CN112731944A - Autonomous obstacle avoidance method for unmanned road roller - Google Patents
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Abstract
The invention relates to an autonomous obstacle avoidance method for an unmanned road roller, which comprises the following steps: step 1: acquiring data collected by three ultrasonic sensors arranged at the front end or the rear end of the unmanned road roller in real time; step 2: selecting a sub-method according to the data execution behaviors acquired in the step 1, judging whether active obstacle avoidance is needed, if so, executing the step 3, otherwise, returning to the step 1; and step 3: and (3) executing the autonomous obstacle avoidance sub-method to complete autonomous obstacle avoidance of the unmanned road roller, and then returning to the step 1. Compared with the prior art, the method has the advantages of ensuring safety and construction quality, along with high accuracy, better obstacle avoidance effect, better construction effect and the like.
Description
Technical Field
The invention relates to the technical field of autonomous obstacle avoidance of unmanned road rollers, in particular to an autonomous obstacle avoidance method of an unmanned road roller.
Background
The road roller is a high-efficiency compaction machine, is widely applied to construction of roads, dams and the like, and in order to meet the compaction working requirement, an excitation mechanism of the road roller can generate violent vibration during working. In addition, the operation of the road roller is monotonous and boring, and a driver is easy to generate driving fatigue, so that the rolling precision and the rolling quality of the road roller are influenced. Therefore, the intelligent unmanned driving of the road roller is of great significance.
In the working process of the road roller, constructors and engineering vehicles often enter a working area, a prompting mark is arranged in the partial rolling area, in order to ensure the safety of the constructors and avoid the collision of the road roller with other engineering vehicles or the prompting mark, the identification of an obstacle needs to be considered in a road roller path planning algorithm, and the operation is continued after the obstacle is actively avoided or the road roller is stopped to wait for the obstacle to pass through.
At present, many people research the obstacle avoidance method of the unmanned vehicle, for example, chinese patent CN111452786A discloses an obstacle avoidance method and system for the unmanned vehicle, the method includes: determining a vehicle motion area; constructing a vehicle obstacle avoidance segmented optimal control model of a continuous state space based on the vehicle motion area; adopting an hp self-adaptive pseudo-spectrum method to convert the vehicle obstacle avoidance segmental optimal control model of the continuous state space into a vehicle obstacle avoidance segmental optimal control model containing an optimized variable; solving a vehicle obstacle avoidance segmented optimal control model containing optimized variables by adopting an interior point method, and obtaining expected longitudinal acceleration and front wheel corners of a vehicle in a prediction time domain; calculating the throttle opening according to the expected longitudinal acceleration; calculating a steering wheel angle according to the front wheel steering angle; and realizing vehicle control according to the accelerator opening and the steering wheel angle. Although the above patent realizes unmanned driving under the condition that an off-line map and a reference track are unknown, when large-scale special engineering machinery such as a road roller is applied, although certain safety is provided, the construction quality and the construction efficiency of the road roller cannot be guaranteed.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide the autonomous obstacle avoidance method of the unmanned road roller, which can simultaneously ensure the safety and the construction quality, has high accuracy, better obstacle avoidance effect and better construction effect.
The purpose of the invention can be realized by the following technical scheme:
an autonomous obstacle avoidance method of an unmanned road roller comprises the following steps:
step 1: acquiring data collected by three ultrasonic sensors arranged at the front end or the rear end of the unmanned road roller in real time;
step 2: selecting a sub-method according to the data execution behaviors acquired in the step 1, judging whether active obstacle avoidance is needed, if so, executing the step 3, otherwise, returning to the step 1;
and step 3: and (3) executing the autonomous obstacle avoidance sub-method to complete autonomous obstacle avoidance of the unmanned road roller, and then returning to the step 1.
