CN113581204B - Method for estimating path speed limit value in unmanned map, electronic equipment and storage medium - Google Patents
Method for estimating path speed limit value in unmanned map, electronic equipment and storage medium Download PDFInfo
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- CN113581204B CN113581204B CN202110882253.6A CN202110882253A CN113581204B CN 113581204 B CN113581204 B CN 113581204B CN 202110882253 A CN202110882253 A CN 202110882253A CN 113581204 B CN113581204 B CN 113581204B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
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Abstract
The embodiment of the invention relates to the technical field of unmanned, and discloses a method for estimating a path speed limit value in an unmanned map, electronic equipment and a storage medium. When the integral speed limit value of the target curve sub-path is determined, the integral performance of the curve is comprehensively considered, so that the integral speed limit value accords with the curve characteristic. Secondly, the smooth speed limiting value is considered, so that the safe speed limiting value not only can meet the speed required by a curve, but also can smoothly decelerate.
Description
Technical Field
The embodiment of the invention relates to the technical field of unmanned aerial vehicle, in particular to a method for estimating a path speed limit value in an unmanned map, electronic equipment and a storage medium.
Background
Driving planning is an important part of unmanned technology, and is divided into global planning and local planning. The global planning is to plan a rough path without considering obstacles, the path is characterized by the spaced path points, and each path point can preset a traffic speed limit, so that when an unmanned vehicle moves to a certain path point, the speed of the unmanned vehicle does not exceed the traffic speed limit of the path point. The local planning is to plan a collision-free and executable route according to the result of global planning and considering the characteristics of vehicle kinematics, etc., and calculate the target speed of each path point on the route in real time, and drive according to the target speed. It can be known that the local planning frequency is very high, the calculated amount is large, the planned route is short, if the unmanned vehicle is in the process of passing through a curve, if a curve speed limit is not given in advance in the process of global planning, the speed can not be reduced smoothly in the process of local planning, and the phenomenon of sudden braking can occur before the curve.
For the current speed limiting method, the curvature of each path point is directly used for calculating the maximum speed which can be achieved by each path point to limit the speed, the integrity of the curve is not considered, and unreasonable speed limits exist, so that the unmanned vehicle cannot smoothly and safely run.
Disclosure of Invention
The technical problem to be solved by the embodiment of the invention is to provide a method for estimating the speed limit value of the path in the unmanned map, electronic equipment and a storage medium.
In order to solve the above technical problem, in a first aspect, an embodiment of the present invention provides a method for estimating a path speed limit value in an unmanned map, including:
dividing a path into a plurality of segments of sub-paths, wherein the sub-paths comprise a plurality of path points;
determining a curved sub-path in the plurality of sections of sub-paths, wherein the curved sub-path is a sub-path belonging to a curve;
Determining the overall speed limit value of a target curve sub-path according to the curvature of each path point on the target curve sub-path and the curvature of each path point on a curve sub-path adjacent to the target curve sub-path, wherein the target curve sub-path is any curve sub-path;
and determining a safe speed limit value of a target path point according to the integral speed limit value of each curve sub-path, a preset speed limit value of the target path point and a smooth speed limit value of the target path point, wherein the target path point is any path point on the path, and the smooth speed limit value of the target path point is the highest speed value of a path point which enables the unmanned vehicle to smoothly travel from the target path point to the next path point of the target path point.
In some embodiments, the step of determining a curved sub-path of the number of segments of sub-paths comprises:
and determining whether the target sub-path is a curve sub-path according to the path points of the target sub-path and the path points on the sub-paths near the target sub-path, wherein the target sub-path is any sub-path.
In some embodiments, the step of determining a curved sub-path of the number of segments of sub-paths further comprises:
If the number of the interval sub-paths between the first curve sub-path and the second curve sub-path is smaller than or equal to a first preset threshold value, determining that all sub-paths between the first curve sub-path and the second curve sub-path are curve sub-paths, wherein the first curve sub-path and the second curve sub-path are any curve sub-path.
In some embodiments, the step of determining whether the target sub-path is a curved sub-path according to a path point of the target sub-path and a path point on a sub-path near the target sub-path includes:
linearly fitting the path points of the target sub-path and the path points on the sub-path near the target sub-path to obtain a fitting straight line;
if the distance from the path point on the target sub-path to the fitting straight line is greater than or equal to a second preset threshold value, determining that the target sub-path is a curve sub-path; or alternatively, the first and second heat exchangers may be,
and if the angle difference between the direction of one path point and the direction of the other path point on the target sub-path is greater than or equal to a preset angle threshold value in the path points on the target sub-path and the path points on the sub-paths near the target sub-path, determining that the target sub-path is a curve sub-path.
In some embodiments, the step of determining the overall speed limit value of the target curve sub-path according to the curvature of each path point on the target curve sub-path and the curvature of each path point on the curve sub-path adjacent to the target curve sub-path includes:
calculating the average value of the curvatures of each path point on the target curve sub-path and each path point on the curve sub-path adjacent to the target curve sub-path;
calculating the integral speed limit value of the target curve sub-path according to the average value and the following formula;
V w ＝sqrt(g*f*fabs(1/K))*safe_r
wherein V is w And g is the gravity acceleration, f is the friction coefficient of the tire, k is the average value, and safe_r is the expansion coefficient.
