Empty vehicle operation strategy for self-driving taxis

Abstract

This invention relates to the field of automotive technology, and more specifically, to an empty vehicle operation strategy suitable for driverless taxis, including an in-vehicle intelligent terminal, a cloud server, and a mobile intelligent terminal; to solve the technical problem of ensuring that driverless vehicles do not operate entirely empty, ensuring that passengers have a ride, reducing operating costs, and reducing passenger waiting time.

Description

Technical Field

[0001] This invention relates to the field of automotive technology, and more specifically, to an empty vehicle operation strategy suitable for driverless taxis. Background Technology

[0002] Driverless taxis are being continuously improved and are entering pilot phases. With the large-scale use of driverless taxis in the future, the operation and management of driverless vehicles will be very important. It is necessary to ensure that the vehicles do not operate empty, which would increase operating costs, and to ensure that passengers have a ride and do not have to wait too long.

[0003] Therefore, based on the cloud database-based autonomous vehicle navigation and driving method of invention patent number 201610269358.3, this invention designs an empty vehicle operation strategy suitable for autonomous taxis. Summary of the Invention

[0004] The purpose of this invention is to provide an empty vehicle operation strategy suitable for driverless taxis, in order to solve the technical problems of ensuring that driverless vehicles are not all operating empty, ensuring that passengers have a ride, reducing operating costs, and reducing passenger waiting time.

[0005] The empty vehicle operation strategy suitable for driverless taxis of the present invention is implemented as follows:

[0006] Suitable strategies for operating empty taxis include in-vehicle intelligent terminals, cloud servers, and mobile intelligent terminals;

[0007] The empty vehicle operation strategy of the driverless taxi is as follows:

[0008] S1: Based on high-precision maps and real-time regional traffic maps, the region is divided into key areas, primary secondary key areas, secondary secondary key areas, and non-key areas; this regional division is stored as an auxiliary map mode on the cloud server.

[0009] S2: The number of available taxis in key areas should be no less than 3 in real time. The number of available taxis in key areas should be set according to time, which is divided into peak and off-peak periods. That is, when the number of available taxis in key areas is less than 3 in peak periods, new available taxis will be dispatched to key areas. If the number of available taxis in key areas is 0 and there are no vehicles available to be dispatched in key areas, vehicles from other secondary areas will be dispatched to key areas for operation. If the number of vehicles in key areas is higher than 5 available taxis for a period of time, three available taxis will be retained for operation, and the rest will return to the driverless taxi parking lot in key areas to park, charge, and wait.

[0010] S3: The number of empty taxis operating in the primary and secondary key areas in real time shall not be less than 2. The number of operating taxis in the primary and secondary key areas shall be set according to time, which shall be divided into peak and off-peak periods. That is, when the number of empty taxis operating in real time during the peak period is less than 2, a new empty taxi shall be dispatched to the primary and secondary key areas. If the number of empty taxis in the primary and secondary key areas is 0 and there are no vehicles available for dispatch in the primary and secondary key areas, vehicles from other secondary key areas shall be dispatched to the primary and secondary key areas for operation. If the number of vehicles in the primary and secondary key areas is higher than 3 empty taxis for a period of time, 2 empty taxis shall be retained for operation and the rest shall return to the driverless taxi parking lot in the primary and secondary key areas for parking, charging and waiting.

[0011] S4: The number of empty taxis operating in the secondary key area in real time shall not be less than 1. The number of operating taxis in the secondary key area shall be set according to time, which shall be divided into peak and off-peak periods. That is, when the number of empty taxis operating in real time during the peak period is less than 1, a new empty taxi shall be dispatched to the secondary key area. If the number of empty taxis in the secondary key area is 0 and there are no vehicles available for dispatch in the secondary key area, vehicles from other secondary key areas shall be dispatched to the secondary key area for operation. If the number of vehicles in the secondary key area is more than 2 empty taxis for a period of time, 1 empty taxi shall be retained for operation and the rest shall return to the driverless taxi parking lot in the secondary key area for parking, charging and waiting.