Preferably, the behavior selection sub-method specifically comprises:
step 2-1: judging whether an obstacle enters a sensor detection area or not according to the sensor data acquired in the step 1, if so, executing a step 2-2, otherwise, continuing to drive or execute operation of the road roller, and executing the step 2-1 again;
step 2-2: executing a parking waiting action, and then executing the step 2-3;
step 2-3: judging whether the sensor data needs to be updated according to a preset barrier movement judgment value, if so, updating the sensor data, and if not, keeping the data as the sensor value of the previous detection period;
the method for judging whether the sensor data needs to be updated specifically comprises the following steps:
if the data change value before and after a single data detection period of the sensor exceeds the obstacle movement judgment value, updating the sensor data, otherwise, not updating, and keeping the data as the sensor value in the last detection period;
step 2-4: judging whether the data change values of the three sensors are all smaller than the judgment value for whether the barrier moves or not, if so, starting a timer, setting timing time, then executing the step 2-5, and if not, returning to the step 2-3;
if the sensor data change exceeds the barrier movement judgment value in the timing period of the timer, resetting the timer and returning to the step 2-1, otherwise, continuing timing;
step 2-5: judging whether the change values of the detection data of the three sensors in the timing time of the timer are all smaller than the judgment value for whether the barrier moves or not, if so, executing whistling reminding operation and resetting the timer by the road roller, and then executing the step 2-6, otherwise, returning to the step 2-1;
step 2-6: after whistling and within the timing time of the timer, if the change amplitude of one sensor data exceeds the obstacle movement judgment value, stopping to wait for the object to leave the detection area, continuing to operate, and returning to the step 2-1; and if the variation range of the data of the three sensors is still smaller than the judgment value of whether the obstacle moves or not, the road roller executes the step 3.
Preferably, the step 3 specifically comprises:
step 3-1: determining obstacle avoidance behaviors according to the obstacle detection information, wherein the obstacle avoidance behaviors comprise reverse obstacle avoidance behavior and autonomous obstacle avoidance behavior along the advancing direction of the road roller;
step 3-2: changing the lane to an obstacle avoidance path;
step 3-3: and judging whether the conditions for finishing the reverse obstacle avoidance behavior or the conditions for finishing the autonomous obstacle avoidance behavior along the advancing direction of the road roller are met, if so, finishing the behavior, returning to the step 1, and otherwise, returning to the step 3-2.
More preferably, the step 3-1 specifically comprises:
firstly, determining the position of an obstacle detection point together with a fan-shaped area and boundaries of six detection areas, wherein the fan-shaped area and the boundaries of the six detection areas are drawn by taking the distance between a road roller and an obstacle, which is detected by a sensor, as a radius;
then judging whether the distance between the detection point of the obstacle close to the road roller side and the road roller is smaller than a preset safety distance, if so, executing a reverse obstacle avoidance behavior, otherwise, executing an autonomous obstacle avoidance behavior along the advancing direction of the road roller;
then, setting a safe radius by taking the obstacle detection point as a circle center, and calculating a local obstacle avoidance path on the basis of the safe radius to obtain a local obstacle avoidance path equation;
and finally determining the driving direction of the road roller in the local obstacle avoidance path equation.
More preferably, the driving direction of the road roller is determined by the number of sensors detecting the obstacle information and the corresponding detection distance.
More preferably, in the step 3-1, after the obstacle avoidance direction is determined, the position of the obstacle is determined according to the real-time data of the sensor, and when the new detection point is located at one side of the straight line where the original detection point is located along the obstacle avoidance direction, the obstacle detection information and the local path plan are updated, otherwise, the information is not updated.
More preferably, the obstacle avoidance path in step 3-2 is specifically:
wherein (x)obj,yobj) Representing coordinates of the obstacle detection point in a navigation coordinate system;
representing the included angle between the current global planning straight-line path and the x axis of the navigation coordinate system; d represents a straight line offset distance set to bypass an obstacle;
the positive sign and the negative sign on the right side of the medium sign in the formula are determined by the obstacle avoidance direction of the road roller, and the specific method is as follows:
more preferably, in the obstacle avoidance process of the road roller in the step 3-2, when the obstacle leaves the detection area of the sensor, the unmanned road roller can drive along the last planned obstacle avoidance path until the front vehicle body and the rear vehicle body bypass the obstacle, and the whole obstacle avoidance process is completed.
More preferably, the condition for ending the autonomous obstacle avoidance behavior along the advancing direction of the road roller is as follows:
the road roller successfully bypasses the barrier;
or when the road roller bypasses the obstacle, the distance between the road roller and the object is less than the set safe distance;
or the distance between the new obstacle detection point and the original obstacle detection point is larger than the linear offset distance of the road roller for obstacle detouring.
More preferably, the ending condition of the reverse obstacle avoidance behavior is as follows:
the detection distance of any sensor in the reverse ultrasonic sensors of the road roller is less than the set safety distance;
or the transverse error and the course error of the road roller and the local obstacle avoidance path are both smaller than the set error value when the road roller runs in the reverse direction.
Compared with the prior art, the invention has the following beneficial effects:
firstly, guarantee security and construction quality simultaneously: the autonomous obstacle avoidance method of the unmanned road roller adopts a behavior selection strategy, and the behavior of the unmanned road roller after encountering obstacles is divided into parking waiting and active obstacle avoidance, so that the safety of constructors can be ensured at the first time, the original path track of the unmanned road roller is maintained as much as possible, and the construction quality is ensured.
