WO2013134924A1

WO2013134924A1 - Apparatus and method for detecting a parking space

Info

Publication number: WO2013134924A1
Application number: PCT/CN2012/072269
Authority: WO
Inventors: Zhijun Li; Leiming Xu
Original assignee: Siemens Aktiengesellschaft
Priority date: 2012-03-13
Filing date: 2012-03-13
Publication date: 2013-09-19
Also published as: CN104169988A; CN104169988B

Abstract

A method for detecting a parking space comprises: collecting signal values, determining whether the signal values are stable, and comparing a difference of an average value of the signal values and a corresponding base value with a second threshold, determining that the parking space is occupied when the signal values are stable and the difference is higher than the second threshold. An apparatus for detecting a parking space which is used to implement the method for detecting the parking space is disclosed.

Description

APPARATUS AND METHOD FOR DETECTING A

PARKING SPACE

Field of the Invention

The present invention relates to detecting a parking space, and more particularly to apparatus and method for detecting a parking space.

Background of the Invention

The parking space is used to parking a car. Sensors are used to monitoring whether the parking space is occupied by a car, so as to automatically monitor condition of the parking space. For example, metal detectors may be disposed underground and used to sensing the status of the parking space.

However, sensors may be influenced by some external conditions, such as temperature, driver's behavior, and interference of other metal object, etc.

Summary of the Invention

The object of the present invention is providing a method and an apparatus for detecting a parking space, which could reduce or eliminate the influence of driver's behavior, interference of other metal object and temperature.

In one aspect of the present invention, a method for detecting a parking space comprises collecting at least one set of signal value of detecting a object in the parking space, determining whether the signal values of said set are stable, computing a difference between the signal values of said set and a base value; comparing the difference with a second threshold; and determining that parking space is occupied when the signal values of said set are stable and the difference is higher than the second threshold.

In another aspect of the present invention, a method for detecting a parking space comprises: collecting at least two sets of signal value of detecting a object in the parking space, wherein the signal values of the sets are of different precision levels; determining whether the signal values of all said sets are stable; computing differences between the signal values of said sets and corresponding base values respectively;comparing each of the differences with a corresponding second threshold respectively; and determining the status of the parking space based on said determining and comparing.

In still another aspect of the invention, a method for detecting a parking space, comprises: collecting at least one set of signal value of detecting a object in the parking space; determining whether the signal values of said set are stable; computing a difference between the signal values of said set and a base value when the signal values are stable; comparing the difference with a second threshold; and determining the status of the parking space based on the results of said comparing.

In still another aspect of the invention, a method for detecting a parking space, comprises: collecting at least two sets of signal value of detecting a object in the parking space, wherein the signal values of the sets are of different precision levels; determining whether the signal values of all said sets are stable; computing differences between the signal values of said sets with corresponding base values respectively when the signal values of all said sets are stable; comparing each of the differences with a corresponding second threshold respectively; and determining the status of the parking space based on said comparing.

In still another aspect of the invention, an apparatus for detecting a parking space comprises: at least one data collector, configured for collecting at least one set of signal value; a first computing unit, configured for determining whether the signal values of said at least one set are stable; and a second computing unit, configured for comparing the signal values of said at least one set with a correponding base value.

In still another aspect of the invention, a manufacture article is disclosed, on which a computer readable code is recorded. The computer readable code comprises: a computer readable code for collecting at least one set of signal value; a computer readable code for determining whether the signal values of said at least one set are stable; and a computer readable code for comparing the signal values for said set to a corresponding base value when the signal values are stable.

Brief Description of the Drawings

Fig. 1 shows the detector's output without external influence.

Fig. 2 shows the output of a detector with influence of temperature drift.

Fig. 3 shows the output of a detector with shortly influence of other metal object.

Fig. 4 shows the output of a detector with influence of driver's behavior.

Fig. 5 shows the range the signal value of higher and lower precision level.

Fig. 6 shows change of outputs of two sets of signal value of different precision levels.

Fig. 7 shows detecting a parking space with stable window.

