Self-driving vehicle and vehicle speed control method, device and system thereof

Abstract

The application provides an automatic driving vehicle and a speed control method, device and system thereof, and relates to the technical field of automatic driving. The speed control method of the automatic driving vehicle comprises the following steps: acquiring a target distance between a position of the automatic driving vehicle at any time in a current update period and a stop line and a historical limit speed corresponding to a previous update period of the current update period, the stop line being a position where the automatic driving vehicle needs to stop and wait; determining a candidate limit speed according to a distance interval where the target distance is located; updating the historical limit speed by using the candidate limit speed to obtain a target limit speed corresponding to the current update period; and controlling a driving speed of the automatic driving vehicle in the current update period to be not more than the target limit speed.

Description

Technical Field

[0001] This application relates to the field of autonomous driving technology, specifically to an autonomous vehicle and its speed control method, device, and system. Background Technology

[0002] When autonomous vehicles approach a stop line at an intersection, additional defensive constraints need to be applied to the target speed to prevent excessive speeds caused by brief anomalies in the perception or decision-making chain. A common practice is to set a single speed limit threshold based on the distance to the stop line, applying a fixed speed limit once the vehicle enters that range. This single-threshold speed limit method has revealed the following problems in engineering practice:

[0003] 1. Single-threshold speed limiting is prone to abrupt speed limit changes near the threshold. If combined with other speed limiting sources, it may cause sudden deceleration changes, affecting ride comfort. 2. It cannot distinguish whether a vehicle has just entered the protection zone or has been continuously driving within it, applying the same speed limit value uniformly, resulting in coarse-grained protection. 3. Using the same speed limit value, when the vehicle's position fluctuates slightly near the threshold (e.g., due to positioning noise or sensor fluctuations), the speed limit setting will repeatedly jump between two values, causing continuous fluctuations in speed planning output. 4. If the vehicle reverses or the route is replanned, causing a reduction in the distance to the stop line, the protective speed limit may be prematurely and incorrectly lifted. Summary of the Invention

[0004] This application provides an autonomous vehicle and its speed control method, device, and system, which can solve the problem of sudden speed changes and vibrations when controlling the speed of an autonomous vehicle.

[0005] The first aspect of this application provides a speed control method for an autonomous vehicle, comprising: obtaining the target distance between the position of the autonomous vehicle at any time in the current update cycle and a stop line, and the historical speed limit corresponding to the previous update cycle, wherein the stop line is the position where the autonomous vehicle needs to stop and wait; determining candidate speed limits based on the distance range in which the target distance is located; updating the historical speed limit using the candidate speed limits to obtain the target speed limit corresponding to the current update cycle; and controlling the driving speed of the autonomous vehicle in the current update cycle to not exceed the target speed limit.

[0006] According to an embodiment of this application, determining a candidate limiting speed based on the distance range in which the target distance is located includes: determining the candidate limiting speed to infinity when the target distance is greater than a first preset distance; determining the candidate limiting speed to a first preset speed when the target distance is greater than a second preset distance and less than or equal to the first preset distance, wherein the first preset distance is greater than the second preset distance; and determining the candidate limiting speed to a second preset speed when the target distance is less than or equal to the second preset distance, wherein the first preset speed is greater than the second preset speed.

[0007] According to an embodiment of this application, the method further includes: obtaining the traffic light signal status currently faced by the autonomous vehicle; when the traffic light signal status indicates prohibition of passage or a transitional warning, increasing a first preset distance and / or a second preset distance, or decreasing a first preset speed and / or a second preset speed; when the traffic light signal status indicates permission to pass, decreasing the first preset distance and / or the second preset distance, or increasing the first preset speed and / or the second preset speed.

[0008] According to an embodiment of this application, updating the historical limit speed using the candidate limit speed to obtain the target limit speed corresponding to the current update cycle includes: determining the candidate limit speed as the target limit speed when the candidate limit speed is less than or equal to the historical limit speed; or updating the target limit speed according to preset update conditions when the candidate limit speed is greater than the historical limit speed.

[0009] According to an embodiment of this application, updating the target limiting speed according to preset update conditions includes: determining the candidate limiting speed as the target limiting speed when the candidate limiting speed is infinite and the target distance is greater than the sum of the first preset distance and the preset hysteresis distance; or determining the historical limiting speed as the target limiting speed when the candidate limiting speed is infinite and the target distance is less than or equal to the sum of the first preset distance and the preset hysteresis distance.

[0010] According to an embodiment of this application, updating the target limiting speed according to preset update conditions further includes: determining the candidate limiting speed as the target limiting speed when the candidate limiting speed is a first preset speed and the target distance is greater than the sum of the second preset distance and the preset hysteresis distance; or determining the historical limiting speed as the target limiting speed when the candidate limiting speed is a first preset speed and the target distance is less than or equal to the sum of the second preset distance and the preset hysteresis distance.

