A journey splicing judgment method based on three-dimensional space-time prism

Abstract

The application discloses a trip splicing judgment method based on three-dimensional space-time prisms, and relates to the field of data processing.The method comprises the following steps: modeling a road network as a directed graph, defining the maximum tolerable driving time and the maximum waiting offset time of a passenger for a trip, constructing a three-dimensional space-time prism of the trip and screening candidate trip pairs; calculating the waiting offset according to the pickup sequence, translating the space-time prisms corresponding to the trips along the time axis, and obtaining a space-time overlapping area through three-dimensional Boolean intersection operation; filtering the space-time overlapping area through step-by-step contraction, extracting a local sub-space-time prism from the second pickup point to the first drop-off point as a carpooling feasible region; judging the splicing according to the feasible region, constructing the whole reachable range, and outputting the carpooling splicing result.The application converts the space-time overlap into an effective carpooling space-time range that meets the complete pickup and drop-off process constraints, and improves the reliability and intuitiveness of the splicing judgment model.

Description

Technical Field

[0001] This invention relates to the field of data processing technology, and in particular to a method for determining the combinatorial feasibility of a three-dimensional spatiotemporal prism. Background Technology

[0002] In ride-sharing systems, trip merging is a core step in merging multiple travel needs. Specifically, it involves determining whether a feasible ride-sharing arrangement exists between two or more independent travel needs, given a departure time, maximum tolerable travel time, and tolerable waiting time. The result of this determination directly impacts the efficiency and rationality of ride-sharing matching, thereby affecting the vehicle dispatching effectiveness and overall operational efficiency of the ride-sharing system.

[0003] Existing methods for determining the feasibility of ride-sharing can be mainly divided into two categories. The first category is matching methods based on path detour constraints. These methods primarily determine whether a trip is feasible by calculating whether the extra distance or time incurred by the driver taking a detour to pick up and drop off passengers exceeds a preset threshold. This type of method can determine local feasibility under the premise of enumerating a given pick-up and drop-off order. It often requires repeated path-level calculations for candidate trip pairs, which is a processing mode of enumeration followed by verification. It lacks the ability to uniformly express all potential orders and is also difficult to express the potential reachability range of the trip under the tolerance constraints as a whole.

[0004] Chinese patent CN107101643B, entitled "A Carpooling Matching Method," discloses a carpooling matching method that primarily filters matching targets step-by-step based on conditions such as departure time constraints, pick-up distance constraints, and latest arrival constraints. This method combines route detour constraints with conditional filtering. While such methods can reflect the local feasibility under a specific pick-up / drop-off sequence, they still rely mainly on the step-by-step filtering of candidate vehicles and route-level verification, without explicitly and continuously modeling the potential reachability of the trip under tolerance constraints.

[0005] The second category is fast candidate screening methods based on spatiotemporal constraint approximation or proximity rules. These methods typically use grids, R-trees, or simplified spatial distance thresholds to quickly filter potential combinable routes. However, their judgment basis is usually the proximity relationship between the origin and destination, Euclidean distance, or simple time overlap. They do not model the spatiotemporal accessibility of the entire route. Even if some methods incorporate road network information, they can only achieve coarse-grained spatiotemporal matching. This can easily generate a large number of redundant candidate pairs that appear to be close but are actually not feasible for co-rides, resulting in low judgment accuracy.

[0006] US Patent Application No. US12345535B2, entitled "SYSTEM AND METHOD FOR RIDESHAREMATCHING BASED ON LOCALITY SENSITIVE HASHING," discloses a carpooling matching method based on Locality Sensitive Hashing (LSH). Its core is to represent the trip and driver's route in a spatiotemporal discretized and vectorized manner, and then use LSH to retrieve potential matching objects, representing a typical spatiotemporal retrieval candidate filtering approach. While this type of method emphasizes large-scale retrieval efficiency, its focus is on efficiently discovering potential matching objects, rather than providing a continuous three-dimensional geometric representation of the potential activity space for a single trip, and it does not establish a three-dimensional feasible region verification process for specific boarding and alighting sequences.

