Other vehicle position estimation apparatus

An other vehicle position estimation apparatus for use in a subject vehicle to estimate a position of another vehicle on a road, the other vehicle position estimation apparatus comprising:

• a communicator configured to transmit a travel state of the subject vehicle and to receive a travel state of the other vehicle;
• an updater configured to sequentially update a position of a particle that is distributed over a map to represent a candidate position of the other vehicle based on at least one of
• map information, and
• the travel state obtained from the other vehicle;
• a likelihood calculator configured to calculate a degree of likelihood of the position of the distributed particle based on a motion state of the distributed particle and the travel state of the other vehicle;
• a position estimator configured to estimate the position of the other vehicle based on the position of the particle;
• and
• a particle number controller configured to determine a number of particles to distribute, wherein
• the particle number controller is further configured to determine the number of particles to distribute to estimate the position of the other vehicle based on at least one of
• a relative relationship between the position of the other vehicle and a position of the subject vehicle,
• an actual vehicle speed of the other vehicle,
• a distribution state of the particles, and
• a relationship between the position of the other vehicle and the road.