Low-speed unmanned vehicle braking redundancy control method and system

Abstract

The invention belongs to the technical field of automatic driving of low-speed unmanned vehicles, and particularly relates to a brake redundancy control method for a low-speed unmanned vehicle. In order to solve the technical problem of brake safety of a low-speed unmanned vehicle, the method comprises the following steps: service brake redundancy control: judging whether actual pressure collected by a hydraulic sensor reaches a target hydraulic value or not, and reaching a brake-by-wire unit holding state; otherwise, whether the brake-by-wire unit can build voltage is judged, and if the brake-by-wire unit can build voltage due to function degradation, the electronic stability control unit participates in voltage building; if the brake-by-wire unit cannot build the voltage, the electronic stability control unit builds the voltage directly; parking brake redundancy control: judging whether the brake-by-wire unit fails or not, if the brake-by-wire unit is effective, issuing a parking instruction to the electronic stability control unit, then the brake-by-wire unit controls a left parking brake, and the electronic stability control unit controls a right parking brake; and if the vehicle fails, the electronic stability control unit controls and issues a parking instruction to control the right parking brake.

Description

Technical Field

[0001] This invention belongs to the field of autonomous driving technology for low-speed unmanned vehicles, and specifically relates to a braking redundancy control method for low-speed unmanned vehicles. Background Technology

[0002] With the rapid development of autonomous driving technology, low-speed unmanned vehicles (UAVs) have seen explosive growth in their application in the logistics field due to their unique advantages. Low-speed UAVs are characterized by relatively low operating speeds and high operational flexibility, enabling them to efficiently complete tasks such as cargo transportation, sorting, and delivery in relatively enclosed or semi-enclosed environments such as warehouses, logistics parks, and distribution stations. This significantly improves the automation level and efficiency of logistics operations, effectively reduces labor costs, and has become a key force driving the intelligent transformation of the logistics industry.

[0003] As a critical safety component of low-speed autonomous vehicles, the stability and reliability of the braking system directly affect the safety of the vehicle and surrounding personnel and property. A malfunction or failure in the braking system could lead to serious accidents, such as loss of control and collisions, or damage to cargo, causing not only economic losses but also potential endangerment of lives. Therefore, ensuring the reliable operation of the braking system under all circumstances is one of the core issues for the safe operation of low-speed autonomous vehicles.

[0004] Currently, most existing low-speed autonomous vehicle braking systems employ a single braking control method. While this design can meet basic braking requirements to some extent, it has significant limitations when facing complex operating conditions and sudden malfunctions. On one hand, the single braking control method lacks sufficient redundancy. When the main braking system fails, it cannot quickly switch to the backup braking mode, causing the vehicle to lose braking ability and thus creating safety hazards. For example, in cases of leakage in the main braking hydraulic system, malfunction of the electronic control unit (ECU), or abnormal sensor signals, the vehicle may fail to brake effectively and in a timely manner, increasing the risk of accidents.

[0005] In summary, existing low-speed unmanned vehicle braking systems have many shortcomings in redundancy design, making it difficult to meet the ever-increasing braking requirements. Therefore, a low-speed unmanned vehicle braking redundancy control method and system are proposed. Summary of the Invention

[0006] To address the technical problem of "braking safety of low-speed unmanned vehicles," this invention provides the following technical solution: Firstly, This invention provides a low-speed unmanned vehicle braking redundancy control method, including: driving brake redundancy control and parking brake redundancy control. 1) The redundant control of the service brake includes: The brake-by-wire unit receives the target hydraulic pressure value from the chassis domain controller and determines whether the actual pressure of the brake or parking brake collected by the hydraulic sensor reaches the target hydraulic pressure value. If it does, the brake-by-wire unit maintains its state; otherwise, it determines whether the brake-by-wire unit can build up pressure. If the brake-by-wire unit can build up pressure with its function degraded, the electronic stability control unit participates in building up pressure to reach the target hydraulic pressure value; if the brake-by-wire unit cannot build up pressure, the electronic stability control unit directly builds up pressure to reach the target hydraulic pressure value. 2) The parking brake redundancy control includes: The brake-by-wire unit receives the parking command from the chassis domain controller and determines whether the brake-by-wire unit has failed. If it is valid, it sends a parking command to the electronic stability control unit, in which case the brake-by-wire unit controls the left parking brake and the electronic stability control unit controls the right parking brake. If it fails, the electronic stability control unit sends a parking command to control the right parking brake.

