Automatic driving control system and method

Abstract

The invention relates to an automatic driving control system, comprising a first control unit used for sending a control instruction for vehicle control based on target detection data; and the second control unit is used for sending out an abnormal control instruction for controlling the vehicle according to the power consumption state of the first control unit. According to the invention, the operation condition of the existing automatic driving system can be monitored, so that the existing automatic driving system can be taken over when an emergency occurs.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to vehicle automatic driving control systems, and more particularly to safety control during vehicle driving. BACKGROUND

[0002] Vehicle automatic driving control has become an important issue for vehicle intelligence and is increasingly implemented. Under the design and operation conditions of advanced automatic driving assistance system (ADAS), various sensors equipped on the vehicle can be used to monitor the vehicle and the driving environment, such as obtaining information of vehicles on the driving road, possible obstacles, etc., so as to continuously perform all dynamic driving tasks. Figure 1 A schematic diagram of an existing automatic driving control ADAS system is shown. As shown, the control system 100 includes a control unit and an execution mechanism. The control unit receives target detection or environment perception data from sensors, such as detection data of vehicles or possible obstacles, and processes the received detection data to identify targets, such as identifying whether it is a vehicle or a confirmable obstacle, etc., and generates corresponding standard control instructions sCMD according to the identification results. The execution mechanism is used to receive the standard control instructions from the control unit to perform corresponding actions, such as deceleration, avoidance or braking, etc.

[0003] Conventionally, if the automatic driving control system exceeds the design and operation conditions, for example, if the radar device or camera cannot correctly detect the surrounding environment or the system cannot identify the target or obstacle, in order to ensure safety, a takeover request needs to be sent to the driver in time, and the driver is notified accordingly that he needs to take over the control of the vehicle, so as to achieve safe takeover of the automatic driving vehicle. However, such safety control logic of the advanced automatic driving system still has safety risks sometimes, for example, the takeover request may not be responded in time sometimes. SUMMARY

[0004] In order to achieve higher safety of vehicle automatic driving, the present application proposes to set a supervision level at the upper level of the control logic of the advanced automatic driving function, such as the ADAS system, for monitoring the operation status of the existing ADAS system, so as to directly issue an abnormal control instruction in case of emergency, instead of sending a takeover request to the driver, so as to realize that the execution mechanism performs corresponding actions according to the abnormal instruction.

[0005] According to an aspect of the present application, there is provided an automatic driving control system, comprising a first control unit configured to issue a control instruction for vehicle control based on target detection data; and a second control unit configured to issue an abnormal control instruction for the vehicle control according to a power consumption state of the first control unit.

[0006] According to another aspect of the present application, there is provided a control method for an autonomous driving control system, the method comprising issuing, by a first control unit, a control instruction for vehicle control according to target detection data; and issuing, by a second control unit, an abnormal control instruction for the vehicle control according to a power consumption state of the first control unit. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 A schematic diagram of a conventional autonomous driving system is shown;

[0008] Figure 2 A schematic diagram of an autonomous driving control system according to an embodiment of the present application is shown;

[0009] Figure 3 A flowchart of a control method according to one example of the present application is shown;

[0010] Figure 4 A flowchart of a control method according to another example of the present application is shown. DETAILED DESCRIPTION

[0011] Before any embodiments of the present application are explained in detail, it is to be understood that the application is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The application is capable of other embodiments and of being practiced or being carried out in various ways.

[0012] As Figure 1As shown, in a conventional autonomous driving control system 100, the control unit typically analyzes sensor data (DATA) provided by sensors such as radar or cameras, including target recognition, to make correct decisions based on a pre-defined control policy, including generating standard control commands (sCMD). For example, during target recognition, the control unit identifies the detected target by matching the target features parsed from the DATA with reference targets in a pre-configured database (DB). Here, the control unit undertakes a large amount of computation and recognition tasks. However, it is possible that an obstacle not encountered by the autonomous driving system 100 (referred to as an 'abnormal obstacle' in this disclosure for ease of description), such as a landslide boulder, may appear on the road. After extracting the target by parsing the detection data, the control unit may not be able to confirm the detected target even after traversing the database (DB). Therefore, in the conventional way, the control unit will repeatedly perform this target recognition operation without being able to issue a timely control command for the abnormal obstacle, which obviously increases the risk. Although in other designs, the system 100 is usually designed to issue a takeover request to the driver, there is still a serious risk if the takeover request is not responded to or is not responded to in a timely manner. According to the solution of the present invention, the driver can intervene in driving control in a timely and direct manner by monitoring the abnormal operation of the autonomous driving system 100, thereby reducing the risk.

