Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a method and a system for controlling a motorcade in an automatic driving special lane.
The aim of the invention can be achieved by the following technical scheme:
according to one aspect of the present invention, there is provided a method of controlling a fleet of vehicles in an autopilot, the method comprising the steps of:
s1, capturing the traffic flow of an entrance ramp in real time, when a crossing vehicle is detected, calculating position, speed and acceleration data of the crossing vehicle, establishing a relation between the position and time of the crossing vehicle, and obtaining and calibrating a space-time window of the automatic driving special lane occupied by the crossing vehicle;
s2, calculating a longitudinal track of the running of the automatic driving vehicle in the automatic driving special lane, and taking a space-time part of the longitudinal track, which is intersected with a space-time window occupied by the crossing vehicle of the automatic driving special lane, as a control range limit;
S3, calculating the track of each automatic driving vehicle in the limit of the control range according to the sequence from far to near from the automatic driving vehicle closest to the crossing point, and solving the optimal acceleration value, the optimal speed value and the optimal position value of the corresponding automatic driving vehicle in each time step so as to obtain a track control instruction;
S4, transmitting the track control instruction to all the automatic driving vehicles involved in track adjustment for execution, and returning to the step S1 to perform new calculation and update the state.
As an preferable technical solution, the specific steps of calculating the position, the speed and the acceleration data of the crossing vehicle and establishing the relationship between the position and the time of the crossing vehicle in S1 are as follows:
S11, monitoring the instantaneous position, the instantaneous speed and the instantaneous acceleration of the vehicle after the vehicle is crossed and enters a monitoring range;
s12, calculating the time for accelerating the passing vehicle to the maximum speed limit and the distance for accelerating the passing vehicle to the maximum speed limit, and establishing the relation between the position of the passing vehicle and the time;
S13, executing S11 and S12 on the crossing vehicle once every a set period of time, updating the time when the vehicle is expected to reach the crossing point until the instant position exceeds the crossing point, and moving the vehicle out of the monitoring range when the instant position exceeds the crossing point.
As a preferred technical solution, the specific formula of the relationship between the position of the passing vehicle and the time is:
Wherein t 'is the time for accelerating the traversing vehicle to the maximum speed limit, vM is the maximum speed limit, vmt is the instantaneous speed of the traversing vehicle, amt is the instantaneous acceleration of the traversing vehicle, s' is the distance between the traversing vehicle and the monitoring point when accelerating the traversing vehicle to the maximum speed limit, namely the relative position of the traversing vehicle,For the predicted time when the passing vehicle reaches the passing point, LR is the distance between the passing point and the detecting point, and t is the current time.
As a preferred technical solution, in S1, a specific way of marking a space-time window is to draw the space-time window in a rectangular form, in the space-time diagram, a top edge of the rectangle represents a downstream safety distance when the vehicle occupies an autopilot lane, a bottom edge of the rectangle represents an upstream safety distance when the vehicle occupies the autopilot lane, a left edge of the rectangle represents an earliest safety moment when the vehicle occupies the autopilot lane, and a right edge of the rectangle represents a latest safety moment when the vehicle occupies the autopilot lane, and the specific formula is as follows:
L1=L+ε
L2=L-ε
Wherein L1 is the downstream safety distance, L2 is the upstream safety distance, t1 is the earliest safety moment, t2 is the latest safety moment, L is the coordinates of the crossing point, ε is the safety distance between the crossing vehicle and the front or rear vehicle in the automated driving special road when the crossing vehicle passes through the crossing point,For the moment when the crossing vehicle center point passes the crossing point, τ is the safety time interval between the crossing vehicle passing the crossing point and the front vehicle or the rear vehicle in the automatic driving special road.
As an optimal technical scheme, the intersection of the space-time diagram and the longitudinal track of the automatic driving vehicle in S2 is collision, and the limit of the intersection is the limit of the control range.
