Method for estimating the suspension stroke of a vehicle and apparatus implementing the same

• US 20090024270A1
• Filed: 07/07/2008
• Published: 01/22/2009
• Est. Priority Date: 07/16/2007
• Status: Active Grant

• Current Assignee: Piaggio & C SPA (Immsi SPA)
• Original Assignee: Piaggio & C SPA (Immsi SPA)
• Inventors: Fabbri, Luca, Spelta, Cristiano, Moneta, Andrea, Tosi, Filippo, Savaresi, Sergio Matteo
• Granted Patent: US 8,498,784 B2
• Time in Patent Office: Days
• US Class Current: 701/29
• CPC Class Codes: B60G 17/018 characterised by the use of a specific signal treatment or control method
• CPC Class Codes: B60G 2300/12 Cycles; Motorcycles
• CPC Class Codes: B60G 2400/106 longitudinal with regard to vehicle, e.g. braking
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2400/5182 Fluid damper
• CPC Class Codes: B60G 2600/60 Signal noise suppression; Electronic filtering means
• CPC Class Codes: B60G 2800/702 Improving accuracy of a sensor signal
• CPC Class Codes: B60G 2800/7022 Calibration of a sensor, e.g. automatically

Abstract

The present invention refers to a method for estimating the suspension stroke of a vehicle comprising the steps consisting of: a) determining a variability law (10) that associates the stroke of the suspension with the pressure inside a shock absorber of the same, based on experimental data; b) estimating the suspension stroke value related to a measured pressure value, based on the variability law (10) identified in step (a); c) detecting/obtaining the longitudinal vehicle dynamics; d) recalibrating (30) the variability law (10) identified in step a), based on the longitudinal vehicle dynamics detected/obtained in step c). The present invention also refers to an apparatus for implementing the estimation method of the suspension stroke of a vehicle according to the invention.

Claims

1. Method for estimating the suspension stroke of a vehicle comprising the steps consisting of:

a) determining a variability law (10) that associates the stroke of the suspension with the pressure inside a shock absorber of the same, based on experimental data;

b) estimating the suspension stroke value related to a measured pressure value, based on the variability law (10) identified in step a);

c) detecting/obtaining the longitudinal vehicle dynamics;

d) recalibrating (30) the variability law (10) identified in step a), based on the longitudinal vehicle dynamics detected/obtained in step c).

2. Method for estimating the suspension stroke according to claim 1, moreover comprising the step that consists of correcting a possible estimation error of step b) through a dynamic filter (20).

3. Method for estimating the suspension stroke according to claim 1, wherein said step (a) of determining the variability law consists of determining the coefficients of a polynomial by means of an identification method applied to the available experimental data.

4. Method for estimating the suspension stroke according to claim 1, wherein said step c) of detecting/obtaining the longitudinal vehicle dynamics consists of determining if the vehicle is in acceleration of braking step.

5. Method for estimating the suspension stroke according to claim 1, wherein said step d) of recalibrating the variability law consists of:

determining (35) a nominal pressure value p_nom based on a suspension stroke value x_stroke (31) related to neutral position conditions;

determining an average pressure value p (32) based on a measured pressure value p (33) and the longitudinal vehicle dynamics (34) detected/obtained in step c);

calculating (36) an offset value as difference between said average pressure P and said nominal pressure p_nom;

translating said variability law determined in step a) along the pressure axis by a value equal to said calculated offset.

6. Method for estimating the suspension stroke according to claim 5, wherein said offset value is correlated with the preceding offset values through a causal digital filtering.

7. Method for estimating the suspension stroke according to claim 2, wherein said correction step of a possible estimation error of step b) consists of filtering the estimation results of said step b) by means of a block (20) modelling a hysteretic behaviour.

8. Method for estimating the suspension stroke according to claim 2, wherein said dynamic filter (20) is a causal digital system.

9. Method for estimating the suspension stroke according to claim 2, wherein the parameters of said dynamic filter (20) are determined by means of an identification method.

10. Apparatus for implementing the estimation method of the suspension stroke of a vehicle according to claim 1 comprising processing means and characterised in that said processing means are connected to a pressure sensor and to a sensor for the longitudinal dynamics.

11. Apparatus according to claim 10, wherein said processing means are a control unit of said vehicle.