[0011] According to an embodiment of this application, before determining the candidate speed limit based on the distance range in which the target distance is located, the method further includes: determining the historical speed limit as the target speed limit when the target distance is determined to be zero.

[0012] The second aspect of this application provides a speed control device for an autonomous vehicle. The device includes: an acquisition module, used to acquire the target distance between the position of the autonomous vehicle and a stop line at any time in the current update cycle and the historical speed limit corresponding to the previous update cycle, wherein the stop line is the position where the autonomous vehicle needs to stop and wait; a determination module, used to determine candidate speed limits based on the distance range in which the target distance is located; an update module, used to update the historical speed limit using the candidate speed limits to obtain the target speed limit corresponding to the current update cycle; and a control module, used to control the driving speed of the autonomous vehicle within the current update cycle to not exceed the target speed limit.

[0013] A third aspect of this application provides a speed control system for an autonomous vehicle, comprising: a distance detector for detecting the target distance between the autonomous vehicle and a stop line at any time in the current update cycle; a memory for storing historical speed limits corresponding to the previous update cycle; and a controller communicatively connected to the distance detector and the memory, configured to: determine candidate speed limits based on the distance interval in which the target distance is located; update the historical speed limits using the candidate speed limits to obtain the target speed limit corresponding to the current update cycle; and control the driving speed of the autonomous vehicle within the current update cycle to not exceed the target speed limit; the memory is also used to store the target speed limit corresponding to the current update cycle.

[0014] The fourth aspect of this application provides an autonomous driving vehicle, including: a vehicle speed control system for the aforementioned autonomous driving vehicle.

[0015] Compared with the prior art, the autonomous driving vehicle and its speed control method, device, and system provided in this application have at least the following beneficial effects:

[0016] (1) By dividing the distance to the stop line into multiple intervals and configuring a corresponding speed limit value for each interval, the candidate speed limit is gradually tightened as the target distance decreases, thus realizing graded speed protection for autonomous vehicles approaching the stop line, avoiding sudden speed limit switching caused by a single threshold, and improving the safety and smoothness of speed control.

[0017] (2) By setting an asymmetric judgment rule that the tightening direction can be updated directly and the relaxation direction can only be updated if the target distance exceeds the boundary threshold and the preset hysteresis distance, the speed limit tightening is zero-delayed and the relaxation is slack. This ensures the timeliness of protection and suppresses the repeated speed limit jumps caused by positioning noise or perception fluctuations near the gear boundary, thus improving the smoothness and stability of speed planning. Attached Figure Description

[0018] The above-mentioned contents, other objects, features and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0019] Figure 1 This illustration schematically depicts an application scenario of a vehicle speed control method for an autonomous vehicle according to an embodiment of this application.

[0020] Figure 2 A flowchart illustrating a method for controlling the speed of an autonomous vehicle according to an embodiment of this application is shown schematically.

[0021] Figure 3 A flowchart illustrating another method for controlling the speed of an autonomous vehicle according to an embodiment of this application is shown schematically.

[0022] Figure 4 This schematic diagram illustrates a structural block diagram of a vehicle speed control device suitable for implementing autonomous vehicles according to an embodiment of this application;

[0023] Figure 5 A schematic block diagram of a vehicle speed control system for an autonomous vehicle according to an embodiment of this application is shown. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments and accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0025] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The terms “comprising,” “including,” etc., as used herein indicate the presence of features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0026] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0027] Figure 1 The diagram illustrates an application scenario of a vehicle speed control method for an autonomous vehicle according to an embodiment of this application.

[0028] like Figure 1As shown, application scenario 100 according to an embodiment of this application may include an autonomous vehicle 101 and a controller 102. The autonomous vehicle 101 and the controller 102 can establish a communication connection via a network 103. The network 103 may be, for example, a controller local area network bus, an in-vehicle Ethernet, etc. The controller 102 can obtain the driving information of the autonomous vehicle 101 (such as the distance from the vehicle to the stop line, the vehicle's current speed, etc.) and send a target limit command to the autonomous vehicle 101 to control the autonomous vehicle 101 to travel at a speed not exceeding the target limit speed.

[0029] The autonomous vehicle 101 can be a passenger car, commercial vehicle, or other vehicle with autonomous driving capabilities. Passenger cars can include sedans, sport utility vehicles (SUVs), etc., while commercial vehicles can include driverless taxis, driverless buses, driverless trucks, etc. The autonomous vehicle 101 can be equipped with various sensors (such as cameras, lidar, millimeter-wave radar, ultrasonic radar, and positioning inertial navigation systems) to collect information about the surrounding environment and the vehicle's own status.

[0030] The controller 102 can be a computing device that provides autonomous driving decision-making and planning functions, such as an electronic control unit, an autonomous driving domain controller, or a vehicle control domain controller. The controller 102 can be a physical controller that is an independent peripheral, an on-board controller integrated into the autonomous vehicle 101, or a distributed control system composed of multiple controllers. The controller 102 can interact with the sensors, actuators, etc., of the autonomous vehicle 101 via the network 103 to receive sensor data and send control commands to the actuators. The controller 102 can run a speed planning module to execute the vehicle speed control method for the autonomous vehicle provided in this embodiment.