[0012] S5: In non-key areas, empty taxis will not be kept in operation. When the cloud server receives an order request from the mobile smart terminal, it will send a signal to the on-board smart terminal of the driverless taxi and dispatch driverless taxis in non-key areas to pick up passengers.

[0013] S6: When a driverless taxi is returning with a passenger, if there is a demand for a ride in a nearby location, the order will be dispatched to the nearest driverless taxi through the cloud server. If there is more than one available vehicle, the cloud server will prioritize the vehicle in the closest area to the corresponding area. If there are vehicles in the same area, the cloud server will select the vehicle with the most battery power to accept the order.

[0014] S7: When the battery level of an unmanned vehicle drops below 10% while it is running empty, it returns to the parking lot to charge and waits for another empty vehicle to be called in for operation.

[0015] As an optional implementation, in S1, shopping malls, office buildings, high-speed rail passenger stations, university areas, industrial parks, scenic spots, social venues, and large supermarkets on the high-precision map are combined with a real-time traffic flow map to divide these areas with high traffic flow into key areas, primary secondary key areas, and secondary secondary key areas.

[0016] The remaining areas are designated as non-priority areas.

[0017] As an optional embodiment, in S1, the pedestrian flow is measured in real time. Figure 1 The map will change in real time. When the flow of people changes, the key areas, primary key areas, and secondary key areas on the high-precision map will change in real time.

[0018] As an optional embodiment, in S1, the identification of non-key areas is made through high-precision maps and real-time traffic flow maps, namely, towns, remote areas, and remote factory areas on the high-precision map.

[0019] As an optional embodiment, in S2, when the number of empty taxis during peak hours is less than 3 and the number of orders received by the cloud server is greater than the total number of driverless taxis in the key area, all driverless taxis in the parking lot in the key area will be dispatched; and vacant driverless taxis in the low-level area will be dispatched to the key area for operation.

[0020] As an optional implementation, in S3, when the number of empty taxis during peak hours is less than 2 and the number of orders received by the cloud server is greater than the total number of driverless taxis in the primary key area, all driverless taxis in the parking lot of the primary key area will be dispatched; and vacant driverless taxis in the low-level area will be dispatched to the primary key area for operation.

[0021] As an optional embodiment, in S4, when the number of empty taxis during peak hours is less than 1 and the number of orders received by the cloud server is greater than the total number of driverless taxis in the secondary key area, all driverless taxis in the parking lot of the secondary key area will be dispatched; and vacant driverless taxis in the low-level area will be dispatched to the secondary key area for operation.

[0022] As an optional implementation, when the flow of people in a non-key area increases at a specific time and the number of orders exceeds 20% of the number of driverless taxis in the non-key area, available vacant driverless taxis can be borrowed from the next higher level.

[0023] As an optional embodiment, in S7, during peak hours, when the battery level of the driverless taxi is below 10%, the driverless taxi returns to the parking lot for a quick battery replacement, and then resumes operation after the battery replacement.

[0024] As an optional implementation, if passengers in non-priority areas encounter a situation where no vehicles are available in the non-priority areas, they can conditionally choose to dispatch vehicles from the next higher level of area.

[0025] Compared with the prior art, the present invention has the following beneficial effects: by setting key areas, primary secondary key areas, secondary secondary key areas, and non-key areas to divide the entire city, the number of empty driverless taxis operating can be more accurately divided into corresponding areas, avoiding excessive empty taxis causing resource waste and increased operating costs.

[0026] By differentiating between peak and off-peak hours, the number of empty driverless taxis operating can be determined more precisely based on regional differentiation. This ensures that empty taxi resources are not wasted, operating costs are reduced, and there are enough vehicles available for passengers. Attached Figure Description

[0027] Figure 1 This represents the system connection relationship in this embodiment. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0029] Example 1:

[0030] Reference Figure 1 As shown, the empty vehicle operation strategy suitable for driverless taxis includes in-vehicle intelligent terminal, cloud server, and mobile intelligent terminal.

[0031] The empty car operation strategy for driverless taxis is as follows:

[0032] S1: Based on high-precision maps and real-time regional traffic maps, the region is divided into key areas, primary secondary key areas, secondary secondary key areas, and non-key areas; this regional division is stored as an auxiliary map mode on the cloud server.

