained, the step (S120) of determining that the offset has occurred in the first pressure sensor 321 is not performed.

[0116] Then, when the first shut-off valve 222c of the first pressure sensor 321 is opened, and until the condition in which the measured value of the first pressure sensor 321 exceeds the first reference pressure is maintained for more than one first reference time, the above process is repeated.

[0117] If it is determined that an offset of the first pressure sensor 321 has occurred, the step (S200) of reacting to the occurrence of the offset of the first pressure sensor 321 is carried out.

[0118] If the motor position sensor 31 is operating normally, step (S210) of calculating the feedback pressure of the first brake device 222 based on the internal pressure value of the first brake device 222 estimated by the motor position sensor 31 is performed.

[0119] Conversely, if the motor position sensor 31 does not operate normally, the step (S200) of reacting to the occurrence of the offset of the first pressure sensor 321 is terminated, and the second brake device 223 immediately performs the step (S300) of performing vehicle braking and the step (S400) of determining whether an offset of the second pressure sensor 322 has occurred.

[0120] The step (S400) of determining whether an offset of the second pressure sensor 322 has occurred includes the step (S410) of measuring the internal pressure of the second brake device 223 by the second pressure sensor, the step (S420) of assuming that an offset has occurred in the second pressure sensor, the step (S430) of reducing the residual pressure of the second brake device 223 during a third reference time, and the step (S440) of determining that an offset has occurred in the second pressure sensor 322.

[0121] After step (S410) of measuring the internal pressure of the second brake device 223 by the second pressure sensor, if the condition in which the measurement of the second pressure sensor 322 exceeds a second reference pressure is maintained for more than a second reference time while the second shut-off valve 222c of the second pressure sensor is open, step (S420) of presuming that an offset has occurred in the second pressure sensor 322 is performed.

[0122] Conversely, if the second shut-off valve 222c of the second pressure sensor is not in an open state, or if the state in which the measurement of the second pressure sensor 322 exceeds the second reference pressure for more than the first reference time is not maintained, the step (S420) of presuming that the offset has occurred in the second pressure sensor 322 is not performed.

[0123] Then, when the second shut-off valve 222c of the second pressure sensor 322 is opened, and until the condition in which the measured value of the second pressure sensor 322 exceeds the second reference pressure is maintained for more than a second reference time, the above process is repeated.

[0124] If the occurrence of the offset of the second pressure sensor 322 is suspected, the step (S430) of reducing the residual pressure of the second brake device 223 during a third reference time is carried out.

[0125] After the step (S430) of reducing the residual pressure of the second brake device 223 during the third reference time is completed, if the condition in which the measurement of the second pressure sensor 322 exceeds a fourth reference pressure is maintained for more than a fourth reference time, the step (S440) of determining that an offset has occurred in the second pressure sensor 322 is carried out.

[0126] Conversely, if the condition in which the measurement of the second pressure sensor 322 exceeds the fourth reference pressure is not maintained for more than one fourth reference time, step (S440) of determining that an offset has occurred in the second pressure sensor 322 is not performed. In this case, the second pressure sensor 322 immediately returns to measuring the internal pressure of the second brake device 223 after step (S410) and repeats the subsequent process.

[0127] If it is determined that an offset of the second pressure sensor 322 has occurred, step (S500) of reacting to the occurrence of the offset of the second pressure sensor 322 is performed. In an exemplary embodiment, if it is determined that an offset of the second pressure sensor 322 has occurred, the fall-back switching device 52 of the offset reaction device 50 switches the second pressure sensor 322 to a fall-back state and outputs externally.

[0128] Although the above has been described with reference to the preferred exemplary embodiments of the present disclosure, the present disclosure is not limited to the configuration of the exemplary embodiments described above.

[0129] In addition, the present disclosure can be modified and altered in various ways by a person skilled in the art in the field to which the present disclosure belongs, without deviating from the spirit and scope of the present disclosure as set out in the following claims.

[0130] Furthermore, the exemplary embodiments can be configured by selectively combining all or part of each exemplary embodiment in such a way that various modifications can be made. 1 Vehicle braking system 10 Control device 11 Engine control unit 12 Brake control device 20 Drive device 21 engine 22 Brake device 221 Brake fluid reservoir 222 First braking device 222a Flow control valve 222b First relay valve 222c First shut-off valve 223 Second braking device 223a Surface-mounted valve 223b Second relay valve 223c Second shut-off valve 30 Sensor device 31 Engine Position Sensor (MPS) 32 Pressure sensor 321 First pressure sensor 322 Second pressure sensor 40 offset determiners 41 First offset determiner 411 First control state determiner 42 Second Offset Determiner 421 Second control state determiner 50 Offset equivalent section 51 Feedback pressure calculator 52 Fall-Back Changeover Device 2 wheel QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] KR 1020210144532