[0007] In addition to the two methods mentioned above, some studies have begun to explore using spatiotemporal prism theory to express the potential reachability of a trip within a given time budget. For example, Li Jiewen et al. proposed a ride-sharing feasibility judgment model based on spatiotemporal prisms, using the potential reachability region of the trip to identify ride-sharing opportunities. Existing spatiotemporal prism models of three-dimensional networks are mainly used for accessibility analysis or individual activity modeling, and a systematic ride-sharing feasibility judgment framework for multi-trip carpooling scenarios has not yet been formed. Furthermore, research on spatiotemporal prisms related to ride-sharing scenarios remains at the two-dimensional expression level, lacking a unified method that combines continuous three-dimensional spatiotemporal reachability domains with verification of specific boarding and alighting sequences. Summary of the Invention

[0008] The purpose of this invention is to address the lack of a unified method in existing technologies that combines continuous three-dimensional spatiotemporal reachability with verification of specific boarding and alighting sequences. This invention proposes a method for determining the combinatorial feasibility of a trip based on a three-dimensional spatiotemporal prism, comprising the following steps: S1. Obtain urban road network data and travel data, and model the road network as a directed graph with travel time as the edge weight; S2. Based on the directed graph, define the maximum tolerable travel time and the maximum waiting offset time for passengers. Construct a three-dimensional spatiotemporal prism for each journey based on the maximum tolerable driving time; Candidate trip pairs are selected based on the maximum tolerable driving time and the maximum waiting offset time. S3. Calculate the waiting offset of the candidate trip pair under different pick-up sequences, and translate the three-dimensional spatiotemporal prism of the trip to which the second pick-up point belongs along the time axis by the waiting offset; perform an intersection operation on the three-dimensional spatiotemporal prism of the translated candidate trip pair to obtain the spatiotemporal overlap region under different pick-up sequences; if the spatiotemporal overlap region is not empty, execute S4; otherwise, the candidate trip pair cannot be combined. S4. Based on the reachable time intervals of the second boarding point and the first alighting point in the spatiotemporal overlap region, the spatiotemporal overlap region is shrunk to obtain the co-ride feasible region. If the co-ride feasible region can be constructed and is not empty, the candidate trip pair is determined to be combinable, and S5 is executed; otherwise, the candidate trip pair cannot be combinable. S5. Based on the carpooling feasible domain, construct the reachability range for the entire journey from boarding to alighting and output the carpooling feasibility result.

[0009] Furthermore, by shrinking the spatiotemporal overlapping region, the feasible region for co-multiplication is obtained, which includes: At the second boarding point, a time constraint projection is performed along the time axis based on the spatiotemporal overlap region to determine the reachable time interval of the second boarding point; Based on the reachable time interval of the second boarding point, the spatiotemporal overlap region is shrunk to construct a transitional sub-spatiotemporal prism from the second boarding point to the termination target node, wherein the termination target node is determined by the spatial position corresponding to the upper time bound of the spatiotemporal overlap region. At the first disembarkation point, a time-constrained projection is performed on the transition sub-spacetime prism to determine the reachable time range of the first disembarkation point; Based on the reachable time range of the first disembarkation point, the transition sub-spacetime prism is shrunk to construct a local sub-spacetime prism from the second boarding point to the first disembarkation point, wherein the local sub-spacetime prism is a co-multiplication feasible region.

[0010] Furthermore, the maximum tolerable travel time for the trip is:

[0011] in, This represents the maximum tolerable travel time for the i-th trip. This represents the original trip duration of the i-th trip. This is a percentage coefficient for additional driving time. This is the maximum threshold for additional driving time; The maximum waiting offset time for the trip is:

[0012] in, This represents the maximum waiting offset time for the i-th trip. This indicates the waiting offset ratio coefficient. This represents the original trip duration of the i-th trip. This is the upper limit threshold for the waiting offset time.

[0013] Furthermore, the steps for filtering candidate trip pairs based on the maximum tolerable travel time and the maximum waiting offset time are as follows: Based on the maximum tolerable travel time and maximum waiting offset time of the trip, the extended time interval of the trip is defined, and the trip is defined. The extended time interval is:

[0014] in, This represents the extended time interval of the i-th trip. Let i be the original departure time of the i-th trip. This represents the maximum tolerable travel time for the i-th trip. This represents the maximum waiting offset time for the i-th trip; Candidate routes must satisfy: The extended time intervals of the trip pairs overlap, and, The travel time from the starting point of the target journey to the shortest Euclidean distance of another journey path shall not exceed the passenger's maximum tolerable travel time for the target journey.

[0015] Furthermore, the three-dimensional spacetime prism of the journey is defined as:

[0016] in, Represents the three-dimensional spacetime prism of the i-th journey. Indicates the starting point of the i-th trip. Reaching the spatial position within the three-dimensional spacetime prism Time, t is spatial location The time of arrival, Let i be the original departure time of the i-th trip. Indicates spatial location Reach the end of the i-th journey. The shortest travel time, This represents the maximum tolerable travel time for the i-th trip.