Fig. 8 illustrates the solution according to one embodiment of present invention.

Fig. 9 shows the flow chart of the method for detecting a parking space, according to one preferred embodiment of the present invention.

Fig. 10 schematically shows an apparatus for detecting a parking space, according to another embodiment of the present invention.

Detailed Description of the Invention

The present invention will be described in detail in terms of preferred embodiments of the invention. Many details are provided in description in order to facilitate thoroughly understanding. However, one skilled in the art can understand that the present invention can also be implemented without some or all of the details. As is known, the sensor, such as metal detector, may collect signal values, which could be the output of the detector, for example, a signal value corresponding to current in the circuit of detector. One skilled in the art will realize that the signal may be pre-processed before the method of the present invention, depending on the particular application.

There is a base value for a metal detector, and the base value can be used to indicate that a parking space is not occupied by a car. When a car is coming, the signal value from the detector goes higher, and reaches the highest level when the car has been completely parked in the space. In general, the processor is used (not necessary) to determine whether the parking space is empty or occupied base on the signal value and the base value.

In below graphs, the vertical axis presents the signal value, and the horizontal axis presents period of time.

Fig. 1 is a graph showing the signal values before, during, and after a car parking. It should be noted that detecting line is formed by connecting a series of point corresponding to certain signal value. These points are resulted from periodically date collection, and are generally discrete digital date. However, in other situation, the date may be collected continuously. The base line is consisted of points corresponding to a base value, which is predefined or can be adjusted when the parking space is empty (not occupied by a car).

As a driver is parking a car, as indicated in Fig. 1, the signal value is increasing. The signal value may be sustained in a higher level and reaches highest level when the car is parked in the space. Also, as the car is leaving, the signal value is decreasing and goes downward to the base value. Therefore, it may be determined that a parking space is occupied or empty by comparing the signal value and the base value.

However, the detector may be influenced by environment temperature and thus a temperature drift of the base line may be resulted. An example of temperature drift of base line is shown in Fig. 2. In this example, the base line declines downwards by the influence of temperature. However, the base line may incline upwards by the influence of temperature.

As shown in Fig. 2, during the period of car parking, the actual base value is increasing over time by the influence temperature. In this regard, when the parking space is empty, the signal value would not go down to the original base value. When the actual base value increases to a level that is sufficient far away from the original base value, the process may determine the parking space is occupied, even though the parking space is actually empty.

As mentioned above, the signal value may be influenced by the external metal. Fig. 3 shows the signal value of detector with shortly interference of an external metal, such as an external metal object passing by. A spiked extrude is formed in the detecting line due to the shortly interference of the external metal. Therefore, this situation may be mistaken for a car parking.

In addition, drive's behaviors may interfere the signal value of the detector. Each driver has different habits and parking skill level. A driver with good parking skill may park a car in place once without repeatedly reversing several times. In contrast, a driver with bad parking skill may reverse the car several times.

As shown in Fig. 4, a driver tries to park a car in a parking space. He/she reverses the car one time and then tries again. In this example, the parking space may be regarded as being occupied two times.

As forgoing discussion, it is needed a new method for detecting parking space, in order to reduce or eliminate the influence of the environment temperature, external metal and driver's behavior.

As is known in the art, the precision of the output of some kind of detector depends on the input current. Therefore, two signal values of different precision levels may be obtained with one detector by regulating the input current. Similarly, more signal values of different precision levels may be collected. Accordingly, one detector may generate more than one set of signal value with different precision levels due to periodically date collection. In other situation, the precision of the output of a detector cannot be regulated and depends on the type of the detector. In this regard, the precision of signal value may be used to characterize to precision of an output, which may be generated by same detector or different detector.

One skilled in the art will understand that the signal value with higher precision level is more sensitive to temperature, that is, the base value of such set of signal value may more likely drift due to temperature. Similarly, a signal value with lower precision level is less sensitive to environment temperature, and the base value of such signal value may not drift easily. In this regard, a set of signal value of lower precision level may be used in order to reduce the influence of environment temperature.

