Vehicle running condition judgement device

A vehicle running condition judgment device, comprising:

• detection means for detecting a state quantity concerning motion of a vehicle;
• memory means for storing non-linear tire characteristics for each of a plurality of assumed road surfaces, wherein the non-linear tire characteristics show non-saturated characteristics;
• slip angle estimation means for estimating a vehicle slip angle for each of the plurality of assumed road surfaces based on the state quantity and the non-linear tire characteristics;
• feedback compensation means for compensating the vehicle slip angle for each of the plurality of assumed road surfaces by compensating a currently estimated vehicle slip angle for each of the plurality of assumed road surfaces based on a current state quantity and a last vehicle slip angle having been estimated for respective assumed road surfaces;
• judgment means for judging current road surface condition based on the vehicle slip angle compensated by said feedback compensation means;
• and
• limit condition judgment means for judging whether or not the vehicle is under a limit condition through comparison between a predetermined limit value and an estimation lateral acceleration corresponding to the current road surface condition judged by said road surface condition judgment means, the estimation lateral acceleration being selected from estimation lateral accelerations calculated by said estimation lateral acceleration calculation means for respective assumed road surfaces, wherein said judgment means comprises
• estimation lateral acceleration calculation means for calculating a lateral acceleration for each of the plurality of assumed road surfaces as an estimation lateral acceleration based on the non-linear tire characteristics and the vehicle slip angle compensated by said feed-back compensation means for each of the plurality of assumed road surfaces, and
• road surface condition judgment means for judging a current road surface condition through comparison between a detected lateral acceleration and the estimation lateral acceleration.

A vehicle running condition detection device, comprising:

• detection means for detecting a state quantity concerning motion of a vehicle;
• memory means for storing non-linear tire characteristics for each of a plurality of assumed road surfaces;
• slip angle estimation means for estimating a vehicle slip angle for each of the plurality of assumed road surfaces based on the state quantity and the non-linear tire characteristics;
• feedback compensation means for compensating the vehicle slip angle for each of the plurality of assumed road surfaces by compensating a currently estimated vehicle slip angle for each of the plurality of assumed road surfaces based on a current state quantity and a last vehicle slip angle having been estimated for the respective assumed road surfaces,
• lateral acceleration estimation means for estimating a lateral acceleration for each of the plurality of assumed road surfaces based on the non-linear tire characteristics and the vehicle slip angle compensated by said feedback compensation means;
• and
• limit condition judgment means for judging whether or not the vehicle is under a limit condition through comparison between a predetermined limit value and a lateral acceleration corresponding to an actual road surface condition, the lateral acceleration being selected from lateral accelerations estimated by said lateral acceleration estimation means for respective assumed road surfaces.

A vehicle running condition detection device, comprising:

• detection means for detecting a state quantity concerning motion of a vehicle;
• memory means for storing non-linear tire characteristics for each of a plurality of assumed road surfaces;
• calculation means for estimating a quantity concerning a vehicle running condition for each of the plurality of assumed road surfaces based on the state quantity and the non-linear tire characteristics;
• and
• limit condition judgment means for judging whether or not the vehicle is under a limit condition through comparison between a predetermined limit value and the quantity estimated by said calculation means corresponding to an actual road surface condition, the quantity being selected from quantities estimated by said calculation means for the respective assumed road surfaces.