In some embodiments, the step of determining the safe speed limit value of the target path point according to the overall speed limit value of each curve sub-path, the preset speed limit value of the target path point and the smooth speed limit value of the target path point includes:
if the target path point is on the curve sub-path and the target path point is not the last path point on the path, the safety speed limit value of the target path point is the minimum value among the whole speed limit value, the preset speed limit value and the smooth speed limit value of the curve sub-path where the target path point is;
If the target path point is on the curve sub-path and the target path point is the last path point of the path, the safety speed limit value of the target path point is the minimum value of the whole speed limit value and the preset speed limit value of the curve sub-path where the target path point is located;
if the target path point is not on the curve sub-path and the target path point is not the last path point on the path, the safety speed limit value of the target path point is the minimum value of the preset speed limit value and the smooth speed limit value;
and if the target path point is not on the curve sub-path and the target path point is the last path point of the path, the safety speed limit value of the target path point is the preset speed limit value.
In some embodiments, the method further comprises:
and determining a smooth speed limit value of the target path point according to the safety speed limit value of the next path point of the target path point.
In some embodiments, the step of determining the smoothed speed limit value for the target path point based on the safety speed limit value for the next path point of the target path point includes:
calculating a smooth speed limit value of the target path point according to the following formula;
V p ＝sqrt(V next +2*a*s)；
Wherein V is p For the smooth speed limit value, V next And a is a preset reference deceleration value, and s is an Euler distance between the target path point and the next path point of the target path point.
In order to solve the above technical problem, in a second aspect, an embodiment of the present invention provides an electronic device, including:
at least one processor, and
a memory communicatively coupled to the at least one processor, wherein,
the memory stores instructions executable by the at least one processor to cause the at least one processor to perform the method as described in the first aspect above.
To solve the above technical problem, in a third aspect, embodiments of the present invention provide a readable storage medium storing a program or instructions that when executed by a processor implement the method according to the first aspect.
The embodiment of the invention has the beneficial effects that: compared with the prior art, the method for estimating the speed limit value of the path in the unmanned map, the electronic equipment and the storage medium provided by the embodiment of the invention are characterized in that the path is divided into a plurality of sections of sub-paths, wherein the sub-paths comprise a plurality of path points, then, the curved sub-paths in the plurality of sections of sub-paths are determined, the integral speed limit value of the target curved sub-path is determined according to the curvature of each path point on the target curved sub-path (any curved sub-path) and the curvature of each path point on the curved sub-path adjacent to the target curved sub-path, and finally, the safe speed limit value of the target path point is determined according to the integral speed limit value of each curved sub-path, the preset speed limit value of the target path point (any path point on the path) and the smooth speed limit value of the target path point. The overall speed limit value of the target curve sub-path is determined based on the curvature of each path point on the target curve sub-path (any curve sub-path) and the curvature of each path point on the curve sub-path adjacent to the target curve sub-path, and the overall integrity of the curve is comprehensively considered, so that the overall speed limit value accords with the curve characteristic. And secondly, based on the smooth speed limit value of the target path point, the safe speed limit value of any target path point on the path is the highest speed value of the next path point for enabling the unmanned vehicle to smoothly travel from the target path point to the target path point, if the target path point is on the curve sub-path, the safe speed limit value is the result of taking the whole speed limit value, the preset speed limit value and the smooth speed limit value of the curve sub-path into consideration, so that the safe speed limit value not only can meet the speed required by the curve, but also can smoothly decelerate, namely, the unmanned vehicle can smoothly and safely travel when the unmanned vehicle travels on the curve, and if the target path point is not on the curve sub-path, the safe speed limit value is the speed limit result of taking the preset speed limit value and the smooth speed limit value into consideration, so that the unmanned vehicle can smoothly and safely travel.
Drawings
One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which the figures of the drawings are not to be taken in a limiting sense, unless otherwise indicated.
Fig. 1 is a schematic diagram of a driving scenario of an unmanned vehicle according to an embodiment of the present application;
fig. 2 is a schematic structural diagram of an electronic device according to an embodiment of the present application;
fig. 3 is a schematic flow chart of a method for estimating a path speed limit value in an unmanned map according to an embodiment of the present application;
fig. 4 is a schematic diagram of a path segment according to an embodiment of the present application.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present invention.
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.
It should be noted that, if not conflicting, the various features of the embodiments of the present invention may be combined with each other, which are all within the protection scope of the present application. In addition, while functional block division is performed in a device diagram and logical order is shown in a flowchart, in some cases, the steps shown or described may be performed in a different order than the block division in the device, or in the flowchart. Moreover, the words "first," "second," "third," and the like as used herein do not limit the data and order of execution, but merely distinguish between identical or similar items that have substantially the same function and effect.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used in this specification includes any and all combinations of one or more of the associated listed items.