[0033] S2: The number of available taxis in key areas should be no less than 3 in real time. The number of available taxis in key areas should be set according to time, which is divided into peak and off-peak periods. That is, when the number of available taxis in key areas is less than 3 in peak periods, new available taxis will be dispatched to key areas. If the number of available taxis in key areas is 0 and there are no vehicles available to be dispatched in key areas, vehicles from other secondary areas will be dispatched to key areas for operation. If the number of vehicles in key areas is higher than 5 available taxis for a period of time, three available taxis will be retained for operation, and the rest will return to the driverless taxi parking lot in key areas to park, charge, and wait.

[0034] S3: The number of empty taxis operating in the primary and secondary key areas in real time shall not be less than 2. The number of operating taxis in the primary and secondary key areas shall be set according to time, which shall be divided into peak and off-peak periods. That is, when the number of empty taxis operating in real time during the peak period is less than 2, a new empty taxi shall be dispatched to the primary and secondary key areas. If the number of empty taxis in the primary and secondary key areas is 0 and there are no vehicles available for dispatch in the primary and secondary key areas, vehicles from other secondary key areas shall be dispatched to the primary and secondary key areas for operation. If the number of vehicles in the primary and secondary key areas is higher than 3 empty taxis for a period of time, 2 empty taxis shall be retained for operation and the rest shall return to the driverless taxi parking lot in the primary and secondary key areas for parking, charging and waiting.

[0035] S4: The number of empty taxis operating in the secondary key area in real time shall not be less than 1. The number of operating taxis in the secondary key area shall be set according to time, which shall be divided into peak and off-peak periods. That is, when the number of empty taxis operating in real time during the peak period is less than 1, a new empty taxi shall be dispatched to the secondary key area. If the number of empty taxis in the secondary key area is 0 and there are no vehicles available for dispatch in the secondary key area, vehicles from other secondary key areas shall be dispatched to the secondary key area for operation. If the number of vehicles in the secondary key area is more than 2 empty taxis for a period of time, 1 empty taxi shall be retained for operation and the rest shall return to the driverless taxi parking lot in the secondary key area for parking, charging and waiting.

[0036] S5: In non-key areas, empty taxis will not be kept in operation. When the cloud server receives an order request from the mobile smart terminal, it will send a signal to the on-board smart terminal of the driverless taxi and dispatch driverless taxis in non-key areas to pick up passengers.

[0037] S6: When a driverless taxi is returning with a passenger, if there is a demand for a ride in a nearby location, the order will be dispatched to the nearest driverless taxi through the cloud server. If there is more than one available vehicle, the cloud server will prioritize the vehicle in the closest area to the corresponding area. If there are vehicles in the same area, the cloud server will select the vehicle with the most battery power to accept the order.

[0038] S7: When the battery level of an unmanned vehicle drops below 10% while it is running empty, it returns to the parking lot to charge and waits for another empty vehicle to be called in for operation.

[0039] Preferably, in S1, shopping malls, office buildings, high-speed rail passenger stations, university areas, industrial parks, tourist attractions, social venues, and large supermarkets on the high-precision map are combined with real-time traffic flow maps to divide these areas with high traffic flow into key areas, primary secondary key areas, and secondary secondary key areas.

[0040] The remaining areas are designated as non-priority areas.

[0041] Preferably, in S1, the pedestrian flow is monitored in real time. Figure 1 The map will change in real time. When the flow of people changes, the key areas, primary key areas, and secondary key areas on the high-precision map will change in real time.

[0042] The principle of storing the auxiliary map for area division in the cloud server in this invention is based on a cloud database-based navigation method for unmanned vehicles, which is based on patent number 201610269358.3. The area division in this invention will change in real time according to the changes in pedestrian flow, so the auxiliary map will be updated in real time. Therefore, the auxiliary map stored in the cloud server will change according to the real-time changes in pedestrian flow, making it a dynamic map.

[0043] The auxiliary map is constructed using high-precision maps and real-time pedestrian flow maps as its underlying logic. Therefore, the auxiliary map may change at any time. The cloud server then uses the auxiliary map to coordinate and change the number of empty driverless taxis in each area in real time.