[0007] Furthermore, when the electronic stability control unit is unable to execute the parking command, the brake-by-wire unit controls the left parking brake assembly to execute the parking command, retaining 50% of the parking capability.

[0008] Furthermore, when the electronic stability control unit is involved in voltage build-up, the brake-by-wire unit and the electronic stability control unit work simultaneously.

[0009] Furthermore, when the chassis domain controller communication signal is lost but the brake-by-wire unit communication is not lost, the brake-by-wire unit will refer to the vehicle speed signal issued by the electronic stability control unit and adopt different control methods according to different vehicle speeds.

[0010] Furthermore, when the vehicle speed is greater than 0.5 km / h, the brake-by-wire unit will build up pressure at a rate of 0.2 MPa / 10 milliseconds until the hydraulic pressure reaches 6 MPa. After the vehicle stops, the pressure is maintained for 3 minutes. After 3 minutes, the two parking brakes are requested to work. The parking brakes perform parking braking. 100 milliseconds after parking is completed, the hydraulic pressure is disengaged. When the vehicle speed is less than or equal to 0.5 km / h, the brake-by-wire unit directly requests the two parking brakes to operate, and the parking brakes perform the parking operation.

[0011] Furthermore, when the chassis domain controller and brake-by-wire unit lose communication simultaneously, the electronic stability control unit adopts different control methods according to different vehicle speeds.

[0012] Furthermore, when the vehicle speed exceeds 0.5 km / h, the electronic stability control unit builds up pressure at a rate of 0.2 MPa / 10 milliseconds until the hydraulic pressure reaches 4 MPa. After the vehicle stops, The vehicle brakes and parking system engages hydraulically 100 milliseconds after the parking maneuver is complete. When the vehicle speed is less than or equal to 0.5 km / h, the electronic stability control unit directly requests the right parking brake, and the right parking brake performs the parking operation.

[0013] Secondly, This invention provides a low-speed unmanned vehicle braking redundancy control system, as a hardware device for performing any of the methods described above, the system comprising: The electronic stability control unit can actively establish hydraulic pressure; it receives wheel speed signals from the four wheels, outputs wheel speed, and performs composite calculations on the wheel speeds to output the overall vehicle speed. The brakes are installed on both front wheels. The brakes use hydraulic pressure to clamp the calipers and slow down the vehicle. The brakes are connected to the electronic stability control unit through brake lines. The parking brake includes a left parking brake for the left wheel and a right parking brake for the right wheel. The parking brake can not only use hydraulic pressure to clamp the caliper and slow down the vehicle, but also use its motor to clamp the caliper and complete the parking. The parking brake is connected to the electronic stability control unit through a brake line; and the left parking brake is connected to the electronic stability control unit. The hydraulic sensor, installed inside the electronic stability control unit, is used to detect the pressure in the brake lines; The brake-by-wire unit communicates with the electronic stability control unit and is used to establish and release the hydraulic pressure of the brake and parking brake by controlling the forward and reverse rotation of the motor; the brake-by-wire unit is connected to the right parking brake. The chassis domain controller is connected to the brake-by-wire unit and the electronic stability control unit, respectively, and can send braking commands to the brake-by-wire unit and the electronic stability control unit. The chassis communication network is connected to the chassis domain controller, brake-by-wire unit, and electronic stability control unit. The chassis domain controller transmits braking commands to the brake-by-wire unit and electronic stability control unit through the chassis communication network.

[0014] Furthermore, it also includes: The chassis communication network is connected to the chassis domain controller, brake-by-wire unit, and electronic stability control unit. The chassis domain controller transmits braking commands to the brake-by-wire unit and electronic stability control unit through the chassis communication network.

[0015] Furthermore, it also includes: Wheel speed sensors are provided for all four wheels. The wheel speed sensors are connected in communication with the electronic stability control unit and output the speed of the four wheels to the electronic stability control unit.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention proposes a braking redundancy control method for low-speed unmanned vehicles, which has redundancy in driving brakes, improving driving brake safety; it also has redundancy in parking brakes, ensuring the braking safety of low-speed unmanned vehicles.

[0017] This invention proposes a braking redundancy control method for low-speed unmanned vehicles. By designing the architecture of the braking system controller, it first realizes the redundancy design of driving brake and parking brake in physical hardware, and then realizes a multi-level braking redundancy control scheme through software control to ensure the braking safety of the whole vehicle.