[0031] It should be understood that Figure 1 The number of autonomous vehicles and controllers shown is merely illustrative. Depending on the implementation requirements, there can be any number of autonomous vehicles and controllers, such as a fleet of multiple autonomous vehicles or a redundant computing platform consisting of multiple controllers.

[0032] Figure 2 A flowchart illustrating a speed control method for an autonomous vehicle according to an embodiment of this application is shown schematically.

[0033] like Figure 2 As shown, the vehicle speed control method for an autonomous vehicle in this embodiment includes the following steps S1 to S4, and this method can be applied to the controller 102 described above.

[0034] Step S1: Obtain the target distance between the position of the autonomous vehicle at any time in the current update cycle and the stop line, and the historical speed limit corresponding to the previous update cycle. The stop line is the position where the autonomous vehicle needs to stop and wait.

[0035] For example, an update cycle refers to a period in which historical speed limits are updated cyclically at preset fixed time intervals, such as updating historical speed limits every 100 milliseconds. Any moment in the current update cycle refers to the moment when data is acquired within the current update cycle; it can be the start, middle, or end of the cycle, not just the start point. A stop line is a marker indicating the location where autonomous vehicles need to stop and wait, typically placed at traffic light intersections, pedestrian crossings, construction zones, toll booths, and other locations where vehicles need to stop or slow down. In this embodiment, the stop line serves as a reference for the target distance. The target distance is the spatial distance between the location of the autonomous vehicle at any moment in the current update cycle and the stop line. Historical speed limits refer to the speed limits calculated and cached by the system at the end of the previous update cycle, serving as a comparison benchmark for speed updates in the current update cycle.

[0036] Step S2: Determine the candidate speed limit based on the distance range in which the target distance is located.

[0037] For example, the distance range of the target distance refers to the range in which the target distance falls after comparing it with multiple preset distance thresholds. Different distance ranges correspond to different candidate speed limits. That is, continuously changing target distances are mapped to discrete speed limit levels, so that the candidate speed limits change in stages as the target distance changes.

[0038] Step S3: Update the historical limit speed using the candidate limit speed to obtain the target limit speed corresponding to the current update period.

[0039] For example, updating refers to comparing the candidate limit speed in the current update cycle with the historical limit speed, deciding whether to replace the historical limit speed with the candidate limit speed, and using the decision result as the target limit speed for the current update cycle. The update operation has two possible outcomes: one is to replace the historical limit speed with the candidate limit speed; the other is to keep the historical limit speed unchanged.

[0040] Step S4: Control the autonomous vehicle to drive at a speed not exceeding the target speed limit during the current update cycle.

[0041] For example, driving speed refers to the instantaneous speed of an autonomous vehicle during actual driving, that is, the vehicle's current speed. This speed is subject to an upper limit of the target speed limit, meaning that the vehicle's driving speed within the current update cycle must not exceed the target speed limit determined in step S3.

[0042] For example, the speed control system of an autonomous vehicle operates in a cycle according to a preset fixed period (e.g., 100ms), and each cycle is called an update cycle. At any time in each update cycle, the target distance (i.e., the net distance from the vehicle to the stop line) and the historical speed limit (i.e., the speed limit value calculated and cached by the system at the end of the previous update cycle, which serves as one of the comparison benchmarks for speed update determination in the current cycle) are obtained. Based on the above information, the vehicle's position can be perceived in real time, providing a data foundation for subsequent speed limit determination.

[0043] For example, the net distance from the vehicle to the stop line can be obtained by subtracting approximately half the vehicle's length (or slightly more than half the vehicle's length) from the distance from the vehicle's center point to the stop line. This target distance can be obtained in this way, regardless of whether the vehicle is approaching or moving away from the stop line, thus controlling the vehicle's speed. The stop line can also be used to generate virtual static obstacles in the system (representing stop line position constraints), allowing the speed limit planning steps described above to work in conjunction with spatial constraints (virtual obstacles) in the speed planning task.

[0044] For example, the speed control system of an autonomous vehicle includes a controller that can send the target speed limit determined in step S3 as an instruction (target speed limit instruction) to the vehicle's longitudinal actuators (such as the drive system and braking system) as a speed limit constraint for the current update cycle. During the vehicle's operation, the actual speed will be limited to within this target speed limit, thereby ensuring that the vehicle approaches or moves away from the stop line at a safe speed.