Secondly, the accuracy is high: according to the autonomous obstacle avoidance method of the unmanned road roller, the area where the detection points on the edge of the obstacle are located is judged according to the number of the sensors for detecting the obstacle and the detection distance of the sensors, the accuracy is higher, and reliable basis is provided for the direction and the track of autonomous obstacle avoidance.
Thirdly, obstacle avoidance effect is better, and construction effect is better: the autonomous obstacle avoidance method of the unmanned road roller has the advantages that the end condition of the behavior of bypassing the obstacle and the end condition of the obstacle avoidance of reverse driving are provided, the logicality of the autonomous obstacle avoidance method of the unmanned road roller is improved, the obstacle avoidance effect is better, and the construction effect is better.
Drawings
Fig. 1 is a schematic flow chart illustrating a behavior selection sub-method executed by an autonomous obstacle avoidance method according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of autonomous obstacle avoidance behavior of the unmanned road roller along the heading direction of the road roller in an embodiment of the invention;
FIG. 3 is a diagram of an obstacle avoidance pattern for a road roller when one sensor detects data in an embodiment of the present invention;
FIG. 4 is a diagram of an obstacle avoidance pattern corresponding to a road roller when two sensors detect data in an embodiment of the present invention;
FIG. 5 is a diagram of an obstacle avoidance pattern corresponding to a road roller when three sensors detect data in an embodiment of the present invention;
fig. 6 is a schematic flow chart of the autonomous obstacle avoidance method according to the embodiment of the present invention when the autonomous obstacle avoidance method executes the autonomous obstacle avoidance sub-method.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, shall fall within the scope of protection of the present invention.
Example 1
An autonomous obstacle avoidance method for an unmanned road roller, the flow of which is shown in fig. 1 and fig. 6, includes:
step 1: acquiring data collected by three ultrasonic sensors arranged at the front end or the rear end of the unmanned road roller in real time;
the three ultrasonic sensors are symmetrically arranged on the front vehicle body and the rear vehicle body respectively, measure the distance from the ultrasonic sensors to an obstacle and convert the distance into analog quantity to be input to the vehicle-mounted controller, the vehicle-mounted controller sends the detection distance of the ultrasonic sensors to the industrial personal computer through the CAN bus, and the industrial personal computer performs obstacle detection and local path planning according to the received sensor data; and when the ultrasonic sensor does not detect the obstacle, the unmanned road roller continues to run or work along the current path. When the ultrasonic sensor detects an obstacle, the road roller preferentially executes a parking waiting action.
Step 2: selecting a sub-method according to the data execution behaviors acquired in the step 1, judging whether active obstacle avoidance is needed, if so, executing the step 3, otherwise, returning to the step 1;
the behavior selection sub-method refers to a behavior decomposition method, and decomposes the behavior of the road roller when encountering the obstacle into two independent behavior units: parking waiting and active obstacle avoidance; the active obstacle avoidance behavior unit has two sub-behaviors: the method specifically comprises the following steps of bypassing obstacles in the current driving direction and driving in the reverse direction:
step 2-1: judging whether an obstacle enters a sensor detection area or not according to the sensor data acquired in the step 1, if so, executing a step 2-2, otherwise, continuing to drive or execute operation of the road roller, and executing the step 2-1 again;
step 2-2: executing a parking waiting action, and then executing the step 2-3;
step 2-3: judging whether the sensor data needs to be updated according to a preset barrier movement judgment value, if so, updating the sensor data, and if not, keeping the data as the sensor value of the previous detection period;
the method for judging whether the sensor data needs to be updated specifically comprises the following steps:
if the data change value before and after a single data detection period of the sensor exceeds the obstacle movement judgment value, updating the sensor data, otherwise, not updating, and keeping the data as the sensor value in the last detection period;
step 2-4: judging whether the data change values of the three sensors are all smaller than the judgment value for whether the barrier moves or not, if so, starting a timer, setting timing time, then executing the step 2-5, and if not, returning to the step 2-3;
if the sensor data change exceeds the barrier movement judgment value in the timing period of the timer, resetting the timer and returning to the step 2-1, otherwise, continuing timing;
step 2-5: judging whether the change values of the detection data of the three sensors in the timing time of the timer are all smaller than the judgment value for whether the barrier moves or not, if so, executing whistling reminding operation and resetting the timer by the road roller, and then executing the step 2-6, otherwise, returning to the step 2-1;
step 2-6: after whistling and within the timing time of the timer, if the change amplitude of one sensor data exceeds the obstacle movement judgment value, stopping to wait for the object to leave the detection area, continuing to operate, and returning to the step 2-1; if the variation range of the data of the three sensors is still smaller than the judgment value of whether the barrier moves or not, the road roller executes the step 3;
