Collision alert device and collision alert method

A collision alert method executed by a computer of a collision alert device, the collision alert method comprising the steps of:

• receiving information of a velocity and a moving direction from each of two moving objects at a prescribed time interval, and repeatedly calculating a time-to-collision at a prescribed time interval, the time-to-collision being obtained by dividing a distance between the two moving objects by a relative velocity based on the received information of the velocity and the moving direction of the two moving objects;
• and
• outputting an alert in at least one of the two moving objects as a condition of the time-to-collision being equal to or less than a predetermined threshold, wherein
• the relative velocity is a centripetal relative velocity of a moving velocity of each of the two moving objects, the centripetal relative velocity being calculated from a centripetal velocity that is a component along a line segment connecting a position of each of the two moving objects, and
• the time-to-collision is a centripetal time-to-collision obtained by dividing the distance between the two moving objects by the centripetal relative velocity.

A collision alert device, comprising a processor, wherein the processor:

• receives information of a velocity and a moving direction from each of two moving objects at a prescribed time interval and operation information of a direction indicator that is transmitted when the direction indicator of the corresponding moving object is operated;
• repeatedly calculates a time-to-collision at a prescribed time interval, the time-to-collision being obtained by dividing a distance between the two moving objects by a relative velocity based on the received information of the velocity and the moving direction of the two moving objects;
• and
• outputs an alert in at least one of the two moving objects as a condition of the time-to-collision being equal to or less than a predetermined threshold, wherein
• the relative velocity is a centripetal relative velocity of a moving velocity of each of the two moving objects, the centripetal relative velocity being calculated from a centripetal velocity that is a component along a line segment connecting positions of the respective two moving objects, and
• the time-to-collision is a centripetal time-to-collision obtained by dividing a distance between the two moving objects by the centripetal relative velocity, wherein
• the processor
• outputs the alert to at least one of the two moving objects when the centripetal time-to-collision is equal to or less than a predetermined threshold value and an intersection of two traveling lines each of which extends from the corresponding moving object as a starting point along the moving direction of the corresponding moving object is located ahead within a predetermined distance from a current position of either of the two moving objects, and
• outputs an alarm to at least one of the two moving objects even when the intersection is not within the range of the predetermined distance from the current positions of the two moving objects, if the operation information of the direction indicator of at least one of the two moving objects indicates that the moving direction will change to a direction approaching the traveling line of the other moving object.