Object recognizing device

1. An object recognition device that recognizes an object by using measurement results of a laser distance measurement sensor, the object recognition device comprising:

an acquisition unit that acquires the measurement results of the laser distance measurement sensor;

a time-series data creation unit that creates time-series data of the measurement results by arranging the measurement results in time series; and

a recognition unit that recognizes a position and a size of the object indicated by the measurement results by grouping the measurement results described by the time-series data,

wherein the time-series data creation unit creates the time-series data by retaining the measurement result described by the time-series data for a predetermined time and deleting the measurement result which is not updated continuously for the predetermined time or more,

the object recognition device further includes a reliability calculation unit that calculates reliability of the position and size of the object recognized by the recognition unit, and

the time-series data creation unit changes a time for retaining the measurement result on the time-series data according to the reliability.

2. The object recognition device according to claim 1 , wherein

the time-series data creation unit creates, as the time-series data, a time-series map of the measurement results by associating the measurement results with grid-shaped cells indicating coordinates in a space in time series, and

the time-series data creation unit creates the time-series map by retaining the measurement results in the cells for a predetermined time and deleting the measurement result retained by the cell which is not associated with the measurement result continuously for the predetermined time or more.

3. The object recognition device according to claim 2 , wherein the time-series data creation unit shortens a time for which the cell retains the measurement result in a case where the reliability is equal to or greater than a reliability threshold value compared to a case where the reliability is less than the reliability threshold value.

4. The object recognition device according to claim 2 , wherein the time-series data creation unit shortens the time for which the cell retains the measurement result as the reliability becomes higher.

5. The object recognition device according to claim 3 , wherein the time-series data creation unit extends the time for which the cell retains the measurement result again when the reliability is less than the reliability threshold value after the reliability is equal to or greater than the reliability threshold value.

6. The object recognition device according to claim 1 , wherein

the reliability calculation unit calculates, as the reliability, a variance value of the position and size of the object recognized by the recognition unit, and

the time-series data creation unit regards the reliability as becoming higher as the variance value becomes smaller.

7. The object recognition device according to claim 6 , wherein

the recognition unit obtains a first recognition result for the position and size of the object by using the recognition result previously performed, and obtains a second recognition result for the position and size of the object by using the measurement result,

the recognition unit recognizes the position and size of the object by combining the first recognition result with the second recognition result to obtain a third recognition result, and

the reliability calculation unit calculates a variance value of the third recognition result as the reliability.

8. The object recognition device according to claim 2 , wherein

the recognition unit estimates a range of the object by grouping the cells which retain the measurement results and are close to each other, and

the recognition unit recognizes the position and size of the object by using the estimated range of the object.

9. The object recognition device according to claim 2 , wherein the time-series data creation unit changes a time for which the cells belonging to the same group through the grouping retain the measurement results on the time-series map according to the reliability corresponding to the group.

10. The object recognition device according to claim 1 , wherein the object recognition device further includes an output unit that outputs the position of the object, the size of the object, and the reliability.

11. The object recognition device according to claim 2 , wherein the time-series data creation unit creates the time-series map by using an orthogonal coordinate system or a polar coordinate system.