and step 3: and (2) executing an autonomous obstacle avoidance sub-method to complete autonomous obstacle avoidance of the unmanned road roller, and then returning to the step 1, wherein the method specifically comprises the following steps:
step 3-1: determining obstacle avoidance behaviors according to obstacle detection information, wherein the obstacle avoidance behaviors comprise reverse obstacle avoidance behavior and autonomous obstacle avoidance behavior along the advancing direction of the road roller, and the method specifically comprises the following steps:
firstly, determining the position of an obstacle detection point together with a fan-shaped area and boundaries of six detection areas, wherein the fan-shaped area and the boundaries of the six detection areas are drawn by taking the distance between a road roller and an obstacle, which is detected by a sensor, as a radius;
the method for acquiring the detection point comprises the following steps:
(1) when only one sensor detects the obstacle, the detection point acquisition method comprises the following steps:
the method comprises the steps that an obstacle is located in a first area, a fifth area or a sixth area, a boundary linear equation of a fan-shaped detection area of a sensor is established, a circular arc where an obstacle detection point is located is determined by combining detection distances of the sensor, and the detection point is taken as the middle point of a chord corresponding to the circular arc.
(2) When two sensors detect an obstacle and an intersection point exists in an arc with the detection distance of the two sensors as the radius, the detection point acquisition method comprises the following steps:
the intersection point between two arcs with the detection distance as the radius is used as the detection point of the obstacle, and the calculation method comprises the following steps:
wherein d is1And d2The detection distances of the two sensors are respectively; (p)x,py) Coordinates of the obstacle detection points; (x)s1,ys1) And (x)s2,ys2) Respectively the coordinates of the two ultrasonic sensors.
When two sensors detect an obstacle and an arc with the detection distance of the two sensors as the radius has no intersection point, the method for acquiring the detection point comprises the following steps:
the detection points comprise a detection point close to the unmanned road roller side and a detection point far away from the unmanned road roller side;
if the detection distance of the second ultrasonic sensor is smaller than that of the first ultrasonic sensor or the third ultrasonic sensor, the detection point close to the unmanned road roller side is located in the sixth area, and the intersection point between the arcs taking the two detection distances as the radius is taken as the detection point close to the unmanned road roller side; the distance from the detection point of the unmanned road roller is determined by the intersection point of the second area boundary and the arc determined by the radius of the first ultrasonic sensor detection distance or the intersection point of the fourth area boundary and the arc determined by the radius of the third ultrasonic sensor detection distance;
if the detection distance of the second ultrasonic sensor is greater than that of the first ultrasonic sensor or the third ultrasonic sensor, the detection point close to the unmanned road roller side is determined by the intersection point of the first area boundary and the arc determined by the radius of the detection distance of the first ultrasonic sensor or the intersection point of the fifth area boundary and the arc determined by the radius of the detection distance of the third ultrasonic sensor; the distance from a detection point of the unmanned road roller is determined by the intersection point of the second area boundary or the fourth area boundary and the arc determined by the radius of the detection distance of the second ultrasonic sensor.
(3) When three ultrasonic sensors detect an obstacle, and the intersection point of the arc determined by the detection distance of the second ultrasonic sensor and the arc determined by the detection distance of the first ultrasonic sensor and the intersection point of the arc determined by the detection distance of the second ultrasonic sensor and the arc determined by the detection distance of the third ultrasonic sensor are both located in the third area, the method for determining the detection points comprises the following steps:
wherein d is1、d2And d3The detection distances of the three sensors are respectively; (p)x1,py1) And (p)x2,py2) Coordinates of two detection points are respectively; (x)s1,ys1)、(xs2,ys2) And (x)s3,ys3) The coordinates of the first ultrasonic sensor, the second ultrasonic sensor and the third ultrasonic sensor are respectively.
When three ultrasonic sensors detect an obstacle and the intersection point of the arc determined by the detection distance of the second ultrasonic sensor and the arc determined by the detection distance of the first ultrasonic sensor or the third ultrasonic sensor is located in the first area or the fourth area, the determination method of the detection point comprises the following steps:
the side detection point close to the unmanned road roller is the intersection point of the arc determined by the detection distance of the second ultrasonic sensor and the arc determined by the detection distance of the first ultrasonic sensor or the third ultrasonic sensor; the lateral detection point of the principle unmanned road roller is the intersection point of an arc and a third area determined by the radius of the detection distance of the first ultrasonic sensor or the detection distance of the third ultrasonic sensor.
