A method and system for cooperative control of electronic hydraulic braking and electronic parking braking of an unmanned vehicle, and an unmanned vehicle

Abstract

The embodiment of the application provides a kind of electronic hydraulic brake and electronic parking brake collaborative control method of unmanned vehicle, this method includes: when electronic hydraulic brake unit is used to brake vehicle, according to the current state signal of vehicle, it is judged whether vehicle enters effective zero speed state;When vehicle enters effective zero speed state, send clamping trigger instruction to electronic parking brake unit, to make electronic parking brake unit start to execute clamping action;In the whole process that electronic parking brake unit starts to execute clamping action to clamping force reaches target clamping force, electronic hydraulic brake unit maintains current brake pressure unchanged, to make vehicle keep still;When it is detected that the clamping force of electronic parking brake unit reaches target clamping force, electronic hydraulic brake unit starts to release pressure with preset pressure relief slope, until the brake pressure of electronic hydraulic brake unit drops to target pressure relief pressure.Using this method, smooth braking, accurate parking and reliable parking of vehicle are realized.

Description

Technical Field

[0001] This invention relates to the field of unmanned vehicle control technology, and in particular to a method, system, and unmanned vehicle for coordinated control of electro-hydraulic braking and electronic parking braking. Background Technology

[0002] Currently, passenger cars are generally equipped with an electronic hydraulic brake (EHB) system and an electronic parking brake (EPB) system. The EHB is responsible for the dynamic service braking of the vehicle, while the EPB realizes the static parking braking. In the automatic parking scenario, after the vehicle is parked, it needs to switch from the EHB service braking to the EPB mechanical parking to lock the vehicle at rest.

[0003] Conventional parking switching logic simply determines that the vehicle speed is zero and immediately releases the EHB pressure and drives the EPB to clamp. The instantaneous decompression of the EHB causes the vehicle to nod and vibrate, resulting in poor driving comfort. In incline scenarios, there is a time gap between the EHB decompression and the EPB clamping, which greatly increases the risk of the vehicle rolling away. Summary of the Invention

[0004] This invention provides a method, system, and unmanned vehicle for coordinated control of electro-hydraulic braking and electronic parking braking, achieving smooth braking, precise parking, and reliable parking.

[0005] Firstly, this embodiment provides a method for coordinated control of electro-hydraulic braking and electronic parking braking of an unmanned vehicle, the method comprising: When the vehicle is braked using an electro-hydraulic braking unit, it is determined whether the vehicle has entered a valid zero-speed state based on the vehicle's current status signal. When the vehicle enters an effective zero-speed state, a clamping trigger command is sent to the electronic parking brake unit so that the electronic parking brake unit begins to perform a clamping action. During the entire process from the start of the clamping action of the electronic parking brake unit to the clamping force reaching the target clamping force, the electro-hydraulic braking unit maintains the current braking pressure unchanged to keep the vehicle stationary. When the clamping force of the electronic parking brake unit is detected to reach the target clamping force, the electronic hydraulic brake unit begins to release pressure at a preset pressure release slope until the braking pressure of the electronic hydraulic brake unit drops to the target pressure release pressure.

[0006] Secondly, this embodiment provides a coordinated control system for the electro-hydraulic braking and electronic parking brake of an unmanned vehicle, used to execute the coordinated control method for the electro-hydraulic braking and electronic parking brake of the unmanned vehicle as described in the first aspect embodiment. The system includes: a main controller, an electro-hydraulic braking unit, an electronic parking brake unit, and a state perception unit. The state perception unit is used to collect the current state signal of the vehicle; The electro-hydraulic braking unit is used to perform the vehicle's service braking; The electronic parking brake unit is used to perform the parking brake of the vehicle; The main controller is used to perform the following steps: When the vehicle is braked using an electro-hydraulic braking unit, it is determined whether the vehicle has entered a valid zero-speed state based on the vehicle's current status signal. When the vehicle enters an effective zero-speed state, a clamping trigger command is sent to the electronic parking brake unit so that the electronic parking brake unit begins to perform a clamping action. During the entire process from the start of the clamping action of the electronic parking brake unit to the clamping force reaching the target clamping force, the electro-hydraulic braking unit maintains the current braking pressure unchanged to keep the vehicle stationary. When the clamping force of the electronic parking brake unit is detected to reach the target clamping force, the electronic hydraulic brake unit begins to release pressure at a preset pressure release slope until the braking pressure of the electronic hydraulic brake unit drops to the target pressure release pressure.

