Detection device and detection method

1. A detection device comprising:

a detection unit that detects an object present around a vehicle;

a specification unit that specifies a detection continuation time period in which the detection unit continuously detects the object; and

an information output unit that outputs presence information indicating that the detection unit detects a detection target object, on condition that the detection continuation time period specified by the specification unit exceeds a determination time period,

wherein the determination time period is lengthened as an amount of rainfall on a road on which the vehicle travels increases,

wherein the detection unit further detects a distance between the object and the vehicle at a time of detecting the object, and

wherein the information output unit does not output the presence information, in a case where the distance at a time when the detection unit first detects the object is equal to or less than a determination distance preset as a distance at which a splash or a mud splash is detected, and in a case where the detection continuation time period is equal to or less than the determination time period.

2. The detection device according to claim 1 ,

wherein the detection unit further detects a relative velocity between the object and the vehicle, and

the information output unit outputs the presence information, on condition that the relative velocity detected by the detection unit is equal to or higher than a predetermined value.

3. The detection device according to claim 1 , further comprising:

a rainfall specification unit that specifies a rainfall condition of the road on which the vehicle travels,

wherein the information output unit determines whether to output the presence information based on the rainfall condition of the road specified by the rainfall specification unit.

4. The detection device according to claim 3 , further comprising:

the rainfall specification unit that specifies the amount of rainfall on the road on which the vehicle travels,

wherein the information output unit lengthens the determination time period as the amount of rainfall specified by the rainfall specification unit increases.

5. The detection device according to claim 1 , further comprising:

another detection unit that detects an object present around the vehicle using a method different from that of the detection unit,

wherein the information output unit outputs the presence information, on condition that an object detected by the another detection unit and an object detected by the detection unit are determined to be a same object.

6. A detection method comprising steps, being executed by a processor installed in a vehicle, of:

detecting an object present around the vehicle;

specifying a detection continuation time period in which the object is continuously detected; and

outputting information indicating that a detection target object is detected, on condition that the specified detection continuation time period exceeds a determination time period,

wherein the determination time period is lengthened as an amount of rainfall on a road on which the vehicle travels increases,

wherein the detecting the object includes detecting a distance between the object and the vehicle at a time of detecting the object, and

wherein the outputting information does not include outputting the information, in a case where the distance at a time when the detecting the object first detects the object is equal to or less than a determination distance preset as a distance at which a splash or a mud splash is detected, and in a case where the detection continuation time period is equal to or less than the determination time period.