[0017] Furthermore, the method for calculating the waiting offset is as follows: Calculate the directional waiting difference for different pick-up sequences for candidate trips, where the directional waiting difference is the difference between the theoretical arrival time of the starting point of the second trip and the original departure time of the second trip; If the directional waiting difference is zero, the waiting offset is zero; if the directional waiting difference is positive, the waiting offset is the smaller of the directional waiting difference and the maximum waiting offset time of the second trip; if the directional waiting difference is negative, the waiting offset is the smaller of the absolute value of the directional waiting difference and the maximum waiting offset time of the first trip, while retaining its directionality.

[0018] Furthermore, S5 specifically refers to: Based on the shared ride feasible region, a local sub-spacetime prism is constructed from the first boarding point to the second boarding point, and a local sub-spacetime prism is constructed from the first alighting point to the second alighting point to verify the temporal continuity and path reachability of the entire pick-up and drop-off process.

[0019] The present invention also proposes a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the above-described method for determining the combinatorial feasibility of a three-dimensional spatiotemporal prism.

[0020] The present invention also proposes an electronic device, including a processor and a memory, wherein the processor and the memory are interconnected, wherein the memory is used to store a computer program, the computer program including computer-readable instructions, and the processor is configured to call the computer-readable instructions to execute the above-described method for determining the combinatorial feasibility of a three-dimensional spacetime prism.

[0021] The present invention also proposes a computer program product, including a computer program / instruction, which, when executed by a processor, implements the steps of the above-described method for determining the combinatorial feasibility of a three-dimensional spatiotemporal prism.

[0022] The beneficial effects of the technical solution provided by this invention are: This invention defines the maximum tolerable travel time and maximum waiting offset time for a trip based on a directed graph of the urban road network. It rapidly filters candidate trip pairs by expanding the time interval and spatial proximity, reducing overall computational complexity and improving the processing efficiency of large-scale trip sets. A three-dimensional spatiotemporal prism of the trip is constructed based on the maximum tolerable travel time. Waiting offsets are calculated according to the pick-up order of the candidate trips. The three-dimensional spatiotemporal prism of the trip to the second pick-up point is translated along the time axis by the waiting offset. The intersection of the three-dimensional spatiotemporal prisms of candidate trip pairs under different pick-up orders is obtained to obtain the spatiotemporal overlapping region. Through the waiting offset mechanism and the bidirectional spatiotemporal overlapping region, the ability to identify flexible carpooling scenarios is improved, and more potential carpooling trip pairs can be identified under the same constraints. A local sub-spatiotemporal prism from the second pick-up point to the first drop-off point is extracted from the spatiotemporal overlapping region as the carpooling feasible region through segmented spatiotemporal constraints. Using the carpooling feasible region as the spatiotemporal constraint body, the temporal constraints of the entire pick-up and drop-off process and the overall reachability are constructed, verifying the temporal continuity and road network accessibility of the carpooling path. The system outputs trip combinability results, ensuring the accuracy of combinability determination while providing direct and usable decision-making basis for vehicle scheduling and route planning. Attached Figure Description

[0023] Figure 1 This is a flowchart of a method for determining the combinability of a three-dimensional spatiotemporal prism according to an embodiment of the present invention; Figure 2This is a schematic diagram of the construction of a single-pass three-dimensional spacetime prism according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the spatiotemporal overlap region for finding the intersection of two-stroke three-dimensional spatiotemporal prisms according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the intersection of perpendicular lines at the second boarding point according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the construction of the transition subprism according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the intersection of perpendicular lines at the first disembarkation point according to an embodiment of the present invention; Figure 7 This is a schematic diagram of a local sub-prism (co-multiplicative feasible region) constructed from the second boarding point to the first alighting point in an embodiment of the present invention; Figure 8 This is a schematic diagram of the intersection of the perpendicular lines at the second boarding point according to an embodiment of the present invention; Figure 9 This is a schematic diagram of a partial sub-prism constructed from the first boarding point to the second boarding point in an embodiment of the present invention; Figure 10 This is a schematic diagram of the final segment of the sub-prism constructed from the first disembarkation point to the second disembarkation point according to an embodiment of the present invention; Figure 11 This is a schematic diagram of a complete spacetime prism combination under the co-multiplication condition of an embodiment of the present invention; Figure 12 This is a block diagram of an electronic device according to an exemplary embodiment of the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0025] A flowchart of a method for determining the combinatorial feasibility of a three-dimensional spatiotemporal prism, as described in an example of this invention, is as follows: Figure 1 Specifically, it includes: S1. Road network modeling and travel constraint modeling.