Fig. 5 shows the output range of signal value of higher and lower precision level, wherein the signal value of higher precision level has a larger range, and the signal value of lower precision level has a smaller ranger. One skilled in the art will understand the particular level of the precision of signal values depends on particular application. The precision level may be any suitable level, as long as the signal value of the lower precision level can still work when it can not be determined the situation of the parking space based on the signal value of the higher precision level , as show in Fig. 6.

Fig. 6 shows changing of outputs of two sets of signal value of different precision level. In the example shown in Fig.6, two different sets of signal value are collected, for example, from one detector or two different detectors. In order to facility understanding, it may be defined the first set of signal value as a set of higher precision level, and the second set of signal value as a set of lower precision level.

As shown in Fig. 6, with the influence of environment temperature, the base value of the first set of signal value may increase (with temperature drift). Accordingly, when a parking space is empty, the signal value falls to its actual base value, which is still high enough to determine the parking space is still occupied. Meanwhile, the base value of the second signal value may be impacted by environment temperature much lower. In this regard, the collected signal value of the second set will fall back to its actual base value that is approximate to the original base value. Accordingly, based on the value of the second set, the parking space may be determined as empty.

Fig. 7 shows detecting a parking space with a stable window so as to reduce or eliminate the influence of the driver's behavior and/or the shortly interference of external metal object.

As shown in previous drawings, the signal value will be stable when a paring space is empty or occupied, although at different level. Accordingly, a time window can be introduced to assist determining the status of a parking space. As show in Fig. 7, in order to facilitate understanding, the first period of the diagram may be regarded as a driver's parking activity (that is, he/she tries two times to park a car), although a external metal object passed by is possible . During the first period, a driver tries to park a car but fails, and he/she reverse the car. There is a spiked extrude corresponding this activity on the line of signal values. When the car is finally parked in the paring space, the collected signal value is stable at a higher level, which means the paring space is occupied. After a car leaves, the signal value will fall back to the base value and keep stable. That is, the parking space is empty.

In this regard, Fig. 8 illustrates solution according to one embodiment of present invention. For detecting a parking space, two sets of signal value are collected. As discussed forgoing, the first set is in higher precision level, while the second set is in lower precision level. The two set data may be collected with one detector or two individual detectors.

When a shortly interference appears, such as external metal object or driver's behavior, there is a spiked extrude formed in the lines of the two set. However, the line of the second set is much flattened than the first set, because the precision of the second set is less than the first set and thus the amplitude of the signal value is smaller.

As discussed above, the signal value of first period is not stable and thus the status of the parking space is not changed, while the signal value of second period is stable in the second period and the status of the parking space is determined as occupied. When a car leaves, the signal value falls back to base value and keeps stable, and thus the paring space is determined as empty.

As described forgoing, if the first set of signal value does not work for determining the status of a parking space, the second set of signal value with lower precision level is used to carry out such determination. As known in the art, a detector generating signal value with higher level has larger detecting scope. In the case of generating two sets of signal value by one detector, when the detector is generating a signal value of higher precision level, the detector has a lager detecting scope. Otherwise, the detector has a smaller detecting scope when it is generating a signal value of lower precision level. In this regard, the two set of signal value of higher and smaller precision level may be generated with one detector alternately, so that the two sets of signal value may be collected almost simultaneously, since the interval of collecting is very short, for example, 1 second.

According to above principle, a flow chart of a method for detecting a parking space is shown in Fig. 9. The method 300 for detecting a paring space is used to monitoring the status of the parking space, for example, as set forth previously, empty or occupied.

As show in Fig. 9, the method 300 comprises the steps of:

Step 310, collect at least one set of signal value. As described forgoing, one set of signal value of lower precision level may be used to determine the status of a parking space. Therefore, said set of signal value may be a set of signal value of lower precision level.

Alternatively, more than one set of signal value may be collected, for example, two sets of signal value. In this regard, the two sets of signal value may be of different precision levels, as described forgoing, one is higher, and the other is lower.