[0001] KR 101656961 [0007, 0010] KR 1020150046867 [0009, 0010]

Claims

[1] Vehicle braking system, which is a braking system for a fully autonomous vehicle, comprising the following: a first braking device comprising a first shut-off valve for controlling a hydraulic brake pressure transmitted to a wheel cylinder; a first pressure sensor for measuring the internal pressure of the first braking device; and a first offset determiner to determine that an offset has occurred in the first pressure sensor when the first shut-off valve is opened, and the condition in which a measurement of the first pressure sensor exceeds a first reference pressure while more than one first reference time is maintained. [2] Vehicle braking system according to claim 1, further comprising: an offset response device for transmitting an instruction and a control signal as an offset response to the first braking device when the first offset determiner determines that an offset of the first pressure sensor has occurred. [3] Vehicle braking system according to claim 2, wherein the offset reaction device comprises a feedback pressure calculator for calculating a feedback pressure of the first braking device based on an estimated internal pressure of the first braking device after the first offset determiner has determined that an offset of the first pressure sensor has occurred. [4] Vehicle braking system according to claim 3, wherein the feedback pressure calculator calculates a feedback pressure of the first brake device based on an internal pressure of the first brake device estimated by a motor position sensor. [5] Vehicle braking system according to claim 4, further comprising: a second braking device comprising a second shut-off valve for controlling a hydraulic brake pressure transmitted to a wheel cylinder, and performing vehicle braking when normal operation of the engine position sensor is impossible. [6] Vehicle braking system according to claim 1, further comprising: a second braking device comprising a second shut-off valve for controlling a hydraulic brake pressure transmitted to a wheel cylinder and performing vehicle braking when an offset of the first pressure sensor occurs in the first offset determiner. [7] Vehicle braking system according to claim 1, further comprising: a second braking device comprising a second shut-off valve for controlling a hydraulic brake pressure transmitted to a wheel cylinder; a second pressure sensor for measuring the internal pressure of the second brake device; and a second offset determiner to determine whether an offset of the second pressure sensor has occurred. [8] Vehicle braking system according to claim 7, wherein the second brake device opens the second relay valve to relieve residual pressure when the second shut-off valve is open and the condition in which a measurement of the second pressure sensor exceeds a second reference pressure is maintained for more than a second reference time, and wherein the second offset determiner determines whether an offset of the second pressure sensor has occurred after the residual pressure of the second brake device has been relieved. [9] Vehicle braking system according to claim 8, wherein the second offset determiner determines that an offset has occurred in the second pressure sensor when the residual pressure of the second brake device is reduced during a third reference time, and then the condition in which a measurement of the second pressure sensor exceeds a fourth reference pressure while being maintained for more than a fourth reference time. [10] Vehicle braking system according to claim 9, wherein the second reference pressure and the fourth reference pressure are formed to be equal. [11] Vehicle braking system according to claim 9, wherein the second reference time and the fourth reference time are formed to be equal. [12] Vehicle braking system according to claim 9, further comprising a fall-back switching device for switching the second pressure sensor to a fall-back state and outputting to the outside after the second offset determiner has determined that an offset has occurred in the second pressure sensor. [13] Method for controlling a vehicle braking system, which is a method for controlling a combustion system for a fully autonomous vehicle, the method comprising the following steps: (a) Measuring the internal pressure of a first braking device by means of a first pressure sensor; (b) Determining by a first offset determiner that an offset has occurred in the first pressure sensor when a first shut-off valve of the first pressure sensor is open, and the condition in which a measurement of the first pressure sensor exceeds a first reference pressure while more than one first reference time is maintained; and (c) Performing vehicle braking by means of the second braking device. [14] Method according to claim 13, wherein prior to step (c) (c0) calculation of a feedback pressure of the first brake device is performed based on an internal pressure of the first brake device estimated by a feedback pressure calculator from a motor position sensor, and wherein at step (c0) if the normal operation of the motor position sensor is impossible, step (c) is performed immediately. [15] The method of claim 13, further comprising the following steps: (d) Determine by means of a second offset determiner that an offset has occurred in a second pressure sensor; and (e) Switching the second pressure sensor to a fall-back state by means of a fall-back switching device according to step (c). [16] The method of claim 15, wherein step (c) comprises the following steps: (d1) Opening a second shut-off valve of the second pressure sensor and maintaining the condition in which a measurement of the second pressure sensor exceeds a second reference pressure for more than a second reference time; (d2) Reduction of residual pressure of the second braking device during a third reference time; and (d3) Determine by the second offset determiner that an offset has occurred in the second pressure sensor when the second shut-off valve is opened and the condition in which a measurement of the second pressure sensor exceeds a fourth reference pressure for more than a fourth reference time is maintained.

Images