[0045] This embodiment divides the target distance into multiple intervals, each corresponding to a different speed limit value. This allows the candidate speed limit to change in stages as the target distance changes, providing finer granular protection compared to a single threshold method and preventing abrupt changes in the speed limit. By comparing the candidate speed limit with historical speed limits to determine whether to update the target speed limit, the update mechanism is independent of the vehicle's specific driving direction (approaching or moving away from the stop line), making the decision solely based on the interval in which the target distance falls and the comparison with historical values. Furthermore, since historical speed limits remain in effect when not updated, slight forward or backward movement of the vehicle near gear boundaries will not immediately alter the speed limit due to interval jumps. This effectively suppresses repeated speed limit jumps caused by positioning noise or perception fluctuations, resulting in more stable speed limit inputs for downstream speed planning. This avoids acceleration shocks caused by sudden speed limit changes and improves ride comfort. Furthermore, this control method relies only on two inputs: target distance and historical speed limit. It is independent of specific autonomous driving planning modes (rule-based planning, AI smoothing, AI enhancement, etc.) and can run continuously in any operating mode without requiring repeated development of speed limit logic for different modes. In some embodiments, determining the candidate speed limit based on the distance range in which the target distance falls includes: determining the candidate speed limit as infinity when the target distance is greater than a first preset distance; determining the candidate speed limit as the first preset speed when the target distance is greater than a second preset distance and less than or equal to the first preset distance, wherein the first preset distance is greater than the second preset distance; and determining the candidate speed limit as the second preset speed when the target distance is less than or equal to the second preset distance, wherein the first preset speed is greater than the second preset speed.

[0046] like Figure 3 As shown, the target distance is compared with a first preset distance and a second preset distance, where the first preset distance is greater than the second preset distance. These two comparisons divide the distance axis into three intervals. In the first case, when the target distance is greater than the first preset distance, it indicates the vehicle is far from the stop line, and no speed limit is required. Therefore, the candidate speed limit is set to infinity, i.e., no speed limit. In the second case, when the target distance is greater than the second preset distance but less than or equal to the first preset distance, it indicates the vehicle has entered the middle section of the defense range, requiring a moderate speed limit. Therefore, the candidate speed limit is set to the first preset speed (e.g., 10 m / s). In the third case, when the target distance is less than or equal to the second preset distance, it indicates the vehicle is very close to the stop line, requiring stricter low-speed protection. Therefore, the candidate speed limit is set to the second preset speed (e.g., 4 m / s). The first preset speed is greater than the second preset speed to reflect the defense logic that the closer the distance, the stricter the speed limit.

[0047] In this embodiment, two distance thresholds are set to divide the distance axis into three intervals, each corresponding to a different candidate speed limit value. This allows the candidate speed limit to gradually tighten as the target distance decreases. Compared to existing single-threshold schemes (where a fixed speed limit is applied once the vehicle enters a certain distance), the three-tiered system achieves finer protection granularity, avoiding abrupt changes in the speed limit value at the defense boundary and reducing the impact of sudden speed limit fluctuations on passenger comfort. Furthermore, the speed limit value does not change continuously within the intervals, preventing frequent adjustments to downstream speed planning due to continuous speed limit fluctuations.

[0048] In some embodiments, the vehicle speed control method further includes: acquiring the traffic light signal status currently faced by the autonomous vehicle; increasing a first preset distance and / or a second preset distance, or decreasing a first preset speed and / or a second preset speed, when the traffic light signal status indicates prohibition of passage or a transitional warning; and decreasing the first preset distance and / or the second preset distance, or increasing the first preset speed and / or the second preset speed, when the traffic light signal status indicates permission to pass.

[0049] For example, the system can acquire the current traffic light signal status faced by the autonomous vehicle. This signal status includes a red light indicating prohibition of passage, a yellow light indicating a transitional warning, and a green light indicating permission to pass. During a red or yellow light, to ensure the vehicle can safely stop before the stop line, the system increases a first preset distance and / or a second preset distance (causing the speed limit to be triggered at a greater distance), or decreases the first preset speed and / or the second preset speed (making the speed limit more stringent). During a green light, to improve traffic efficiency, the system decreases the first preset distance and / or the second preset distance (causing the speed limit to be triggered closer), or increases the first preset speed and / or the second preset speed (making the speed limit more lenient).

[0050] Specifically, increasing the first preset distance and / or the second preset distance means either increasing the first preset distance, increasing the second preset distance, or simultaneously increasing both the first and second preset distances. Decreasing the first preset speed and / or the second preset speed means either decreasing the first preset speed, decreasing the second preset speed, or simultaneously decreasing both the first and second preset speeds. Decreasing the first preset distance and / or the second preset distance means either decreasing the first preset distance, decreasing the second preset distance, or simultaneously decreasing both the first and second preset distances. Increasing the first preset speed and / or the second preset speed means either increasing the first preset speed, increasing the second preset speed, or simultaneously increasing both the first and second preset speeds.

[0051] This embodiment incorporates traffic light signal status into speed limit parameter adjustment, enabling the speed limit strategy to adaptively adjust based on different signal states. During red or yellow lights, earlier triggering of the speed limit or applying a stricter speed limit ensures vehicles have sufficient deceleration distance before the stop line, reducing the risk of sudden braking or even running a red light. During green lights, vehicles are allowed to approach the intersection at higher speeds or the speed limit is applied closer, avoiding unnecessary deceleration losses and improving traffic efficiency. Thus, traffic efficiency is balanced with safety.