[0007] Thirdly, this embodiment provides an unmanned vehicle, including: a coordinated control system for the electro-hydraulic braking and electronic parking brake of the unmanned vehicle as described in the second aspect embodiment.

[0008] This invention provides a method for coordinated control of electro-hydraulic braking and electronic parking brake in an unmanned vehicle. The method includes: when the vehicle is braked using an electro-hydraulic braking unit, determining whether the vehicle has entered a valid zero-speed state based on the vehicle's current state signal; when the vehicle enters a valid zero-speed state, sending a clamping trigger command to the electronic parking brake unit to initiate clamping action; throughout the entire process from the start of clamping action to the clamping force reaching the target clamping force, the electro-hydraulic braking unit maintains its current braking pressure to keep the vehicle stationary; when the clamping force of the electronic parking brake unit reaches the target clamping force, the electro-hydraulic braking unit begins to release pressure at a preset pressure release slope until the braking pressure of the electro-hydraulic braking unit drops to the target pressure release pressure. Unlike conventional parking brake switching logic in existing technologies that simply releases pressure from the electro-hydraulic braking unit and drives it to clamp after the vehicle speed reaches zero, causing the electro-hydraulic braking unit to suddenly depressurize and resulting in vehicle pitching, impact, and vibration, leading to poor driving comfort, the above-mentioned technical solution maintains a constant braking pressure throughout the entire process from the start of the clamping action to the achievement of the target clamping force. This keeps the vehicle stationary. Only when the clamping force reaches the target force does the electro-hydraulic braking unit begin to depressurize at a preset depressurization slope. This process achieves a "soft handover" of braking force, avoiding vehicle pitching or swaying caused by sudden depressurization of the electro-hydraulic braking unit, resulting in smooth braking, precise parking, and reliable parking. Even on slopes, it avoids any gaps between the electro-hydraulic braking unit and the electronic parking brake unit, thus preventing the vehicle from rolling backward.

[0009] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a flowchart illustrating a method for coordinated control of electro-hydraulic braking and electronic parking braking of an unmanned vehicle, as provided in Embodiment 1 of the present invention. Figure 2 This is a schematic diagram of the structure of a coordinated control system for an unmanned vehicle's electro-hydraulic braking and electronic parking brake, provided in Embodiment 2 of the present invention. Detailed Implementation

[0012] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0013] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0014] Example 1 Figure 1 This is a flowchart illustrating a coordinated control method for electro-hydraulic braking and electronic parking brake of an unmanned vehicle according to Embodiment 1 of the present invention. This method is applicable to parking control of unmanned vehicles. The method can be executed by a coordinated control system for electro-hydraulic braking and electronic parking brake of the unmanned vehicle. This coordinated control system for electro-hydraulic braking and electronic parking brake of the unmanned vehicle can be implemented in hardware and / or software and is generally integrated into the unmanned vehicle.

[0015] like Figure 1 As shown in the figure, the coordinated control method of electro-hydraulic braking and electronic parking braking of an unmanned vehicle provided in this embodiment may specifically include the following steps: S101. When the vehicle is braked using an electro-hydraulic braking unit, determine whether the vehicle has entered an effective zero-speed state based on the vehicle's current status signal.

[0016] In this embodiment, the coordinated control method of the unmanned vehicle's electro-hydraulic braking and electronic parking brake can be executed by the coordinated control system of the unmanned vehicle's electro-hydraulic braking and electronic parking brake. This system includes: a main controller: acting as the decision-making core, receiving vehicle status signals and outputting control commands; an electro-hydraulic braking unit: including a hydraulic pump, valve body, and wheel cylinder pressure sensors, responsible for service braking; an electronic parking brake unit: including a motor, calipers, and clamping force sensors, responsible for parking braking; a status perception unit: including wheel speed sensors, an inertial measurement unit, and a slope sensor; and a safety monitoring unit: a hardware circuit independent of the main controller, used to monitor the main controller's status and key signals, and to take over in case of abnormalities.