[0013] Figure 2 An autonomous driving control system 200 according to an embodiment of the present invention is shown, including an autonomous driving control subsystem 100 and a second control unit 300. Here, the autonomous driving subsystem 100 can be a conventional autonomous driving system, for example, it can be... Figure 1 The system 100 shown is a conventional autonomous driving system or other advanced driver assistance systems (ADAS) known in the prior art. Here, system 100 includes a first control unit 101 and an actuator 102, whose operation is similar to... Figure 1 The control unit shown is the same as the actuator. The second control unit 300 is located outside the control subsystem 100 to monitor the operating status of the control subsystem 100, wherein the second control unit 300 determines whether to intervene in vehicle control based on the operating status of the control subsystem 100.

[0014] The first control unit 101 in the autonomous driving subsystem 100 is configured to perform control tasks for autonomous driving, for example, by performing target recognition algorithms to process target detection data received from sensors such as radars (e.g., ultrasonic radar, millimeter wave radar, laser radar, etc.), various cameras, etc., to perform target analysis processing, so the first control unit 101 will consume a certain amount of energy in the process of performing control tasks such as target recognition, and obviously the amount of energy consumption will change depending on the size of the workload of the first control unit 101 processing data, time, etc. Generally, when the sensor does not detect a target or obstacle, the first control unit 101 is basically in a dormant state or low power consumption state; or when the sensor detects a target that is an object frequently encountered in the training or learning of the autonomous driving system, the first control unit 101 can quickly identify the detected target and output a standard control instruction sCMD. For example, when the first control unit 101 identifies a vehicle in front of the adjacent lane based on the camera and the vehicle is approaching the host vehicle, a standard instruction sCMD to reduce the vehicle speed is output to the actuator 102; and the actuator 102 performs braking or reduces the throttle opening degree based on the sCMD instruction. Generally, if the sensor-detected target can be quickly identified within a reasonable time, the energy consumed by the first control unit 101 is also low, i.e., within a reasonable energy consumption range. Therefore, in this article, the standard control instruction sCMD output by the first control unit 101 is also referred to as a 'normal control instruction'. It should be pointed out here that in the present application, the first control unit 101 can be an independent element, such as a vehicle-grade processing unit CPU, or a subsystem configured to complete the target recognition task.

[0015] However, when the first control unit 101 fails to perform effective control tasks—for example, when it cannot extract or parse target attributes (such as target contour features) based on the detection data DATA from the sensors, or when it cannot find a matching target when traversing the database DB based on the extracted target attributes—that is, when it cannot identify the target detected by the sensors—in these specific abnormal situations, according to conventional design, the first control unit 101 will typically perform high-density calculations based on the updated detection data from the sensors in an attempt to identify the target. This will cause the power consumption of the first control unit 101 to continuously and significantly increase until the target is identified or it is confirmed that the target cannot be identified, at which point it will issue a takeover request to the driver. However, this control logic may lead to an accident or danger that cannot be avoided due to the loss of the opportunity to deal with danger in a timely manner. For example, when a large boulder suddenly appears on the road ahead while the vehicle is traveling at high speed, although the radar or vision sensor can detect the object in time, the unpredictable size and shape of the boulder may cause the first control unit 101 to fail to identify the suddenly appearing boulder. In this case, issuing a takeover request to the user to judge and deal with the unknown object may lead to a huge risk of collision.