[0052] In some embodiments, updating the historical limit speed using the candidate limit speed to obtain the target limit speed corresponding to the current update period includes: determining the candidate limit speed as the target limit speed when the candidate limit speed is less than or equal to the historical limit speed; or updating the target limit speed according to preset update conditions when the candidate limit speed is greater than the historical limit speed.

[0053] Please continue reading. Figure 3 Historical speed limit refers to the speed limit value cached and effective in the previous update cycle, serving as the benchmark for comparison in the current update cycle. Candidate speed limit refers to the speed limit value recalculated based on the target distance in the current update cycle. When the candidate speed limit is less than or equal to the historical speed limit, it indicates that the speed limit calculated based on the current distance is stricter or the same as the previous cycle. For example, if a vehicle moves from 45 meters to 15 meters from the stop line, the candidate speed limit changes from the first preset speed (medium speed) to the second preset speed (low speed). In this case, the system directly sets the candidate speed limit as the target speed limit, and the update takes effect immediately. When the candidate speed limit is greater than the historical speed limit, it indicates that the speed limit calculated based on the current distance is more lenient than the previous cycle. For example, if a vehicle reverses or moves away from the stop line from 15 meters to 22 meters, the candidate speed limit changes from the second preset speed (low speed) to the first preset speed (medium speed). In this case, the system does not update immediately but needs to further determine whether relaxation is allowed based on preset update conditions.

[0054] This embodiment compares candidate speed limits with historical speed limits, enabling directional determination of speed limit updates. Tightening the speed limit (candidate speed limit less than or equal to historical speed limit) takes effect without delay, ensuring timely protection. Relaxing the speed limit (candidate speed limit greater than historical speed limit) introduces preset update conditions as criteria, avoiding frequent speed limit jumps caused by minor vehicle movement near gear boundaries or positioning noise. As a result, the downstream speed planning module (receiving speed limit commands) obtains a more stable speed limit input, avoiding acceleration shocks caused by repeated speed limit switching and improving the smoothness of speed control.

[0055] In some embodiments, updating the target limiting speed according to preset update conditions includes: determining the candidate limiting speed as the target limiting speed when the candidate limiting speed is infinite and the target distance is greater than the sum of the first preset distance and the preset hysteresis distance; or determining the historical limiting speed as the target limiting speed when the candidate limiting speed is infinite and the target distance is less than or equal to the sum of the first preset distance and the preset hysteresis distance.

[0056] Please continue reading. Figure 3 When the candidate speed limit is infinite (i.e., the candidate speed limit is unrestricted), it indicates that the target distance in the current update cycle is greater than the first preset distance (i.e., the first preset distance used to determine the candidate speed limit). According to the hierarchical logic, the system should exit the speed limit state. However, the system does not immediately update the speed limit value to infinity. Instead, it further determines whether the target distance is greater than the sum of the first preset distance and the preset hysteresis distance. The preset hysteresis distance is a configurable distance margin, its value being greater than or equal to the distance the autonomous vehicle would travel inertial coasting for one update cycle at the current speed, for example, 5 meters. If the target distance is greater than the sum of the two, it means the vehicle has sufficiently moved away from the stop line and clearly departed from the speed limit boundary. In this case, the candidate speed limit (infinity) is allowed to be determined as the target speed limit, i.e., the speed limit is completely lifted. Conversely, if the target distance is less than or equal to the sum of the first preset distance and the preset hysteresis distance, it means the vehicle has briefly left the speed limit area but is still near the boundary. In this case, the historical speed limit remains unchanged, and the speed limit state continues.

[0057] For example, suppose the first preset distance is 50 meters and the preset lag distance is 5 meters. When the target distance is 52 meters, the candidate is no speed limit (greater than 50 meters), but 52 meters is not greater than 55 meters, so the historical speed limit is maintained and the speed limit is not lifted. Only when the target distance is greater than 55 meters is the speed limit truly lifted. In comparison, the vehicle initially entered the speed limit state only when the target distance was less than or equal to 50 meters. Therefore, the condition for exiting the speed limit (50 meters + 5 meters) is more stringent than the condition for entering the speed limit (50 meters).

[0058] This embodiment introduces a preset hysteresis distance into the relaxation determination process, making the conditions for exiting a speed-limited gear more stringent than those for entering it. When the vehicle moves slightly back and forth near the gear boundary (e.g., between 48 and 52 meters), the speed limit will not be immediately lifted even if the target distance occasionally exceeds 50 meters. The speed limit is only truly lifted when the vehicle continuously moves away and clearly exceeds the boundary plus the hysteresis range. This effectively suppresses repeated jumps in the speed limit state when the vehicle position vibrates near the gear boundary due to positioning noise or perception fluctuations. The downstream speed planning module obtains a more stable speed limit input, avoiding sudden acceleration changes caused by frequent speed limit lifting and restoration, thus improving the smoothness of speed control. Simultaneously, tightening the steering (entering the speed limit) still maintains a zero-delay response, ensuring timely protection.