[0026] Acquire urban road network data and travel data, and model the road network as a directed graph. ,in A set of road network nodes, which typically represent: road intersections, road endpoints, or important locations in the topology; This refers to a collection of roadside sections, which typically represent road segments and have a directional characteristic, indicating the direction of vehicle travel. Let be the set of edge weights, where each edge weight represents the travel time for the corresponding road segment.

[0027] Define any two nodes The shortest travel time between is:

[0028] in, Indicates from node To the node The set of all feasible paths, For road section The corresponding edge weights, i.e., travel times. For any given journey... For the i-th trip, map the start and end points of each trip to road network nodes, which will serve as the start point nodes for that trip. and the endpoint The original departure time was The original trip duration was .

[0029] To quantify passengers' tolerance for extra travel time caused by carpooling, an additional travel time is added to the original trip duration. This additional travel time is constrained by both a proportion of the original trip duration and an absolute time limit. The passenger's tolerance for the additional travel time is defined. Maximum tolerable driving time:

[0030] in, This represents the maximum tolerable travel time for the i-th trip. This represents the original trip duration of the i-th trip. This is a percentage coefficient for additional driving time. This is the upper limit threshold for additional driving time.

[0031] At the same time, a maximum waiting offset limit is set for each trip, which represents the amount of time offset that the trip is allowed to occupy during the carpooling process:

[0032] in, This represents the maximum waiting offset time for the i-th trip. This indicates the waiting offset ratio coefficient. This is the upper limit threshold for the waiting offset time.

[0033] S2, Construction of 3D Spatiotemporal Prisms and Screening of Candidate Run-Line Pairs.

[0034] (1) Construction of three-dimensional spacetime prism Based on the maximum tolerable travel time, a three-dimensional spatiotemporal prism is constructed for each trip. For any trip, let a spatial location x on the road network be a potential reachable point at time t. If this spatiotemporal point (x,t) simultaneously satisfies the following constraints, then this spatiotemporal point is considered to belong to the potential spatiotemporal reachable region of the trip: 1) This spacetime location can be reached from the starting node before the current time; 2) It is still possible to reach the destination node from this spatiotemporal location within the remaining time; 3) The current time is within the maximum tolerable travel time range of this trip.

[0035] Therefore, the i-th trip

[0036]

[0037] in, Represents the three-dimensional spacetime prism of the i-th journey. Indicates the starting point of the i-th trip. Reaching the spatial position within the three-dimensional spacetime prism Time, t is spatial location The time of arrival, Let i be the original departure time of the i-th trip. Indicates spatial location Reach the end of the i-th journey. The shortest travel time, This represents the maximum tolerable travel time for the i-th trip.

[0038] In one embodiment, the three-dimensional spatiotemporal prism can be formed by discretizing the time dimension and constructing spatial regions that simultaneously satisfy forward and backward accessibility constraints at each time layer, and then combining them along the time dimension.

[0039] In a specific implementation, a road network-based reachability search method is used for construction, including: A forward reachability search is performed starting from the origin of the journey to obtain nodes reachable within a given time threshold and their corresponding arrival times. A reverse reachability search is performed starting from the destination to obtain nodes reachable within the remaining time budget and their corresponding arrival times. For boundary segments crossing the current time threshold, the boundary positions are interpolated based on the arrival times of the nodes at both ends of the edge to obtain continuous boundary points for the corresponding time layer. Based on these boundary points, forward and backward reachable regions for each time layer can be constructed, and their spatial intersection is performed to obtain a two-dimensional spatial reachable section for that time layer. Combining multiple two-dimensional spatial reachable sections along the time axis allows the generation of corresponding three-dimensional spatiotemporal prisms using a three-dimensional mesh construction method. Stacking all the two-dimensional sections of the time layers along the time axis constructs the journey. Three-dimensional spacetime prism ,like Figure 2 As shown.

[0040] (2) Itinerary-based screening Based on the maximum tolerable travel time and the maximum waiting offset time of the trip, an extended time interval for the trip is defined. The trip pairs are then subjected to time coarse filtering and geometric proximity filtering according to the extended time interval and the maximum tolerable travel time to obtain candidate trip pairs.

[0041] ① Time coarse filtering The time coarse filtering mechanism is as follows: Define the extended time interval of the i-th trip as:

[0042] in, This represents the extended time interval of the i-th trip. Let i be the original departure time of the i-th trip. This represents the maximum tolerable travel time for the i-th trip. This represents the maximum waiting offset time for the i-th trip.