[0016] According to embodiments of the present invention, it is noted that under these specific abnormal conditions, the energy consumption of the first control unit 101 will increase significantly. Therefore, by setting a second control unit 300 on the autonomous driving subsystem 100 to monitor the energy consumption status of the first control unit 101 to determine whether to take over the first control unit 101, and by directly issuing a control command aCMD to the actuator 102 to take over the control of the first control unit 101, thereby avoiding danger in time. Since the control command aCMD is issued by the second control unit 300 when the first control unit 101 may be abnormal, the control command aCMD is also referred to as the abnormal control command aCMD in this document. Taking the prominent collapse of the boulder in the above example as an example, the first control unit 101 receives detected signal DATA from the sensor, such as radar reflection signal or image video signal related to the boulder. By executing the target recognition algorithm, it extracts target attributes or features from the signal data DATA and traverses the database DB to retrieve reference targets that match the extracted target attributes. However, since the boulder feature is not pre-registered in the database DB, the first control unit 101 cannot identify a reference target matching the target attribute, i.e., it cannot determine what the target 'boulder' currently detected by the sensor is. Therefore, as the vehicle moves, the first control unit 101 will continue to identify the same target 'boulder' according to the traditional strategy Policy, based on the detection signals collected by the sensor. As a result, the first control unit 101 will enter a high-density computing state, and due to the increased computing burden, the power consumption of the first control unit 101 will increase significantly. The second control unit 300 monitors the power consumption PowUse of the first control unit 101 in real time. When it is determined that the power consumption PowUse is greater than or equal to the power consumption threshold P... THR In one implementation, the first control unit 101 can be directly taken over and an abnormal control command aCMD can be directly output to the actuator 102. For example, the aCMD command is a signal used to control the vehicle to a safe speed by an emergency and significant reduction in speed, such as emergency reduction of the accelerator and / or braking. Thus, the actuator 102 can quickly apply emergency braking to the vehicle according to the abnormal command aCMD, thereby timely controlling the vehicle to reduce risk. Alternatively, in another implementation, when the second control unit 300 determines that the power consumption PowUse is greater than or equal to the power consumption threshold P... THRAt this time, it can be further confirmed whether the first control unit 101 has issued a standard control command sCMD to the actuator 102 for the current target (for example, in some cases, the first control unit 101 has identified the current target detected by the sensor after high-density calculation). Only when it is confirmed that the first control unit 101 has not issued a standard control command sCMD to the actuator 102 will the first control unit 101 be taken over and an abnormal command aCMD be immediately output to control the actuator 102 to perform emergency operations according to the command aCMD, such as a sudden and significant reduction in vehicle speed. When it is determined that the power consumption PowUse is greater than or equal to the power consumption threshold P THR If it is confirmed that the first control unit 101 has issued the standard control command sCMD to the actuator 102, the second control unit 300 will not intervene in the driving control, and the actuator 102 will operate according to the standard command sCMD.

[0017] According to an embodiment of the present invention, simultaneously or shortly after the second control unit 300 issues the abnormal control command aCMD, the autonomous driving subsystem 100 can still control the original control policy to issue a takeover request or an alarm to the user because the target cannot be effectively identified. This allows the user to promptly view the 'rock' risk and take over control of the vehicle. Therefore, by utilizing the solution of the present invention, the increased risk caused by the traditional autonomous driving system 100's inability to identify the target and the user's inability to take over in a timely manner can be avoided.

[0018] In another embodiment of the present invention, a time window W may be set considering factors such as the computing power of the first control unit 101, and used together with the power consumption PowUse to monitor the operation of the first control unit 101. For example, when it is determined that the power consumption PowUse is greater than or equal to the power consumption threshold P THR Furthermore, the second control unit 300 only outputs the abnormal control command aCMD when the time T from the initial power consumption to the current power consumption PowUse exceeds the time window W. Here, the initial power consumption can be the low power consumption state maintained by the first control unit 101 during normal driving. Here, the time window W can be a predetermined value or a value that varies based on vehicle speed, for example, it can be inversely proportional to vehicle speed.