[0044] The cloud server includes a cloud database: The cloud database includes:

[0045] 1) High-precision map, containing various types of road information, real-time traffic information and real-time vehicle location information: The road information it contains includes traffic markings, road intersections, road traffic lights, road traffic signs and location service information;

[0046] 2) The driving plan planning system plans the driving route and driving plan based on the vehicle's current location and destination information uploaded by the onboard terminal, according to road and traffic information. This information is then transmitted to the onboard terminal. Based on the vehicle's real-time location provided by the vehicle positioning system, real-time traffic information and updated road information from high-precision maps, and destination change information uploaded by the onboard terminal, the system promptly adjusts the driving route and driving plan, and then sends reminders and revised plans to the vehicle's onboard terminal.

[0047] 3) The vehicle monitoring system includes two subsystems: a vehicle status monitoring system and a vehicle positioning system. The vehicle status monitoring system receives real-time driving information of the vehicle uploaded by the on-board terminal. The real-time driving information of the vehicle includes speed, acceleration, steering angle and angular velocity, as well as the vehicle's equipment status information, including the on-board computer and sensors. The vehicle positioning system obtains the real-time location of the vehicle and integrates it into a high-precision map to determine whether there has been a route deviation or other issues. It can also determine potentially congested or already congested road sections based on the location information of each vehicle.

[0048] Information sources for high-precision maps include:

[0049] 1) Existing map;

[0050] 2) Map information collected by professional map data collectors;

[0051] 3) Real-time information uploaded by autonomous vehicles connected to the cloud database:

[0052] After receiving real-time information from autonomous vehicles, the cloud will automatically update the data of the high-precision map in a timely manner.

[0053] Preferably, in S2, when the number of empty taxis during peak hours is less than 3 and the number of orders received by the cloud server is greater than the total number of driverless taxis in the key area, all driverless taxis in the parking lot in the key area will be dispatched; and vacant driverless taxis in the lower-level areas will be dispatched to the key area for operation.

[0054] Preferably, in S3, when the number of empty taxis during peak hours is less than 2 and the number of orders received by the cloud server is greater than the total number of driverless taxis in the primary key area, all driverless taxis in the parking lot of the primary key area will be dispatched; and vacant driverless taxis in the lower-level areas will be dispatched to the primary key area for operation.

[0055] Preferably, in S4, when the number of empty taxis during peak hours is less than 1 and the number of orders received by the cloud server is greater than the total number of driverless taxis in the secondary key area, all driverless taxis in the parking lot of the secondary key area will be dispatched; and vacant driverless taxis in the low-level area will be dispatched to the secondary key area for operation.

[0056] Preferably, in S1, the identification of non-key areas is made through high-precision maps and real-time traffic flow maps, namely, towns, remote areas, and remote factory areas on the high-precision map.

[0057] Even in remote areas, there may be tourist attractions and social venues that experience high visitor volumes during specific periods. When determining the classification of these remote areas, in addition to referring to high-precision regional maps and real-time visitor flow maps, we also consider the visitor flow patterns of these areas over different time periods in previous years. This comprehensive assessment determines whether the area is a key area, a first-level secondary key area, a second-level secondary key area, or a non-key area within each corresponding time period. Therefore, the classification of key areas, first-level secondary key areas, second-level secondary key areas, or non-key areas is not static; the determination of an area's nature changes in real time.

[0058] Once the cloud server determines the corresponding number of empty driverless taxis to be dispatched, these empty taxis will travel in a loop according to the routes set by the cloud server based on high-precision maps and real-time traffic flow maps.

[0059] The number of driverless taxis in key areas, first-level secondary key areas, second-level secondary key areas, and non-key areas decreases sequentially. When the classification of these areas changes, the cloud server coordinates the corresponding number of driverless taxis in those areas to make changes.

[0060] Preferably, when the flow of people in a non-key area increases at a specific time and the number of orders exceeds 20% of the number of driverless taxis in the non-key area, available vacant driverless taxis can be borrowed from the next higher level.