As described forgoing, the signal values are collected periodically, and thus, the time window are formed during collecting a series of data of signal values. The collected signal values may be stored in a storage unit, step 312. One skilled in the art will understand that the storage unit may be any suitable device, for example, hardware, software or firmware, or any combination thereof.

Then, as indicated in step 320, the stored data would be computed to determine whether collected signal values are stable. Obviously, such a computation will be performed for each set of signal value. For example, in the case of one set of signal value, the maximum and minimum value in the set can be found out. In particular, the maximum (or minimum) value may be stored in the individual storage space, which may be a combination of hardware and software, and would be replaced when a higher value (or lower value) is collected. A difference between the maximum value and minimum value may be computed, step 322. The difference can be compared with a first threshold (step 324), and the set of signal value would be regarded as stable when the difference is lower a first threshold. That is, the difference between the maximum and minimum value is small enough to be regarded as stable. In the case of collecting two sets of signal value, the difference shall be computed for each individual set, and will be compared with the threshold for each set respectively. The first thresholds for each set are different because of different precision level. The first threshold may be predefined, or may be regulated by means of any suitable known method.

As indicated in step 330, the set of signal value can be compared with its base value when it is determined to be stable. A mean of the set of signal value may be computed (step 332) and used to compare with the base value. In one examples, a arithmetic mean is used to compare with the base value. In particular, a difference between the mean and the base value is computed (step 334) and compared with a second threshold (step 336). The status of the corresponding parking space is determined based on the result of such comparing. The parking space will be determined as empty if the difference is lower than the second threshold, otherwise, the parking space will be determined as occupied. As discussed forgoing, a set of signal value of lower precision level may be used to determine the status of a parking space. The precision level may be selected depending on the particular application, as long as the influence of the environment temperature to the signal value is negligible or such influence can not lead to a error result.

Also, two or more sets of signal value may be used together to determine the status of a parking space, so as to reduce or eliminate the influence of environment temperature. The base value of each set may be different. In this regard, the mean of respective each set should be compared with the base value of itself. That is, for each set, the difference of the mean and the base value will be computed and be compared to the second threshold. The second threshold for each set may be different and may be predefined or may be regulated by means of any suitable known method.

Fig. 10 shows an apparatus for detecting a parking space, which can be used to implement the above method.

The apparatus 200 comprises at least one data collector 210, which is configured to collect signal value from at least one detector. In one example, the apparatus 200 comprises only one collector, which is configured to collect one set of signal value from one detector. In another example, the apparatus 200 still comprises only one collector, which is configured to collect two sets of signal values of different precision levels from one detector. In still another example, the apparatus 200 comprises one collector, which is configured to collect two sets of signal values of different precision levels from two detectors. Similar, in other situation, the apparatus 200 may comprise more than one collector, which are configured to collect more than two sets of signal values of different precision levels from two or more detectors.

The collected signal values are stored in a storage unit 220. As described forgoing, the storage unit 220 can be any suitable hardware, software or firmware, or any combination thereof.

The apparatus 200 further comprises a first computing unit 230, which is configured to determining whether the signal values of said at least one set are stable. In particular, the first computing unit 230 comprises a first difference-computing unit 232 configured to compute a difference (hereinafter "first difference") between a maximum value and a minimum value of said at least one set. In the case of more than one set of signal value, the first difference-computing unit 232 is configured to compute such a first difference for each set. The first computing unit 230 also comprises a first comparing unit 234 configured to compare the first difference with a first threshold and communicate the compare result to a processing unit 250. Similarly, in the case of more than one set of signal value, the first comparing unit 234 is configured to compare the respective first difference for each set to a corresponding first threshold. One skilled in the art will understand that the threshold may be different for the sets of signal value of different precision levels.

The processing unit 250 is part of the apparatus 200, and may be any suitable device, such as hardware, software, or firmware, or any combination thereof, as long as the processing unit 250 can be used to make a logical judgment. The processing unit 250 may determine whether the set of signal value is stable according to the corresponding comparing result.