[0017] This step determines whether the vehicle has entered a valid zero-speed state. The upper-level planning system issues a "Parking complete, execute parking" command, which the main controller receives. After receiving the parking complete command from the upper-level planning system, the main controller first controls the main drive wheel drive motor to perform energy recovery for initial deceleration, and then drives the electro-hydraulic braking unit to establish hydraulic braking force, controlling the vehicle's deceleration to a set speed threshold, achieving a smooth stop. When the electro-hydraulic braking unit is used to brake the vehicle, the current status signal of the vehicle is continuously monitored to determine whether the vehicle has entered a valid zero-speed state.

[0018] As described above, if the average linear velocity of the four wheels in the vehicle's current state signal remains below a first speed threshold for a period of time equal to a first time threshold, and the braking pressure of the electro-hydraulic braking unit remains stable at the target braking pressure, then the vehicle is determined to have entered an effective zero-speed state. In this embodiment, a combination of vehicle speed threshold, duration, and stable braking pressure is used as the determination condition for the vehicle to enter an effective zero-speed state. The first speed threshold, first time threshold, and target braking pressure can all be set according to actual conditions. For example, the first speed threshold is set to 0.5 km / h, the first time threshold to 200 ms, and the target braking pressure to 5 MPa. Specifically, the wheel speed sensor feeds back the average linear velocity of the four wheels, and the pressure sensor feeds back the wheel cylinder braking pressure of the electro-hydraulic braking unit. These can all be considered as the vehicle's current state signal. If the average linear velocity of the four wheels in the vehicle's current state signal remains below the first speed threshold for a period of time equal to a first time threshold, and the braking pressure of the electro-hydraulic braking unit remains stable at the target braking pressure, then the vehicle is determined to have entered an effective zero-speed state. For example, the wheel speed sensor feeds back a vehicle speed that drops below 0.5 km / h for 200 ms. Simultaneously, the pressure sensor indicates that the wheel cylinder pressure of the electro-hydraulic braking unit has stabilized at 5 MPa, and the main controller determines that the vehicle has achieved a valid zero-speed state. If any of the above conditions are not met, the vehicle is determined not to have entered a valid zero-speed state.

[0019] S102. When the vehicle enters an effective zero-speed state, a clamping trigger command is sent to the electronic parking brake unit so that the electronic parking brake unit begins to perform a clamping action.

[0020] In this embodiment, the main controller determines that the vehicle has reached a valid zero-speed state and sends a clamping trigger command to the electronic parking brake unit, which then begins the clamping action. Essentially, after the electro-hydraulic brake unit has built up pressure, when the main controller detects that the vehicle is in a valid zero-speed state, the electronic parking brake unit is triggered, and a clamping trigger command is sent to the electronic parking brake unit to initiate the clamping action.

[0021] S103. Throughout the entire process from the start of the clamping action of the electronic parking brake unit to the clamping force reaching the target clamping force, the electronic hydraulic braking unit maintains the current braking pressure unchanged so as to keep the vehicle stationary.

[0022] The target clamping force can be set according to actual conditions. This step is used to maintain the pressure of the electro-hydraulic braking unit. Before the electronic parking brake unit fully engages, the electro-hydraulic braking unit system maintains the current braking pressure unchanged, that is, maintains the target braking pressure unchanged, to keep the vehicle absolutely stationary. For example, at the same time as the electronic parking brake unit is triggered, the electro-hydraulic braking unit maintains the current braking pressure at 5 MPa for 500 ms to ensure that the vehicle is absolutely stationary.

[0023] S104. When the clamping force of the electronic parking brake unit is detected to reach the target clamping force, the electronic hydraulic brake unit begins to depressurize at a preset depressurization slope until the braking pressure of the electronic hydraulic brake unit drops to the target depressurization pressure.

[0024] The preset pressure relief slope can be set according to actual conditions, for example, a preset pressure relief slope value of 10 MPa / s. If the vehicle is on a slope, a pressure relief slope matching the threshold can be configured according to the slope gradient. For example, the steeper the slope, the smaller the pressure relief slope should be to avoid the risk of the vehicle rolling away. The target pressure relief pressure can be set to 0.