[0059] In some embodiments, updating the target limiting speed according to preset update conditions further includes: determining the candidate limiting speed as the target limiting speed when the candidate limiting speed is a first preset speed and the target distance is greater than the sum of the second preset distance and the preset hysteresis distance; or determining the historical limiting speed as the target limiting speed when the candidate limiting speed is a first preset speed and the target distance is less than or equal to the sum of the second preset distance and the preset hysteresis distance.

[0060] Please continue reading. Figure 3 If the candidate speed limit is the first preset speed (i.e., the first preset speed determined based on the target distance mentioned above), it indicates that the target distance in the current update cycle is greater than the second preset distance (i.e., the second preset distance used to determine the candidate speed limit) and less than or equal to the first preset distance, meaning the vehicle is in the medium speed limit range. At this point, the system determines whether the target distance is greater than the sum of the second preset distance and the preset hysteresis distance (which may differ from the preset hysteresis distance mentioned above). If it is greater, it means the vehicle has sufficiently moved away from the boundary of the low-speed gear and has clearly left the low-speed limit area, allowing the candidate speed limit (the first preset speed) to be determined as the target speed limit. If it is less than or equal to the sum of the two, it means the vehicle has briefly left the low-speed limit area but is still near the boundary; in this case, the historical speed limit remains unchanged, and the current stricter speed limit is maintained.

[0061] For example, when the target distance is 22 meters, the candidate speed limit is the first preset speed (22 meters is greater than the second preset distance of 20 meters), but 22 meters is not greater than 25 meters (20 meters + 5 meters), so the historical speed limit (second preset speed) is maintained, and the speed limit is not relaxed. Only when the target distance is greater than 25 meters is it allowed to adjust the speed limit from the second preset speed to the first preset speed. Therefore, the condition for exiting low gear (25 meters) is more stringent than the condition for entering low gear (20 meters).

[0062] This embodiment introduces a preset hysteresis distance in the low-speed gear release determination, making the conditions for exiting a low-speed limited gear more stringent than those for entering it. When the vehicle moves slightly back and forth near the low-speed gear boundary, the speed limit will not be immediately released simply because the target distance occasionally exceeds a second preset distance. The speed limit is only truly released when the vehicle continuously moves away and clearly exceeds the boundary plus the hysteresis range. This effectively suppresses repeated jumps in the speed limit state when the vehicle position vibrates near the gear boundary due to positioning noise or perception fluctuations. The downstream speed planning module obtains a more stable speed limit input, avoiding sudden acceleration changes caused by frequent speed limit switching and improving the smoothness of speed control.

[0063] In some embodiments, before determining the candidate speed limit based on the distance range in which the target distance is located, the speed control method further includes: determining the historical speed limit as the target speed limit when the target distance is determined to be zero.

[0064] For example, a target distance of zero indicates that the front end of the autonomous vehicle has reached the physical position of the stop line. In this case, the historical speed limit from the previous update cycle will be directly maintained as the target speed limit for the current update cycle, without calculating or updating candidate speed limits.

[0065] This embodiment avoids graded back-calculation at zero distance by using pre-judgment, preventing invalid or abnormal speed limit updates due to the distance falling into a low-speed range. Simultaneously, maintaining historical speed limits ensures the continuity of speed limit output, preventing the speed limit value from being incorrectly zeroed or reset when the vehicle is exactly at the stop line.

[0066] Based on the aforementioned speed control method for autonomous vehicles, this application also provides a speed control device for autonomous vehicles. The following will be combined with... Figure 3 The device is described in detail.

[0067] Figure 4 A schematic block diagram of a vehicle speed control device for an autonomous vehicle according to an embodiment of this application is shown.

[0068] like Figure 4 As shown, the vehicle speed control device 400 of the autonomous vehicle in this embodiment includes an acquisition module 401, a determination module 402, an update module 403, and a control module 404.

[0069] The acquisition module 401 is used to acquire the target distance between the position of the autonomous vehicle and the stop line at any time in the current update cycle and the historical speed limit corresponding to the previous update cycle. The stop line is the position where the autonomous vehicle needs to stop and wait. In one embodiment, the acquisition module 401 can be used to execute step S1 described above, which will not be repeated here.

[0070] The determining module 402 is used to determine candidate speed limits based on the distance range in which the target distance falls. In one embodiment, the determining module 402 can be used to perform step S2 as described above, which will not be repeated here.

[0071] The update module 403 is used to update the historical limit speed using the candidate limit speed to obtain the target limit speed corresponding to the current update cycle. In one embodiment, the update module 403 can be used to execute step S3 described above, which will not be repeated here.