[0018] This invention proposes a hardware design scheme for implementing redundant braking control of low-speed unmanned vehicles.

[0019] This invention proposes a control method in which the braking hardware actively establishes pressure or executes parking when communication with the chassis domain controller is lost, thereby ensuring the braking safety of the entire vehicle. Attached Figure Description

[0020] Figure 1 This is a block diagram of the overall hardware configuration of the braking redundancy control system of the present invention; Figure 2 The principle flow of redundant control for vehicle braking in this invention Figure 1 ; Figure 3 The following is the flow chart of the redundant control principle for vehicle braking in this invention. Figure 2 ; Figure 4 This is a flowchart illustrating the parking brake redundancy control principle of the present invention. Detailed Implementation

[0021] The technical solution of the present invention will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0022] Example 1 A method for redundant braking control of a low-speed unmanned vehicle includes: redundant control of the driving brake and redundant control of the parking brake. 1) The redundant control of the service brake includes: The brake-by-wire unit receives the target hydraulic value from the chassis domain controller and determines whether the actual pressure collected by the hydraulic sensor reaches the target hydraulic value. If it does, the brake-by-wire unit maintains its state; otherwise, it determines whether the brake-by-wire unit can build up pressure. If the brake-by-wire unit can build up pressure with its function degraded, the electronic stability control unit participates in building up pressure to reach the target hydraulic value; if the brake-by-wire unit cannot build up pressure, the electronic stability control unit directly builds up pressure to reach the target hydraulic value. 2) The parking brake redundancy control includes: The brake-by-wire unit receives the parking command from the chassis domain controller and determines whether the brake-by-wire unit has failed. If it is valid, it sends a parking command to the electronic stability control unit, in which case the brake-by-wire unit controls the left parking brake and the electronic stability control unit controls the right parking brake. If it fails, the electronic stability control unit sends a parking command to control the right parking brake.

[0023] Specifically, Service brake redundancy control: (1) Under normal working conditions of each component: The chassis domain controller sends the target hydraulic value to the chassis communication network. The brake-by-wire unit controls the motor to perform work according to the received target hydraulic value. The hydraulic pressure fed back by the signal collected by the hydraulic sensor inside the electronic stability control unit is used for closed-loop control. When the hydraulic sensor collects the actual pressure value of the brake or parking brake and it reaches the target hydraulic value, the brake-by-wire unit maintains this state. (2) When the function of the brake-by-wire unit is downgraded and the target pressure value cannot be reached, the electronic stability control unit will intervene to build up pressure so that the actual pressure reaches the target value requirement; at this time, the brake-by-wire unit and the electronic stability control unit work at the same time.

[0024] (3) When the brake-by-wire unit fails to build up pressure, the electronic stability control unit will perform pressure building to achieve the target pressure requirement.

[0025] (4) When the chassis domain controller communication signal is lost, the brake-by-wire unit will refer to the vehicle speed signal sent by the electronic stability control unit and adopt different control methods according to different vehicle speeds: When the vehicle speed is greater than 0.5 km / h, the brake-by-wire unit will build up pressure at a rate of 0.2 MPa / 10 milliseconds until the hydraulic pressure reaches 6 MPa. After the vehicle stops, the pressure is maintained for 3 minutes. After 3 minutes, the two parking brakes are requested to operate (the brake-by-wire unit itself will control the left parking brake to operate and simultaneously send a parking command to the chassis communication network. After receiving the command, the electronic stability control unit will control the right parking brake to operate). The parking brake will perform the parking brake operation. 100 milliseconds after parking is completed, the hydraulic pressure will disengage. When the vehicle speed is less than or equal to 0.5 km / h, the brake-by-wire unit directly requests the two parking brakes to operate (the brake-by-wire unit itself controls the left parking brake to operate, and at the same time sends a parking command to the chassis communication network. After receiving the command, the electronic stability control unit controls the right parking brake to operate), and the parking brakes perform the parking operation.

[0026] (5) When the chassis domain controller and the brake-by-wire unit lose communication simultaneously, the electronic stability control unit adopts different control methods according to different vehicle speeds: When the vehicle speed exceeds 0.5 km / h, the electronic stability control unit builds up pressure at a rate of 0.2 MPa / 10 milliseconds until the hydraulic pressure reaches 4 MPa. After the vehicle stops, it requests... The parking brake engages the parking brake, and hydraulically disengages 100 milliseconds after parking is completed. When the vehicle speed is less than or equal to 0.5 km / h, the electronic stability control unit directly requests the right parking brake, and the right parking brake performs the parking operation.