[0025] This step is equivalent to a pressure transfer step. When the electronic parking brake unit is fully activated, the electro-hydraulic brake unit begins to slowly release pressure at a fixed depressurization rate until the braking pressure of the electro-hydraulic brake unit drops to 0. This process achieves a "soft transfer" of braking force, avoiding vehicle nodding or swaying caused by sudden pressure release of the electro-hydraulic brake unit.

[0026] To more clearly illustrate the coordinated control method for electro-hydraulic braking and electronic parking brake of the unmanned vehicle provided in this embodiment of the invention, a specific application scenario is used as an example. For instance, the execution process of the coordinated control method for electro-hydraulic braking and electronic parking brake of the unmanned vehicle in this application scenario can be described as follows: the main controller receives an instruction, the main drive wheels perform energy recovery deceleration, and the electro-hydraulic braking unit is controlled to decelerate at -2 m / s². 2 The deceleration allows the vehicle to brake smoothly. The wheel speed sensor reports that the vehicle speed has dropped below 0.5 km / h and remains so for 200 ms. Simultaneously, the pressure sensor reports that the wheel cylinder braking pressure of the electro-hydraulic braking unit has stabilized at 5 MPa. The main controller determines that the vehicle has entered an "effective zero-speed state" and sends an clamping command to the electronic parking brake unit. The electronic parking brake unit begins to operate, maintaining a pressure of 5 MPa until it fully engages. Once the clamping force of the electronic parking brake unit reaches the target, the electro-hydraulic braking unit slowly depressurizes at a rate of 10 MPa / s until it reaches 0. After depressurization, the electronic parking brake unit remains clamped as the sole parking mechanism. The main controller receives a "clamping complete" signal from the electronic parking brake unit, and the vehicle enters a low-power sleep state.

[0027] Unlike conventional parking brake switching logic in existing technologies that simply releases pressure from the electro-hydraulic braking unit and drives it to clamp after the vehicle speed reaches zero, causing the electro-hydraulic braking unit to suddenly depressurize and resulting in vehicle pitching, impact, and vibration, leading to poor driving comfort, the above-mentioned technical solution maintains a constant braking pressure throughout the entire process from the start of the clamping action to the achievement of the target clamping force. This keeps the vehicle stationary. Only when the clamping force reaches the target force does the electro-hydraulic braking unit begin to depressurize at a preset depressurization slope. This process achieves a "soft handover" of braking force, avoiding vehicle pitching or swaying caused by sudden depressurization of the electro-hydraulic braking unit, resulting in smooth braking, precise parking, and reliable parking. Even on slopes, it avoids any gaps between the electro-hydraulic braking unit and the electronic parking brake unit, thus preventing the vehicle from rolling backward.

[0028] As an optional embodiment of the present invention, based on the above embodiments, this optional embodiment can further optimize the method by including: a1) If it is detected that the braking pressure of the electro-hydraulic braking unit cannot be established or is abnormally lost, the electronic parking brake unit is triggered to enter the emergency clamping mode to decelerate and stop the vehicle.

[0029] This step describes the takeover of the electronic parking brake unit in the event of a failure of the electro-hydraulic braking unit. If the main controller detects that the braking pressure of the electro-hydraulic braking unit cannot be established or is abnormally lost, the safety monitoring unit directly triggers the electronic parking brake unit to enter emergency clamping mode via hard wiring, causing the vehicle to decelerate and stop.

[0030] b1) If the electronic parking brake unit fails to clamp, the electronic hydraulic brake unit is triggered to enter the pressure holding mode to maintain the current braking pressure and trigger an alarm.

[0031] This step describes how the electro-hydraulic braking unit takes over parking when the electronic parking brake unit fails. If the electronic parking brake unit fails to clamp, it will command the electro-hydraulic braking unit to enter a pressure-holding mode, maintaining braking pressure for an extended period as a temporary parking measure, and triggering an alarm. For example, the alarm could be an audible and visual alarm.

