ROAD SURFACE FRICTION COEFFICIENT ESTIMATING DEVICE
First Claim
1. A road surface friction coefficient estimating device which estimates a friction coefficient of a road surface, on which a vehicle is traveling, while updating the friction coefficient, the device comprising:
- a first estimating element of a to-be-compared external force which defines a predetermined type of an external force component acting on a vehicle due to a resultant force of road surface reaction forces acting on each wheel of the vehicle from a road surface as a to-be-compared external force and finds a first estimated value of the to-be-compared external force by using a friction characteristic model representing a relationship between a slip between the wheel of the vehicle and the road surface and a road surface reaction force, an estimated value of a friction coefficient which has been already determined, and an observed value of a predetermined type of a quantity to be observed, which is related to a behavior of the vehicle;
a second estimating element of a to-be-compared external force which finds a value of an external force component balancing out an inertial force corresponding to the to-be-compared external force on the basis of an observed value of a motion state quantity of the vehicle that defines the inertial force, which is a part of an inertial force generated by a motion of the vehicle, and obtains the found value of the external force component as a second estimated value of the to-be-compared external force;
a first friction coefficient increasing/decreasing manipulated variable determining element and a second friction coefficient increasing/decreasing manipulated variable determining element, each of which determines an increasing/decreasing manipulated variable of an estimated value of the friction coefficient of the road surface on the basis of at least the first estimated value and the second estimated value; and
a friction coefficient estimated value updating element which determines a new estimated value of a friction coefficient by updating the estimated value of the friction coefficient of the road surface on the basis of at least any one of the increasing/decreasing manipulated variables, which have been determined by the first friction coefficient increasing/decreasing manipulated variable determining element and the second friction coefficient increasing/decreasing manipulated variable determining element, respectively,wherein;
the second friction coefficient increasing/decreasing manipulated variable determining element determines the increasing/decreasing manipulated variable on the basis of at least a deviation between the first estimated value and the second estimated value such that the deviation therebetween is converged to zero; and
the first friction coefficient increasing/decreasing manipulated variable determining element determines the increasing/decreasing manipulated variable on the basis of at least a deviation between a (1—
1)th estimated filtering value obtained by passing the first estimated value through a (1—
1)th filter for frequency component adjustment and a (2—
1)th estimated filtering value obtained by passing the second estimated value through a (2—
1)th filter for frequency component adjustment having the same frequency characteristic as the (1—
1)th filter, such that the deviation is converged to zero.
1 Assignment
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Accused Products
Abstract
A road surface friction coefficient estimating device includes a means which finds a first estimated value Mnsp_estm of an external force to be compared (S102 to S116, S118-2), a means which finds a second estimated value Mnsp_sens (S118-1), and a plurality of increasing/decreasing manipulated variable determining means 34_k, each of which determines the increasing/decreasing manipulated variable Δμ_k of the friction coefficient estimated value on the basis of the first estimated value Mnsp_estm and the second estimated value Mnsp_sens, and updates the friction coefficient estimated value according to Δμ_k. The increasing/decreasing manipulated variable determining means 34—1 and 34—2 determine Δμ—1 and Δμ—2 according to a deviation in filtering value between the first estimated value and the second estimated value, and the increasing/decreasing manipulated variable determining means 34—3 determines Δμ—1 according to the deviation between the first estimated value and the second estimated value.
32 Citations
27 Claims
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1. A road surface friction coefficient estimating device which estimates a friction coefficient of a road surface, on which a vehicle is traveling, while updating the friction coefficient, the device comprising:
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a first estimating element of a to-be-compared external force which defines a predetermined type of an external force component acting on a vehicle due to a resultant force of road surface reaction forces acting on each wheel of the vehicle from a road surface as a to-be-compared external force and finds a first estimated value of the to-be-compared external force by using a friction characteristic model representing a relationship between a slip between the wheel of the vehicle and the road surface and a road surface reaction force, an estimated value of a friction coefficient which has been already determined, and an observed value of a predetermined type of a quantity to be observed, which is related to a behavior of the vehicle; a second estimating element of a to-be-compared external force which finds a value of an external force component balancing out an inertial force corresponding to the to-be-compared external force on the basis of an observed value of a motion state quantity of the vehicle that defines the inertial force, which is a part of an inertial force generated by a motion of the vehicle, and obtains the found value of the external force component as a second estimated value of the to-be-compared external force; a first friction coefficient increasing/decreasing manipulated variable determining element and a second friction coefficient increasing/decreasing manipulated variable determining element, each of which determines an increasing/decreasing manipulated variable of an estimated value of the friction coefficient of the road surface on the basis of at least the first estimated value and the second estimated value; and a friction coefficient estimated value updating element which determines a new estimated value of a friction coefficient by updating the estimated value of the friction coefficient of the road surface on the basis of at least any one of the increasing/decreasing manipulated variables, which have been determined by the first friction coefficient increasing/decreasing manipulated variable determining element and the second friction coefficient increasing/decreasing manipulated variable determining element, respectively, wherein; the second friction coefficient increasing/decreasing manipulated variable determining element determines the increasing/decreasing manipulated variable on the basis of at least a deviation between the first estimated value and the second estimated value such that the deviation therebetween is converged to zero; and the first friction coefficient increasing/decreasing manipulated variable determining element determines the increasing/decreasing manipulated variable on the basis of at least a deviation between a (1—
1)th estimated filtering value obtained by passing the first estimated value through a (1—