[0019] In the above embodiments, the power consumption threshold P THR A fixed threshold can be preset, so that as long as the actual power consumption PowUse is greater than this threshold P... THR, the second control unit 300 takes over the control unit 101 and outputs an abnormal instruction aCMD for emergency deceleration or braking to the actuator 102. In another embodiment of the present invention, considering the possible changes in the energy consumption level due to the differences in the duration and complexity of high-density computing, the present invention can match the driving speed of the autonomous vehicle according to the energy consumption level. For example, when the energy consumption PowUse is greater than the first threshold P THR1 the second control unit 300 can output an abnormal instruction to reduce the vehicle speed to the first speed V1; and when the further monitored energy consumption PowUse is greater than the second threshold P THR2 the second control unit 300 can output an abnormal instruction to further reduce the vehicle speed to the second speed V2, where the threshold P THR2 >P THR1 , and V2 < V1. According to an example of the present invention, a pre-designed specific energy consumption threshold / speed curve or graph P-V can be stored in the driving control system 200. The P-V curve can be determined by experiments, or further autonomously learned and optimized by the driving control system 200 through actual applications from the main learning. Thus, using the P-V curve or graph, the second control unit 300 determines a suitable target vehicle speed V by comparing the actually measured power consumption PowUse with the power consumption threshold P THR . Thus, under the control of the intervening second control unit 300, by generating an abnormal control instruction aCMD indicating, for example, emergency deceleration, the actuator 102 can control the vehicle to the safe target vehicle speed V, so as to effectively control the autonomously driving vehicle when the first control unit 101 fails to handle it in time. It should be noted here that in another example, when generating the abnormal instruction aCMD, the second control unit 300 can further consider other environmental information. For example, according to the road conditions, the target vehicle speed V can be further adjusted. For example, when the current driving road is relatively complex, the target vehicle speed V determined based on the energy consumption threshold / speed curve or graph P-V should be further reduced.

[0020] In another example of the present invention, the second control unit 300 can also be designed to determine whether to output the abnormal instruction aCMD based on the energy consumption rate ΔP / ΔT of the first control unit 101. Here, ΔT can be set to the aforementioned predetermined time window W, or any other predetermined duration, and ΔP represents the change amount of the actually detected energy consumption PowUse within the duration of ΔT. Thus, by comparing the real-time calculated energy consumption rate ΔP / ΔT with the energy consumption rate threshold ΔP T a suitable abnormal instruction aCMD is determined, such as an instruction indicating the target vehicle speed V or emergency stop. Here, the energy consumption rate threshold / speed curve or graph ΔP-V can also be used to determine the target vehicle speed V.

[0021] In different embodiments of the present invention, the second control unit 300 can monitor the energy consumption of the autonomous driving control subsystem 100 to achieve intervention control in any manner known in the prior art. Specifically, it can be configured to monitor the power consumption of the first control unit 101, for example, by directly monitoring the power supply of the first control unit 101, such as current. In another implementation, the power consumption (PowUse) of the first control unit 101 can be determined by monitoring its heat generation (Heat). This is because the heat generation of a chip or system is usually correlated with the actual power consumption (PowUse), so the heat generation of the first control unit 101 directly reflects its power consumption status. As one implementation, a temperature sensor can be used to measure the heat generation temperature data (Heat) of the first control unit 101, and the second control unit 300 determines or estimates the actual power consumption (PowUse) of the first control unit 101 based on the heat data. The determination or estimation of the actual power consumption (PowUse) can be based on practical experience or the design specifications of the control unit (e.g., when the control unit is implemented as a chip, the chip design specifications typically include parameters related to heat generation). In another implementation of the invention, the second control unit 300 may also directly generate an abnormal command aCMD based on the monitored heat output (Heat). For example, this can be achieved through experimental measurement or further by the driving control system 200 through autonomous learning and optimization in practical applications to establish a heat output temperature / vehicle speed curve or graph (HV). Thus, using the HV curve or graph, the second control unit 300 uses the actually measured heat output temperature (Heat) and the temperature threshold H... THR The appropriate target vehicle speed V is determined by comparison, and the second control unit 300 generates an abnormal command aCMD based on the target vehicle speed.

[0022] Therefore, according to the embodiments of the present invention, by setting dual control units 101 and 300 in the automatic driving control system 200 to perform the automatic driving control task, system risks can be effectively reduced and driving safety can be improved.

[0023] Figure 3This illustration shows a driving control method implemented by a control system 200 according to an embodiment of the present invention. In step 301, after enabling the autonomous driving control ADAS function, the power consumption status of the autonomous driving control subsystem 100 is simultaneously monitored, particularly the power consumption PowUse of the core unit used to perform autonomous driving control tasks, such as target detection and recognition tasks, such as the first control unit 101 in this embodiment of the invention. For example, in this example, power consumption monitoring can be achieved by enabling a supervisory module, such as the second control unit 300. Here, the first control unit 101 performs autonomous driving control tasks, such as receiving target detection data Data from sensors, performing target parsing and recognition processing on the target detection data Data, including extracting the attributes or features of the target based on the detection data Data, and comparing the parsed target with reference targets in the database DB to identify the currently detected target.