[0043] For any two journeys and If the extended time intervals of the two trips do not overlap, then the trip pair is considered to have no potential co-multiplication possibility after considering the maximum tolerance time and waiting offset, and can be directly filtered out. The judgment condition is:

[0044] ② Geometric Proximity Filtering Set the itinerary The starting node and the ending node are respectively and ,journey The starting node and the ending node are respectively and .Will and The approximate line segments formed by connecting them are used as the path for calculation. Find the shortest Euclidean distance to the route and convert that distance into an equivalent travel time based on the road network speed limits. If the equivalent travel time is greater than the distance traveled... The maximum tolerable driving time indicates The starting point relative to If the main path deviates too far in space, it can be filtered directly. Symmetrically, this can also be determined... Is it deviating? The main path is too long.

[0045] After the above time coarse filtering and geometric coarse filtering, the candidate set of route pairs is obtained.

[0046] S3, construction of the double-connection driving sequence translation and spatiotemporal overlapping area.

[0047] For any candidate trip pair, calculate the shortest travel time for the following two pick-up directions: the shortest travel time from the start of the first trip to the start of the second trip (O1→O2); and the shortest travel time from the start of the second trip to the start of the first trip (O2→O1). These two pick-up directions correspond to the scenarios of "pick up the first trip first, then the second trip" and "pick up the second trip first, then the first trip," respectively.

[0048] (1) Waiting for offset calculation Taking the O1→O2 direction as an example, let the difference between the theoretical arrival time of the vehicle from the starting point of the first journey to the starting point of the second journey and the original departure time of the second journey be the directional waiting difference. If the difference is positive, it means that passengers of the second journey are waiting for the vehicle; if the difference is negative, it means that the vehicle that has already picked up passengers of the first journey is waiting for passengers of the second journey.

[0049] This invention does not directly treat the waiting as a failure condition. Instead, it truncates it according to the maximum waiting offset limit of the corresponding journey and obtains the waiting offset, which is then converted into a translation offset on the time axis. The waiting offset is determined as follows: if the directional waiting difference is zero, the waiting offset is zero; if the directional waiting difference is positive, the waiting offset is the smaller of the difference and the maximum waiting offset limit of the second journey; if the directional waiting difference is negative, the waiting offset is the smaller of the absolute value of the difference and the maximum waiting offset limit of the first journey, while retaining its directionality. After obtaining the waiting offset, the three-dimensional spatiotemporal prism of the journey corresponding to the second boarding point is translated along the time axis.

[0050] (2) Intersection of three-dimensional spacetime prisms After translating the spacetime prism accordingly, a two-stage processing approach is adopted: First, a coarse screening is performed using 3D fast intersection detection; second, a 3D mesh Boolean intersection operation is performed on the candidate stroke pairs that pass the coarse screening to obtain the original spacetime overlapping region.

[0051]

[0052] in, The three-dimensional spacetime prism representing the first journey. The three-dimensional spacetime prism representing the second journey. and This represents the result of the Boolean intersection operation following the corresponding formula. This represents the three-dimensional spacetime prism after the second journey has undergone waiting offset translation in the first receiving direction. This represents the three-dimensional spacetime prism after the first journey, under the second receiving direction, undergoes a waiting offset translation. If... or If the spacetime is not empty, it indicates that there exists at least one overlapping spatiotemporal region in the direction of the pick-up. A schematic diagram of the overlapping spatiotemporal region obtained by intersecting a two-stroke three-dimensional spatiotemporal prism in this embodiment of the invention is shown below. Figure 3 As shown. The spatiotemporal overlap region is the original overlapping area between the two trips in space and time, representing potential carpooling possibilities. If the intersection is empty, it is directly determined that carpooling is not possible, and the following steps are not performed.

[0053] S4, Constraint contraction of the spatiotemporal overlap region After obtaining the directional spatiotemporal overlap region, the present invention further filters it by segment-by-segment spatiotemporal constraints to prepare for the extraction of the subsequent co-multiplication feasible region.

[0054] The candidate trip pairs are validated sequentially using four different sequences: O1-O2-D1-D2, O1-O2-D2-D1, O2-O1-D1-D2, and O2-O1-D2-D1. Here, O1 and D1 represent the start and end points of the first trip, respectively, and O2 and D2 represent the start and end points of the second trip, respectively. The attached diagram uses the O1-O2-D1-D2 sequence as an example. The specific processing is as follows: (1) The first constraint contraction of the spatiotemporal overlapping region ① Select the directional spatiotemporal overlap region corresponding to the current sequence. Based on the first two boarding points in this sequence, select the spatiotemporal overlap region generated in the corresponding pick-up direction. When the first two nodes in the sequence are O1-O2, select the spatiotemporal overlap region generated in the O1→O2 direction; when the first two nodes in the sequence are O2-O1, select the spatiotemporal overlap region generated in the O2→O1 direction.