[0032] The above technical solution adopts a redundant safety mechanism to achieve bidirectional redundancy backup between the electro-hydraulic braking unit and the electronic parking brake unit. When the braking pressure of the electro-hydraulic braking unit fails to build up, the safety monitoring unit hard-wires the electronic parking brake unit to clamp urgently to decelerate and stop the vehicle, thus solving the risk of dynamic service brake failure. When the electronic parking brake unit fails to clamp, the electro-hydraulic braking unit is controlled to maintain pressure for a long time as a temporary parking mechanism and a simultaneous audible and visual alarm is triggered to eliminate the risk of vehicle rollover.

[0033] As an optional embodiment of the present invention, based on the above embodiments, this optional embodiment can be optimized to further include the following steps before determining whether the vehicle has entered a valid zero-speed state: according to the parking completion instruction of the upper-level planning system, first control the main drive wheel of the vehicle to perform energy recovery deceleration, and then control the electro-hydraulic braking unit to apply braking pressure to the vehicle so that the vehicle brakes to a speed lower than the first speed threshold.

[0034] In this embodiment, the upper-level planning system issues a parking completion command of "Parking complete, execute parking" and the main controller receives the command. After receiving the parking completion command from the upper-level planning system, the main controller first controls the main drive wheel drive motor to perform energy recovery to achieve initial deceleration, and then drives the electro-hydraulic braking unit to establish hydraulic braking force, controlling the overall vehicle deceleration to a set speed threshold, thereby achieving a smooth stop. In this embodiment, the set speed threshold is denoted as the first speed threshold, for example, the first speed threshold can be 0.5 km / h.

[0035] Understandably, the main drive wheels are driven by a drive motor. Upon receiving a parking completion command, the vehicle first activates regenerative braking, where the drive motor reverses to generate electricity, converting the vehicle's kinetic energy into electrical energy to recharge the battery. Simultaneously, it drags the wheels in the opposite direction to achieve deceleration, serving as the first stage of deceleration. However, regenerative braking only provides low to medium intensity deceleration. When the vehicle is about to come to a complete stop, regenerative braking alone is insufficient to achieve stable braking and maintain static hydraulic pressure. Therefore, the main controller superimposes electro-hydraulic braking, precisely controlling the wheel cylinder braking pressure and controlling the electro-hydraulic braking unit to apply braking pressure to the vehicle, allowing it to decelerate and brake according to the target deceleration rate. For example, the target deceleration rate can be -2 m / s². 2 .

[0036] The aforementioned technical solution achieves a smooth transition from high to low speeds through the synergy of energy recovery deceleration and linear braking by the electro-hydraulic braking unit. It prioritizes the use of the main drive wheel's electric motor braking for energy recovery, converting the vehicle's kinetic energy into electrical energy to recharge the power battery, thus improving energy utilization efficiency. Pre-controlled deceleration ensures that the wheel speed sensors can accurately and synchronously capture the critical moment when the vehicle speed drops below a set speed threshold, creating a stable prerequisite for the accurate determination of the vehicle's effective zero-speed state.

[0037] As an optional embodiment of the present invention, based on the above embodiments, this optional embodiment can optimize the step of determining whether the vehicle has entered a valid zero-speed state based on the vehicle's current state signal, including: a2) If the average linear velocity of the four wheels in the current state signal of the vehicle is lower than the first speed threshold for a period of time that reaches the first time threshold, and the braking pressure of the electro-hydraulic braking unit is maintained at the target braking pressure, then the vehicle is determined to have entered an effective zero-speed state.

[0038] In this embodiment, a combination of vehicle speed threshold, duration, and stable braking pressure is used as the criteria for determining whether the vehicle has entered an effective zero-speed state. The first speed threshold, first time threshold, and target braking pressure can all be set according to actual conditions. For example, the first speed threshold can be 0.5 km / h, the first time threshold can be 200 ms, and the target braking pressure can be 5 MPa. Specifically, the wheel speed sensor reports the average linear velocity of the four wheels, and the pressure sensor reports the wheel cylinder braking pressure of the electro-hydraulic braking unit. These can be considered as the vehicle's current state signals. If the average linear velocity of the four wheels in the vehicle's current state signal remains below the first speed threshold for a duration equal to the first time threshold, and the braking pressure of the electro-hydraulic braking unit remains stable at the target braking pressure, then the vehicle is determined to have entered an effective zero-speed state. For example, the wheel speed sensor reports that the vehicle speed has dropped below 0.5 km / h for 200 ms. Simultaneously, the pressure sensor reports that the wheel cylinder braking pressure of the electro-hydraulic braking unit is stable at 5 MPa, and the main controller determines that the vehicle has achieved an effective zero-speed state.