[0024] In step 303, it is determined whether the power consumption PowUse is greater than a preset threshold P. THR Typically, when the sensor does not detect objects such as targets or obstacles, or when the first control unit 101 can quickly identify the target based on the detection data provided by the sensor, the first control unit 101 consumes very little power (PowUse), while the threshold P... THR The setting or selection ensures that the power consumption PowUse is less than the threshold P. THR Accordingly, in step 303, after determining that the power consumption PowUse is less than the threshold P THR In this case, the automatic control subsystem 100 operates according to the conventional control policy, and the second control unit 300 does not intervene in the automatic driving control.

[0025] However, if in step 303 it is determined that the power consumption PowUse is greater than or equal to a preset threshold P THR If this occurs, it can be determined that the control unit 101 is currently performing high-density calculations. For example, if the subsystem 100 cannot identify the currently detected target, such as an obstacle, based on the current detection data Data (e.g., the target contour attribute features cannot be extracted or parsed based on the detection data DATA from the sensor, or a matching target cannot be found when traversing the database DB based on the extracted target attributes), then proceed to step 305.

[0026] In step 305, the second control unit 300 further confirms whether the automatic control subsystem 100 has issued a standard command sCMD to the actuator. If the subsystem 100 has issued the corresponding standard command sCMD in response to the target currently detected by the sensor, the process returns to step 301 to continue monitoring power consumption. Otherwise, if the automatic control subsystem 100 has not issued a standard command, the process proceeds to step 307. In step 307, the second control unit 300 takes over the control of the first control unit 101 and outputs an abnormal control command aCMD to the actuator. For example, this command is used to signal an emergency, significant speed reduction to bring the vehicle to a safe speed, thereby enabling the actuator 102 to quickly and promptly control the vehicle to reduce risk. As an example, the safe speed can be determined by looking up the power consumption-speed relationship table PV. In another example, the second control unit 300 can also output an emergency stop abnormal command Acmd.

[0027] According to another embodiment of the present invention, the driving speed of autonomous driving can also be matched based on changes in power consumption. Figure 4 The flow chart of the automatic control method according to the present invention is shown. First, similar to step 301, in step 401, after enabling the automatic driving control function, a supervisory level is simultaneously enabled to monitor the power consumption of the automatic driving control subsystem 100. For example, a second control unit 300 located outside the system 100 is enabled to monitor the real-time power consumption PowUse of the first control unit 101 in the subsystem 100 that performs the automatic control task.

[0028] In step 403, it is determined whether the power consumption PowUse has triggered the first threshold condition P. THR1 For example, whether the power consumption PowUse is greater than or equal to P THR1 If not triggered, the process returns to step 401 to continue monitoring power consumption. Otherwise, if it is determined that the current power consumption PowUse is greater than or equal to the threshold P... THR1 If so, the process proceeds to step 405.

[0029] In step 405, it is further confirmed whether the automatic control subsystem 100 issues a standard instruction sCMD to the actuator at this time. If, in response to the target currently detected by the sensor, the subsystem 100 issues a corresponding standard instruction sCMD, then no takeover of the subsystem 100 (such as the takeover of the second control unit 101 in this example) is intervened, and the subsystem 100 is still responsible for autonomous driving, and it returns to step 401 to continue monitoring the power consumption status. Otherwise, if the automatic control subsystem 100 still does not issue a standard instruction sCMD at this time, then step 407 is entered. In step 407, the second control unit 300 enters the takeover mode of the traditional control strategy Polycy of the first control unit 101. In step 407, in the takeover mode, the specific energy consumption threshold / speed curve or graph P-V pre-stored in the autonomous driving system 200 is queried to determine the vehicle speed V1 corresponding to the current energy consumption PowUse or the threshold P THR1 matched, and an abnormal instruction aCMD1 corresponding to the speed V1 is generated for the actuator; at the same time, the power consumption monitoring of the first control unit 101 is continued, and then step 409 is entered.