As an preferable technical scheme, in S2, the calculation of the longitudinal track of the driving vehicle in the driving lane specifically is to establish a vehicle position and speed transfer equation between two adjacent unit time steps, and establish a relationship between the driving vehicle position and time, and the specific formula is as follows:
vi+1＝vi+ai·Δt
Where t0 is the time at which the initial state of the vehicle track is calculated, t is the time at which the position coordinates st need to be calculated, s0 is the coordinates of the initial state of the vehicle track when the vehicle track is calculated, st is the displacement of the vehicle at the time t, v0 is the speed of the initial state of the vehicle track when the vehicle track is calculated, vt is the speed of the vehicle at the time t, a0 is the acceleration of the initial state of the vehicle track when the vehicle track is calculated, at is the acceleration of the vehicle at the time t, Δt is the unit time step, i is the number of the time step, i.e. the initial time of the i-th time step,For the round down operator,% is the remainder operator.
As a preferable technical solution, in S3, calculating the track of each autonomous vehicle is specifically to solve the optimal track of the autonomous vehicle by constraint conditions, and the specific formula is as follows:
Where n is the number of the automatic driving vehicle, ai,n is the acceleration of the vehicle n at the i-th time interval initial time, t is the current time, Δt is the unit time step, t0 is the time of calculating the initial state of the vehicle track, and i is the number of the time step, i.e. the initial time of the i-th time step.
As a preferred solution, the constraint condition for calculating the trajectory of each autonomous vehicle in S3 includes a first constraint to a seventh constraint, and the specific formula is:
Wherein the first constraint describes a coordinate transfer equation of any vehicle n in a control range, the second constraint describes a speed transfer equation of n, the third and fourth constraints limit the track from crossing any rectangle, the fifth constraint limits the speed from exceeding the maximum speed limit vmax, and is not negative, i.e. no reversing occurs, the sixth constraint limits the safety distance mu between two vehicles in succession, i.e. no crossing occurs between two autonomous vehicles, the seventh constraint limits the controllable acceleration ai,n of the vehicle n in a step length i to be selected only in a limited number of values, for example, a+ represents an acceleration value designated when the vehicle accelerates, a- represents a deceleration value designated when the vehicle decelerates, 0 represents the vehicle does not accelerate and decelerate, si,n represents the speed of the vehicle n in an i-th time span initial time, st1 represents the speed of the vehicle n in an i-th time span initial time, st2 represents the coordinates of the autonomous vehicle t2, L represents the coordinates of the autonomous vehicle in an autonomous time length L represents the vehicle crossing point, a- represents a deceleration value designated when the vehicle accelerates and a speed limit is zero, a 0 represents a speed limit between two vehicles passing through a speed limit points of a speed limit value designated when the vehicle passes through a speed limit crossing point, and a speed limit value of the vehicle is no more than a speed limit value designated when the vehicle speed limit value of a speed limit is zero, and a speed limit value of a is no designated when the vehicle crosses a speed limit value of a speed crossing point is zero.
As an preferable technical solution, when it is determined in S2 that the autopilot vehicle track crosses the space-time window of the lane occupied by the crossing vehicle, the situation that the autopilot vehicle track crosses the crossing vehicle includes the situation that the vehicle is far away from the downstream safe distance and the situation that the vehicle is close to the upstream safe distance, and the specific formula is as follows:
Wherein st1 is the coordinates of the automatic driving vehicle at the time t1, s12 is the coordinates of the automatic driving vehicle at the time t2, L is the length of the automatic driving vehicle, L is the coordinates of the crossing point, and ε is the half distance between the front automatic driving vehicle and the rear automatic driving vehicle in the automatic driving special road when the crossing vehicle passes through the crossing point.