[0055] ② Extract the top spatiotemporal information of the spatiotemporal overlap region For a selected directional spatiotemporal overlap region, its highest point on the time axis and the corresponding spatial center position of the highest layer are extracted. This spatial center position is then mapped to the nearest node in the road network, serving as the termination target node for the subsequent construction of the transition sub-prism. This top-level key spatiotemporal information represents the latest potential intersection point that two journeys can jointly extend to within the current directional spatiotemporal overlap region.

[0056] ③ Second boarding point constraint filtering That is, find the intersection of perpendicular lines at the second boarding point to determine the reachable time interval of the second boarding point.

[0057] Let the first boarding point in the current sequence be Oa (either O1 or O2), the second boarding point be Ob (either O2 or O1), the first alighting point be Da (either D1 or D2), and the second alighting point be Db (either D2 or D1). At the second boarding point Ob, a vertical projection is made along the time axis onto the selected directional spatiotemporal overlap region to find the intersection. The effective time intersection segment between this vertical projection and the spatiotemporal overlap region is then determined, such as... Figure 4 As shown. If there is no valid intersection at Ob, it means that the vehicle cannot complete the second boarding within the spatiotemporal overlap region in the current sequence, and the current sequence is directly determined to be infeasible. If there is an intersection, the time interval corresponding to the intersection represents the allowed boarding time range of the second boarding point Ob in the current directional spatiotemporal overlap region.

[0058] ④ Construct a transitional sub-prism leading from the second boarding point to the top of the spatiotemporal overlap region. Starting from the road network node corresponding to the second boarding point Ob, and ending at the key node at the top of the directional spatiotemporal overlap region, and taking the starting point of the reachable time interval of the second boarding point obtained in the previous step as the starting time, the spatiotemporal overlap region is contracted to construct a transitional sub-spatiotemporal prism, such as... Figure 5 As shown, this transitional sub-spacetime prism describes the potential spacetime reachable region formed by a vehicle continuing to travel from the second boarding point within the allowable range of the current directional spacetime overlap region after completing its second boarding. If this transitional sub-spacetime prism cannot be constructed, it indicates that spacetime continuity cannot be maintained after the second boarding under the current sequence, and the current sequence is determined to be infeasible.

[0059] (2) Second constraint contraction and co-multiplication feasible region extraction in the spatiotemporal overlapping region This step, based on the first contraction, further filters and completes the second constraint contraction of the effective region, i.e., the transition sub-prism, to extract the final co-multiplication feasible region. The co-multiplication feasible region is contained within the spatiotemporal overlap region and is the effective carpooling spatiotemporal range obtained from the original spatiotemporal overlap region through stepwise constraint filtering.

[0060] ① First disembarkation point constraint filtering At the first disembarkation point Da, draw a perpendicular line along the time axis to the transition sub-spacetime prism to determine the upper reachable limit of the first disembarkation segment, such as... Figure 6 As shown. This time interval is defined as:

[0061] in, This indicates the earliest time that the vehicle can arrive at Da after departing from Ob, under the constraints of time and space. This represents the latest time a vehicle can arrive at Da after departing from Ob, provided that the travel tolerance time and road network accessibility constraints are met. The span of this time domain is... The degree of spatiotemporal freedom of carpooling is represented by the larger the span, the wider the range of driving routes and times that the vehicle can choose, and the larger the actual driving range of the entire carpooling trip.

[0062] If there is no valid intersection at point Da, it means that after the second boarding is completed, the vehicle cannot reach the first drop-off point while maintaining spatiotemporal continuity, and the current sequence is determined to be infeasible; if there is a valid intersection, the current sequence is determined to be feasible. Furthermore, the upper bound of this intersection is used to constrain the latest reachable time from the second boarding point Ob to the first drop-off point Da, providing a time constraint for the subsequent construction of the carpooling feasible region.

[0063] ② Construct a local sub-prism (co-multiply feasible region) from the second boarding point to the first alighting point. Based on the reachable time interval of the second boarding point Ob obtained in step (1) ③ of S4 and the reachable time upper bound of the first alighting point Da obtained in step (2) ① of S4, taking the road network nodes of Ob as the starting point and the road network nodes of Da as the ending point, the original spatiotemporal overlap region is further shrunk to construct a local sub-spatiotemporal prism Ob-Da. This prism is the co-ride feasible region under the current order, representing the maximum spatiotemporal range under all constraints where passengers of the two journeys can travel together. Figure 7 As shown. The carpooling feasible region represents the potential spatiotemporal region of the entire process from the second pick-up point to the first drop-off point after the vehicle picks up passengers for both trips in the current order. If the feasible region can be successfully constructed and is not empty, then the current order meets the carpooling conditions; otherwise, the current order is determined to be infeasible.