[0030] In step 409, it is further monitored whether the updated energy consumption level PowUse of the first control unit 101 is greater than or equal to the threshold P THR2 , where the threshold P THR2 >P THR1 . If PowUse is less than P THR2 , then in step 411, the execution of the original abnormal instruction is continued, for example, the vehicle speed is still maintained at V1. However, if the newly monitored energy consumption level PowUse in step 409 is greater than or equal to the threshold P THR2 when, then step 413 is entered. In step 4​​Optionally, according to the method of the present invention, after detecting the aCMD abnormal command, the system can also choose to issue a TakeOver request or an Alert to the user, so that the user can view the target in a timely manner and manually take over the control of the vehicle. Thus, by using the solution of the present invention, the increased risk caused by the inability of traditional autonomous driving systems to recognize the abnormal command or the user's inability to take over in a timely manner can be avoided.

[0032] While different embodiments of the invention have been described above with reference to specific examples, those skilled in the art will recognize that the various illustrative logical units and method steps described in connection with this disclosure can be implemented as electronic hardware, computer software, or a combination of both. For example, the control unit according to the invention can be implemented as a processor or main controller and a memory, wherein the memory stores modules in the form of a computer program, and the processor implements the method of the invention by executing these modules. Furthermore, another embodiment of the invention provides a machine-readable medium storing machine-readable instructions that, when executed by a processor, cause the processor to perform any of the foregoing methods disclosed herein. These embodiments are also within the scope of protection of the invention.

Claims

1. An automatic driving control system, comprising: The first control unit is used to issue control commands for vehicle control based on target detection data; The second control unit is used to issue abnormal control commands for vehicle control based on the power consumption status of the first control unit.

2. The control system of claim 1, wherein the second control unit is further configured to: When it is determined that the power consumption of the first control unit has changed abruptly and the first control unit has not output any control commands, the second control unit issues the abnormal control command.

3. The control system of claim 2, wherein the second control unit is further configured to: determine the power consumption mutation by detecting whether the power consumption of the first control control unit exceeds a threshold.

4. The control system of claim 3, wherein the second control unit detects the power consumption of the first control unit by: The power consumption is estimated based on the heating state of the first control unit.

5. The control system according to any one of claims 1-4, further comprising: The driving control subsystem includes: The first control unit; and An actuator is used to execute corresponding vehicle control actions based on control commands from the first control unit or abnormal control commands from the second control unit.

6. The control system of claim 5, wherein the second control unit is further configured to output the abnormal control command to cause the actuator to control the vehicle speed according to the abnormal command to match the power consumption level.

7. The control system of claim 6, wherein the second control unit is further configured to: When the power consumption level reaches a first threshold, a first abnormal control command is output to reduce the vehicle speed to a first vehicle speed; and When the power consumption level reaches the second threshold, a second abnormal control command is output to reduce the vehicle speed to the second vehicle speed. Wherein the first threshold is less than the second threshold, and the first vehicle speed is greater than the second vehicle speed.

8. A control method for an automatic driving control system, the method comprising: The first control unit issues control commands for vehicle control based on target detection data; and The second control unit issues abnormal control commands for vehicle control based on the power consumption status of the first control unit.

9. The control method of claim 8, wherein when it is determined that the power consumption of the first control unit undergoes a sudden change and the first control unit does not output any control command, the abnormal control command is issued.

10. The control method of claim 9, wherein the power consumption mutation is determined by detecting whether the power consumption of the first control unit exceeds a threshold.

11. The control method of claim 10, wherein detecting the power consumption of the first control unit includes: The power consumption is estimated based on the heating state of the first control unit.

12. The control method according to any one of claims 8-11, further comprising: The actuator outputs control commands from the first control unit or abnormal control commands from the second control unit to perform corresponding vehicle control actions.

13. The control method of claim 12, further comprising: The abnormal control command is output so that the actuator controls the vehicle speed according to the abnormal control command to match the power consumption level.

14. The control method of claim 13, further comprising: When the power consumption level reaches a first threshold, a first abnormal command is output to reduce the vehicle speed to a first vehicle speed. as well as When the power consumption level reaches the second threshold, a second abnormal command is output to reduce the vehicle speed to the second vehicle speed. Wherein the first threshold is less than the second threshold, and the first vehicle speed is greater than the second vehicle speed.

15. A driving control system comprising a storage medium storing an executable program and a processor, wherein when the processor executes the program, it implements the method of any one of claims 8-14.

16. A computer program product comprising computer-readable program code, wherein, when executed by a computing device, the code causes the computing device to perform the method of any one of claims 8-14.

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