When three ultrasonic sensors detect an obstacle and the intersection points of the circular arcs determined by the first ultrasonic sensor, the second ultrasonic sensor and the third ultrasonic sensor are not in the second area, the third area and the fourth area, the determination method of the detection points comprises the following steps:
three detection circles are respectively determined by taking the detection distances of the three ultrasonic sensors as radii, and the intersection point of the detection circle corresponding to each ultrasonic sensor and the detection boundary of the sensor is determined as a detection point.
Then judging whether the distance between the detection point of the obstacle close to the road roller side and the road roller is smaller than a preset safety distance, if so, executing a reverse obstacle avoidance behavior, otherwise, executing an autonomous obstacle avoidance behavior along the advancing direction of the road roller;
then, setting a safe radius by taking the obstacle detection point as a circle center, and calculating a local obstacle avoidance path on the basis of the safe radius to obtain a local obstacle avoidance path equation;
finally, determining the driving direction of the road roller in the local obstacle avoidance path equation;
the running direction of the road roller is determined by the number of sensors for detecting the obstacle information and the corresponding detection distance;
after the obstacle avoidance direction is determined, judging the position of an obstacle according to real-time data of a sensor, and updating obstacle detection information and local path planning when a new detection point is positioned at one side of a straight line where an original detection point is positioned along the obstacle avoidance direction, otherwise, not updating the information;
step 3-2: changing the lane to an obstacle avoidance path;
the obstacle avoidance path specifically comprises:
wherein (x)obj,yobj) Representing coordinates of the obstacle detection point in a navigation coordinate system;
representing the included angle between the current global planning straight-line path and the x axis of the navigation coordinate system; d represents a straight line offset distance set to bypass an obstacle;
the positive sign and the negative sign on the right side of the medium sign in the formula are determined by the obstacle avoidance direction of the road roller, and the specific method is as follows:
in the obstacle avoidance process of the road roller, when an obstacle leaves a sensor detection area, the unmanned road roller can drive along the last planned obstacle avoidance path until the front vehicle body and the rear vehicle body bypass the obstacle, and the whole obstacle avoidance process is completed;
step 3-3: judging whether a reverse obstacle avoidance behavior ending condition or an autonomous obstacle avoidance behavior ending condition along the advancing direction of the road roller is met, if so, ending the behavior, returning to the step 1, otherwise, returning to the step 3-2;
the conditions for finishing the autonomous obstacle avoidance behavior along the advancing direction of the road roller are as follows:
the road roller successfully bypasses the barrier;
or when the road roller bypasses the obstacle, the distance between the road roller and the object is less than the set safe distance;
or the distance between the new obstacle detection point and the original obstacle detection point is larger than the linear offset distance of the road roller for obstacle detouring.
The finishing conditions of the reverse obstacle avoidance behavior are as follows:
the detection distance of any sensor in the reverse ultrasonic sensors of the road roller is less than the set safety distance;
or the transverse error and the course error of the road roller and the local obstacle avoidance path are both smaller than the set error value when the road roller runs in the reverse direction.
Example 2
(1) First, as shown in fig. 1, different situations encountered by the unmanned road roller during running or work are judged from data detected by the ultrasonic sensor, and a behavior unit is selected accordingly. The judgment sequence in the strategy is as follows:
1) when the road roller does not detect that an obstacle enters the sensor area, the road roller can continue to run or operate along the current path; when an obstacle entering the sensor area is detected, the road roller preferentially executes a parking waiting action.
2) When the road roller detects that the obstacle stops, taking the data detection period of the ultrasonic sensor as 1s and the judgment value of whether the obstacle moves +/-10 cm as an example, if the change amplitude of the data of the front 1s of the sensor and the current data exceeds +/-10 cm, the obstacle is considered to be in a moving state, and the data of the sensor is updated. If the data change of the previous and the next two times is less than +/-10 cm, the data of the previous 1s are used continuously, and updating is not carried out. When the data change of the three sensors is less than +/-10 cm, a timer is started, and the timing time is 5s for example. In the timing process, if the data change of the sensor exceeds +/-10 cm, the timer is reset, otherwise, the timing is continued. The road roller can circularly detect the obstacles, and the operation is continued after the moving object leaves the sensor detection area.
