Method and system for detecting a vibration level of a wheel within a resonating frequency range of a vehicle suspension

• US 7,991,529 B2
• Filed: 06/23/2008
• Issued: 08/02/2011
• Est. Priority Date: 06/23/2008
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Nardi, Flavio, Moshchuk, Nikolai K.
• Primary Examiner(s): To; Toan C
• Application Number:
  US12/144,027
• Publication Number:
  US 20090319123A1
• Time in Patent Office: 1,135 Days
• Field of Search: 701/36, 701/37, 701/38
• US Class Current: 701/38
• CPC Class Codes: B60G 17/018 characterised by the use of a specific signal treatment or control method
• CPC Class Codes: B60G 17/08 Characteristics of fluid dampers adjusting fluid dampers in general F16F9/44 - F16F9/53
• CPC Class Codes: B60G 2400/202 Piston speed; Relative velocity between vehicle body and wheel
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2400/91 Frequency
• CPC Class Codes: B60G 2401/10 Piezoelectric elements
• CPC Class Codes: B60G 2500/10 Damping action or damper

Abstract

A method that detects whether the vibration level of the wheel is within the resonating frequency range by utilizing discrete velocity measurements. The method includes continuously measuring velocity levels of a wheel relative to a sprung mass vehicle component. These measurements are continuously recorded over a period of time. A periodic algorithm is provided, and the periodic algorithm and the velocity measurements are utilized to determine an output value. The output value is utilized to determine whether the vibration level of the wheel is within the resonating frequency range.

Claims

1. A method of detecting a vibration level of a wheel within a resonating frequency range of a vehicle suspension comprising:

determining velocities of the wheel relative to a sprung mass of said vehicle;

recording velocities over a selected time period;

providing at least one periodic algorithm;

determining an output value by utilizing the at least one periodic algorithm and the recorded velocities over the selected time period; and

determining whether the vibration level of the wheel is within the resonating frequency range by utilizing the output value.

2. The method of claim 1, wherein providing at least one periodic algorithm comprises providing at least two periodic algorithms and wherein determining the output value by utilizing the periodic algorithm comprises determining the output value by utilizing the at least two periodic algorithms.

3. The method of claim 2, wherein at least one periodic algorithm has a frequency below a natural resonance frequency of the vehicle suspension and at least one periodic algorithm has a frequency above the natural resonance frequency of the vehicle suspension.

4. The method of claim 1, wherein providing at least one periodic algorithm comprises providing a Fourier series approximation algorithm and wherein determining the output value by utilizing the at least one periodic algorithm comprises determining the output value by utilizing a set of Fourier coefficients of the Fourier series approximation algorithm.

5. The method of claim 4, wherein the Fourier series approximation algorithm is:

ż

_damper=a sin(ω

t)+b cos(ω

t),

wherein

ż

_damper is the measured velocity of the wheel relative to the sprung mass of said vehicle cat a given time t;

a and b are Fourier coefficients, and

ω

is a selected frequency value.

6. The method of claim 5, wherein determining the output value comprises:

determining a solution of coefficient a by utilizing an integral

7. The method of claim 6, wherein at least 100 velocities are determined over the selected time period.

8. The method of claim 6, wherein determining the output value comprises:

determining a solution of determined velocity amplitude

|ż

_damper|_ω

=√

{square root over (a²+b²)}, wherein |ż

_damper|_ω

is the output value.

10. The method of claim 1, wherein providing at least one periodic algorithm comprises providing first, second and third Fourier series algorithms, wherein;

the first Fourier series algorithm is ż

_damper=a<sub>ω

1</sub> sin(ω

₁t)+b<sub>ω

1</sub> cos(ω

₁ t),

the second Fourier series algorithm is ż

_damper=a<sub>ω

2</sub> sin(ω

₂t)+b<sub>ω

2</sub> cos(ω

₂t),

and

the third Fourier series algorithm is ż

_damper=a<sub>ω

3</sub> sin(ω

₃ t)+b<sub>ω

3</sub> cos(ω

₃t),

wherein

ż

_damper is the measured velocity level of the wheel relative to the sprung mass of said vehicle at a given time t,