[0027] Parking brake redundancy: (1) The brake-by-wire unit and the electronic stability control unit each control one parking brake. Under normal working conditions, the brake-by-wire unit receives the parking command from the chassis domain controller and sends the command to the electronic stability control unit. The brake-by-wire unit controls the left parking brake, and the electronic stability control unit controls the right parking brake. (2) When the brake-by-wire unit fails and cannot execute and issue EPB (electronic parking brake system) control commands, the electronic stability control unit directly issues parking commands and controls the right parking brake assembly to execute parking commands, retaining 50% of the parking capacity. (3) When the electronic stability control unit is unable to execute the parking command, the brake-by-wire unit controls the left parking brake assembly to execute the parking command, retaining 50% of the parking capability; Example 2 like Figure 1 As shown, the present invention provides a low-speed unmanned vehicle braking redundancy control system as a hardware device for executing the method described in Embodiment 1. The system includes: Wheel speed sensors are provided on all four wheels to detect the rolling of the toothed rings on the four wheels and output the rotational speed signals of the four wheels; the wheel speed sensors are communicatively connected to the electronic stability control unit. The electronic stability control unit can actively establish hydraulic pressure; it can output wheel speed by receiving wheel speed signals from the four wheels, and perform composite calculations on the wheel speeds to output the overall vehicle speed. The brakes are installed on both front wheels. The brakes use hydraulic pressure to clamp the calipers and slow down the vehicle. The brakes are connected to the electronic stability control unit through brake lines. The parking brake is installed on each of the two rear wheels, including a left parking brake and a right parking brake. The parking brake not only uses hydraulic pressure to clamp the calipers and slow the vehicle down, but also uses a motor to clamp the calipers and complete the parking maneuver. The parking brake is connected to the electronic stability control unit via brake lines. The hydraulic sensor, installed inside the electronic stability control unit, is used to detect the pressure in the brake lines; The brake-by-wire unit, communicating with the electronic stability control unit, is used to establish and release the hydraulic pressure of the brakes and parking brake by controlling the forward and reverse rotation of its motor. The brake-by-wire unit is connected to the right parking brake corresponding to the right rear wheel; parking is achieved by outputting current from the brake-by-wire unit to activate the right parking brake. The chassis domain controller is connected to the brake-by-wire unit and the electronic stability control unit, respectively, and can send braking commands to the brake-by-wire unit and the electronic stability control unit. The chassis communication network is connected to the chassis domain controller, brake-by-wire unit, and electronic stability control unit. The chassis domain controller transmits braking commands (which can be hydraulic control commands and parking commands) to the brake-by-wire unit and electronic stability control unit through the chassis communication network.

[0028] The electronic stability control unit receives hydraulic pressure values ​​detected by the hydraulic sensors and feeds them back to the chassis communication network. When the brake-by-wire unit experiences a decrease or loss of brake pressure build-up, the electronic stability control unit intervenes to execute hydraulic braking commands. Parking is activated by the electronic stability control unit outputting current to engage the parking brake.

[0029] The above technical features constitute the preferred embodiment of the present invention, which has strong adaptability and optimal implementation effect. Non-essential technical features can be added or removed according to actual needs to meet the needs of different situations.

[0030] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for redundant braking control of a low-speed unmanned vehicle, characterized in that, include: Service brake redundancy control and parking brake redundancy control 1) The redundant control of the service brake includes: The brake-by-wire unit receives the target hydraulic value from the chassis domain controller and determines whether the actual pressure of the brake or parking brake collected by the hydraulic sensor has reached the target hydraulic value. If it has, the brake-by-wire unit maintains its state; otherwise, it determines whether the brake-by-wire unit can build up pressure. If the brake-by-wire unit can build up pressure after its function is downgraded, the electronic stability control unit participates in building up pressure to make the actual pressure reach the target hydraulic value; if the brake-by-wire unit cannot build up pressure, the electronic stability control unit directly builds up pressure to make the actual pressure reach the target hydraulic value. 2) The parking brake redundancy control includes: The brake-by-wire unit receives the parking command from the chassis domain controller and determines whether the brake-by-wire unit has failed. If it is valid, it sends a parking command to the electronic stability control unit, and the brake-by-wire unit controls the left parking brake, while the electronic stability control unit controls the right parking brake. If it fails, the electronic stability control unit sends a parking command to control the right parking brake.