Also, the apparatus 200 comprises a second computing unit 240, which is configured to compare the signal values of said at least one set to a corresponding base value. The second computing unit 240 may be operable when the processing unit 250 determines that the signal values of said at least one set is stable, although the second computing unit 240 may be operable depending on particular application, as described hereinafter.

The second computing unit 240 further comprises a second difference-computing unit 242, which is configured to compute an average value of said set and a difference (hereinafter "second difference") between the average value and the base value. In the case of more than one set of signal value, the second difference-computing unit 242 is configured to compute such average and second difference for each set of signal value, and wherein the base value of the sets may be different, as discussed above.

The second computing unit 240 also comprises a second comparing unit 244, which is configured to compare the second difference with a second threshold and may communicate the comparing result to the processing unit 250. In the case of more than one set of signal value, the second comparing unit is configured to compare respective second difference for each set with corresponding threshold, and wherein the threshold for each set may be different, as discussed above.

The parking space may be regarded as empty if the second difference is lower than the second threshold, and as occupied if the second difference is higher than the second threshold. In the case of collecting more than one set of signal values, the comparing results of each set may be conflict. For example, in one example, for the first set (of higher precision level as described above), the second difference of the set is higher than its corresponding second threshold, while, for the second set (of lower precision level as described above), the second difference of the set is lower that its corresponding second threshold. In this regard, the second set will be taken into account. Generally, the set of signal value of lower precision level is preferred when the comparing results of each set are not conformal. The above mentioned judgment may be performed by the processing unit 250 based on the output of the second comparing unit.

Although the second computing unit 240 is described above as operating after the collected set(s) of signal value are determined stable, the sequence of the operating of the first computing unit 230 and second computing unit 240 is only exemplary, not a limitation to the present invention. The first and second computing unit may operate in parallel, that is, the first and second computing unit may operate simultaneously or in sequence (not limited to the sequence of first computing unit to second computing unit), and they may operating same or difference data collection, as one skilled in the art may understand. For example, the first and second computing unit may operate for different set of signal value simultaneously, and may operate for same set of signal value alternatively, although other manner is possible depending on the particular application.

One skilled in the art will understand that the processing unit 250 is optional and may be replaced by, for example, a logic gate in some particular application. There are many other means in the art to archive the function of the processing unit 250, which is only exemplary and described herein for facilitating understanding and.

Similarly, regarding the method 300 as described above, the step (330) of comparing the set of signal value with its base value can be performed simultaneously with the step (320) of determine whether the set of signal value is stable. The two steps may be performed simultaneously or alternatively, similar as the first and second computing unit.

In still another embodiment of the invention, a manufacture article is disclosed, on which a computer readable code is recorded. The computer readable code comprises: a computer readable code for collecting at least one set of signal value; a computer readable code for determining wheter the signal values of said at least one set are stable; and a computer readable code for comparing the signal values fo said set to a corresponding base value when the signal values are stable.

Further, the computer readable code for determining whether the signal values of said set are stable further comprises: a computer readable code for computing a first difference between a maximum value and a minimum value of each set of signal value; and a computer readable code for comparing the first difference with a corresponding first threshold.

The computer readable code for comparing the signal values for said set to a corresponding base value comprises: a computer readable code for computing a second difference between an average of the set and its corresponding base value; and a computer readable code for comparing the second difference with a corresponding second threshold.

Although the invention is described in terms of its several embodiments, there are many other replacement, permutation, modification and equivalent. Therefore, it should be interpreted that the all of such replacement, permutation, modification and equivalent fall into the scope of the invention as defined in the claim.

Claims

Claims What is claimed is:

1. A method for detecting a parking space, comprises:

collecting at least one set of signal value of detecting a object in the parking space;

determining whether the signal values of said set are stable;

computing a difference between the signal values of said set and a base value; comparing the difference with a second threshold; and

determining that parking space is occupied when the signal values of said set are stable and the difference is higher than the second threshold.

2. The method of claim 1, wherein said signal values are outputs of a metal detector that are less sensitive to temperatue.

3. The method of claim 1, wherein said determining whether signal values of said set are stable comprises:

comparing a difference between a maximum value and a minimum value of said set with a first threshold.

