A brake lamp switch detection and control device and a driver braking request recognition method

Abstract

The present invention discloses a brake lamp switch detection and control device, a method for processing the signal of a pedal travel sensor of an electronic control braking system, and a discrimination method for controlling the lighting of the tail lamp during braking derived from the switch detection and control device and its signal processing method, providing a reliable and stable brake tail lamp lighting control signal to the body controller; in addition, the technical processing method of the pedal travel sensor signal also provides a method for reliably identifying the braking demand of the vehicle driver, providing a basis for braking energy recovery control.

Description

Technical Field

[0001] The present invention relates to the technical field of ADAS, and particularly to a brake lamp switch detection and control device and a driver braking request recognition method. Background Art

[0002] There is a certain gap between the brake pedal input rod and the reaction disk in the brake assist system and the traditional vacuum brake booster. This gap is a free gap, which is generally used to prevent actual braking behavior caused by non-braking intentions due to the bumpy vibration of the vehicle on an uneven road surface; in the design intention, this free gap is also an error correction adjustment mechanism for when the driver misjudges and applies the brake. When the vehicle is driving and vibrating bumpily, but the driver has no subjective intention to brake, due to the existence of this free gap, non-intentional braking behavior will not occur. This free gap absorbs the vibration displacement of the pedal input rod.

[0003] However, in the case of an electronically controlled brake assist system, since the pedal input rod is closely related to the pedal travel sensor, due to vibration, even a small stroke of the pedal input rod will cause the pedal travel sensor to generate a signal. Therefore, in order to reliably identify the driver's braking intention and braking demand, the signal of the pedal travel sensor requires some technical means for processing.

[0004] In addition, the electro-mechanical-hydraulic intelligent brake assist device that does not rely on a vacuum source at all is a control execution device for new energy vehicles to achieve higher braking energy efficiency, shorten the braking distance, and improve safety. Its biggest feature is that it replaces the traditional vacuum booster. In addition to realizing the performance of the traditional vacuum booster, it can realize value-added functions: (1) artificial intelligent pedal feel control; (2) braking execution of advanced assisted driving automatic emergency braking AEB and braking execution of adaptive cruise control ACC; (3) braking control for the recovery and regeneration of braking energy.

[0005] Since this mechanism needs to be provided with a sensor for detecting the displacement stroke of the brake pedal input rod, the function of this sensor can replace the traditional switch analog brake lamp switch, provide a highly reliable digital signal with high confidence to the body control module BCM (Body Control Module), improve the driving safety of the vehicle, remove the mechanical brake lamp switch, and reduce costs.

[0006] The brake tail lamp signal (BLS: BrakeLightSwitch) is a mandatory automotive regulation item. The premise for triggering the function of the automotive anti-lock braking system ABS is that the driver steps on the brake pedal. At the same time, the brake lamp switch signal is sent to the electronic control unit ECU for plausibility judgment of the ABS control strategy to ensure the safety and stability of the vehicle longitudinal braking control execution.

[0007] In terms of the related item definition BLS of the functional safety definition of the vehicle lateral stability control ESC and the longitudinal stability control ABS, since the related item BLS can be included, the ESC / ABS system can effectively monitor the BLS signal status, and the signal of BLS can achieve redundant verification. Therefore, the functional safety design of the vehicle system reduces the risk of functional failure.

[0008] In addition, the function of the brake tail lamp is also a consideration factor in the functional safety evaluation of the ADAS function automatic emergency braking AEB. When the driver steps on the brake pedal, the two situations of the normal lighting and the non-lighting due to functional failure of the brake tail lamp function are one of the design evaluation indicators for the maximum braking deceleration that AEB can implement.

[0009] In the prior art, in the Chinese invention patent with the patent number CN201710940474.8, the applicant, Mando Corporation, disclosed an electronic braking system and its control method. The electronic braking system of the first embodiment of the present invention includes an oil pressure control device that generates hydraulic pressure by using a piston that operates based on an electrical signal output corresponding to the displacement of the brake pedal. The electronic braking system includes: a pedal stroke sensing unit that measures the moving distance and the change amount of the moving distance of the brake pedal; and a control unit that determines the driver's initial braking intention based on the measured moving distance and the change amount of the moving distance of the pedal, and when it is determined that there is an initial braking intention, executes initial braking control.