In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
In automatic driving and assisted driving, the unmanned vehicle can sense the surrounding environment through sensors. Among them, the sensors may include, but are not limited to, millimeter wave radar, laser radar, ultrasonic radar, vision sensor, and the like. The unmanned vehicle can detect and classify the environment around the vehicle through the sensor, and transmit the information to the control module to form a decision on the future driving direction and speed of the vehicle, and finally the decision is executed through the actuator to complete the whole auxiliary driving or automatic driving process. It will be appreciated that the unmanned vehicle should also follow the speed limit regulations of the road, for example the speed limit regulations in the "road traffic safety law" when driving on the road.
In one example, a driving scenario for an unmanned vehicle is shown in FIG. 1. In the driving scenario shown in fig. 1, the unmanned vehicle needs to travel from a starting point to a destination, and the path planned on the map is path 1#. As can be seen from FIG. 1, the unmanned vehicle needs to turn around and turn around in the running process, the speed limit of the sign on the road shows that the speed limit is 20km/h at the turning around place, 30km/h at the turning around place and 60km/h at other gentle places. When the unmanned vehicle runs to the corresponding position, the maximum speed of the unmanned vehicle cannot exceed the corresponding speed limit of the position.
In addition, in order to ensure the smoothness and the safety of the unmanned vehicle in the running process, besides the traffic speed limit regulated by the road traffic law, speed limit planning can be carried out on each section on the road according to the characteristics of the road, and a speed limit scheme planned in advance is transmitted to a control module of the unmanned vehicle, so that the control module can also adjust the running speed by combining the speed limit scheme, and the smoothness and the safety of the unmanned vehicle in the running process are ensured.
For example, the speed limit value of each point on the route is set according to the characteristics of the route passing through schools, hospitals or tunnels. It can be understood that when the speed limit planning is performed on the path, a plurality of path points can be set on the path, namely, a plurality of sequential path points are connected in series to form the path, and the position, the orientation angle, the curvature, the speed limit value and the traffic speed limit value of the path point are recorded on each path point. The traffic speed limit value can be regulated by the road traffic safety law, and the speed limit value is set according to the smoothness and/or safety of the unmanned vehicle in the running process. Then, the data of each route point is transmitted to a control module of the unmanned vehicle, so that the unmanned vehicle can adjust the speed in real time according to the running position of the unmanned vehicle, and the speed at the running position is smaller than each speed limit value of the route point corresponding to the running position.
In the existing speed limiting method, the curvature of each path point is directly used for calculating the maximum speed which can be achieved by each path point to limit the speed, the integrity of a curve cannot be considered, unreasonable speed limits exist, and therefore the unmanned vehicle cannot smoothly and safely run.
Therefore, in order to ensure smoothness and safety of the unmanned vehicle in the driving process, the embodiment of the application provides a path speed limit value estimation method in the unmanned map, so that the unmanned vehicle can run smoothly and safely.
The method for estimating the path speed limit value in the unmanned map can be executed by a chip, a processor or a device for determining the safety speed limit value, wherein the chip, the processor or the device for determining the safety speed limit value can be installed in electronic equipment so as to execute the method for estimating the path speed limit value in the unmanned map provided by the embodiment of the application through the chip, the processor or the device for determining the safety speed limit value. In some embodiments, the chip, the processor or the device for determining the safety speed limit value may also be installed in an unmanned vehicle, where the electronic device is the unmanned vehicle. It is to be understood that the electronic device may be any device having computing processing capabilities, such as a computer, server or mobile terminal, without any limitation to the specific form of electronic device.
In the following description of the electronic device, another embodiment of the present application further provides an electronic device, referring to fig. 2, the electronic device 10 includes at least one processor 11 and a memory 12 (bus connection, one processor is taken as an example in fig. 2) which are communicatively connected.
The processor 11 is configured to provide computing and control capabilities to control the electronic device 10 to perform corresponding tasks, for example, to control the electronic device 10 to perform any one of the path speed limit value estimation methods in the unmanned map provided in the following embodiments.
It is understood that the processor 11 may be a general-purpose processor, including a central processing unit (Central Processing Unit, CPU), a network processor (Network Processor, NP), etc.; but also digital signal processors (Digital Signal Processing, DSP), application specific integrated circuits (Application Specific Integrated Circuit, ASIC), field programmable gate arrays (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.
The memory 12 is used as a non-transitory computer readable storage medium, and can be used to store a non-transitory software program, a non-transitory computer executable program, and a module, such as a program instruction/module corresponding to the path speed limit value estimation method in the unmanned map in the embodiment of the invention. The processor 11 may implement the path limit value estimation method in the unmanned map in any of the method embodiments described below by running non-transitory software programs, instructions and modules stored in the memory 12. In particular, the memory 12 may include high-speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, flash memory device, or other non-transitory solid state storage device. In some embodiments, memory 12 may also include memory located remotely from the processor, which may be connected to the processor via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
The following describes in detail the method for estimating the speed limit value of the path in the unmanned map provided in the embodiment of the present application, referring to fig. 3, the method S20 includes, but is not limited to, the following steps:
s21: the path is divided into a number of segments of sub-paths, wherein the sub-paths comprise a plurality of path points.