1)th filter for frequency component adjustment and a (2—
1)th estimated filtering value obtained by passing the second estimated value through a (2—
1)th filter for frequency component adjustment having the same frequency characteristic as the (1—
1)th filter, such that the deviation is converged to zero. - View Dependent Claims (4, 7, 10, 13, 16, 19, 22, 25)
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2. A road surface friction coefficient estimating device which estimates a friction coefficient of a road surface, on which a vehicle is traveling, while updating the friction coefficient, the device comprising:
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a first estimating element of a to-be-compared external force which defines a predetermined type of an external force component acting on a vehicle due to a resultant force of road surface reaction forces acting on each wheel of the vehicle from a road surface as a to-be-compared external force and finds a first estimated value of the to-be-compared external force by using a friction characteristic model representing a relationship between a slip between the wheel of the vehicle and the road surface and a road surface reaction force, an estimated value of a friction coefficient which has been already determined, and an observed value of a predetermined type of a quantity to be observed, which is related to a behavior of the vehicle; a second estimating element of a to-be-compared external force which finds a value of an external force component balancing out an inertial force corresponding to the to-be-compared external force on the basis of an observed value of a motion state quantity of the vehicle that defines the inertial force, which is a part of an inertial force generated by a motion of the vehicle, and obtains the found value of the external force component as a second estimated value of the to-be-compared external force; first to (N+1)th friction coefficient increasing/decreasing manipulated variable determining elements, which are (N+1) (N;
2 or a greater integer) friction coefficient increasing/decreasing manipulated variable determining elements, each of which determines an increasing/decreasing manipulated variable of an estimated value of the friction coefficient of the road surface on the basis of at least the first estimated value and the second estimated value; anda friction coefficient estimated value updating element which determines a new estimated value of a friction coefficient by updating the estimated value of the friction coefficient of the road surface on the basis of at least any one of the increasing/decreasing manipulated variables, which have been determined by the first to (N+1)th friction coefficient increasing/decreasing manipulated variable determining elements, respectively, wherein; the (N+1)th friction coefficient increasing/decreasing manipulated variable determining element determines the increasing/decreasing manipulated variable on the basis of at least a deviation between the first estimated value and the second estimated value such that the deviation therebetween is converged to zero; a k-th friction coefficient increasing/decreasing manipulated variable determining element (k;
any one of integers 1 to N), which is any arbitrary one of the first to (N+1)th friction coefficient increasing/decreasing manipulated variable determining elements, determines the increasing/decreasing manipulated variable on the basis of at least a deviation between a (1_k)th estimated filtering value obtained by passing the first estimated value through a (1_k)th filter for frequency component adjustment and a (2_k)th estimated filtering value obtained by passing the second estimated value through a (2_k)th filter for frequency component adjustment having the same frequency characteristic as the (1_k)th filter, such that the deviation is converged to zero; andthe respective frequency characteristics of the (1_1)th to (1_N)th filters are set to frequency characteristics different from one another. - View Dependent Claims (5, 8, 11, 14, 17, 20, 23, 26)
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3. A road surface friction coefficient estimating device which estimates a friction coefficient of a road surface, on which a vehicle is traveling, while updating the friction coefficient, the device comprising:
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a first estimating element of a to-be-compared external force which defines a predetermined type of an external force component acting on a vehicle due to a resultant force of road surface reaction forces acting on each wheel of the vehicle from a road surface as a to-be-compared external force and finds a first estimated value of the to-be-compared external force by using a friction characteristic model representing a relationship between a slip between the wheel of the vehicle and the road surface and a road surface reaction force, an estimated value of a friction coefficient which has been already determined, and an observed value of a predetermined type of a quantity to be observed, which is related to a behavior of the vehicle; a second estimating element of a to-be-compared external force which finds a value of an external force component balancing out an inertial force corresponding to the to-be-compared external force on the basis of an observed value of a motion state quantity of the vehicle that defines the inertial force, which is a part of an inertial force generated by a motion of the vehicle, and obtains the found value of the external force component as a second estimated value of the to-be-compared external force; first to N-th friction coefficient increasing/decreasing manipulated variable determining elements, which are N (N;
2 or a greater integer) friction coefficient increasing/decreasing manipulated variable determining elements, each of which determines an increasing/decreasing manipulated variable of an estimated value of the friction coefficient of the road surface on the basis of at least the first estimated value and the second estimated value; anda friction coefficient estimated value updating element which determines a new estimated value of a friction coefficient by updating the estimated value of the friction coefficient of the road surface on the basis of at least any one of the increasing/decreasing manipulated variables, which have been determined by the first to N-th friction coefficient increasing/decreasing manipulated variable determining elements, respectively, wherein; a k-th friction coefficient increasing/decreasing manipulated variable determining element (k;
any one of integers 1 to N), which is any arbitrary one of the first to (N+1)th friction coefficient increasing/decreasing manipulated variable determining elements, determines the increasing/decreasing manipulated variable on the basis of at least a deviation between a (1_k)th estimated filtering value obtained by passing the first estimated value through a (1_k)th filter for frequency component adjustment and a (2_k)th estimated filtering value obtained by passing the second estimated value through a (2_k)th filter for frequency component adjustment having the same frequency characteristic as the (1_k)th filter, such that the deviation is converged to zero; andthe respective frequency characteristics of the (1_1)th to (1_N)th filters are set to frequency characteristics different from one another. - View Dependent Claims (6, 9, 12, 15, 18, 21, 24, 27)
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Specification