Method and system for determining a tyre load during the running of a motor vehicle

• US 20070010928A1
• Filed: 07/04/2003
• Published: 01/11/2007
• Est. Priority Date: 07/04/2003
• Status: Active Grant

• Current Assignee: Pirelli Pneumatici S.P.A. (Pirelli & C SPA)
• Original Assignee: Pirelli Pneumatici S.P.A. (Pirelli & C SPA)
• Inventors: Mancosu, Federico, Brusarosco, Massimo, Arosio, Daniele
• Granted Patent: US 7,945,361 B2
• Time in Patent Office: Days
• US Class Current: 701/70
• CPC Class Codes: B60C 23/06 Signalling devices actuated by deformation of the tyre , e.g. tyre mounted deformation sensors or indirect determination of tyre deformation based on wheel speed, wheel-centre to ground distance or inclination of wheel axle
• CPC Class Codes: B60C 23/064 comprising tyre mounted deformation sensors, e.g. to determine road contact area
• CPC Class Codes: G01B 21/12 of objects while moving
• CPC Class Codes: G01G 19/025 wheel-load scales
• CPC Class Codes: G06F 17/40 Data acquisition and logging for input to computer G06F3/00
• CPC Class Codes: G16Z 99/00 Subject matter not provided for in other main groups of this subclass

Abstract

A method for determining a load exerted on a tyre, fitted on a vehicle, during running of the vehicle on a rolling surface, is disclosed. The method includes acquiring a first signal comprising a first signal portion representative of a radial deformation; measuring an amplitude of the radial deformation in the first signal portion; estimating a rotation speed of the tyre corresponding to the radial deformation; estimating an inflation pressure of the tyre corresponding to the radial deformation; and deriving the load exerted on the tyre from the amplitude, the rotation speed, and the inflation pressure. The first signal portion is representative of the radial deformation to which a first tread area portion of the tyre is subjected during passage of the first tread area portion through a contact region between the tyre and the rolling surface. A system for determining the load exerted on the tyre is also disclosed.

Claims

1-47. -47. (canceled)

48. A method for determining a load exerted on a tyre, fitted on a vehicle, during running of the vehicle on a rolling surface, the method comprising:

acquiring a first signal comprising a first signal portion representative of a radial deformation;

measuring an amplitude of the radial deformation in the first signal portion;

estimating a rotation speed of the tyre corresponding to the radial deformation;

estimating an inflation pressure of the tyre corresponding to the radial deformation; and

deriving the load exerted on the tyre from the amplitude, the rotation speed, and the inflation pressure;

wherein the first signal portion is representative of the radial deformation to which a first tread area portion of the tyre is subjected during passage of the first tread area portion through a contact region between the tyre and the rolling surface.

49. The method of claim 48, wherein the first signal comprises a radial acceleration signal.

50. The method of claim 48, wherein measuring the amplitude of the radial deformation comprises measuring a difference between:

a maximum value of the first signal in the first signal portion; and

a minimum value of the first signal in the first signal portion.

51. The method of claim 48, further comprising:

low-pass filtering the first signal before measuring the amplitude of the radial deformation.

52. The method of claim 48, wherein estimating the rotation speed of the tyre comprises:

measuring an average value of the first signal in a second signal portion;

wherein a time period associated with the second signal portion does not overlap a time period associated with the first signal portion.

53. The method of claim 48, wherein estimating the rotation speed of the tyre comprises measuring an average value of the first signal corresponding to an entire revolution of the tyre.

54. The method of claim 48, further comprising:

acquiring a second signal representative of a radial acceleration to which a second tread area portion of the tyre is subjected.

55. The method of claim 54, wherein estimating the rotation speed of the tyre comprises:

measuring a value of the second signal during passage of the first tread area portion through the contact region between the tyre and the rolling surface.

56. The method of claim 48, further comprising:

sampling the first signal at a frequency greater than or equal to 5 kHz before measuring the amplitude of the radial deformation.

57. The method of claim 48, further comprising:

sampling the first signal at a frequency greater than or equal to 7 kHz before measuring the amplitude of the radial deformation.

58. The method of claim 48, further comprising:

providing characteristic functions describing an expected radial-deformation amplitude versus rotation speed that correspond to predetermined conditions of load exerted on the tyre and inflation pressure.

59. The method of claim 58, wherein the characteristic functions comprise polynomial functions.

60. The method of claim 58, wherein deriving the load exerted on the tyre comprises:

identifying a set of characteristic functions corresponding to the estimated inflation pressure; and

determining, from the set of characteristic functions, a corresponding set of expected radial-deformation amplitudes corresponding to the estimated rotation speed.

61. The method of claim 60, wherein deriving the load exerted on the tyre further comprises:

comparing the measured radial-deformation amplitude with any one of the set of expected radial-deformation amplitudes in order to identify a closest expected radial-deformation amplitude; and

establishing the load exerted on the tyre based on the closest expected radial-deformation amplitude.