S22: and determining a curved sub-path in the plurality of sections of sub-paths, wherein the curved sub-path is a sub-path belonging to a curve.
S23: and determining the overall speed limit value of the target curve sub-path according to the curvature of each path point on the target curve sub-path and the curvature of each path point on the curve sub-path adjacent to the target curve sub-path, wherein the target curve sub-path is any curve sub-path.
S24: and determining a safe speed limit value of a target path point according to the integral speed limit value of each curve sub-path, a preset speed limit value of the target path point and a smooth speed limit value of the target path point, wherein the target path point is any path point on the path, and the smooth speed limit value of the target path point is the highest speed value of a path point which enables the unmanned vehicle to smoothly travel from the target path point to the next path point of the target path point.
As shown in fig. 4, the path is divided into a plurality of sub-paths, and a plurality of path points are set on the basis of the path, so that one sub-path includes a plurality of path points. It can be understood that the path point is a virtual position point, a plurality of sequential path points are connected in series to form the path, and the position, the orientation angle, the curvature, various speed limit values and the like of the path point are recorded on each path point.
Specifically, the total length of the path is the sum S0 of the distances between every two adjacent path points, and the distance between any two adjacent path points is the euler distance between the two path points. If the maximum segment distance is S1, the number of segments r=ceil (S0/S1), and thus the actual segment distance s2=s0/r.
After the several segments of sub-paths are acquired, the curved sub-paths in the several segments of sub-paths are determined, and it can be understood that the curved sub-paths are sub-paths belonging to a curve. It will be appreciated that the sub-paths may be numbered sequentially, for example, reference number 1 being the first sub-path and reference number i being the i-th sub-path. For example, determining sub-path 2 and sub-path 3 in FIG. 4 as curve sub-paths, it will be appreciated that the path segments in FIG. 4 are merely illustrative and do not constitute any limitation on paths and path segments. Specifically, in some embodiments, whether a sub-path is a curve sub-path may be determined according to a radius of curvature of the sub-path, for example, if an average radius of curvature of the sub-path is greater than or equal to a preset curvature threshold, the sub-path is determined to be a curve sub-path.
And for any curve sub-path, namely a target curve sub-path, determining the overall speed limit value of the target curve sub-path according to the curvature of each path point on the target curve sub-path and the curvature of each path point on the curve sub-path adjacent to the target curve sub-path. For example, if both the sub-paths i-1 and i+1 adjacent to the target curve sub-path i are not curve sub-paths, the overall speed limit value of the target curve sub-path is determined directly according to the curvatures of the path points on the target curve sub-path i, and if both the sub-paths i-1 and i+1 adjacent to the target curve sub-path i are curve sub-paths, the overall speed limit value of the target curve sub-path is determined according to the curvatures of the path points on the curve sub-paths i-1, i and i+1. For example, the curvature of each path point on the target curve sub-path and the mapping relationship between the average value of the curvature of each path point on the curve sub-path adjacent to the target curve sub-path and the overall speed limit value may be set, so that the corresponding overall speed limit value may be determined according to the average value of each curvature.
It is known that the overall speed limit value of the target curve sub-path is determined based on the curvature of each path point on the target curve sub-path (any curve sub-path) and the curvature of each path point on the curve sub-path adjacent to the target curve sub-path, and the overall speed limit value of the target curve sub-path is determined by only the curvature of each path point on the target curve sub-path, in which the overall integrity of the curve is considered so that the overall speed limit value conforms to the curve characteristics.
And for any path point on the path, namely the target path point, determining the safety speed limit value of the target path point according to the integral speed limit value of each curve sub-path, the preset speed limit value of the target path point and the smooth speed limit value of the target path point. The preset speed limit value may be a speed limit value specified by a traffic law, and the smooth speed limit value is a highest speed value for enabling the unmanned vehicle to smoothly travel from the target path point to a next path point of the target path point.
For example, if the target path point is on the curve sub-path, the safe speed limit value of the target path point may be smaller than the overall speed limit value of the curve sub-path and smaller than the preset speed limit value and the smooth speed limit value, and if the target path point is not on the curve sub-path, the safe speed limit value of the target path point is smaller than the preset speed limit value and the smooth speed limit value.
That is, if the target path point is on the curve sub-path, the safe speed limit value is a result of considering the whole speed limit value, the preset speed limit value and the smooth speed limit value of the curve sub-path, so that the safe speed limit value not only can meet the speed required by the curve, but also can smoothly decelerate, that is, the unmanned vehicle can smoothly and safely run when the unmanned vehicle runs on the curve, and if the target path point is not on the curve sub-path, the safe speed limit value is a result of considering the preset speed limit value and the smooth speed limit value, so that the unmanned vehicle can smoothly and safely run.
