State quantity calculation device, control device, and vehicle

A state quantity calculating device for controlling driving force distribution in a vehicle having an engine, front wheels, rear wheels, right wheels, and left wheels, wherein the state quantity calculating device comprises:

• a ground contact load calculating section which calculates a ground contact load that is a load acting in a vertical direction under a spring of a vehicle;
• an input quantity calculating section which calculates an input quantity that is a value including a longitudinal force and a lateral force with use of at least a longitudinal acceleration and a lateral acceleration that are sensor values of a G sensor that is included in the vehicle;
• a first state quantity calculating section which calculates a first state quantity of the vehicle by inputting the input quantity, which is calculated by the input quantity calculating section, into a vehicle model;
• an observable calculating section which calculates a tire stroke displacement from the ground contact load, which is calculated by the ground contact load calculating section, and a spring constant gain of a tire, the tire stroke displacement being an observable which is expressed by a unit of length and being an amount of a change in a tire radius;
• and
• a second state quantity calculating section which constitutes a Kalman filtering block and which calculates a second state quantity of the vehicle by correcting, by Kalman filtering, the first state quantity of the vehicle, which is calculated by the first state quantity calculating section, with use of the observable, which is calculated by the observable calculating section, and a Kalman gain,
• wherein the ground contact load calculating section further includes:
• an inertia load calculating section which calculates an inertia load that is a ground contact load component resulting from a change in behavior of the vehicle due to an inertial force;
• a road surface load calculating section which calculates, from a wheel speed variation, a steady-state value, and the inertia load, a road surface load that is a ground contact load component resulting from unevenness of a road surface;
• and
• a ground contact load computing section which computes the ground contact load from the inertia load and the road surface load;
• wherein a calculation obtained with the state quantity calculating device is used to control distribution of a driving force of the engine between:
• the front wheels and the rear wheels, and/or
• the left wheels and the right wheels.