2. The low-speed unmanned vehicle braking redundancy control method according to claim 1, characterized in that, In step 2), when the electronic stability control unit is unable to execute the parking command, the brake-by-wire unit controls the left parking brake assembly to execute the parking command, retaining 50% of the parking capability.

3. The low-speed unmanned vehicle braking redundancy control method according to claim 1, characterized in that, When the electronic stability control unit is involved in voltage build-up, the brake-by-wire unit and the electronic stability control unit work simultaneously.

4. The low-speed unmanned vehicle braking redundancy control method according to claim 1, characterized in that, When the chassis domain controller communication signal is lost but the brake-by-wire unit communication is not lost, the brake-by-wire unit will refer to the vehicle speed signal sent by the electronic stability control unit and take different control methods according to different vehicle speeds.

5. The low-speed unmanned vehicle braking redundancy control method according to claim 4, characterized in that, When the vehicle speed is greater than 0.5 km / h, the brake-by-wire unit will build up pressure at a rate of 0.2 MPa / 10 milliseconds until the hydraulic pressure reaches 6 MPa. After the vehicle stops, the pressure is maintained for 3 minutes. After 3 minutes, the two parking brakes are requested to work. The two parking brakes perform parking braking. 100 milliseconds after parking is completed, the hydraulic pressure is released. When the vehicle speed is less than or equal to 0.5 km / h, the brake-by-wire unit directly requests the two parking brakes to operate, and the parking brakes perform the parking operation.

6. The low-speed unmanned vehicle braking redundancy control method according to claim 1, characterized in that, When the chassis domain controller and brake-by-wire unit lose communication simultaneously, the electronic stability control unit adopts different control methods according to different vehicle speeds.

7. The low-speed unmanned vehicle braking redundancy control method according to claim 6, characterized in that, When the vehicle speed exceeds 0.5 km / h, the electronic stability control unit builds up pressure at a rate of 0.2 MPa / 10 milliseconds until the hydraulic pressure reaches 4 MPa. After the vehicle comes to a stop, The vehicle brakes and parking system engages hydraulically 100 milliseconds after the parking maneuver is complete. When the vehicle speed is less than or equal to 0.5 km / h, the electronic stability control unit directly requests the right parking brake, and the right parking brake performs the parking operation.

8. A low-speed unmanned vehicle braking redundancy control system, characterized in that, As a hardware device for performing the method according to any one of claims 1-7, the system comprises: The electronic stability control unit can actively establish hydraulic pressure; it receives wheel speed signals from the four wheels, outputs wheel speed, and performs composite calculations on the wheel speeds to output the overall vehicle speed. The brakes are installed on both front wheels. The brakes use hydraulic pressure to clamp the calipers and slow down the vehicle. The brakes are connected to the electronic stability control unit through brake lines. The parking brake includes a left parking brake for the left wheel and a right parking brake for the right wheel. The parking brake can not only use hydraulic pressure to clamp the caliper and slow down the vehicle, but also use its motor to clamp the caliper and complete the parking. The parking brake is connected to the electronic stability control unit through a brake line; and the left parking brake is connected to the electronic stability control unit. The hydraulic sensor, installed inside the electronic stability control unit, is used to detect the pressure in the brake lines; The brake-by-wire unit communicates with the electronic stability control unit and is used to establish and release the hydraulic pressure of the brake and parking brake by controlling the forward and reverse rotation of the motor; the brake-by-wire unit is connected to the right parking brake. The chassis domain controller is connected to the brake-by-wire unit and the electronic stability control unit, and can issue braking commands to the brake-by-wire unit and the electronic stability control unit.

9. A low-speed unmanned vehicle braking redundancy control system according to claim 8, characterized in that, Also includes: The chassis communication network is connected to the chassis domain controller, brake-by-wire unit, and electronic stability control unit. The chassis domain controller transmits braking commands to the brake-by-wire unit and electronic stability control unit through the chassis communication network.

10. A low-speed unmanned vehicle braking redundancy control system according to claim 8, characterized in that, Also includes: Wheel speed sensors are provided for all four wheels. The wheel speed sensors are connected in communication with the electronic stability control unit and output the speed of the four wheels to the electronic stability control unit.

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