[0061] Preferably, if passengers in non-key areas encounter a situation where no vehicles are available in the non-key areas, they can conditionally choose to be dispatched to vehicles in the next higher level area.

[0062] Preferably, the battery level of the driverless taxi is uploaded to the cloud server in real time. When the cloud server receives an order from the mobile smart terminal, the battery level of the driverless taxi is also one of the screening conditions when the cloud server dispatches the order. The power consumption required for the driverless taxi to go to and from the destination is calculated based on the data uploaded by the mobile smart terminal. If the remaining power of the driverless taxi does not meet the requirements, the cloud server will not select the vehicle and will prioritize selecting vehicles that meet the requirements to pick up passengers.

[0063] Preferably, in S7, during peak hours, when the battery level of the driverless taxi drops below 10%, the driverless taxi returns to the parking lot for a quick battery replacement, and then resumes operation after the battery replacement.

[0064] When the cloud server determines peak usage periods based on auxiliary maps, it sends a peak signal to all driverless taxis in that area. Upon receiving the peak signal, if the driverless taxi's battery level is below 10%, the original command to return for charging is replaced with a command to return for a fully charged battery. This shortens the charging wait time for driverless taxis and improves their operational capacity during peak hours.

[0065] As needed, temporary battery replacement stations for driverless taxis can be set up in suitable locations to facilitate faster battery replacement and resuming operation. Suitable locations can include gas stations and charging stations, primarily chosen for their convenient and quick battery replacement capabilities.

[0066] Preferably, if the number of orders exceeds the total number of empty vehicles within the same time period, and none of the empty vehicles meet the battery requirements of the orders, the rule of returning to charge or replace the battery when the remaining battery is 10% is ignored, and the vehicle immediately goes to the battery replacement location to replace the battery with a fully charged one and continues to operate.

[0067] If the number of orders is less than the total number of available taxis in the same time period, and the available taxis in operation do not meet the battery requirements, then driverless taxis waiting in the parking lot will be reallocated to pick up passengers. If there are no waiting vehicles in the parking lot, then the available taxi with the lowest battery level will be selected to replace the battery before accepting orders.

[0068] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0069] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0070] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A strategy for operating empty taxis suitable for driverless taxis, characterized in that, This includes in-vehicle smart terminals, cloud servers, and mobile smart terminals; The empty vehicle operation strategy of the driverless taxi is as follows: S1: Based on high-precision maps and real-time regional traffic maps, the region is divided into key areas, primary secondary key areas, secondary secondary key areas, and non-key areas; this regional division is stored as an auxiliary map mode on the cloud server. S2: The number of available taxis in key areas should be no less than 3 in real time. The number of available taxis in key areas should be set according to time, which is divided into peak and off-peak periods. That is, when the number of available taxis in key areas is less than 3 in peak periods, new available taxis will be dispatched to key areas. If the number of available taxis in key areas is 0 and there are no vehicles available to be dispatched in key areas, vehicles from other secondary areas will be dispatched to key areas for operation. If the number of vehicles in key areas is higher than 5 available taxis for a period of time, three available taxis will be retained for operation, and the rest will return to the driverless taxi parking lot in key areas to park, charge, and wait. S3: The number of empty taxis operating in the primary and secondary key areas in real time shall not be less than 2. The number of operating taxis in the primary and secondary key areas shall be set according to time, which shall be divided into peak and off-peak periods. That is, when the number of empty taxis operating in real time during the peak period is less than 2, a new empty taxi shall be dispatched to the primary and secondary key areas. If the number of empty taxis in the primary and secondary key areas is 0 and there are no vehicles available for dispatch in the primary and secondary key areas, vehicles from other secondary key areas shall be dispatched to the primary and secondary key areas for operation. If the number of vehicles in the primary and secondary key areas is higher than 3 empty taxis for a period of time, 2 empty taxis shall be retained for operation and the rest shall return to the driverless taxi parking lot in the primary and secondary key areas for parking, charging and waiting. S4: The number of empty taxis operating in the secondary key area in real time shall not be less than 1. The number of operating taxis in the secondary key area shall be set according to time, which shall be divided into peak and off-peak periods. That is, when the number of empty taxis operating in real time during the peak period is less than 1, a new empty taxi shall be dispatched to the secondary key area. If the number of empty taxis in the secondary key area is 0 and there are no vehicles available for dispatch in the secondary key area, vehicles from other secondary key areas shall be dispatched to the secondary key area for operation. If the number of vehicles in the secondary key area is more than 2 empty taxis for a period of time, 1 empty taxi shall be retained for operation and the rest shall return to the driverless taxi parking lot in the secondary key area for parking, charging and waiting. S5: Empty taxis will not be kept in non-key areas. When the cloud server receives an order request from the mobile smart terminal, it will send a signal to the on-board smart terminal of the driverless taxi and dispatch driverless taxis in non-key areas to pick up passengers. S6: When a driverless taxi is returning with a passenger, if there is a demand for a ride in a nearby location, the order will be dispatched to the nearest driverless taxi through the cloud server. If there is more than one available vehicle, the cloud server will prioritize the vehicle in the closest area to the corresponding area. If there are vehicles in the same area, the cloud server will select the vehicle with the most battery power to accept the order. S7: When the battery level of an unmanned vehicle drops below 10% while it is running empty, it returns to the parking lot to charge and waits for another empty vehicle to be called in for operation.