3) If the change range of the detection data of the three sensors is not more than +/-10 cm within 5s, the obstacle is considered to be in a static state, and the road roller firstly whistles to remind and resets the timer.
4) And in 5s after the whistle, if the variation amplitude of one sensor data exceeds +/-10 cm, the object is considered to start to move, and the road roller stops to wait for the object to leave the detection area and then continues to operate. And if the variation range of the data of the three sensors in 5s after whistling is still less than +/-10 cm, the road roller executes active obstacle avoidance action.
(2) Next, as shown in fig. 2, the active obstacle avoidance operation will be described by taking the active obstacle avoidance during forward movement as an example.
In the active obstacle avoidance behavior, the unmanned road roller realizes obstacle avoidance according to the number of sensors for detecting obstacle information and the corresponding detection distance.
The autonomous obstacle avoidance behavior of the unmanned road roller can be divided into two sub-behaviors: and bypassing the barrier in the current driving direction and driving in the reverse direction to change the lane to the locally planned path. The unmanned road roller preferentially selects to avoid the obstacle by bypassing the obstacle in the current driving direction. In order to ensure that the unmanned road roller can reliably pass around the obstacle, a safe radius of 1m is set by taking a detection point on the obstacle as a circle center, as shown in fig. 2. The unmanned road roller bypasses the obstacle by adopting a reaction-based local path planning method, and the method is implemented as follows:
1) when the obstacle avoidance is started, judging the obstacle avoidance direction of the road roller according to the obstacle detection information;
2) and changing the lane to the path shown in the following formula for driving.
Wherein (x)obj,yobj) Representing coordinates of the obstacle detection point in a navigation coordinate system;
representing the included angle of the x axis of the current global planning straight-line path; d represents a straight line offset distance set to bypass an obstacle. Obstacle avoidance of road roller for positive and negative signs on right side of medium signThe direction is determined as shown in the following formula:
3) after the obstacle avoidance direction is determined, the unmanned road roller can judge the obstacle information in real time according to the sensor data. And when the new detection point is positioned at one side of the straight line where the original detection point is positioned along the obstacle avoidance direction, updating the obstacle detection information and the local obstacle avoidance path, otherwise, not updating the information. When the obstacle leaves the detection area of the sensor, the road roller can drive along the last planned obstacle avoidance path until the front vehicle body and the rear vehicle body bypass the obstacle to complete the whole obstacle avoidance process.
(3) As shown in fig. 3, 4 and 5, according to the number of sensors detecting obstacle information and corresponding detection distances, the detection ranges of three sensors on one side of the unmanned road roller are divided into 6 different areas, as shown in fig. 3 to 5, and the obstacle avoidance directions of the unmanned road roller are discussed.
1) Only one sensor detects obstacle information
As shown in fig. 3, when only the left sensor detects that the obstacle is located in the 1 st area, the road roller avoids the obstacle to the right according to the detection point of the left sensor. And similarly, when only the right sensor detects that the obstacle is located in the 5 th area, the road roller carries out obstacle avoidance leftwards according to the detection point of the right sensor. When the obstacle is detected to be located in the 6 th area, the distance between the road roller and the obstacle is smaller than the safe distance, and the sub-behaviors of reverse obstacle avoidance and obstacle avoidance can be switched to.
2) Having two sensors detecting obstacle information
Three obstacle distributions are shown in fig. 4 (taking right and middle sensors as examples, and left and middle sensors are similar): under the condition that the left-side obstacles are distributed, the right sensor and the middle sensor simultaneously detect data, the detection distance of the middle sensor is smaller than the safety distance, and the unmanned road roller is switched to a sub-behavior of reverse obstacle avoidance; under the condition of middle obstacle distribution, the unmanned road roller carries out obstacle avoidance leftwards according to the round intersection point detected by the two sensors; and under the condition that the right side obstacles are distributed, the unmanned road roller carries out obstacle avoidance leftwards according to the detection point of the middle sensor. And simultaneously detecting data by the left sensor and the middle sensor, and avoiding the obstacle rightwards by the road roller.
3) All three sensors detect obstacle information
Three obstacle distributions are shown in fig. 5 (taking right and middle sensors as examples, and left and middle sensors are similar): under the condition that the left side obstacles are distributed, the three sensors detect that circles intersect at one point, and the unmanned road roller firstly judges which side of the longitudinal axis of the front vehicle body the detection point is positioned on. When the detection point is on the left side of the front vehicle body, the road roller avoids the obstacle rightwards, otherwise, the road roller avoids the obstacle leftwards; under the condition of middle obstacle distribution, the intersection point of the right sensor and the middle sensor is positioned in the 4 th area, the road roller avoids obstacles rightwards according to the circle intersection point detected by the two sensors, and similarly, when the intersection point of the left sensor and the middle sensor is positioned in the 2 nd area, the road roller avoids obstacles leftwards; under the condition that the right-side obstacles are distributed, no intersection point of the three sensors is located in a shadow area shown in the attached drawing 5, the unmanned road roller avoids the obstacles leftwards according to a left sensor detection point farthest away, and similarly, when the detection point is located on the other side of the vehicle body, the road roller avoids the obstacles rightwards.