[0039] b2) Otherwise, determine that the vehicle has not entered a valid zero-speed state.

[0040] In this embodiment, if any of the above conditions is not met, it is determined that the vehicle has not entered a valid zero-speed state.

[0041] The above technical solution specifies the steps for determining the effective zero-speed state of the vehicle, providing a basis for whether to trigger the electronic parking brake unit to tighten it.

[0042] As an optional embodiment of the present invention, based on the above embodiments, this optional embodiment can be optimized, and the method further includes: when it is detected that the vehicle is on a slope with a slope exceeding a preset slope threshold, configuring a target braking pressure that matches the slope for the electro-hydraulic braking unit.

[0043] In this embodiment, the vehicle's pitch angle is monitored in real time by an inertial measurement unit or the slope is detected by a slope sensor to determine whether the vehicle is on a slope. If the vehicle is on a slope, slope compensation is performed. The preset slope threshold can be set according to actual conditions; for example, the preset slope threshold can be 5%. If the vehicle is detected on a slope exceeding the preset slope threshold, the target braking pressure of the electro-hydraulic braking unit dynamically increases according to the slope.

[0044] The above technical solution avoids the risk of vehicle rollback by increasing the target braking pressure of the electro-hydraulic braking unit in slope scenarios.

[0045] As an optional embodiment of the present invention, based on the above embodiments, this optional embodiment can be optimized, and the method further includes: when it is detected that the vehicle is on a slope with a gradient exceeding a preset slope threshold, controlling the main drive wheel of the vehicle to form a mechanical parking clamping force on the vehicle, and the entire process of establishing the clamping of the main drive wheel overlaps with the stage of the electro-hydraulic braking unit maintaining the current braking pressure.

[0046] In this embodiment, when the vehicle is detected to be on a slope with a gradient exceeding a preset gradient threshold, active clamping is applied. The main drive wheels first stop on the slope and maintain a high degree of overlap with the pressure of the electro-hydraulic braking unit, completely eliminating the slippage gap. The steeper the slope, the higher the main drive wheel clamping force threshold.

[0047] The above technical solution avoids the risk of vehicle rollover by adding a main drive wheel for reinforcement compensation in slope scenarios.

[0048] As an optional embodiment of the present invention, based on the above embodiments, this optional embodiment can be optimized to further include, after the wheel cylinder pressure of the electro-hydraulic braking unit drops to the target pressure relief pressure, controlling the vehicle to enter a low-power sleep state after receiving the clamping completion signal of the electronic parking brake unit.

[0049] In this embodiment, after the electronic parking brake unit reaches the required clamping force and the electro-hydraulic brake unit releases pressure, the electronic parking brake unit remains clamped as the sole parking mechanism. Upon receiving the clamping completion signal from the electronic parking brake unit, the main controller initiates a low-power sleep state for the entire vehicle.

[0050] The above technical solution controls the vehicle to enter a low-power sleep state after the vehicle is successfully parked, thereby reducing the static power consumption of the entire vehicle and extending the battery life.

[0051] Example 2 Figure 2 This is a schematic diagram of the structure of a coordinated control system for electro-hydraulic braking and electronic parking braking of an unmanned vehicle according to Embodiment 2 of the present invention. This system is applicable to situations involving vehicle parking control. The coordinated control system for electro-hydraulic braking and electronic parking braking of the unmanned vehicle can be implemented in hardware and / or software, and is generally integrated into the unmanned vehicle. For example... Figure 2 As shown, the system includes: a main controller 21, an electro-hydraulic braking unit 22, an electronic parking brake unit 23, and a status sensing unit 24; The state sensing unit 24 is used to collect the current state signal of the vehicle; The electro-hydraulic braking unit 22 is used to perform the vehicle's service braking. The electronic parking brake unit 23 is used to perform the parking brake of the vehicle; The main controller 21 is used to perform the following steps: When the vehicle is braked using an electro-hydraulic braking unit, it is determined whether the vehicle has entered a valid zero-speed state based on the vehicle's current status signal. When the vehicle enters an effective zero-speed state, a clamping trigger command is sent to the electronic parking brake unit so that the electronic parking brake unit begins to perform a clamping action. During the entire process from the start of the clamping action of the electronic parking brake unit to the clamping force reaching the target clamping force, the electro-hydraulic braking unit maintains the current braking pressure unchanged to keep the vehicle stationary. When the clamping force of the electronic parking brake unit is detected to reach the target clamping force, the electronic hydraulic brake unit begins to release pressure at a preset pressure release slope until the braking pressure of the electronic hydraulic brake unit drops to the target pressure release pressure.