2. The empty vehicle operation strategy suitable for driverless taxis according to claim 1, characterized in that, In S1, shopping malls, office buildings, high-speed rail passenger stations, university areas, industrial parks, tourist attractions, social venues, and large supermarkets on the high-precision map are combined with real-time traffic flow maps to divide these areas with high traffic flow into key areas, primary secondary key areas, and secondary secondary key areas. The remaining areas are designated as non-priority areas.

3. The empty vehicle operation strategy suitable for driverless taxis according to claim 2, characterized in that, In S1, the real-time pedestrian flow map changes throughout the day. As pedestrian flow changes, the key areas, primary secondary key areas, and secondary secondary key areas on the high-precision map will also change in real time.

4. The empty vehicle operation strategy suitable for driverless taxis according to claim 3, characterized in that, In S1, non-key areas are identified through high-precision maps and real-time pedestrian flow maps, namely, towns, remote areas, and remote factory areas on the high-precision map.

5. The empty vehicle operation strategy suitable for driverless taxis according to claim 4, characterized in that, In S2, when the number of empty taxis during peak hours is less than 3 and the number of orders received by the cloud server is greater than the total number of driverless taxis in the key area, all driverless taxis in the parking lot in the key area will be dispatched. And dispatch vacant driverless taxis in low-level areas to key areas for operation.

6. The empty vehicle operation strategy suitable for driverless taxis according to claim 5, characterized in that, In S3, when the number of empty taxis during peak hours is less than 2 and the number of orders received by the cloud server is greater than the total number of driverless taxis in the primary key area, all driverless taxis in the parking lot of the primary key area will be dispatched. And dispatch vacant driverless taxis in lower-level areas to operate in first-level secondary key areas.

7. The empty vehicle operation strategy suitable for driverless taxis according to claim 6, characterized in that, In S4, when the number of empty taxis during peak hours is less than 1 and the number of orders received by the cloud server is greater than the total number of driverless taxis in the secondary key area, all driverless taxis in the parking lot of the secondary key area will be dispatched. And dispatch vacant driverless taxis in lower-level areas to operate in secondary key areas.

8. The empty vehicle operation strategy suitable for driverless taxis according to claim 7, characterized in that, When the flow of people in a non-key area increases at a specific time and the number of orders exceeds 20% of the number of driverless taxis in the non-key area, available vacant driverless taxis can be borrowed from the next higher level.

9. The empty vehicle operation strategy suitable for driverless taxis according to claim 8, characterized in that, In the S7, during peak hours, when the battery level of a driverless taxi drops below 10%, the driverless taxi returns to the parking lot for a quick battery replacement, and then resumes operation after the battery replacement.

10. The empty vehicle operation strategy suitable for driverless taxis according to claim 9, characterized in that, Passengers in non-priority areas who encounter no available vehicles in the non-priority area may, under certain conditions, choose to be dispatched to vehicles in the next higher level area.

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