Position detector, position detecting method, data determination apparatus, data determination method, computer program, and storage medium
A controller of a cell phone serving as the position detector reads time-sequentially anteroposterior positional information P i−1 , P i+1 , together with interest positional information P i that is an object of determination (S 103 ), and calculates, for example, vectors V 1 and V 2 showing a shift from P i−1 , to P i and a shift from P i to P i+1 , respectively (S 104 , S 105 ), in order to calculate an amplitude of fluctuation representing a direction of change. The amplitude of fluctuation representing a direction of change is expressed by a value of dot product of the calculated vectors V 1 and V 2 (S 106 ). When the value of dot product is lower than a predetermined value (S 107 : YES), a position is shown to greatly deviate in the vicinity of the interest positional information P i . Therefore, the amplitude of fluctuation representing a direction of change is judged to be large, and the positional information is determined to be error (S 108 ).
1. A data determination apparatus, comprising:
a judgment unit that judges whether or not an amplitude of fluctuation representing a direction of change between a shift from a first data among plural data representing sequential situations of an object to an interest data to be processed representing a situation sequentially later than a situation represented by the first data among the plural data and a shift from the interest data to a second data among the plural data representing a situation sequentially later than the situation represented by the interest data to be processed is larger than a predetermined value;
a first vector calculation unit that calculates a first vector representing a shift from a variable shown by the first data to a variable shown by the interest data;
a second vector calculation unit that calculates a second vector representing a shift from the variable shown by the interest data to a variable shown by the second data;
a dot product calculation unit that calculates a dot product of the first vector calculated by the first vector calculation unit and the second vector calculated by the second vector calculation unit; and
a determination unit that determines whether or not the interest data representing a situation of the object is unreliable;
wherein
the judgment unit judges that the amplitude of fluctuation is larger than the predetermined value, when the dot product calculated by the dot product calculation unit is smaller than a given value; and
the determination unit determines that the interest data is unreliable, when the judgment unit judges that the amplitude of fluctuation is larger than the predetermined value.
2. A data determination apparatus according to claim 1 , further comprising:
a detection unit that detects a position of a movable body, time-sequentially; wherein
the plural data correspond to positional information based on the position detected by the detection unit;
the first data corresponds to positional information time-sequentially preceding to the second data; and
the determination unit determines that the interest data is error as information representing the position of the movable body, when the judgment unit judges that the amplitude of fluctuation is larger than the predetermined value.
3. A data determination apparatus according to claim 2 , further comprising:
a dividing correction unit that corrects the dot product calculated by the dot product calculation unit, through dividing by elapsed time since a time point corresponding to a positional information based on the first data until a time point corresponding to a positional information based on the interest data and dividing by elapsed time since the time point corresponding to the positional information based on the interest until a time point corresponding to the positional information based on the second data;
wherein
the judgment unit judges that the amplitude of fluctuation is larger than the predetermined value, when the dot product being corrected by the dividing correction unit is less than a given value.
4. A data determination apparatus according to claim 3 , further comprising:
an extracting unit that extracts a plurality of the first data and a plurality of the second data; and
a mean value calculation unit that calculates a mean value of the dot product corrected by the dividing correction unit, for each set of the first data and the second data extracted by the extracting unit; wherein
the first vector calculation unit and the second vector calculation unit calculates vectors, for the each set of the first data and the second data extracted by the extracting unit; and
the judgment unit judges that the amplitude of fluctuation is larger than the predetermined value, when the mean value calculated by the mean value calculation unit, instead of the dot product being corrected by the dividing correction unit, is less than a given value.
5. A data determination apparatus according to claim 3 , further comprising:
a ratio calculation unit that calculates, with respect to an entirety of data extracted by the extracting unit, a ratio of the data whose dot product being corrected by the dividing correction unit is judged to be less than the given value by the judgment unit;
wherein
the judgment unit judges that the amplitude of fluctuation is larger than the predetermined value for the entirety of data extracted by the extracting unit, when the ratio calculated by the ratio calculation unit is not less than a predetermined ratio; and
the determination unit determines that data are error for the entirety of data extracted by the extracting unit, when the amplitude of fluctuation is judged to be larger than the predetermined value for the entirety of data extracted by the extracting unit.
