Wheel information estimating apparatus

• US 6,142,026 A
• Filed: 06/01/1995
• Issued: 11/07/2000
• Est. Priority Date: 06/06/1994
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toyota Chuo Kenkyusho (Toyota Motor Corporation), Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Kabushiki Kaisha Toyota Chuo Kenkyusho (Toyota Motor Corporation), Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Kawai, Hiroyuki, Ohashi, Hideki, Umeno, Takaji, Asano, Katsuhiro, Kojima, Hiroyoshi, Onogi, Nobuyoshi, Naito, Toshiharu
• Primary Examiner(s): DOMBROSKE, GEORGE M
• Application Number:
  US08/458,099
• Time in Patent Office: 1,986 Days
• Field of Search: 73/117, 73/146, 73/146.2, 73/146.3, 73/146.5, 701/37, 701/65
• US Class Current: 73/865.9
• CPC Class Codes: B60C 23/061 by monitoring wheel speed measuring distance traversed on the ground by vehicles G01C22/00
• CPC Class Codes: B60C 23/062 Frequency spectrum analysis of wheel speed signals, e.g. using Fourier transformation

Abstract

A wheel information estimating apparatus, which includes: a detecting device for detecting a wheel motion state relating to a movement of a tired wheel of a motor vehicle; an estimating device for estimating wheel information relating to the tired wheel, on the basis of the wheel motion state detected by the detecting device; and a modifying device for modifying an element relating to estimation of the wheel information, so as to improve an accuracy of estimating the wheel information. The element to be modified is selected from a movement of a center of rotation of the tired wheel as viewed in a plane in which the wheel is rotated, a signal applied from the detecting device to the estimating device, and an internal parameter used by the estimating means for estimating the wheel information.

Claims

1. A wheel information estimating apparatus, comprising:

a detecting device for detecting a wheel motion state relating to a movement of a tired wheel of a motor vehicle;

estimating means for estimating wheel information relating to the tired wheel, on the basis of said wheel motion state detected by said detecting device, by using a model of the tired wheel and an internal parameter which is a constant of a mechanical element of said model, said model having a rim and a belt which are connected to each other by a torsion spring; and

modifying means for modifying said internal parameter so as to improve accuracy of the estimated value of the wheel information obtained by said estimating means.

2. A wheel information estimating apparatus according to claim 1, wherein said wheel motion state has a plurality of frequency components, the apparatus further comprising frequency characteristic modifying means for modifying a frequency characteristic of said wheel motion state to be supplied to the estimating means, such that a ratio of a strength of the selected one of the plurality of frequency components of said wheel motion state, said selected one being within a selected frequency range, to a strength of the other frequency components outside said selected frequency range is increased.

3. A wheel information estimating apparatus according to claim 2, wherein said frequency characteristic modifying means comprises a pre-processing filter disposed between said detecting device and said estimating means, for selecting a component of a signal supplied from said detecting device to said estimating means, the selected component being within said selected frequency range, and for supplying the selected component to said estimating means.

5. A wheel information estimating apparatus according to claim 2, wherein said frequency characteristic modifying means comprises means for changing said selected frequency range so that an amount of variation of an estimated value of said wheel information obtained by said estimating means is not greater than a predetermined value.

6. A wheel information estimating apparatus according to claim 1, wherein said estimating means comprises (a) a disturbance observer for estimating a disturbance acting on the tired wheel as wheel information, on the basis of a basic value of said internal parameter, and said wheel motion state received from said detecting device, said disturbance observer estimating said disturbance as one of a plurality of variables in an equation of state indicative of a rotary motion of said wheel, and said internal parameter being a moment of inertia J_R of the rim, a moment of inertia J_B of the belt, and a spring constant K of said torsion spring, and (b) means for estimating an amount of change from said basic value to a value indicative of an actual state of said wheel information, on the basis of said disturbance estimated by said disturbance observer.

7. A wheel information estimating apparatus according to claim 6, further comprising (c) basic value compensating means as said modifying means for compensating said basic value of the internal parameter, on the basis of said amount of change estimated by said change amount estimating means, so that the estimated amount of change is not larger than a predetermined value;

and (d) wheel information estimating means for estimating said compensated internal parameter basic value as said wheel information.

8. A wheel information estimating apparatus according to claim 7, wherein said rim and said belt of said model of the tired wheel are rotatable relative to each other, said disturbance observer estimating an angular velocity ω

_B of the belt, a torsion angle θ

_RB between the rim and the belt, and a disturbance w₂, on the basis of a detected value of an angular velocity ω

_R of the rim as said wheel motion state, and basic values of said moment of inertia J_R of the rim, said moment of inertia J_B of the belt, and said spring constant K, as said internal parameter basic value, said change amount estimating means estimating an amount of change Δ

K from the basic value of said spring constant K to a value indicative of an actual spring constant, on the basis of estimated values of said angular velocity ω

_B of the belt, said torsion angle θ

_RB, and said disturbance w₂, said basic value compensating means compensating the basic value of said spring constant K, so that the estimated amount of change Δ

K is not larger than a predetermined value, said wheel information estimating means estimating the basic value of the spring constant K as said wheel information, when said amount of change Δ

K is not larger than said predetermined value.