(4) After the obstacle avoidance direction and the obstacle avoidance path are determined, as shown in an execution flow chart of an active obstacle avoidance behavior unit shown in fig. 6, an end condition of a behavior of the unmanned road roller to bypass the obstacle is given:
condition 1: the road roller successfully bypasses the barrier;
condition 2: when the road roller bypasses the obstacle, the distance between the road roller and the object is less than the set safe distance;
condition 3: the distance between the new obstacle detection point and the original obstacle detection point is larger than the linear offset distance of the road roller for obstacle detouring.
The judgment method of the above condition 1 is: when the included angle between the vector direction of the obstacle detection point pointing to the tail center point of the road roller and the course angle is an acute angle, the road roller is considered to successfully bypass the obstacle, and the following formula is shown as follows:
in the formula: (x)R,yR) Representing the coordinates (x) of the center of the tail of the road roller in a navigation coordinate systemS,yS) Representing coordinates of the obstacle detection point in a navigation coordinate system;
representing the angle of the heading to the east direction. When this condition is met, the road roller will continue to travel or operate according to the established route.
The judgment method of the above condition 2 is: the determination is made by calculating the distance from the obstacle detection point to each boundary of the vehicle body. When the condition is met, the road roller is considered to collide with the obstacle in the forward driving direction, and the road roller changes the backward driving direction to a local obstacle avoidance path.
When the condition 3 is met, the road roller is not considered to bypass the original barrier and a new barrier appears, and the road roller is switched to a parking waiting behavior at the moment.
The conditions for finishing the reverse driving obstacle avoidance are as follows:
condition 1: any detection distance of the reverse ultrasonic sensors of the road roller is smaller than a set safety distance;
condition 2: and when the road roller runs reversely, the transverse error and the course error between the road roller and the local obstacle avoidance path are smaller than the set error value.
When the condition 1 is met, the road roller is considered to collide with an obstacle in the reverse driving direction; when the above condition 2 is satisfied, the road roller is considered to have completed the lane change. Under both conditions, the roller switches to a sub-act of forward direction bypassing the obstacle.
While the invention has been described with reference to specific embodiments, the invention is not limited thereto, and various equivalent modifications and substitutions can be easily made by those skilled in the art within the technical scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. An autonomous obstacle avoidance method of an unmanned road roller is characterized by comprising the following steps:
step 1: acquiring data collected by three ultrasonic sensors arranged at the front end or the rear end of the unmanned road roller in real time;
step 2: selecting a sub-method according to the data execution behaviors acquired in the step 1, judging whether active obstacle avoidance is needed, if so, executing the step 3, otherwise, returning to the step 1;
and step 3: and (3) executing the autonomous obstacle avoidance sub-method to complete autonomous obstacle avoidance of the unmanned road roller, and then returning to the step 1.
2. The autonomous obstacle avoidance method of the unmanned road roller according to claim 1, wherein the behavior selection sub-method specifically comprises:
step 2-1: judging whether an obstacle enters a sensor detection area or not according to the sensor data acquired in the step 1, if so, executing a step 2-2, otherwise, continuing to drive or execute operation of the road roller, and executing the step 2-1 again;
step 2-2: executing a parking waiting action, and then executing the step 2-3;
step 2-3: judging whether the sensor data needs to be updated according to a preset barrier movement judgment value, if so, updating the sensor data, and if not, keeping the data as the sensor value of the previous detection period;
the method for judging whether the sensor data needs to be updated specifically comprises the following steps:
if the data change value before and after a single data detection period of the sensor exceeds the obstacle movement judgment value, updating the sensor data, otherwise, not updating, and keeping the data as the sensor value in the last detection period;
step 2-4: judging whether the data change values of the three sensors are all smaller than the judgment value for whether the barrier moves or not, if so, starting a timer, setting timing time, then executing the step 2-5, and if not, returning to the step 2-3;
if the sensor data change exceeds the barrier movement judgment value in the timing period of the timer, resetting the timer and returning to the step 2-1, otherwise, continuing timing;
step 2-5: judging whether the change values of the detection data of the three sensors in the timing time of the timer are all smaller than the judgment value for whether the barrier moves or not, if so, executing whistling reminding operation and resetting the timer by the road roller, and then executing the step 2-6, otherwise, returning to the step 2-1;
step 2-6: after whistling and within the timing time of the timer, if the change amplitude of one sensor data exceeds the obstacle movement judgment value, stopping to wait for the object to leave the detection area, continuing to operate, and returning to the step 2-1; and if the variation range of the data of the three sensors is still smaller than the judgment value of whether the obstacle moves or not, the road roller executes the step 3.