[0010] The idea of the above patent is to judge the driver's braking intention by setting multiple critical values, that is, to confirm the driver's braking will by the depth of the driver stepping on the brake pedal (the moving distance of the pedal stroke and the change amount of the moving distance of the pedal stroke). However, the algorithm determination threshold for the start of the initial braking in the above patent is a fixed threshold A, which cannot implant the dynamic compensation required for the wear and aging of each related component and the pedal vibration signal noise during the service life of the vehicle. In terms of considering the functional safety of the electronic braking system, there is no consideration of the redundant scheme for the brake pedal displacement electrical signal, and the safety measures for fault failure are missing. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to provide a brake lamp switch detection device for an electronic braking system and a processing method for the signal of the pedal travel sensor in view of the above technical status, so as to provide a discrimination method for controlling the lighting of the brake tail lamp during braking, and provide a reliable and stable brake tail lamp lighting control signal to the body controller; in addition, the technical processing method for the signal of the pedal travel sensor provides a method for reliably identifying the braking demand of the vehicle driver, and provides a basis for the control of brake energy recovery.

[0012] To achieve the above object, the present invention provides the following technical solutions:

[0013] A braking light switch detection and its control method, which includes the following processes:

[0014] S1. After stepping on the pedal, the original signal of the pedal stroke is input by the stroke sensor;

[0015] S2. The original signal of the pedal stroke sensor is processed by shaping such as offset difference to obtain the calibrated stroke signal value Pt;

[0016] S3. If Pt is greater than the dynamic threshold Th for determining the lighting of the braking tail light BLS, execute BLS-ON. If Pt is less than Th, then keep BLS-Off;

[0017] S4. When Pt > Th, transmit the BLS-ON status signal to the vehicle data bus. After the body control module obtains the BLS status signal from the data bus, it triggers the lighting of the braking tail light;

[0018] S5. When the braking pedal is released, the BLS-ON status remains unchanged temporarily. When Pt < Th appears, after maintaining the BLS-ON status for ∆t time, then implement BLS-Off.

[0019] As a specific technical solution of the present invention, Th = Pf + Cs. The signal Pf is obtained after Pt passes through low-pass filtering, and Cs is a bias constant, which is set in consideration of the hysteresis between the pedal stroke sensor signal and the mechanism movement.

[0020] As a further explanation of the present invention, under the condition of meeting BLS-ON, the dynamic condition of the driver's braking request is calculated according to the gradient, and the magnitude of grd = ∆m / ∆τ is used to identify the intensity of the braking intention. The larger the grd value, the stronger the braking intention. This information is transmitted to the vehicle data bus, and the vehicle control unit calculates and coordinates the braking torque to implement the control of braking energy recovery.

[0021] As a specific technical solution of the present invention, ∆t is the time difference between the critical state when Pt < Th and when Pt drops to a low-frequency signal.

[0022] A device for detecting and controlling a brake light switch using the above control method, which is built into a brake and is characterized in that: it includes a power-assisting motor, a motor shaft of the power-assisting motor is connected to a ball screw through a gear transmission pair, the ball screw is hollow inside to form a channel, a pedal input rod is inserted in the channel, a magnet is sleeved on the pedal input rod, a sensor chip is fixed on the inner wall of the brake, the sensor chip is facing the magnet, when the pedal input rod reciprocates, it can drive the magnet to move, thereby causing the magnetic flux of the sensor chip to change, the sensor chip is connected to an ECU, the sensor chip can output the magnetic flux change data to the ECU in the form of an electrical signal to implement redundant simulation verification, the ECU is connected to the power-assisting motor, if the magnetic circuit and chip circuit associated with the sensor device fail, the fault diagnosis mechanism of the ECU can block the execution of the electric control brake and trigger an alarm display;

[0023] It also includes a brake master cylinder, in which a piston push rod is arranged, and a reaction disk is sleeved on the rear end of the piston push rod. The reaction disk is located within the stroke range of the pedal input rod, and the front end of the pedal input rod can contact the reaction disk.

[0024] As an improvement of the present invention, the sensor device composed of the magnetic circuit including the pedal input rod and the sensor chip generates a linear signal for the displacement stroke signal, which is convenient for accurate control of the brake assist.