In this embodiment, the path is divided into a plurality of segments of sub-paths, wherein the sub-paths include a plurality of path points, then a curved sub-path of the segments of sub-paths is determined, an overall speed limit value of the target curved sub-path is determined according to a curvature of each path point on the target curved sub-path (any curved sub-path) and a curvature of each path point on a curved sub-path adjacent to the target curved sub-path, and finally a safe speed limit value of the target path point is determined according to the overall speed limit value of each curved sub-path, a preset speed limit value of the target path point (any path point on the path), and a smooth speed limit value of the target path point. The overall speed limit value of the target curve sub-path is determined based on the curvature of each path point on the target curve sub-path (any curve sub-path) and the curvature of each path point on the curve sub-path adjacent to the target curve sub-path, and the overall integrity of the curve is comprehensively considered, so that the overall speed limit value accords with the curve characteristic. And secondly, based on the smooth speed limit value of the target path point is the highest speed value of the path point which enables the unmanned vehicle to smoothly travel from the target path point to the next path point of the target path point, if the target path point is on the curve sub-path, the safe speed limit value is the result of taking the whole speed limit value, the preset speed limit value and the smooth speed limit value of the curve sub-path into consideration, so that the safe speed limit value not only can meet the speed required by the curve, but also can smoothly decelerate, namely, the unmanned vehicle can smoothly and safely run when the unmanned vehicle travels on the curve, and if the target path point is not on the curve sub-path, the safe speed limit value is the speed limit result of taking the preset speed limit value and the smooth speed limit value into consideration, and the unmanned vehicle can smoothly and safely run.
In some embodiments, step S22 specifically includes:
s221: and determining whether the target sub-path is a curve sub-path according to the path points of the target sub-path and the path points on the sub-paths near the target sub-path, wherein the target sub-path is any sub-path.
For example, for the target sub-path i, it may be determined whether the target sub-path is a curved sub-path according to all the path points from the sub-path w to the sub-path i+1, where w < i, that is, the sub-path w to the sub-path i-1 and the sub-path i are sub-paths near the target sub-path.
In order to avoid misjudging the target sub-path as a curved sub-path without interference from other curved sub-paths, in some embodiments, w=max (u+1, i-P0), where u is the first curved sub-path to go forward of sub-path i-1, and P0 is an empirical value, which may be 3. Therefore, when u+1 is greater than i-P0, it is explained that the first curve sub-path u before the target sub-path i is closer to the target sub-path i, and the sub-path after the first curve sub-path u before is taken for judging whether the target sub-path is the curve sub-path, so that erroneous judgment of the target sub-path i as the curve sub-path due to the fact that the curvature of the path point on the first curve sub-path u before is greater can be avoided, namely, the influence of the first curve sub-path u before is avoided. When u+1 is smaller than i-P0, it is indicated that the first curve sub-path u before is far away from the target sub-path i, and then the sub-paths of the previous sections of the target sub-path i (i.e. sub-paths i-P0 to i-1) are taken for judging whether the target sub-path is the curve sub-path, so that accuracy can be increased. For example, if the target sub-path i is a gentle portion of a large L curve, it is highly possible to misjudge the target sub-path i as a non-curved sub-path if only the path point on the target sub-path i is considered, and such a situation can be effectively avoided by considering the path point on the sub-path near the target sub-path i.
In this embodiment, whether the target sub-path is a curve sub-path is determined according to the path point of the target sub-path and the path points on the sub-paths near the target sub-path, so that accuracy can be improved and erroneous judgment can be reduced.
In some embodiments, step S221 further comprises:
s2211: and linearly fitting the path points of the target sub-path and the path points on the sub-path near the target sub-path to obtain a fitting straight line.
S2212: and if the distance from the path point on the target sub-path to the fitting straight line is greater than or equal to a second preset threshold value, determining that the target sub-path is a curve sub-path.
For example, for the target sub-path i, the coordinate positions of all the path points on the sub-paths u+1 to i+1 are linearly fitted to obtain a fitting straight line. Specifically, a least square method may be used for linear fitting.
And then, calculating the distance between each path point on the target sub-path i and the fitting straight line, and if the distance between one path point on the target sub-path and the fitting straight line is larger than or equal to a second preset threshold value, determining that the target sub-path is a curve sub-path if the degree of deviation of the target sub-path from the fitting straight line is larger.
It should be noted that the second preset threshold is a set empirical value, and may be determined by those skilled in the art according to experiments. In some embodiments, the second preset threshold may be 0.5 meters.
In this embodiment, the fitted straight line represents the trend of the target sub-path and the sub-paths nearby the target sub-path, and if the distance from the path point on the target sub-path to the fitted straight line is greater than or equal to the second preset threshold value, it is indicated that the target sub-path deviates from the trend, and it can be accurately determined that the target sub-path is a curve sub-path.
In some embodiments, it may also be determined whether the target sub-path is a curve sub-path through step S2213 described below.
Specifically, step S2213: and if the angle difference between the direction of one path point and the direction of the other path point on the target sub-path is greater than or equal to a preset angle threshold value in the path points on the target sub-path and the path points on the sub-paths near the target sub-path, determining that the target sub-path is a curve sub-path.