According to another aspect of the present invention, there is provided an in-lane fleet control system for automated driving, the system operating using an in-lane fleet control method as described above, the system comprising a video detector, a roadside controller, and a communicator;
the video detector adopts a universal road traffic monitoring camera and is used for completely shooting a ramp and an acceleration lane area, monitoring and identifying vehicles on the ramp in real time, calculating real-time position coordinates, speed and acceleration data of the vehicles by using an image processing technology configured in the video detector, and sending the data to a road side controller;
The road side controller is placed in the control area and is used for receiving data of the video detector and the automatic driving vehicle, establishing a relation between the position of the crossing vehicle and time, calculating the longitudinal track of the automatic driving vehicle in the automatic driving special road, calculating a track control instruction and transmitting the track control instruction to all the automatic driving vehicles related to track adjustment;
the communication device is arranged in the video detector, the road side controller and the automatic driving vehicle, the video detector sends data of the vehicles passing through the ramp to the road side controller through the communication device, the automatic driving vehicle sends track data of the vehicles in the special road for automatic driving to the road side controller through the communication device, and the road side controller gives track control instructions to the automatic driving vehicle through the communication device.
Compared with the prior art, the invention has the following beneficial effects:
1. The method comprises the steps of shooting an entrance ramp traffic flow in real time, calculating position, speed and acceleration data of a crossing vehicle when the crossing vehicle is detected, establishing a relation between the position and time of the crossing vehicle, obtaining and calibrating a space-time window occupied by the crossing vehicle by an automatic driving special lane, calculating a longitudinal track of the automatic driving vehicle in the automatic driving special lane, taking a space-time part of the longitudinal track crossing the space-time window occupied by the crossing vehicle as a control range limit, calculating the track of each automatic driving vehicle in the control range limit from the automatic driving vehicle closest to a crossing point according to the sequence from far to near to obtain track control instructions, finally transmitting the track control instructions to all automatic driving vehicles related to track adjustment, repeating the steps after a sampling time interval, and calculating and updating states for a new round. The mixed flow control can be realized without cooperation among an automatic driving vehicle on the ramp, a guiding vehicle on the main line and an auxiliary vehicle (cooperative vehicle), and the effective control of a vehicle team in the automatic driving special road can be realized when the vehicle is driven by all people on the ramp.
2. The specific mode of marking the time-space window is that the time-space window is drawn in a rectangular form, in the time-space diagram, the top edge of the rectangle represents the downstream safety distance when the vehicle is in the automatic driving special lane, the bottom edge represents the upstream safety distance when the vehicle is in the automatic driving special lane, the left edge represents the earliest safety moment when the vehicle is in the automatic driving special lane, and the right edge represents the latest safety moment when the vehicle is in the automatic driving special lane. And adjusting the acceleration of the main road automatic driving vehicle to avoid the space-time window by predicting the time when the ramp vehicle passes through the vehicle crossing point and establishing the space-time window. The invention is not only suitable for the ramp vehicles to be manual driving vehicles, but also suitable for the ramp vehicles to be automatic driving vehicles, namely, the automatic driving vehicles are used as manual driving vehicles to track and predict the track, thereby widening the application range of the method and leading the fleet control method to have universality.
3. According to the method, the track of each automatic driving vehicle in the control range limit is calculated according to the sequence from far to near from the automatic driving vehicle closest to the crossing point, so that the track control instruction is obtained, the distance between the automatic driving vehicles is increased when the crossing vehicles exist, the distance between the automatic driving vehicles is narrowed after the crossing vehicles leave, the automatic driving vehicle control problem in the scene that the manual driving vehicle crosses the automatic driving special road is solved, and the driving efficiency in the automatic driving special road is improved.
4. The method comprises the steps of calculating the track of each automatic driving vehicle, specifically solving the optimal track of the automatic driving vehicle by limiting a first constraint condition to a seventh constraint condition, wherein the first constraint describes a coordinate transfer equation of any vehicle n in a control range, the second constraint describes a speed transfer equation of n, the third constraint and the fourth constraint limit the track not to cross any rectangle, the fifth constraint limits the speed not to exceed the maximum speed limit and not to be negative, namely reversing does not occur, the sixth constraint limits the safety distance between two vehicles successively, the seventh constraint limits the controllable acceleration of the vehicle n in a step length to be selected in a limited value, and the times of vehicle acceleration can be regulated as little as possible by using the constraint conditions, so that the vehicle can be stably avoided with smaller control cost, the energy consumption is minimized while the vehicle is prevented from being avoided, and the transportation efficiency is ensured.