[0052] It should be noted that the main controller, as the decision-making core, receives vehicle status signals and outputs control commands. The electro-hydraulic braking unit, including a hydraulic pump, valve body, and wheel cylinder pressure sensors, is responsible for service braking. The electronic parking brake unit, including a motor, calipers, and clamping force sensors, is responsible for parking braking. The status sensing unit includes wheel speed sensors, an inertial measurement unit, and a slope sensor.

[0053] Unlike conventional parking brake switching logic in existing technologies that simply releases pressure from the electro-hydraulic braking unit and drives it to clamp after the vehicle speed reaches zero, causing the electro-hydraulic braking unit to suddenly depressurize and resulting in vehicle pitching, impact, and vibration, leading to poor driving comfort, the above-mentioned technical solution maintains a constant braking pressure throughout the entire process from the start of the clamping action to the achievement of the target clamping force. This keeps the vehicle stationary. Only when the clamping force reaches the target force does the electro-hydraulic braking unit begin to depressurize at a preset depressurization slope. This process achieves a "soft handover" of braking force, avoiding vehicle pitching or swaying caused by sudden depressurization of the electro-hydraulic braking unit, resulting in smooth braking, precise parking, and reliable parking. Even on slopes, it avoids any gaps between the electro-hydraulic braking unit and the electronic parking brake unit, thus preventing the vehicle from rolling backward.

[0054] Optionally, the system further includes a security monitoring unit, which is used for: If the braking pressure of the electro-hydraulic braking unit is detected to be unable to be established or to be abnormally lost, the electronic parking brake unit is triggered to enter the emergency clamping mode to slow down and stop the vehicle. If the electronic parking brake unit fails to clamp, the electro-hydraulic braking unit is triggered to enter the pressure-holding mode to maintain the current braking pressure and trigger an alarm.

[0055] It should be noted that the safety monitoring unit is a hardware circuit independent of the main controller. It is used to monitor the status and critical signals of the main controller and take over in case of abnormalities. The hardware architecture achieves redundant takeover of the electro-hydraulic braking unit and the electronic parking brake unit through the independent safety monitoring unit.

[0056] The coordinated control system for the electro-hydraulic braking and electronic parking brake of the unmanned vehicle provided in the embodiments of the present invention can execute the coordinated control method for the electro-hydraulic braking and electronic parking brake of the unmanned vehicle provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0057] This invention also provides an unmanned vehicle, including a coordinated control system for the electro-hydraulic braking and electronic parking brake of the unmanned vehicle as provided in any embodiment of this invention.

[0058] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0059] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for coordinated control of electro-hydraulic braking and electronic parking braking in an unmanned vehicle, characterized in that, include: When the vehicle is braked using an electro-hydraulic braking unit, it is determined whether the vehicle has entered a valid zero-speed state based on the vehicle's current status signal. When the vehicle enters an effective zero-speed state, a clamping trigger command is sent to the electronic parking brake unit so that the electronic parking brake unit begins to perform a clamping action. During the entire process from the start of the clamping action of the electronic parking brake unit to the clamping force reaching the target clamping force, the electro-hydraulic braking unit maintains the current braking pressure unchanged to keep the vehicle stationary. When the clamping force of the electronic parking brake unit is detected to reach the target clamping force, the electronic hydraulic brake unit begins to release pressure at a preset pressure release slope until the braking pressure of the electronic hydraulic brake unit drops to the target pressure release pressure.