Wherein the orientation of the path point is the tangential direction of the sub-path at the path point. For example, for the target sub-path i, if the angle between the direction of one path point a and the direction of the other path point b on the target sub-path is greater than or equal to the preset angle threshold value, the trend of the target sub-path is changed, and the target sub-path is determined to be the curve sub-path.
It should be noted that the preset angle threshold is a set empirical value, and may be determined by those skilled in the art according to experiments. In some embodiments, the preset angle threshold may be 90 °.
In this embodiment, by comparing the angular orientation of the path point on the target sub-path with the angular orientations of the other path points, it is possible to accurately determine that the target sub-path is a curve sub-path.
To avoid missed determination of the curve sub-path, in some embodiments, step S22 further includes:
s222: if the number of the interval sub-paths between the first curve sub-path and the second curve sub-path is smaller than or equal to a first preset threshold value, determining that all sub-paths between the first curve sub-path and the second curve sub-path are curve sub-paths, wherein the first curve sub-path and the second curve sub-path are any curve sub-path.
For example, for any one of the curved sub-paths i and j, i.e., the first curved sub-path i and the second curved sub-path j, if i-j is less than or equal to a first preset threshold, all sub-paths between the first curved sub-path i and the second curved sub-path j are determined to be curved sub-paths. Therefore, the situation that the local gentle sub-path among the curve sub-paths is misjudged to be the non-curve sub-path can be avoided, and further the unmanned vehicle is prevented from accelerating in the curve.
For the exemplary illustration of a U-bend, if the entire U-bend is divided into 3 sections, the first section is a bend (sub-path i), the second section is a straight middle (sub-path i+1), and the third section is a bend (sub-path j), if the determination in step S221 is made as a non-bend, the straight middle (i.e., sub-path i+1) may be regarded as a non-bend, which may cause the unmanned vehicle to accelerate on the straight middle of the U-bend during the turning, resulting in a safety hazard.
In this embodiment, all the sub-paths between the closely spaced curved sub-paths are further used as curved sub-paths, so that the above situation can be effectively avoided, that is, the middle straight path of the U-shaped curve cannot be misjudged as a non-curved path, and the unmanned vehicle is safer to run.
In some embodiments, step S23 specifically includes:
s231: calculating the average value of the curvatures of each path point on the target curve sub-path and each path point on the curve sub-path adjacent to the target curve sub-path;
s232: calculating the integral speed limit value of the target curve sub-path according to the average value and the following formula;
V w ＝sqrt(g*f*fabs(1/K))*safe_r
wherein V is w And g is the gravity acceleration, f is the friction coefficient of the tire, k is the average value, and safe_r is the expansion coefficient.
For example, for the target curve sub-path i, if the sub-path i-1 adjacent thereto is a curve sub-path and the sub-path i+1 is not a curve sub-path, the average value of the curvatures of the respective path points on the target curve sub-path i and the curve sub-path i-1 is calculated, and if the sub-path i-1 adjacent thereto and the sub-path i+1 are both curve sub-paths, the average value of the curvatures of the respective path points on the target curve sub-path i, the sub-path i-1 and the sub-path i+1 is calculated. It will be appreciated that the average value can reflect the degree of curvature of the target curve sub-path.
Then, according to formula V w =sqrt (g×f×fabs (1/K)) ×safe_r calculates the overall speed limit value of the target curve sub-path, where g is the gravitational acceleration, f is the friction coefficient of the tire, K is the average value, safe_r is the scaling coefficient, and in some embodiments, the scaling coefficient safe_r may be 0.75. It can be seen that the overall speed limit value V w Inversely proportional to the average value K of the curvature. The larger the average value of the curvature, i.e., the greater the degree of curvature of the target curved sub-path, the smaller the overall speed limit value thereof.
In this embodiment, the overall speed limit value of the target curve sub-path is determined based on an average value of curvatures of each path point on the target curve sub-path and each path point on the curve sub-path adjacent to the target curve sub-path, and the overall speed limit value is inversely proportional to the average value of the curvatures so that the overall speed limit value conforms to the curve characteristic of the target curve sub-path.
In some embodiments, step S24 specifically includes:
s241: and if the target path point is on the curve sub-path and the target path point is not the last path point on the path, the safety speed limit value of the target path point is the minimum value among the whole speed limit value, the preset speed limit value and the smooth speed limit value of the curve sub-path where the target path point is.
S242: and if the target path point is on the curve sub-path and the target path point is the last path point of the path, the safety speed limit value of the target path point is the minimum value of the whole speed limit value and the preset speed limit value of the curve sub-path where the target path point is located.
S243: and if the target path point is not on the curve sub-path and the target path point is not the last path point on the path, the safety speed limit value of the target path point is the minimum value of the preset speed limit value and the smooth speed limit value.
S244: and if the target path point is not on the curve sub-path and the target path point is the last path point of the path, the safety speed limit value of the target path point is the preset speed limit value.