5. The invention introduces a time space margin when constructing a space-time window occupied by a crossing vehicle, namely epsilon and tau are half distance between front and rear automatic driving vehicles in an automatic driving special road when epsilon crossing vehicles pass through crossing points,In order to pass through the central point of the vehicle and pass through the point, tau is a half of the safety time interval from the passing point of the front and rear vehicles in the automatic driving special road to the passing point of the rear vehicle head of the front vehicle when the passing vehicle passes through the passing point. By introducing the two parameters, the success rate of the manual driving vehicle to pass through the automatic driving special road is improved, and the overall safety is improved.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
Examples
Existing autopilot following technologies, such as collaborative adaptive cruise (Cooperative Adaptive Cruise Control, CACC), can implement front and rear following travel of an autopilot fleet based on data interaction between multiple vehicles, but their information is limited to between autopilots. When a manual driving vehicle passes through an automatic driving vehicle team, the CACC cannot effectively cope in time, and emergency deceleration measures are taken until the vehicle stops and passes through when only the first vehicle of the automatic driving vehicle team detects the manual driving passing through behavior through the sensor of the first vehicle, so that the passing efficiency is greatly reduced.
In the embodiment, an automatic driving special road inner vehicle team control system is constructed, and an automatic driving special road inner vehicle team control method is adopted to realize the control of the automatic driving vehicle team track in the special road in the entrance ramp converging area of the expressway provided with the outer automatic driving special road, so that the entrance ramp traffic can orderly pass through the automatic driving special road and enter the expressway inner vehicle road to run, and the speed reduction, the parking and the congestion caused by the passing difficulty are avoided. Wherein the passing vehicle can be either a manually driven vehicle or an automatically driven vehicle.
In this embodiment, the built in-lane fleet control system for autopilot includes a video detector, a roadside controller, and a communicator.
In the embodiment, the video detector adopts the universal road traffic monitoring camera, can completely shoot the ramp and the accelerating lane area, detects and identifies the vehicle target on the ramp in real time, and can give the real-time position coordinates, speed and acceleration of the vehicle. The road side controller is placed in the control area range, can communicate with the automatic driving vehicle and the video detector, and executes the control algorithm of the motorway in the special automatic driving way of the expressway. The video detector, the road side controller and the automatic driving vehicle are all provided with communicators, the video detector and the automatic driving vehicle send vehicle track data in the ramp and vehicle track data in the automatic driving special road to the road side controller through the communicators, and the road side controller can give an instruction for adjusting acceleration to the automatic driving vehicle through the communicators.
In this embodiment, the applied method for controlling the fleet of vehicles in the autopilot lane is shown in fig. 2, and mainly includes the following steps:
s1, capturing the traffic flow of an entrance ramp in real time, when a crossing vehicle is detected, calculating position, speed and acceleration data of the crossing vehicle, establishing a relation between the position and time of the crossing vehicle, and obtaining and calibrating a space-time window of the automatic driving special lane occupied by the crossing vehicle;
s2, calculating a longitudinal track of the running of the automatic driving vehicle in the automatic driving special lane, and taking a space-time part of the longitudinal track, which is intersected with a space-time window occupied by the crossing vehicle of the automatic driving special lane, as a control range limit;
S3, calculating the track of each automatic driving vehicle in the limit of the control range according to the sequence from far to near from the automatic driving vehicle closest to the crossing point, and solving the optimal acceleration value, the optimal speed value and the optimal position value of the corresponding automatic driving vehicle in each time step so as to obtain a track control instruction;
S4, transmitting the track control instruction to all the automatic driving vehicles related to track adjustment, returning to the step S1 after a sampling time interval, and performing new calculation and updating the state.