2. The method according to claim 1, characterized in that, Also includes: If the braking pressure of the electro-hydraulic braking unit is detected to be unable to be established or to be abnormally lost, the electronic parking brake unit is triggered to enter the emergency clamping mode to decelerate and stop the vehicle. If the electronic parking brake unit fails to clamp, the electro-hydraulic braking unit is triggered to enter the pressure-holding mode to maintain the current braking pressure and trigger an alarm.

3. The method according to claim 1, characterized in that, The step of determining whether the vehicle has entered a valid zero-speed state based on the vehicle's current state signal includes: If the average linear velocity of the four wheels in the current state signal of the vehicle remains below the first speed threshold for a period of time that reaches the first time threshold, and the braking pressure of the electro-hydraulic braking unit is maintained at the target braking pressure, then the vehicle is determined to have entered an effective zero-speed state. Otherwise, it is determined that the vehicle has not entered a valid zero-speed state.

4. The method according to claim 1, characterized in that, Also includes: When the vehicle is detected to be on a slope with a gradient exceeding a preset gradient threshold, the electro-hydraulic braking unit is configured with a target braking pressure that matches the gradient.

5. The method according to claim 1, characterized in that, Also includes: When the vehicle is detected to be on a slope with a gradient exceeding a preset slope threshold, the main drive wheels of the vehicle are controlled to form a mechanical parking clamping force on the vehicle, and the entire process of establishing the clamping of the main drive wheels overlaps with the stage of the electro-hydraulic braking unit maintaining the current braking pressure.

6. The method according to claim 3, characterized in that, Before determining whether the vehicle has entered a valid zero-speed state, the method further includes: According to the parking completion command from the upper-level planning system, the main drive wheels of the vehicle are first controlled to perform energy recovery and deceleration, and then the electro-hydraulic braking unit is controlled to apply braking pressure to the vehicle so that the vehicle brakes to a speed lower than the first speed threshold.

7. The method according to claim 1, characterized in that, After the wheel cylinder pressure of the electro-hydraulic braking unit drops to the target relief pressure, the method further includes: After receiving the clamping completion signal from the electronic parking brake unit, the vehicle is controlled to enter a low-power sleep state.

8. A coordinated control system for electro-hydraulic braking and electronic parking braking of an unmanned vehicle, characterized in that, The system for implementing the coordinated control method of electro-hydraulic braking and electronic parking braking of an unmanned vehicle as described in any one of claims 1-7 includes: a main controller, an electro-hydraulic braking unit, an electronic parking braking unit, and a state sensing unit. The state perception unit is used to collect the current state signal of the vehicle; The electro-hydraulic braking unit is used to perform the vehicle's service braking; The electronic parking brake unit is used to perform the parking brake of the vehicle; The main controller is used to perform the following steps: When the vehicle is braked using an electro-hydraulic braking unit, it is determined whether the vehicle has entered a valid zero-speed state based on the vehicle's current status signal. When the vehicle enters an effective zero-speed state, a clamping trigger command is sent to the electronic parking brake unit so that the electronic parking brake unit begins to perform a clamping action. During the entire process from the start of the clamping action of the electronic parking brake unit to the clamping force reaching the target clamping force, the electro-hydraulic braking unit maintains the current braking pressure unchanged to keep the vehicle stationary. When the clamping force of the electronic parking brake unit is detected to reach the target clamping force, the electronic hydraulic brake unit begins to release pressure at a preset pressure release slope until the braking pressure of the electronic hydraulic brake unit drops to the target pressure release pressure.

9. The system according to claim 8, characterized in that, It also includes a security monitoring unit, which is used for: If the braking pressure of the electro-hydraulic braking unit is detected to be unable to be established or to be abnormally lost, the electronic parking brake unit is triggered to enter the emergency clamping mode to decelerate and stop the vehicle. If the electronic parking brake unit fails to clamp, the electro-hydraulic braking unit is triggered to enter the pressure-holding mode to maintain the current braking pressure and trigger an alarm.

10. An unmanned vehicle, characterized in that, include: The coordinated control system for the electro-hydraulic braking and electronic parking brake of the unmanned vehicle as described in any one of claims 8-9.

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