Method and device for controlling the path of a motor vehicle travelling in a traffic lane and associated vehicle

A device for controlling a path of a motor vehicle traveling in a traffic lane, comprising:

• a computer and a memory provided with a database having a finite number of locations, said computer being configured to:
• detect a turn in the traffic lane, then, when the motor vehicle enters said turn;
• determine a first quantity and a second quantity for a plurality of successive sampling increments, based on state variables characteristic of movement of the motor vehicle;
• determine a first stored value and a second stored value, said first stored value being a function of the first quantity determined for the current sampling increment and of first quantities determined for at least one preceding sampling increment of a plurality of preceding sampling increments, said second stored value being a function of the second quantity determined for the current sampling increment and of second quantities determined for at least one of the preceding sampling increments;
• save in memory said first stored value and said second stored value determined for each sampling increment, then when the motor vehicle exits said turn:
• determine a value of an understeer gradient as a function of said first stored value and said second stored value saved in the memory;
• correcting the value of the understeer gradient in order to determine an intermediate value of the understeer gradient, said intermediate value of the understeer gradient being determined based on a weighting between the value of the understeer gradient that has been determined and a predetermined value;
• and
• determine a command for the motor vehicle based on the intermediate value of the understeer gradient.