For example, if the target path point D is on the curve sub-path D and the target path point D is not the last path point on the path, the safe speed limit value=mi n of the target path point D (the overall speed limit value of the curve sub-path D, the preset speed limit value of the target path point D, the smooth speed limit value of the target path point D). Therefore, the safety speed limit value of the target path point D does not exceed the integral speed limit value of the corresponding curve sub-path D, does not exceed the preset speed limit value and does not exceed the smooth speed limit value, and accordingly, the safety speed limit value of the target path point D is a result of taking the integral speed limit value of the curve sub-path D, the preset speed limit value of the target path point D and the smooth speed limit value into consideration, so that the safety speed limit value can meet the speed required by a curve, smoothly decelerate to the next path point, and the unmanned vehicle can smoothly and safely run when running the curve.
If the target path point E is on the curve sub-path E and the target path point E is the last path point on the path, the safe speed limit value=mi of the target path point E (the overall speed limit value of the curve sub-path E, the preset speed limit value of the target path point E). Therefore, the safety speed limit value of the target path point E cannot exceed the integral speed limit value of the corresponding curve E and the corresponding preset speed limit value, and the safety of curve running is met.
If the target path point F is on the straight-path sub-path F and the target path point F is not the last path point of the path, the safe speed limit value=mi of the target path point F (preset speed limit value of the target path point F, smooth speed limit value of the target path point F). Therefore, the safe speed limit value of the target path point f does not exceed the preset speed limit value or the smooth speed limit value, and the unmanned vehicle can smoothly decelerate from the target path point f to the next path point.
If the target path point h is on the straight path sub-path F and the target path point h is the last path point of the path, the safety speed limit value of the target path point h is the preset speed limit value of the target path point h. Therefore, the safety speed limit value of the target path point h cannot exceed the corresponding preset speed limit value, and the driving safety can be met.
In this embodiment, for the path point on the curve sub-path, the safe speed limit value thereof is the minimum value of the total speed limit value of the curve sub-path and the preset speed limit value and the smooth speed limit value of the path point, so that the safe speed limit value not only can meet the speed required by the curve, but also can smoothly decelerate, i.e., the unmanned vehicle can smoothly and safely run when driving in the curve, and for the path point on the non-curve sub-path, the safe speed limit value thereof is the minimum value of the preset speed limit value and the smooth speed limit value, so that the safe speed limit value can ensure the unmanned vehicle to smoothly and safely run.
In some embodiments, the method S20 further comprises:
s25: and determining a smooth speed limit value of the target path point according to the safety speed limit value of the next path point of the target path point.
It can be understood that the safety speed limit value of the last path point (i.e. the end point) of the path is a preset speed limit value, and the smooth speed limit value of the last path point N-1 can be reversely pushed from the end point N, so that the unmanned vehicle can smoothly decelerate from the path point N-1 to the path point N. And determining the safety speed limit value of the path point N-1 by combining the smooth speed limit value of the path point N-1 with the curve characteristic of the sub-path where the path point N-1 is positioned. And the like, and then, the smooth speed limit value of the path point N-2 is reversely pushed according to the safe speed limit value of the path point N-1, so that the unmanned vehicle can smoothly decelerate from the path point N-2 to the path point N-1.
It can be understood that the smooth speed limit value of each path point on the path can be reversely deduced from the back to the front and from the first path point according to the rule, so that the unmanned vehicle can smoothly run on the whole path, the condition of sudden braking can not occur, and the stability and the safety are high.
In some embodiments, the step S25 specifically includes:
Calculating a smooth speed limit value of the target path point according to the following formula;
V p ＝sqrt(V next +2*a*s)；
wherein V is p For the smooth speed limit value of the target path point, V next And a is a preset reference deceleration value, and s is an Euler distance between the target path point and the next path point of the target path point. In some embodiments, a may be 1.
It will be appreciated that the smoothing speed V of the target path point p The method is a result of comprehensively considering the safety speed limit value of the next path point and the distance between the safety speed limit value and the next path point, is in direct proportion to the safety speed limit value and the distance of the next path point, namely, determines the smooth speed limit value of the target path point from the two aspects of the distance and the target speed (the safety speed limit value of the next path point) after speed change, and is more reasonable.
In this embodiment, the smooth speed limit value of the target path point is determined from both the distance and the target speed (the safe speed limit value of the next path point) after the speed change, so that the smooth speed limit value of the target path point is more reasonable.
Another embodiment of the present application further provides a readable storage medium storing a program or instructions that when executed by a processor implement a method for estimating a path limit value in a driverless map according to any of the above method embodiments.