4. The method of claim 1, wherein said difference is between an average value of said set and the base value.

5. A method for detecting a parking space, comprises:

collecting at least two sets of signal value of detecting a object in the parking space, wherein the signal values of the sets are of different precison levels;

determining whether the signal values of all said sets are stable;

computing differences between the signal values of said sets and corresponding base values respectively;

comparing each of the differences with a corresponding second threshold respectively; and

determining the status of the parking space based on said determining and comparing.

6. The method of claim 5, wherein said signal values are outputs of one metal detector alternately.

7. The method of claim 5, wherein said signal values are outputs of two metal detectors respectively.

8. The method of claim 5, wherein said determining whether the signal values of all said sets are stable comprises:

comparing a difference between a maximum value and a minimum values of respective each set with a corresponding first threshold respectively.

9. The method of claim 5, wherein each of said differences is between an average value of each set and said corresponding base value.

10. A method for detecting a parking space, comprises:

determining whether the signal values of said set are stable;

computing a difference between the signal values of said set and a base value when the signal values are stable;

comparing the difference with a second threshold; and

determining the status of the parking space based on the results of said comparing.

11. The method of claim 10, wherein said signal values are outputs of a metal detector that are less sensitive to temperatue.

12. The method of claim 10, wherein said determining whether signal values of said set are stable comprises:

13. The method of claim 10, wherein said difference is between an average value of said set and the base value.

14. A method for detecting a parking space, comprises:

collecting at least two sets of signal value of detecting a object in the parking space, wherein the signal values of the sets are of different precision levels; determining whether the signal values of all said sets are stable; computing differences between the signal values of said sets with corresponding base values respectively when the signal values of all said sets are stable;

determining the status of the parking space based on said comparing.

15. The method of claim 14, wherein said signal values are outputs of one metal detector alternately.

16. The method of claim 14, wherein said signal values are outputs of two metal detectors respectively.

17. The method of claim 14, wherein said determining whether the signal values of all said sets are stable comprises:

18. The method of claim 14, wherein each of said differences is between an average value of each set and said corresponding base value.

19. An apparatus for detecting a parking space, comprises:

at least one data collector, configured for collecting at least one set of signal value of detecting a object in the parking space;

a first computing unit, configured for determining whether the signal values of said at least one set are stable; and

a second computing unit, configured for comparing the signal values of said at least one set with a correponding base value.

20. The apparatus of claim 19, comprises one data collector, configured for collecting at least two sets of signal value, wherein the signal values of the sets are in differenct precison levels.

21. The apparatus of claim 19, comprises at least two detector, each configured for collecting at least two sets of signal values respectively, wherein the signal values of the sets are in different precision levels.

22. The apparatus of claim 19, wherein the first computing unit further comprises:

a first difference-computing unit, configured to compute a first difference between a maximum value and a minimum value of said set; and

a first comparing unit, configured to compare the first difference with a corresponding first threshold.

23. The apparatus of claim 19, wherein the second computing unit further comprises:

a second difference-computing unit, configured to compute a second difference between an average value of said set and the corresponding base value

a second comparing unit, configured to compare the second difference with a corresponding second threshold.

24. A manufacture article, on which a computer readable code is recorded, wherein, the computer readabble code comprises:

a computer readable code for collecting at least one set of signal value;

a computer readable code for determining wheter the signal values of said at least one set are stable; and

a computer readable code for comparing the signal values fo said set to a corresponding base value when the signal values are stable.

25. The manufacture article of claim 24, wherein the computer readable code for determining whether the signal values of said set are stable further comprises:

a computer readable code for computing a first difference between a maximum value and a minimum value of said set; and

a computer readable code for comparing the first difference with a corresponding first threshold.

26. The manufacture article of claim 24, wherein the computer readable code for comparing the signal values for said set to a corresponding base value comprises: a computer readable code for computing a second difference betwee an average value of said set and the corresponnding base value; and

a computer readable code for comparing the second difference with a corresponding second value.