Vehicle control apparatus and method for controlling the same, and vehicle control system

1. A vehicle control apparatus comprising:

an input/output portion configured to receive a plurality of pieces of relative position information acquired at different timings by an external world recognition apparatus and each indicating a position of a preceding vehicle relative to a subject vehicle, the preceding vehicle being a target that the subject vehicle follows ahead thereof;

a storage portion configured to store the received plurality of pieces of relative position information; and

a calculation portion configured to calculate an approximation equation of an N-th degree function as a movement trajectory of the preceding vehicle from at least two pieces of relative position information in each of a plurality of retrospective ranges set as ranges to which the vehicle control apparatus date back from newest relative position information in a history of the stored plurality of pieces of relative position information, and calculates a coefficient of a predetermined degree in each approximation equation, wherein N is an integer equal to or greater than one in this case, and in the calculation of the coefficient of the predetermined degree, use an approximation equation calculated from the at least two pieces of relative position information acquired when setting the retrospective range to same range as when calculating a coefficient of a relatively low degree or a narrower range compared to when calculating a coefficient of a relatively low degree, when calculating a coefficient of a relatively high degree, use an approximation equation calculated from the at least two pieces of relative position information acquired when setting the retrospective range to a narrower range compared to when calculating a coefficient of a lowest degree, at least when calculating a coefficient of a highest degree, and

output an instruction according to the calculated coefficient of each degree to a steering control apparatus of the subject vehicle,

wherein the vehicle control apparatus is configured to perform adaptive cruise control according to the instruction such that the subject vehicle runs while following the preceding vehicle running ahead thereof based on a vehicle speed, a yaw rate of the subject vehicle, and the relative position information.

2. The vehicle control apparatus according to claim 1 , wherein the retrospective range when the coefficient of the relatively high degree is calculated is set so as to be narrower compared to the retrospective range when the coefficient of the relatively low degree is calculated.

3. The vehicle control apparatus according to claim 2 , wherein the N-th function is a quadratic function.

4. The vehicle control apparatus according to claim 2 , wherein, as a speed of the subject vehicle increases, a difference increases between the retrospective range when the coefficient of the relatively high degree is calculated, and the retrospective range when the coefficient of the relatively low degree is calculated.

5. A vehicle control method comprising:

receiving a plurality of pieces of relative position information acquired at different timings by an external world recognition apparatus and each indicating a position of a preceding vehicle relative to a subject vehicle, the preceding vehicle being a target that the subject vehicle follows ahead thereof;

storing the received plurality of pieces of relative position information;

calculating an approximation equation of an N-th degree function as a movement trajectory of the preceding vehicle from at least two pieces of relative position information in each of a plurality of retrospective ranges set as ranges to which the vehicle control apparatus date back from newest relative position information in a history of the stored plurality of pieces of relative position information, and calculating a coefficient of a predetermined degree in each approximation equation, wherein N is an integer equal to or greater than one in this case,

the calculating the coefficient of the predetermined degree including:

using an approximation equation calculated from the at least two pieces of relative position information acquired when setting the retrospective range to same range as when calculating a coefficient of a relatively low degree or a narrower range compared to when calculating a coefficient of a relatively low degree, when calculating a coefficient of a relatively high degree, and

using an approximation equation calculated from the at least two pieces of relative position information acquired when setting the retrospective range to a narrower range compared to when calculating a coefficient of a lowest degree, at least when calculating a coefficient of a highest degree; and

outputting an instruction according to the calculated coefficient of each degree to a steering control apparatus of the subject vehicle, wherein

adaptive cruise control is performed according to the instruction such that the subject vehicle runs while following the preceding vehicle running ahead thereof based on a vehicle speed, a yaw rate of the subject vehicle, and the relative position information.

6. A vehicle control system comprising:

an external world recognition portion configured to acquire relative position information indicating a position of a preceding vehicle relative to a subject vehicle, the preceding vehicle being a target that the subject vehicle follows ahead thereof;

a storage portion configured to receive a plurality of pieces of relative position information acquired at different timings by the external world recognition portion and store the received plurality of pieces of relative position information; and

a calculation portion configured to calculate an approximation equation of an N-th degree function as a movement trajectory of the preceding vehicle from at least two pieces of relative position information in each of a plurality of retrospective ranges set as ranges to which the vehicle control apparatus date back from newest relative position information in a history of the plurality of pieces of relative position information stored by the storage portion, and calculate a coefficient of a predetermined degree in each approximation equation, wherein N is an integer equal to or greater than one in this case,

wherein, in the calculation of the coefficient of the predetermined degree, the calculation portion:

uses an approximation equation calculated from the at least two pieces of relative position information acquired when the retrospective range is set to same range as when calculating a coefficient of a relatively low degree or a narrower range compared to when calculating a coefficient of a relatively low degree, when calculating a coefficient of a relatively high degree, and

uses an approximation equation calculated from the at least two pieces of relative position information acquired when the retrospective range is set to a narrower range compared to when calculating a coefficient of a lowest degree, at least when calculating a coefficient of a highest degree, and

wherein the vehicle control system further includes an output portion configured to provide an output to a steering control apparatus of the subject vehicle upon receiving an instruction according to the calculated coefficient of each degree, wherein

the vehicle control system is configured to perform adaptive cruise control according to the instruction such that the subject vehicle runs while following the preceding vehicle running ahead thereof based on vehicle speed, yaw rate, and the relative position information.