It should be noted that the above-described apparatus embodiments are merely illustrative, and the units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
From the above description of embodiments, it will be apparent to those skilled in the art that the embodiments may be implemented by means of software plus a general purpose hardware platform, or may be implemented by hardware. Those skilled in the art will appreciate that all or part of the processes implementing the methods of the above embodiments may be implemented by a computer program for instructing relevant hardware, where the program may be stored in a computer readable storage medium, and where the program may include processes implementing the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read-On-y Memory (ROM), a random access Memory (Random Access Memory, RAM), or the like.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; the technical features of the above embodiments or in the different embodiments may also be combined within the idea of the invention, the steps may be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (10)
1. A method for estimating a path limit value in an unmanned map, comprising:
dividing a path into a plurality of segments of sub-paths, wherein the sub-paths comprise a plurality of path points;
determining a curved sub-path in the plurality of sections of sub-paths, wherein the curved sub-path is a sub-path belonging to a curve;
determining the overall speed limit value of a target curve sub-path according to the curvature of each path point on the target curve sub-path and the curvature of each path point on a curve sub-path adjacent to the target curve sub-path, wherein the target curve sub-path is any curve sub-path;
And determining a safe speed limit value of a target path point according to the integral speed limit value of each curve sub-path, a preset speed limit value of the target path point and a smooth speed limit value of the target path point, wherein the target path point is any path point on the path, the smooth speed limit value of the target path point is the highest speed value of a path point which enables the unmanned vehicle to smoothly travel from the target path point to the next path point of the target path point, and the preset speed limit value is a preset speed limit value.
2. The method of claim 1, wherein the step of determining a curved sub-path of the plurality of segments of sub-paths comprises:
and determining whether the target sub-path is a curve sub-path according to the path points of the target sub-path and the path points on the sub-paths near the target sub-path, wherein the target sub-path is any sub-path.
3. The method of claim 2, wherein the step of determining a curved sub-path of the number of segments of sub-paths further comprises:
if the number of the interval sub-paths between the first curve sub-path and the second curve sub-path is smaller than or equal to a first preset threshold value, determining that all sub-paths between the first curve sub-path and the second curve sub-path are curve sub-paths, wherein the first curve sub-path and the second curve sub-path are any curve sub-path.
4. The method of claim 2, wherein the step of determining whether the target sub-path is a curved sub-path based on a path point of the target sub-path and a path point on a sub-path near the target sub-path, comprises:
linearly fitting the path points of the target sub-path and the path points on the sub-path near the target sub-path to obtain a fitting straight line;
if the distance from the path point on the target sub-path to the fitting straight line is greater than or equal to a second preset threshold value, determining that the target sub-path is a curve sub-path; or alternatively, the first and second heat exchangers may be,
and if the angle difference between the direction of one path point and the direction of the other path point on the target sub-path is greater than or equal to a preset angle threshold value in the path points on the target sub-path and the path points on the sub-paths near the target sub-path, determining that the target sub-path is a curve sub-path.
5. The method of claim 1, wherein the step of determining the overall speed limit value for the target curve sub-path based on the curvature of each path point on the target curve sub-path and the curvature of each path point on the curve sub-path adjacent to the target curve sub-path comprises:
Calculating the average value of the curvatures of each path point on the target curve sub-path and each path point on the curve sub-path adjacent to the target curve sub-path;
calculating the integral speed limit value of the target curve sub-path according to the average value and the following formula;
V w ＝sqrt(g*f*fabs(1/K))*safe_r
wherein V is w And g is the gravity acceleration, f is the friction coefficient of the tire, k is the average value, and safe_r is the expansion coefficient.
6. The method of claim 1, wherein the step of determining the safe speed limit value of the target path point based on the overall speed limit value of each curve sub-path, the preset speed limit value of the target path point, and the smooth speed limit value of the target path point, comprises:
if the target path point is on the curve sub-path and the target path point is not the last path point on the path, the safety speed limit value of the target path point is the minimum value among the whole speed limit value, the preset speed limit value and the smooth speed limit value of the curve sub-path where the target path point is;
if the target path point is on the curve sub-path and the target path point is the last path point of the path, the safety speed limit value of the target path point is the minimum value of the whole speed limit value and the preset speed limit value of the curve sub-path where the target path point is located;
If the target path point is not on the curve sub-path and the target path point is not the last path point on the path, the safety speed limit value of the target path point is the minimum value of the preset speed limit value and the smooth speed limit value;
and if the target path point is not on the curve sub-path and the target path point is the last path point of the path, the safety speed limit value of the target path point is the preset speed limit value.
7. The method of claim 6, wherein the method further comprises:
and determining a smooth speed limit value of the target path point according to the safety speed limit value of the next path point of the target path point.
8. The method of claim 7, wherein the step of determining a smoothed speed limit value for the target waypoint based on the safe speed limit value for the next waypoint for the target waypoint comprises:
calculating a smooth speed limit value of the target path point according to the following formula;
V p ＝sqrt(V next +2*a*s)；
wherein V is p For the smooth speed limit value, V next And a is a preset reference deceleration value, and s is an Euler distance between the target path point and the next path point of the target path point.
9. An electronic device, comprising:
at least one processor, and
a memory communicatively coupled to the at least one processor, wherein,
the memory stores instructions executable by the at least one processor to cause the at least one processor to perform the method of any one of claims 1-8.
10. A readable storage medium, characterized in that it stores a program or instructions which, when executed by a processor, implement the method according to any of claims 1-8.
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