In this embodiment, the autonomous vehicles travel in a queue in the autonomous dedicated road in a cooperative adaptive cruise mode, and the longitudinal position coordinates, instantaneous speed, instantaneous acceleration data of each autonomous vehicle along the highway mileage are broadcast to the outside through the communicator, which can be directly received by the roadside controller. The manual driving vehicle enters the expressway from the entrance ramp and needs to pass through the automatic driving special road to enter the inner lane for driving. The crossing point of the manual driving vehicle is positioned on the central line of the automatic driving lane, and after the vehicles on the entrance ramp are accelerated by the accelerating lane, the central point of the vehicles crosses the automatic driving lane from the crossing point and enters the inner lane. The control range limit is set at the position of the automatic driving special track distance manual driving vehicle crossing point L meters, when the automatic driving vehicle center point enters the control range limit, the automatic driving vehicle track data can be received by the road side controller, and the automatic driving vehicle can also receive the track control instruction issued by the road side controller.
In this embodiment, after the track control instruction is solved by the method for controlling the motorcade in the expressway autopilot special for the manually driven vehicle, the track control instruction is transmitted to the autopilot vehicle through the communicator, wherein the specific information includes the acceleration value, the speed value and the position value of the corresponding vehicle at a specific moment.
In this embodiment, a scene of a merging area of a highway is set as shown in fig. 1, and the lane at the outermost side of the road is an autopilot dedicated road, and after a traversing vehicle on a ramp needs to traverse the autopilot dedicated road, the vehicle enters the lane at the inner side of a main line. The control range is l=200m, and a video detector is arranged on the ramp at a distance of LR =100deg.m from the crossing point. A roadside controller is arranged on the main line roadside in the control range, each automatic driving vehicle is provided with a communicator, and the video detector and each vehicle can exchange data with the roadside controller.
The embodiment adopts a control method of a motorcade in an automatic driving special lane, the specific flow of the method is shown in fig. 3, and the specific process is as follows:
s1, capturing the traffic flow of an entrance ramp in real time, when a crossing vehicle is detected, calculating position, speed and acceleration data of the crossing vehicle, establishing a relation between the position and time of the crossing vehicle, and obtaining and calibrating a space-time window of the automatic driving special lane occupied by the crossing vehicle;
s1 specifically comprises the following steps:
S11, utilizing a video detector which is arranged on the ramp and is used for manually driving the vehicle passing through point LR, namely, a universal road traffic monitoring camera which is used for tracking the vehicle in the field of view, measuring the distance between the position of the center point of the vehicle and the position where the camera is arranged, and measuring the instantaneous speed, the instantaneous acceleration and the like of the vehicle.
S12, after a vehicle enters the detection range of the video detector, giving the vehicle a unique number m=1, 2 according to the vehicle entering sequence, detecting an instantaneous position Smt, an instantaneous speed vmt and an instantaneous acceleration amt of the vehicle M at a time t, wherein the instantaneous position Smt is the distance from the center point of the vehicle M to the position where the video detector is located.
S13, predicting moment when vehicle m reaches passing point of manually driven vehicle
S131, calculating time t' = (vM-vmt)/amt) of accelerating the vehicle m to the maximum speed limit vM and distance of accelerating to vM
S132 if S' < LR, thenIf s'. Gtoreq.LR, then
Wherein t 'is the time for accelerating the traversing vehicle to the maximum speed limit, vM is the maximum speed limit, vmt is the instantaneous speed of the traversing vehicle, amt is the instantaneous acceleration of the traversing vehicle, s' is the distance between the traversing vehicle and the monitoring point when accelerating the traversing vehicle to the maximum speed limit, namely the relative position of the traversing vehicle,For the predicted time when the passing vehicle reaches the passing point, LR is the distance between the passing point and the detecting point, and t is the current time.
The time when each passing vehicle of the predicted entrance ramp is expected to reach the passing point is shown in table 1.
S14, executing S12 and S13 once every delta t time for each vehicle m within the range of the video detector, and updating the moment when the vehicle m is expected to reach the crossing pointUntil Smt≥LR, and moving vehicle m out of the video detector tracking range. If the vehicle m is closer to the crossing point, prediction is madeThe more accurate.