[0025] Compared with the prior art, the advantages of the present invention are: establishing an electronically controlled brake system brake switch detection device and a method for processing pedal travel sensor signals thereof, thereby providing a method for determining whether the taillights are lit during braking, and providing a reliable and stable brake taillight lighting control signal to the vehicle body controller; the magnet of the pedal travel sensor in this case is fixed to the input rod, the magnet is selected as a multi-segment SN pole, and the sensor chip is placed in a fixed position of the brake system housing ( Figure 1). When the brake pedal input rod moves, the magnetic flux of the chip changes, and the two-way signals of the sensor chip generated are output to the ECU for redundant simulation verification. If a failure occurs in the magnetic circuit and chip circuit associated with the sensor device, the fault diagnosis mechanism of the ECU shuts off the execution of the electro-hydraulic brake and triggers an alarm display to ensure vehicle safety. Since the stroke range of the brake pedal input rod is generally below 50 mm, it is required that this sensor has a very high resolution (0.01 mm) to correspond to the pressure control of up to 100 Bar in the braking system. In this case, a low-pass filter is used to set a dynamic threshold to determine the authenticity of the braking implementation intention, which can eliminate the pedal stroke signal noise caused by the looseness impact generated by the wear of the brake pedal hinge and other connecting components, and provide a stable input signal for the control of the brake tail lamp. In addition, the trigger condition for the longitudinal stability control anti-lock braking system (ABS) of the braking wheels is that the driver steps on the pedal to apply the brake. Having a stable and reliable braking true intention discrimination signal BLS is a necessary condition for ensuring the safe and reliable timely function of the ABS. In addition, the technical processing method of the pedal stroke sensor signal provides a method for reliably identifying the braking demand of the vehicle driver, and provides a basis for the control of braking energy recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 FIG. is a schematic structural diagram of an electro-hydraulic brake assist system in an embodiment of the present invention;

[0027] Figure 2 FIG. is a schematic diagram of a pedal stroke sensor signal in an embodiment of the present invention;

[0028] Figure 3 FIG. is a BLSOn-Off discrimination and braking request gradient flow chart. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The present invention will be further described in detail below in conjunction with the embodiments of the drawings.

[0030] As shown in the drawings, this embodiment is a brake lamp switch detection and control device and a method for identifying a driver's braking request, which is mounted on an electro-hydraulic brake assist system. The structure of the electro-hydraulic assist system is as Figure 1As shown in the figure, it includes an assist motor M. A ball screw 2 is connected to the motor shaft of the assist motor through a gear transmission pair 1. The inside of the ball screw is hollow to form a channel, and a pedal input rod 3 is inserted into the channel. A magnet 4 is sleeved on the pedal input rod. A sensor chip 5 is fixed on the inner wall of the brake. The sensor chip and the magnet constitute a stroke sensor. The sensor chip faces the magnet. When the pedal input rod reciprocates, it can drive the magnet to move, thereby causing a change in the magnetic flux of the sensor chip. The sensor chip is connected to the ECU. The sensor chip can output the magnetic flux change data to the ECU in the form of two-way electrical signals for redundant simulation verification. The ECU is connected to the assist motor. If a fault occurs in the magnetic circuit and chip circuit associated with the sensor device, the fault diagnosis mechanism of the ECU can cut off the execution of the electric control brake and trigger an alarm display;

[0031] It also includes a master brake cylinder 6. A piston push rod 7 is arranged in the master brake cylinder. A reaction disc 8 is sleeved on the rear end of the piston push rod. The reaction disc is within the stroke range of the pedal input rod, and the front end of the pedal input rod can come into contact with the reaction disc.

[0032] The brake pedal pushes the piston push rod of the master brake cylinder to move through a pedal push rod, and the electric brake assist device is used to assist in pushing the piston push rod of the master brake cylinder to move. The electric brake assist device adopts a ball screw pair combined with a reaction disc structure, which can convert the torque output by the rotation of the motor into the linear motion of the output rod. Furthermore, during the braking process, by controlling the rotation of the motor, the movement of the piston push rod of the master brake cylinder is achieved.

[0033] The working principle of this embodiment is that when the driver steps on the brake pedal, due to the movement of the pedal input rod, the stroke sensor generates a signal. According to this signal, the control strategy calculates the response requirements for the required brake assist, determines the drive execution instruction of the assist motor, the motor drives the gear reduction mechanism, drives the ball screw nut to rotate, and the ball screw realizes a reciprocating propulsion motion, assisting in pushing the reaction disc to establish the pressure of the master brake cylinder, thereby realizing the electric control brake assist function. Subsequently, the original signal of the pedal stroke sensor undergoes shaping processing such as offset difference to obtain the calibrated stroke signal value Pt (such as Figure 3 BLSOn - Off discrimination and brake request gradient flow chart).

[0034] Pt is filtered through a low - pass filter to obtain the signal Pf. Using a low - pass filter to set a dynamic threshold to judge the authenticity of the braking implementation intention can eliminate the pedal stroke signal noise caused by the looseness impact generated by the wear of the brake pedal hinge and other connecting components, and provide a stable input signal for the control of the brake tail lamp.

[0035] The dynamic threshold for judging the lighting of the brake tail lamp BLS: Th = Pf + Cs.