[0072] The control module 404 is used to control the driving speed of the autonomous vehicle within the current update cycle to not exceed the target speed limit. In one embodiment, the control module 404 can be used to perform step S4 described above, which will not be repeated here.

[0073] According to an embodiment of this application, the determining module 402 is further configured to determine the candidate limiting speed as infinite when the target distance is greater than the first preset distance; determine the candidate limiting speed as the first preset speed when the target distance is greater than the second preset distance and less than or equal to the first preset distance, wherein the first preset distance is greater than the second preset distance; and determine the candidate limiting speed as the second preset speed when the target distance is less than or equal to the second preset distance, wherein the first preset speed is greater than the second preset speed.

[0074] According to an embodiment of this application, the acquisition module 401 is further configured to acquire the traffic light signal status currently faced by the autonomous vehicle; the determination module 402 is further configured to increase the first preset distance and / or the second preset distance, or decrease the first preset speed and / or the second preset speed, when the traffic light signal status indicates that passage is prohibited or a transitional warning is issued; and to decrease the first preset distance and / or the second preset distance, or increase the first preset speed and / or the second preset speed, when the traffic light signal status indicates that passage is permitted.

[0075] According to an embodiment of this application, the update module 403 is further configured to determine the candidate limit speed as the target limit speed when the candidate limit speed is less than or equal to the historical limit speed; or to update the target limit speed according to preset update conditions when the candidate limit speed is greater than the historical limit speed.

[0076] According to an embodiment of this application, the update module 403 is further configured to determine the candidate limiting speed as the target limiting speed when the candidate limiting speed is infinite and the target distance is greater than the sum of the first preset distance and the preset hysteresis distance; or to determine the historical limiting speed as the target limiting speed when the candidate limiting speed is infinite and the target distance is less than or equal to the sum of the first preset distance and the preset hysteresis distance.

[0077] According to an embodiment of this application, the update module 403 is further configured to determine the candidate restricted speed as the target restricted speed when the candidate restricted speed is the first preset speed and the target distance is greater than the sum of the second preset distance and the preset hysteresis distance; or to determine the historical restricted speed as the target restricted speed when the candidate restricted speed is the first preset speed and the target distance is less than or equal to the sum of the second preset distance and the preset hysteresis distance.

[0078] According to an embodiment of this application, the update module 403 is further configured to determine the historical speed limit as the target speed limit when the target distance is determined to be zero, before determining the candidate speed limit based on the distance range in which the target distance is located.

[0079] According to embodiments of this application, any multiple modules among the acquisition module 401, determination module 402, update module 403, and control module 404 can be combined into one module, or any one of these modules can be split into multiple modules. Alternatively, at least some of the functions of one or more of these modules can be combined with at least some of the functions of other modules and implemented in one module. According to embodiments of this application, at least one of the acquisition module 401, determination module 402, update module 403, and control module 404 can be at least partially implemented as hardware circuitry, such as field-programmable gate arrays, programmable logic arrays, systems-on-a-chip, systems-on-a-substrate, systems-on-package, application-specific integrated circuits, or any other reasonable means of integrating or packaging circuitry, or implemented in software, hardware, or firmware, or in any appropriate combination of any of these three implementation methods. Alternatively, at least one of the acquisition module 401, determination module 402, update module 403, and control module 404 can be at least partially implemented as a computer program module, which can perform corresponding functions when the computer program module is run.

[0080] Based on the aforementioned speed control method for autonomous vehicles, this application also provides a speed control system for autonomous vehicles. The following will be combined with... Figure 5 The system is described in detail.

[0081] Figure 5 A schematic block diagram of a vehicle speed control system for an autonomous vehicle according to an embodiment of this application is shown.

[0082] like Figure 5As shown, the vehicle speed control system for an autonomous vehicle according to an embodiment of this application includes: a distance detector 501 for detecting the target distance between the autonomous vehicle 101 and the stop line at any time in the current update cycle; a memory 502 for storing the historical speed limit corresponding to the previous update cycle; and a controller 102, which is communicatively connected to the distance detector 501 and the memory 502, and is configured to: determine candidate speed limits based on the distance range in which the target distance is located; update the historical speed limits using the candidate speed limits to obtain the target speed limit corresponding to the current update cycle; and control the driving speed of the autonomous vehicle 101 in the current update cycle to not exceed the target speed limit; the memory 502 is also used to store the target speed limit corresponding to the current update cycle.

[0083] Based on the above-described speed control method for autonomous vehicles, this application also provides an autonomous vehicle, including: a speed control system for an autonomous vehicle according to any of the above embodiments.

[0084] In the description of this application, it should be understood that the terms "upper," "lower," "middle," etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or constructions will be omitted when they may cause confusion in understanding this application. Furthermore, the shape, size, and positional relationship of each component in the drawings do not reflect the actual size, scale, and actual positional relationship.