TABLE 1 time at which each traversing vehicle of the predicted entrance ramp is predicted to reach the traversing point
In this embodiment, the following control parameters are set according to the actual scene:
L＝200m,Δt＝1s,l＝18m,vo＝12m/s,vmax＝22m/s,ε＝40m,τ＝3s,a+＝2m/s2,a-＝-3m/s2.
s2, calculating a longitudinal track of the running of the automatic driving vehicle in the automatic driving special lane, and taking a space-time part of the longitudinal track, which is intersected with a space-time window occupied by the crossing vehicle of the automatic driving special lane, as a control range limit;
In this embodiment, the specific process of S2 is as follows:
s21, establishing a vehicle position and speed transfer equation between two adjacent time steps delta t:
vi+1＝vi+ai·Δt
s22, deriving a position coordinate St of the automatic driving vehicle at the time t as follows:
Where t0 is the time at which the initial state of the vehicle track is calculated, t is the time at which the position coordinates st need to be calculated, s0 is the coordinates of the initial state of the vehicle track when the vehicle track is calculated, st is the displacement of the vehicle at the time t, v0 is the speed of the initial state of the vehicle track when the vehicle track is calculated, vt is the speed of the vehicle at the time t, a0 is the acceleration of the initial state of the vehicle track when the vehicle track is calculated, at is the acceleration of the vehicle at the time t, Δt is the unit time step, i is the number of the time step, i.e. the initial time of the i-th time step,For the round down operator,% is the remainder operator. The coordinate 0 point is the coordinate of the control range limit, and the coordinate of the passing point of the manual driving vehicle is L. The formula can calculate the vehicle coordinates from any initial time t0 to any time t (t0 < t).
S23, establishing a time-space diagram. And (3) drawing a space-time window of the entrance ramp obtained in the step (S1) crossing the vehicle occupying special lane in a rectangular form in a space-time diagram of the step, as shown in fig. 7. Wherein the top side of the rectangle represents the downstream safety distance when the crossing vehicle occupies, the bottom side represents the upstream safety distance when the crossing vehicle occupies, the left side represents the earliest safety moment when the crossing vehicle occupies, and the right side represents the latest safety moment when the crossing vehicle occupies. And (3) updating the prediction of the ramp crossing vehicle track once again in the step S1, and updating the space-time window rectangle in the space-time diagram established in the step in real time once.
In this embodiment, the time when the center point of the passing vehicle passes through the passing point is set asThe space-time window rectangle is expressed on a space-time diagram as shown in fig. 4, and the four-sided expression is specifically:
s231 is the downstream safe distance L1 =l+epsilon;
s232 is the upstream safe distance, L2 =l-epsilon;
S233 is the earliest safe time:
S234 is the latest security time:
wherein epsilon is the safety distance between the crossing vehicle and the front vehicle or the rear vehicle in the automatic driving special road when the crossing vehicle passes through the crossing point,For the moment when the crossing vehicle center point passes the crossing point, τ is the safety time interval between the crossing vehicle passing the crossing point and the front vehicle or the rear vehicle in the automatic driving special road.
Table 2 time when each automated guided vehicle n enters the detection range
S24, calculating the relation between the vehicle and the rectangular boundary from any initial state of the vehicle, including the position S0, the speed v0 and the acceleration a0, the coordinates St1 from the moment t1 and the coordinates St2 from the moment t2, by using an St formula for any vehicle. If the following relationship is satisfied, the situations where the track of the autonomous vehicle does not intersect the passing vehicle include the situation where the vehicle is far from the downstream safety distance and the situation where the vehicle is close to the upstream safety distance, the judgment rules are as shown in fig. 5, specifically:
s241 is the situation that the vehicle is far away from the downstream safety distance, and the specific formula is as follows:
s242 is a case where the vehicle approaches the upstream safety distance, and the specific formula is:
S243 is a case where the track of the automatically driven vehicle crosses the passing vehicle, and St1 and St2 satisfy the following relationship:
And is also provided with
And S25, if a plurality of crossing vehicles exist in the detection range of the entrance ramp, namely, step S1 provides a plurality of time-space windows (rectangles) for crossing the special lanes occupied by the vehicles, then the rectangles are given unique numbers m=1 and 2 according to the sequence of crossing the vehicles, namely, the rectangles which are closer to the left side are considered firstly, and then the crossing condition of the vehicle track and the rectangles in any special lane is judged in sequence. The rectangular number of the track intersecting the vehicle is recorded.