[0036] Cs is set as a constant as a bias quantity in consideration of the hysteresis between the pedal travel sensor signal and the mechanism movement.

[0037] When the brake pedal is depressed and Pt > Th, BLS-ON is executed (otherwise, BLS-Off is maintained); the BLS-ON status signal is transmitted to the vehicle data bus, and after the body control module obtains the BLS status signal from the data bus, it triggers the opening and closing of the brake tail lamp.

[0038] Under the condition of satisfying BLS-ON, the dynamic condition of the driver's braking request is calculated according to the gradient:

[0039] The magnitude of grd = ∆m1 / ∆τ1 identifies the intensity of the braking intention. This information is transmitted to the vehicle data bus, and the vehicle control unit calculates and coordinates the braking torque to implement the control of braking energy recovery.

[0040] When the brake pedal is released, the BLS-ON status is temporarily maintained unchanged. When Pt < Th appears, after maintaining the BLS-ON status for ∆t time, BLS-Off is implemented. The significance of maintaining BLS-ON for ∆t time lies in the hysteresis effect of the hydraulic pressure return of the vehicle braking system. Since it is still in the braking execution stage, it is necessary to continue to keep the brake tail lamp lit (BLS-ON).

[0041] However, when starting to determine the lighting of the brake tail lamp (BLS-ON), there is no design for a lag lighting time. The purpose is to light the tail lamp in time to notify the driver of the following vehicle to take control to ensure a safe distance.

[0042] The above is only the preferred implementation manner of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A control method for a brake light, which includes the following processes: S1. After stepping on the pedal, the original pedal travel signal is input by the travel sensor; S2. The original signal of the pedal travel sensor is processed by offset differential shaping to obtain the calibrated travel signal value Pt; S3. If Pt is greater than the dynamic threshold Th for determining the illumination of the brake tail lamp BLS, execute BLS-ON. If Pt is less than Th, then keep BLS-Off. Th = Pf + Cs. After Pt passes through low-pass filtering, the signal Pf is obtained. Cs is a bias constant, which is set considering the hysteresis between the pedal travel sensor signal and the mechanism movement; S4. When Pt > Th, transmit the BLS-ON status signal to the vehicle data bus. After the body control module obtains the BLS-ON status signal from the data bus, it triggers the illumination of the brake tail lamp; S5. When the brake pedal is released, the BLS-ON status remains temporarily unchanged. When Pt < Th appears, after maintaining the BLS-ON status for a duration of ∆t, then implement BLS-Off.

2. The control method of the brake lamp according to claim 1, wherein: Under the condition of meeting BLS-ON, the dynamic condition of the driver's braking request is calculated according to the gradient, and the magnitude of grd = ∆m / ∆τ is used to identify the intensity of the braking intention. The larger the grd value, the stronger the braking intention. This information is transmitted to the vehicle data bus, and the vehicle control unit calculates and coordinates the braking torque to implement the control of braking energy recovery, where Δm represents the gradient change amount of the pedal travel amplitude, and Δτ represents the time change amount.

3. The control method of the brake lamp according to claim 1, wherein: ∆t is the time difference between the critical state when Pt < Th and when Pt drops to a low-frequency signal.

4. An apparatus for detecting and controlling a brake lamp switch by using the control method as described in claim 1, which is built into a brake, characterized in that: It includes an assist motor. A ball screw is connected to the motor shaft of the assist motor through a gear transmission pair. The inside of the ball screw is hollow to form a channel. A pedal input rod is inserted into the channel. A magnet is sleeved on the pedal input rod. A sensor chip is fixed on the inner wall of the brake. The sensor chip faces the magnet. When the pedal input rod reciprocates, it can drive the magnet to move, thereby causing a change in the magnetic flux of the sensor chip. The sensor chip is connected to the ECU. The sensor chip can output the magnetic flux change data to the ECU in the form of two-way electrical signals for redundant simulation verification. The ECU is connected to the assist motor. If a fault occurs in the magnetic circuit and chip circuit associated with the sensor device, the fault diagnosis mechanism of the ECU can cut off the execution of the electro-hydraulic brake and trigger an alarm display; it also includes a brake master cylinder. A piston push rod is arranged in the brake master cylinder. A reaction plate is sleeved at the rear end of the piston push rod. The reaction plate is within the travel range of the pedal input rod, and the front end of the pedal input rod can come into contact with the reaction plate.

5. The device for detecting and controlling a brake light switch according to claim 4, characterized in that: The sensor device composed of the magnetic circuit including the pedal input rod and the sensor chip generates a displacement travel signal that is a linear signal, which is convenient for accurately controlling the brake assist.

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