3. The autonomous obstacle avoidance method of the unmanned road roller according to claim 1, wherein the step 3 is specifically as follows:
step 3-1: determining obstacle avoidance behaviors according to the obstacle detection information, wherein the obstacle avoidance behaviors comprise reverse obstacle avoidance behavior and autonomous obstacle avoidance behavior along the advancing direction of the road roller;
step 3-2: changing the lane to an obstacle avoidance path;
step 3-3: and judging whether the conditions for finishing the reverse obstacle avoidance behavior or the conditions for finishing the autonomous obstacle avoidance behavior along the advancing direction of the road roller are met, if so, finishing the behavior, returning to the step 1, and otherwise, returning to the step 3-2.
4. The autonomous obstacle avoidance method of the unmanned road roller according to claim 3, wherein the step 3-1 is specifically as follows:
firstly, determining the position of an obstacle detection point together with a fan-shaped area and boundaries of six detection areas, wherein the fan-shaped area and the boundaries of the six detection areas are drawn by taking the distance between a road roller and an obstacle, which is detected by a sensor, as a radius;
then judging whether the distance between the detection point of the obstacle close to the road roller side and the road roller is smaller than a preset safety distance, if so, executing a reverse obstacle avoidance behavior, otherwise, executing an autonomous obstacle avoidance behavior along the advancing direction of the road roller;
then, setting a safe radius by taking the obstacle detection point as a circle center, and calculating a local obstacle avoidance path on the basis of the safe radius to obtain a local obstacle avoidance path equation;
and finally determining the driving direction of the road roller in the local obstacle avoidance path equation.
5. The autonomous obstacle avoidance method of an unmanned road roller according to claim 4, wherein the driving direction of the road roller is determined by the number of sensors detecting obstacle information and the corresponding detection distance.
6. The autonomous obstacle avoidance method of the unmanned road roller according to claim 3, wherein in the step 3-1, after the obstacle avoidance direction is determined, the position of the obstacle is judged according to real-time data of the sensor, and when the new detection point is located at one side of the straight line of the original detection point along the obstacle avoidance direction, the detection information of the obstacle and the local path plan are updated, otherwise, the information is not updated.
7. The autonomous obstacle avoidance method of the unmanned road roller according to claim 3, wherein the obstacle avoidance path in the step 3-2 is specifically:
wherein (x)obj,yobj) Representing coordinates of the obstacle detection point in a navigation coordinate system;
representing the included angle between the current global planning straight-line path and the x axis of the navigation coordinate system; d represents a straight line offset distance set to bypass an obstacle;
the positive sign and the negative sign on the right side of the medium sign in the formula are determined by the obstacle avoidance direction of the road roller, and the specific method is as follows:
8. the autonomous obstacle avoidance method of the unmanned road roller according to claim 3, wherein in the obstacle avoidance process of the road roller in the step 3-2, when an obstacle leaves the detection area of the sensor, the unmanned road roller can drive along the last planned obstacle avoidance path until the front vehicle body and the rear vehicle body bypass the obstacle, and the whole obstacle avoidance process is completed.
9. The autonomous obstacle avoidance method of the unmanned road roller according to claim 3, wherein the end condition of the autonomous obstacle avoidance behavior along the advancing direction of the road roller is as follows:
the road roller successfully bypasses the barrier;
or when the road roller bypasses the obstacle, the distance between the road roller and the object is less than the set safe distance;
or the distance between the new obstacle detection point and the original obstacle detection point is larger than the linear offset distance of the road roller for obstacle detouring.
10. The autonomous obstacle avoidance method of the unmanned road roller according to claim 3, wherein the end conditions of the reverse obstacle avoidance behavior are as follows:
the detection distance of any sensor in the reverse ultrasonic sensors of the road roller is less than the set safety distance;
or the transverse error and the course error of the road roller and the local obstacle avoidance path are both smaller than the set error value when the road roller runs in the reverse direction.
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