And S26, for the automatic driving vehicles in the special lane entering the limit of the control range, sequentially giving unique numbers n=1, 2 to the vehicles according to the order of the vehicles entering the range, namely, the vehicles closest to the crossing point, and judging whether all the rectangles are crossed according to the judging method in S24. The numbers of vehicles that cross and the numbers of the corresponding cross rectangles are recorded.
In this embodiment, as shown in fig. 7, the solid line is a new control track, the rectangle is a space-time diagram of the passing vehicle, and the dotted line is an original running track of the first autonomous vehicle (n=1), which obviously intersects with a time-space window of the first manual passing vehicle (m=1). At this point, step S3 must be entered to calculate a new control trajectory for the autopilot n=1.
S3, calculating the track of each automatic driving vehicle in the limit of the control range according to the sequence from far to near from the automatic driving vehicle closest to the crossing point, and solving the optimal acceleration value, the optimal speed value and the optimal position value of the corresponding automatic driving vehicle in each time step so as to obtain a track control instruction;
in this embodiment, the specific process of S3 is as follows:
S31, in order to adjust the times of vehicle acceleration as few as possible, avoiding passing through the vehicle is realized smoothly with smaller control cost, and the optimal track meets the following formula by taking the minimum sum of absolute values of acceleration of all vehicles in a control range as a target:
The 1 st constraint describes a coordinate transfer equation of any vehicle n in a control range, the 2 nd constraint describes a speed transfer equation of n, the 3 rd and 4 th constraints limit that the track does not cross any rectangle, the 5 th constraint limits that the speed does not exceed the maximum speed limit vmax and is not negative (i.e. no reversing occurs), the 6 th constraint limits the safety distance mu between two vehicles in succession (i.e. no crossing occurs between two autopilots), the 7 th constraint limits that the controllable acceleration ai,n of the vehicle n in the step length i can only be selected from a limited number of values, such as a+ indicates an acceleration value designated when the vehicle accelerates, a- indicates a deceleration value designated when the vehicle decelerates, and 0 indicates that the vehicle does not accelerate or decelerate.
S32, providing a simple and feasible solution algorithm for meeting the inequality constraint.
S321, for the vehicles in the lane within the control range, sequentially calculating in order of n=1, 2.
S322, verifying whether the crossover occurs by using the S24 method. If n crosses the corresponding rectangle m, the acceleration is immediately processed at the current moment, and the vehicle is pressed from the initial moment t0Assigning a+ to ai,n, recalculating vi,n and si,n, and calculating st1,m,n and st2,m,n untilConditions are as above. In addition to n=1, the positional relationship between n and n-1 is considered ifIf sk,n+μ＞sk,n-1 exists, the safety distance between the front workshop and the rear workshop is insufficient, and the following should be forced to deal withThe imparting a- decelerates the vehicle n. If vi,n＞vmax appears or after all step size calculation is finished, it is not satisfiedIt is determined that the acceleration operation is not possible and the operation proceeds to S323 deceleration operation. Otherwise, the process proceeds directly to S325. The flow chart of step S322 is shown in fig. 6 a.