[0064] S5. Construction of the entire reachable range and determination of combinability. (1) Construction of the entire reachable range Using the feasible region of shared rides (Ob→Da) as a constraint, a local sub-prism from Oa→Ob is constructed in reverse to verify the pick-up process, i.e., whether there is a complete, continuous, and reachable travel process from the first boarding to the second boarding; then, the final segment sub-prism from Da→Db is constructed to verify the delivery status of the final segment. The specific steps are as follows: At the second boarding point Ob, a perpendicular line is drawn along the time axis into the feasible region of co-multiplication. The schematic diagram of the intersection of the perpendicular lines at the second boarding point Ob in this embodiment of the invention is shown below. Figure 8 As shown, a new upper bound for the reachable time interval is obtained. Then, taking the first boarding point Oa as the starting point and the second boarding point Ob as the ending point, and combining this new upper bound, a sub-spacetime prism Oa-Ob is constructed, as follows. Figure 9 As shown.

[0065] From the feasible start time of the first drop-off point obtained in step (2) ① of S4, with the first drop-off point Da as the starting point and the second drop-off point Db as the ending point, construct the final segment sub-spacetime prism Da-Db, as follows: Figure 10As shown, the upper bound of its termination time is determined by the maximum tolerable travel time of the journey to which the second drop-off point belongs. When a waiting offset time axis translation is applied to the three-dimensional spatiotemporal prism of a certain journey during the generation of the directional spatiotemporal overlap region, if the journey to which the second drop-off point Db belongs is the translated journey, then when constructing the Da-Db sub-spatiotemporal prism, it is necessary to superimpose the same waiting offset as described above on the upper bound of the termination time to ensure that the sequential verification is consistent with the time translation in the aforementioned directional spatiotemporal overlap region.

[0066] (2) Determination of compatibility and quantification of opportunities If at least one boarding / alighting sequence corresponds to a co-riding feasible domain (Ob→Da) that can be constructed and is not empty, then the trip pair is determined to be combinable; Otherwise, carpooling is not possible. Furthermore, the likelihood of carpooling can be quantified based on the time span, spatial range, and spatiotemporal volume of the feasible carpooling domain. The above... This refers to the time span of the carpooling feasible region. The time span reflects temporal flexibility, the spatial extent reflects route coverage, and the spatiotemporal volume comprehensively measures carpooling potential. A larger feasible region indicates higher spatiotemporal freedom for carpooling, greater carpooling opportunities, and more flexible route selection. The complete spatiotemporal prism under carpooling conditions is as follows: Figure 11 As shown.

[0067] In one exemplary embodiment, a computer-readable storage medium is included, which stores a computer program that, when executed by a processor, implements the above-described method for determining the combinatorial feasibility of a three-dimensional spatiotemporal prism.

[0068] Please see Figure 12 In one exemplary embodiment, the device further includes an electronic device including at least one processor, at least one memory, and at least one communication bus.

[0069] The memory stores a computer program, which includes computer-readable instructions. The processor calls the computer-readable instructions stored in the memory through the communication bus to execute the above-mentioned method for determining the combinatorial feasibility of a three-dimensional spatiotemporal prism.

[0070] In one exemplary embodiment, a computer program product is proposed, including a computer program / instruction that, when executed by a processor, implements the steps of the above-described method for determining the combinatorial feasibility of a three-dimensional spatiotemporal prism.