9. A wheel information estimating apparatus according to claim 8, wherein said disturbance observer defines said disturbance w₂ as represented by the following equation:

space="preserve" listing-type="equation">w.sub.2 =(-1/J.sub.B)T.sub.d +(Δ

K/J.sub.B)θ

.sub.RB

where T_d is a disturbance torque applied from a road surface to said belt of the wherein wheel, and

wherein said change amount estimating means estimates said amount of change Δ

K according to a relationship between the estimated values of said disturbance w₂ and said torsion angle θ

_RB.

10. A wheel information estimating apparatus according to claim 9, wherein said change amount estimating means calculates a normalized value obtained by dividing a cross-correlation function of the estimated values of said disturbance w₂ and said torsion angle θ

_RB, by an auto-correlation function of the estimated value of said torsion angle θ

_RB, and estimates said amount of change Δ

K, on the basis of said normalized value as a variable representative of a relationship between said disturbance w₂ and said torsion angle θ

_RB.

11. A wheel information estimating apparatus according to claim 7, wherein said disturbance observer assumes an equivalent model of the tired wheel which is equivalent to a basic model in which a rim is coupled with a belt through a torsion spring and a damper which are connected in parallel with each other, such that said rim and said belt are rotatable relative to each other, said equivalent model being designed such that a rim is coupled with a belt through a torsion spring and a damper which are connected in parallel with each other, such that said rim and said belt are displaceable relative to each other in one linear direction, said disturbance observer estimating an equivalent linear displacement velocity x_B '"'"' of the belt, an equivalent relative linear displacement x_RB between the rim and the belt, and a disturbance w₂, on the basis of a detected value of an equivalent linear displacement velocity x_R '"'"' of said rim, as said wheel motion state, and basic values of an equivalent inertial mass m_R of the rim, an equivalent inertial mass m_B of the belt, a spring constant K_W and a damping coefficient D_W, as said wheel information basic value, said change amount estimating means estimating an amount of change Δ

K_W from the basic value of said spring constant K_W to a value indicative of an actual spring constant, and an amount of change Δ

D_W from the basic value of said damping coefficient D_W to a value indicative of an actual damping coefficient, on the basis of estimated values of said equivalent linear displacement velocity x_B '"'"' of the belt, said equivalent relative linear displacement x_RB and said disturbance w₂, said basic value compensating means compensating the basic values of the spring constant K_W and the damping coefficient D_W, so that the estimated amounts of change Δ

K_W and Δ

D_W are not larger than respective predetermined values, said wheel information estimating means estimating the basic values of the spring constant K_W and the damping coefficient D_W as the actual spring constant and damping coefficient, when said estimated amounts of change Δ

K_W and Δ

D_W are not larger than said respective predetermined values.

12. A wheel information estimating apparatus according to claim 11, wherein said disturbance observer defines said disturbance w₂ as represented by the following equation:

space="preserve" listing-type="equation">w.sub.2 =(Δ

D.sub.W /m.sub.B)(x.sub.R '"'"'-x.sub.B '"'"')+(Δ

K.sub.W /m.sub.B)x.sub.RB +F.sub.d /m.sub.B

where F_d is a disturbance received by said belt from a road surface, and

wherein said change amount estimating means estimates the amounts of change Δ

D_W and Δ

K_W on the basis of estimated values of said disturbance w₂, said equivalent linear displacement velocity x_B '"'"' of the belt, and said equivalent relative linear displacement x_RB, and said detected value of the equivalent linear displacement velocity x_R '"'"' of the rim.

13. A wheel information estimating apparatus according to claim 12, wherein said wheel information estimating means estimates said amount of change Δ

D_W and said amount of change Δ

K_W, on the basis of the estimated values of the disturbance w₂, the equivalent linear displacement velocity x_B '"'"' of the belt, and the equivalent relative linear displacement x_RB, and the detected value of the equivalent linear displacement velocity x_R '"'"' of the rim, such that respective estimated values of said amount of change Δ

D_W and said amount of change Δ

K_W are determined so as to substantially minimize a sum of the squares of a difference between the estimated value of the disturbance w₂ and a theoretical approximate value thereof.

14. A wheel information estimating apparatus according to claim 7, further comprising tire pressure estimating means for estimating an air pressure P of a tire attached to said tired wheel, on the basis of said wheel information estimated by said wheel information estimating means.

4. A wheel method of assaying translational recoding in vitro comprising

(a) providing a translational reporter vector comprising a polylinker interposed between first and second luciferase coding sequences wherein said first and second luciferase coding sequences are in different reading frames;

(b) inserting a DNA to be tested in said reporter vector at the polylinker to form a test vector such that the first and second luciferase coding sequences remain in different reading frames;

(c) inserting the DNA to be tested in said reporter vector at the polylinker to form a control vector such that the first and second luciferase coding sequences are in the same reading frame;

(d) separately transcribing said reporter vector, said test vector, and said control vector in vitro to result in respective RNAs comprising transcription copies of said first luciferase coding sequence said DNA to be tested, and said second luciferase coding sequence;

(e) separating translating each of said RNAs in vitro to result in translation products thereof;

(f) determining luminescences attributable to each of said translation products, wherein the tranaslation products of the reporter vector contributed background luminescence, the translation products of the control vector contribute normal luminescence, and the translation products of the test vector contribute test luminescence;

(g) subtracting background luminescence from said normal and said test luminescences and normalizing said test luminescence wiht respect to said normal luminescence.