S323, if crossing occurs but acceleration operation is not feasible, immediately adopting deceleration control at the current moment, and pressing the vehicle from the initial moment t0Assigning a- to ai,n, recalculating vi,n and si,n, and calculating st1,m,n and st2,m,n untilConditions are as above. In addition to n=1, the positional relationship between n and n-1 is considered ifIf sk,n+μ＞sk,n-1 exists, the safety distance between the front workshop and the rear workshop is insufficient, and the following should be forced to deal withThe imparting a- decelerates the vehicle n. If vi+1,n is less than or equal to 0, a- cannot be assigned after ai,n, and a value of 0 is assigned. The flow chart of step S323 is shown in fig. 6 b.
If the vehicle has performed deceleration control in the previous round of decision and the intersection in S322 does not occur in the present round of decision, the acceleration control is preferentially executed once in the present round of decision to compensate for the speed loss caused by the deceleration control, and the process is the same as S322. If not, the process proceeds to S325.
S325, if no cross appears in the decision of the round, pressingAi,n is assigned a value of 0.
S326, after Δt time step, updating all vehicles n=1, 2 with the latest observed state value, position coordinates S0,n, speed v0,n, acceleration a0,n, and if vehicles and windows in the control range change, updating n=1, 2 with the latest vehicles and corresponding state parameters, N, and simultaneously re-executing S1 to obtain updated m=1, 2, M and parameters thereof. Returning to S322 to perform a new round of decisions.
In this embodiment, as shown in fig. 7, n=1 crosses one rectangle m=1 and does not cross the other rectangle m, and the acceleration process is immediately performed at the current time, and the vehicle is started from the initial time t0 and is pressedAssigning a+ to ai,n, recalculating vi,n and si,n, and calculating st1,m,n and st2,m,n untilConditions are as above. If vi,n＞vmax does not appear in the current computing object, the acceleration operation is feasible, and the process proceeds directly to S325.
In S325, if a crossover occurs in the present round of decision, ai,n cannot be assigned a value of 0. At this point the calculation of n=1 ends. And then the operations of S2 and S3 are performed on n=2, 3,4,5 and 6. Where n=2, when step S322 is performed, the acceleration operation is not possible, and therefore, the process proceeds to S323, and S323 is performed. S323 is executed and then S324 is executed sequentially, and since deceleration control is performed in the present round of decision (time t), acceleration control is preferentially performed once for n=2 in the decision process of the next round of decision (time t+Δt) to compensate for the speed loss caused by deceleration control, and the process is the same as S322.
Through the above calculation, a deceleration control trajectory sequence of n=2 is obtained, and after deceleration is completed, acceleration control is performed to reduce the interval with n=1.
In this embodiment, the operations S2 and S3 for n=3, 4,5, and 6 are similar to the above procedure, and can be analogized. The trajectories of n=1, 2,3,4,5,6 passing vehicles for autonomous driving vehicle avoidance m=1, 2,3,4,5 in this embodiment are shown in fig. 8, where the rectangle is a space-time window and the solid line is an autonomous driving vehicle trajectory.
S4, transmitting the track control instruction to all the automatic driving vehicles related to track adjustment, returning to the step S1 after a sampling time interval, and performing new calculation and updating the state.
In this embodiment, the specific process of S4 is:
And S41, the road side controller obtains acceleration instructions (acceleration, deceleration and non-acceleration and deceleration) of each automatic driving vehicle in a control range through the operation of the step S3, and transmits the instructions to all the automatic driving vehicles related to track adjustment through a communicator.
S42, starting from the moment when the automatic driving vehicle starts to conduct acceleration adjustment, repeating the steps S1, S2 and S3 within a sampling time interval delta t, and conducting calculation of optimal acceleration, speed and position parameters of each time step of a new round. And the calculated acceleration instructions (acceleration, deceleration and non-acceleration and deceleration) are transmitted to all the automatic driving vehicles related to track adjustment through a communicator, and the time interval between each automatic driving vehicle starting to perform acceleration adjustment and the last adjustment time is one sampling time interval.
While the invention has been described with reference to certain preferred embodiments, it will be understood by those skilled in the art that various changes and substitutions of equivalents may be made and equivalents will be apparent to those skilled in the art without departing from the scope of the invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.