[0071] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for determining the combinability of a route based on a three-dimensional spatiotemporal prism, characterized in that, Includes the following steps: S1. Obtain urban road network data and travel data, and model the road network as a directed graph with travel time as the edge weight; S2. Based on the directed graph, define the maximum tolerable travel time and the maximum waiting offset time for passengers. Construct a three-dimensional spatiotemporal prism for each journey based on the maximum tolerable driving time; Candidate trip pairs are selected based on the maximum tolerable driving time and the maximum waiting offset time. S3. Calculate the waiting offset of the candidate trip pair under different pick-up sequences, and translate the three-dimensional spatiotemporal prism of the trip to which the second pick-up point belongs along the time axis by the waiting offset; perform an intersection operation on the three-dimensional spatiotemporal prism of the translated candidate trip pair to obtain the spatiotemporal overlap region under different pick-up sequences; if the spatiotemporal overlap region is not empty, execute S4; otherwise, the candidate trip pair cannot be combined. S4. Based on the reachable time intervals of the second boarding point and the first alighting point in the spatiotemporal overlap region, the spatiotemporal overlap region is shrunk to obtain the shared feasible region. If the co-route feasible domain can be constructed and is not empty, then the candidate route pair is determined to be combinable, and S5 is executed; otherwise, the candidate route pair is not combinable. S5. Based on the carpooling feasible region, construct the reachability range for the entire journey from boarding to alighting and output the carpooling feasibility result; The three-dimensional spacetime prism of the journey is defined as follows: in, Represents the three-dimensional spacetime prism of the i-th journey. Indicates the starting point of the i-th trip. Reaching the spatial position within the three-dimensional spacetime prism Time, t is spatial location The time of arrival, Let i be the original departure time of the i-th trip. Indicates spatial location Reach the end of the i-th journey. The shortest travel time, This represents the maximum tolerable travel time for the i-th trip; Shrinking the spatiotemporal overlapping region yields the following feasible regions for co-multiplication: At the second boarding point, a time constraint projection is performed along the time axis based on the spatiotemporal overlap region to determine the reachable time interval of the second boarding point; Based on the reachable time interval of the second boarding point, the spatiotemporal overlap region is shrunk to construct a transitional sub-spatiotemporal prism from the second boarding point to the termination target node, wherein the termination target node is determined by the spatial position corresponding to the upper time bound of the spatiotemporal overlap region. At the first disembarkation point, a time-constrained projection is performed on the transition sub-spacetime prism to determine the reachable time range of the first disembarkation point; Based on the reachable time range of the first disembarkation point, the transition sub-spacetime prism is shrunk to construct a local sub-spacetime prism from the second boarding point to the first disembarkation point, wherein the local sub-spacetime prism is a co-multiplication feasible region.

2. The method for determining the combinability of a three-dimensional spatiotemporal prism according to claim 1, characterized in that, The maximum tolerable driving time for the trip is: in, This represents the maximum tolerable travel time for the i-th trip. This represents the original trip duration of the i-th trip. This is a percentage coefficient for additional driving time. This is the maximum threshold for additional driving time; The maximum waiting offset time for the trip is: in, This represents the maximum waiting offset time for the i-th trip. This indicates the waiting offset ratio coefficient. This represents the original trip duration of the i-th trip. This is the upper limit threshold for the waiting offset time.

3. The method for determining the combinability of a three-dimensional spatiotemporal prism according to claim 1, characterized in that, The steps for selecting candidate trip pairs based on the maximum tolerable travel time and the maximum waiting offset time are as follows: Based on the maximum tolerable travel time and maximum waiting offset time of the trip, the extended time interval of the trip is defined, and the trip is defined. The extended time interval is: in, This represents the extended time interval of the i-th trip. Let i be the original departure time of the i-th trip. This represents the maximum tolerable travel time for the i-th trip. This represents the maximum waiting offset time for the i-th trip; Candidate routes must satisfy: The extended time intervals of the trip pairs overlap, and, The travel time from the starting point of the target journey to the shortest Euclidean distance of another journey path shall not exceed the passenger's maximum tolerable travel time for the target journey.

4. The method for determining the combinability of a three-dimensional spatiotemporal prism according to claim 1, characterized in that, The method for calculating the waiting offset is as follows: Calculate the directional waiting difference for different pick-up sequences for candidate trips, where the directional waiting difference is the difference between the theoretical arrival time of the starting point of the second trip and the original departure time of the second trip; If the directional waiting difference is zero, the waiting offset is zero; if the directional waiting difference is positive, the waiting offset is the smaller of the directional waiting difference and the maximum waiting offset time of the second trip; if the directional waiting difference is negative, the waiting offset is the smaller of the absolute value of the directional waiting difference and the maximum waiting offset time of the first trip, while retaining its directionality.

5. The method for determining the combinability of a three-dimensional spatiotemporal prism according to claim 1, characterized in that, S5 specifically refers to: Based on the shared ride feasible region, a local sub-spacetime prism is constructed from the first boarding point to the second boarding point, and a local sub-spacetime prism is constructed from the first alighting point to the second alighting point to verify the temporal continuity and path reachability of the entire pick-up and drop-off process.

6. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1 to 5.

7. An electronic device, characterized in that, The device includes a processor and a memory, the processor being interconnected with the memory, wherein the memory is used to store a computer program, the computer program including computer-readable instructions, and the processor is configured to invoke the computer-readable instructions to perform the method as described in any one of claims 1 to 5.

8. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the method described in any one of claims 1 to 5.

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