ω

₁ is a first selected frequency level,

ω

₂ is a second selected frequency level,

ω

₃ is a third selected frequency level,

a<sub>ω

1</sub> and b<sub>ω

1</sub> are Fourier coefficients of the first Fourier series algorithm,

a<sub>ω

2</sub> and b<sub>ω

2</sub> are Fourier coefficients of the second Fourier series algorithm, and

a<sub>ω

3</sub> and b<sub>ω

3</sub> are Fourier coefficients of the third Fourier series algorithm.

11. The method of claim 10, further comprising:

determining solutions for Fourier coefficients a<sub>ω

1</sub>, b<sub>ω

1</sub>, a<sub>ω

2</sub>, b<sub>ω

2</sub>, a<sub>ω

3</sub>, and b<sub>ω

3</sub> using summation approximations utilizing the recorded measured velocities over the selected time period; and

determining the output value based on the solutions of a<sub>ω

1</sub>, b<sub>ω

1</sub>, a<sub>ω

2</sub>, b<sub>ω

2</sub>, a<sub>ω

3</sub>, and b<sub>ω

3</sub>.

12. The method of claim 11, wherein determining the output value based on the solutions of a_ω

₁, b<sub>ω

1</sub>, a<sub>ω

2</sub>, b<sub>ω

2</sub>, a<sub>ω

3</sub>, and b<sub>ω

3</sub> comprises utilizing the equation;

|ż

_damper|=√

{square root over ((a<sub>ω

1</sub>²+b<sub>ω

1</sub>²))}+√

{square root over ((a<sub>ω

2</sub>²+b<sub>ω

2</sub>²))}+√

{square root over ((a<sub>ω

3</sub>²+b<sub>ω

3</sub>²))},

wherein |ż

_damper| is the output value.

13. The method of claim 1, wherein determining the velocities of the wheel relative to the sprung mass of the vehicle comprises:

measuring a position of the wheel relative to the sprung mass of said vehicle at predetermined interval, and

calculating the velocity of the wheel relative to the sprung mass of said vehicle based on at least two position measurements and an interval of time therebetween.

14. The method of claim 13, wherein position measurements are made using a deflection sensor.

15. The method of claim 1, wherein the resonating frequency range is between about 70% and 130% of a natural resonance frequency of the suspension.

16. The method of claim 1, wherein the selected time period is equal to a time period of between about 100 and 500 milliseconds.

17. The method of claim 1, wherein the selected time period is at least as long as two times a maximum wave period of a frequency within the resonating frequency range.

18. The method of claim 1, further comprising:

selectively implementing a resonant damping control strategy when the output value indicates that the vibration level of the wheel is within the resonating range.

9. The method 8, further comprising:

determining whether the output value is above a predetermined threshold value indicative of a vibration level within the resonating frequency range; and

selectively implementing a resonant damping control strategy when the output value is above the threshold value.

19. A method of detecting a vibration level of a wheel within a resonating frequency range of a vehicle suspension comprising:

monitoring a velocity level of the wheel relative to a sprung vehicle component;

recording the monitored velocity levels over a selected time period at least as long as two times a maximum wave period of the resonating frequency range;

providing a Fourier series algorithm;

determining a value for each of two Fourier series coefficients by utilizing the Fourier series algorithm, the recorded monitored velocities, and a selected frequency level; and

utilizing the values of the two Fourier series coefficients to detect whether the vibration level of the wheel is within the resonating frequency range.

20. A system of detecting a vibration level of a vehicle within a resonating frequency range of a vehicle suspension comprising:

a sensor configured to provide a signal indicative of position of a wheel relative to a sprung vehicle component;

a controller configured to

receive the signals indicative of position of the wheel,

utilize the signals to determine a set of velocity measurements,

record the set of velocity measurements over a selected time period, and

detect whether the vibration level of the wheel is within the resonating frequency range based on the recorded set of velocity measurements.