6. A data determination apparatus according to claim 1 , further comprising:
a storage that stores the interest data determined to be an error data by the determination unit as being an invalid data.
7. A data determination apparatus according to claim 1 , further comprising:
a computation unit that computes a median value or a mean value of multiple data that are time-sequentially in neighborhood of the interest data determined to be an error data by the determination unit; and
a correction unit that corrects the interest data determined to be an error data by the determination unit, with using the median value or the mean value computed by the computation unit.
8. A data determination apparatus according to claim 1 , further comprising:
an extracting unit that extracts a plurality of the first data and a plurality of the second data;
a multiplication unit that multiply elapsed time since a time point corresponding to a positional information based on the first data until a time point corresponding to a positional information based on the interest data by elapsed time since the time point corresponding to the positional information based on the interest until a time point corresponding to the positional information based on the second data; and
a correlation coefficient calculation unit that calculates a correlation coefficient between the dot product calculated by the dot product calculation unit and the multiplied results by the multiplication unit, for each set of the plurality of the first data and the plurality of the second data extracted by the extracting unit;
wherein
the judgment unit judges that the amplitude of fluctuation is larger than the predetermined value, when the correlation coefficient calculated by the correlation coefficient calculation unit is less than a given value.
9. A data determination apparatus according to claim 1 , wherein the interest data is an estimated position, the first data is a previously estimated position and the second data is a later estimated position.
10. A data determination apparatus according to claim 1 , wherein when the determination unit determines that the interest data is unreliable, the interest data is removed.
11. A data determination method for determining whether a data is unreliable or not, the method being implemented on a device, said device comprising a controller configured to perform the method, said method comprising the steps of:
selecting an interest data to be processed among plural of data;
calculating a first vector representing a shift from a variable shown by a first data among the plural data representing sequential situations of an object to a variable shown by the selected interest data representing a situation sequentially later than a situation represented by the first data;
calculating a second vector representing a shift from the variable shown by the selected interest data to a variable shown by a second data among the plural data representing a situation sequentially later than the situation represented by the interest data to be processed;
calculating a dot product of the first vector and the second vector;
judging whether or not an amplitude of fluctuation representing a direction of change between a shift from the first data to the interest data and a shift from the interest data to the second data is larger than a predetermined value, in accordance with the calculated dot product; and
determining that the selected interest data to be processed representing a situation of the object is unreliable, when the amplitude of fluctuation is judged to be larger than the predetermined value.
12. A data determination method according to claim 11 , further comprising the step of:
detecting a position of a movable body, time-sequentially;
wherein
the plural data correspond to positional information based on the detected position;
the first data corresponds to positional information time-sequentially preceding to the second data; and
the selected interest data is determined to be unreliable as information representing the position of the movable body, when the amplitude of fluctuation is judged to be larger than the predetermined value.
13. A non-transitory computer readable medium having stored thereon computer executable program for determining whether a data is unreliable or not, wherein
the computer program when executed causes a computer system to execute steps of:
selecting an interest data to be processed among plural data;
calculating a first vector representing a shift from a variable shown by a first data among the plural data representing sequential situations of an object to a variable shown by the selected interest data representing a situation sequentially later than a situation represented by the first data;
calculating a second vector representing a shift from the variable shown by the selected interest data to a variable shown by a second data among the plural data representing a situation sequentially later than the situation represented by the interest data to be processed;
calculating a dot product of the first vector and the second vector;
judging whether or not an amplitude of fluctuation representing a direction of change between a shift from the first data to the interest data and a shift from the interest data to the second data is larger than a predetermined value, in accordance with the calculated dot product; and
determining that the selected interest data to be processed representing a situation of the object is unreliable, when the amplitude of fluctuation is judged to be larger than the predetermined value.
14. A non-transitory computer readable medium according to claim 13 , wherein
the computer program causes the computer system to execute further the step of detecting a position of a movable body, time-sequentially,
wherein
the plural data correspond to positional information based on the detected position;
the first data corresponds to positional information time-sequentially preceding to the second data; and
the selected interest data is determined to be unreliable as information representing the position of the movable body, when the amplitude of fluctuation is judged to be larger than the predetermined value.