Travel lane estimation device, travel lane estimation method, and computer-readable non-transitory storage medium

A travel lane estimation method for a vehicle comprising:

• acquiring a position of a distance measurement point detected by a distance measurement sensor that transmits an exploration wave around the vehicle, receives a reflection wave of the exploration wave reflected by an object, and detects the position of the distance measurement point with respect to the vehicle, the position being disposed on a surface of the object at which the exploration wave is reflected;
• estimating a lateral position of a road boundary to be a position in a right-left direction of the vehicle indicated by a most frequent value of each of a right side and a left side of the vehicle as a center in a frequency distribution that indicates a distribution status of a distance measurement point group, which is a group of the distance measurement points whose positions are sequentially acquired, for each position in the right-left direction of the vehicle;
• determining whether estimation of the lateral position of the road boundary is in an unstable state, according to information about a plurality of peaks when the plurality of peaks having a frequency in the frequency distribution equal to or higher than a predetermined value are disposed on one side of a left side and a right side of the vehicle as a center;
• acquiring a map data including information about a numerical number of traffic lanes;
• specifying a vehicle position of the vehicle on a map according to an acquired map data;
• estimating the travelling lane of the vehicle based on the information about the numerical number of traffic lanes corresponding to a specified vehicle position and included in an acquired map data, and a position relationship between an estimated lateral position of the road boundary and the vehicle position;
• and
• estimating the driving lane of the vehicle without using an estimation result of the lateral position of the road boundary, which is determined to be the unstable state.

A computer readable non-transitory storage medium including instructions executed by a computer, the instructions comprising:

• acquiring a position of a distance measurement point detected by a distance measurement sensor that transmits an exploration wave around the vehicle, receives a reflection wave of the exploration wave reflected by an object, and detects the position of the distance measurement point with respect to the vehicle, the position being disposed on a surface of the object at which the exploration wave is reflected;
• estimating a lateral position of a road boundary to be a position in a right-left direction of the vehicle indicated by a most frequent value of each of a right side and a left side of the vehicle as a center in a frequency distribution that indicates a distribution status of a distance measurement point group, which is a group of the distance measurement points whose positions are sequentially acquired, for each position in the right-left direction of the vehicle;
• determining whether estimation of the lateral position of the road boundary is in an unstable state, according to information about a plurality of peaks when the plurality of peaks having a frequency in the frequency distribution equal to or higher than a predetermined value are disposed on one side of a left side and a right side of the vehicle as a center;
• acquiring a map data including information about a numerical number of traffic lanes;
• specifying a vehicle position of the vehicle on a map according to an acquired map data;
• estimating the travelling lane of the vehicle based on the information about the numerical number of traffic lanes corresponding to a specified vehicle position and included in an acquired map data, and a position relationship between an estimated lateral position of the road boundary and the vehicle position;
• and
• estimating the driving lane of the vehicle without using an estimation result of the lateral position of the road boundary, which is determined to be the unstable state.