[0085] Similarly, to simplify this application and aid in understanding one or more of the various disclosed aspects, in the above description of exemplary embodiments of this application, various features of this application are sometimes grouped together into a single embodiment, figure, or description thereof. The use of terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0086] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. Furthermore, the word "a" or "an" preceding an element does not exclude the presence of multiple such elements.

[0087] The above specific embodiments further illustrate the purpose, technical solution and beneficial effects of this application. It should be understood that the above are only specific embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for controlling the speed of an autonomous vehicle, characterized in that, include: The system obtains the target distance between the position of the autonomous vehicle at any time in the current update cycle and the stop line, and the historical speed limit corresponding to the previous update cycle of the current update cycle. The stop line is the position where the autonomous vehicle needs to stop and wait. Candidate speed limits are determined based on the distance range in which the target distance is located; The candidate limit speed is used to update the historical limit speed to obtain the target limit speed corresponding to the current update period; The driving speed of the autonomous vehicle during the current update cycle shall not exceed the target speed limit.

2. The vehicle speed control method for an autonomous vehicle according to claim 1, characterized in that, Determining candidate speed limits based on the distance range in which the target distance lies includes: If the target distance is greater than a first preset distance, the candidate speed limit is determined to be infinite. If the target distance is greater than the second preset distance and less than or equal to the first preset distance, the candidate speed limit is determined to be the first preset speed, where the first preset distance is greater than the second preset distance. If the target distance is less than or equal to the second preset distance, the candidate speed limit is determined to be the second preset speed, and the first preset speed is greater than the second preset speed.

3. The speed control method for an autonomous vehicle according to claim 2, characterized in that, The method further includes: Obtain the status of the traffic light signal currently being faced by the autonomous vehicle; When the traffic light signal status indicates a prohibition to pass or a transitional warning, the first preset distance and / or the second preset distance may be increased, or the first preset speed and / or the second preset speed may be decreased. When the traffic light signal indicates that passage is permitted, the first preset distance and / or the second preset distance may be reduced, or the first preset speed and / or the second preset speed may be increased.

4. The vehicle speed control method for an autonomous vehicle according to claim 1, characterized in that, The candidate limit speed is used to update the historical limit speed to obtain the target limit speed corresponding to the current update period, including: If the candidate speed limit is less than or equal to the historical speed limit, the candidate speed limit is determined as the target speed limit; or If the candidate speed limit is greater than the historical speed limit, the target speed limit is updated according to preset update conditions.

5. The vehicle speed control method for an autonomous vehicle according to claim 4, characterized in that, Update the target speed limit according to preset update conditions, including: If the candidate limiting speed is infinite and the target distance is greater than the sum of a first preset distance and a preset hysteresis distance, then the candidate limiting speed is determined as the target limiting speed; or If the candidate limiting speed is infinite and the target distance is less than or equal to the sum of the first preset distance and the preset hysteresis distance, the historical limiting speed is determined as the target limiting speed.

6. The speed control method for an autonomous vehicle according to claim 4 or 5, characterized in that, Updating the target speed limit according to preset update conditions also includes: If the candidate limiting speed is a first preset speed, and the target distance is greater than the sum of a second preset distance and a preset hysteresis distance, then the candidate limiting speed is determined as the target limiting speed; or If the candidate speed limit is a first preset speed, and the target distance is less than or equal to the sum of the second preset distance and the preset hysteresis distance, the historical speed limit is determined as the target speed limit.

7. The speed control method for an autonomous vehicle according to claim 1, characterized in that, Before determining the candidate speed limit based on the distance range in which the target distance falls, the method further includes: If the target distance is determined to be zero, the historical speed limit is determined as the target speed limit.

8. A speed control device for an autonomous vehicle, characterized in that, The device includes: The acquisition module is used to acquire the target distance between the position of the autonomous vehicle and the stop line at any time in the current update cycle and the historical speed limit corresponding to the previous update cycle of the current update cycle, wherein the stop line is the position where the autonomous vehicle needs to stop and wait. The determination module is used to determine candidate speed limits based on the distance range in which the target distance is located; The update module is used to update the historical limit speed using the candidate limit speed to obtain the target limit speed corresponding to the current update cycle; The control module is used to control the driving speed of the autonomous vehicle during the current update cycle to not exceed the target speed limit.

9. A speed control system for an autonomous vehicle, characterized in that, include: Distance detectors are used to detect the target distance between autonomous vehicles and the stop line at any point in the current update cycle; The memory is used to store the historical speed limit corresponding to the previous update cycle of the current update cycle; The controller is communicatively connected to the distance detector and the memory, respectively, and is configured to: Candidate speed limits are determined based on the distance range in which the target distance is located; The candidate limit speed is used to update the historical limit speed to obtain the target limit speed corresponding to the current update period; Control the autonomous vehicle to ensure that its driving speed during the current update cycle does not exceed the target speed limit. The memory is also used to store the target speed limit corresponding to the current update cycle.

10. An autonomous vehicle, characterized in that, include: The vehicle speed control system for an autonomous vehicle according to claim 9.

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