62. A method of controlling a vehicle having at least one tyre fitted on the vehicle, the method comprising:

determining a load exerted on the at least one tyre;

passing the determined load to a vehicle control system of the vehicle; and

adjusting at least one parameter in the vehicle control system based on the determined load;

wherein the load exerted on the at least one tyre is determined by a method comprising;

acquiring a first signal comprising a first signal portion representative of a radial deformation;

measuring an amplitude of the radial deformation in the first signal portion;

estimating a rotation speed of the at least one tyre corresponding to the radial deformation;

estimating an inflation pressure of the at least one tyre corresponding to the radial deformation; and

deriving the load exerted on the at least one tyre from the amplitude, the rotation speed, and the inflation pressure; and

wherein the first signal portion is representative of the radial deformation to which a first tread area portion of the at least one tyre is subjected during passage of the first tread area portion through a contact region between the at least one tyre and a rolling surface.

63. The method of claim 62, wherein the vehicle control system comprises:

a brake control system;

wherein adjusting the at least one parameter comprises adjusting a braking force on the at least one tyre.

64. The method of claim 62, wherein the vehicle control system comprises:

a steering control system;

wherein adjusting the at least one parameter comprises selecting a maximum variation allowed from steering commands.

65. The method of claim 62, wherein the vehicle control system comprises:

a suspension control system;

wherein adjusting the at least one parameter comprises adjusting stiffness of a suspension spring associated with the at least one tyre.

66. The method of claim 62, wherein the vehicle comprises at least one tyre fitted on each of two opposite sides of the vehicle,

wherein the vehicle control system comprises an active roll control system, and

wherein adjusting the at least one parameter comprises compensating an unequal load distribution between the at least one tyre fitted on each of two opposite sides of the vehicle.

67. A system for determining a load exerted on a tyre, fitted on a vehicle, during running of the vehicle on a rolling surface, the system comprising:

a measuring device;

a pressure sensor;

a device for estimating a rotation speed of the tyre; and

at least one processing unit;

wherein the measuring device is adapted to acquire a signal representative of a deformation to which a first tread area portion of the tyre is subjected during passage of the first tread area portion through a contact region between the tyre and the rolling surface,

wherein the pressure sensor is adapted to sense an inflation pressure of the tyre,

wherein the at least one processing unit is adapted to determine an amplitude of a radial deformation in a first portion of the signal, and

wherein the at least one processing unit also is adapted to derive the load exerted on the tyre from the rotation speed, the inflation pressure, and the amplitude.

68. The system of claim 67, wherein the measuring device comprises:

a radial accelerometer.

69. The system of claim 67, wherein the measuring device comprises:

a sampling device;

wherein the sampling device is adapted to sample the signal at a frequency greater than or equal to 5 kHz.

70. The system of claim 67, wherein the measuring device comprises:

a sampling device;

wherein the sampling device is adapted to sample the signal at a frequency greater than or equal to 7 kHz.

71. The system of claim 67, further comprising:

at least one memory;

wherein the at least one memory is associated with the at least one processing unit.

72. The system of claim 71, wherein the at least one memory comprises:

pre-stored characteristic functions;

wherein the pre-stored characteristic functions describe an expected radial-deformation amplitude versus rotation speed that corresponds to predetermined conditions of load exerted on the tyre and inflation pressure.

73. The system of claim 72, wherein the pre-stored characteristic functions comprise polynomial functions.

74. The system of claim 71, wherein the at least one memory comprises pre-stored instructions for the at least one processing unit.

75. The system of claim 74, wherein the pre-stored instructions comprise at least one first set of instructions adapted to:

identify a set of characteristic functions corresponding to a sensed inflation pressure; and

determine, from the set of characteristic functions, a corresponding set of expected radial-deformation amplitudes corresponding to the estimated rotation speed.

76. The system of claim 75, wherein the pre-stored instructions comprise at least one second set of instructions adapted to:

compare the determined radial-deformation amplitude with any one of the set of expected radial-deformation amplitudes in order to identify a closest expected radial-deformation amplitude; and

establish the load exerted on the tyre based on the closest expected radial-deformation amplitude.

77. The system of claim 67, wherein the measuring device is included in a sensor device disposed in a tread area portion of the tyre.

78. The system of claim 77, wherein the sensor device is disposed near an equatorial plane of the tyre.

79. The system of claim 77, wherein the sensor device is secured to an inner liner of the tyre.

80. The system of claim 79, further comprising:

a damping element between the sensor and the inner liner.

81. The system of claim 77, wherein the sensor device comprises a transmitting device.

82. The system of claim 81, wherein the transmitting device is operatively connected to a first antenna.

83. The system of claim 67, further comprising:

a filtering device;

wherein the filtering device is adapted for low-pass filtering the signal.

84. The system of claim 77, wherein the sensor device further comprises a power source.

85. The system of claim 84, wherein the power source comprises a battery.

86. The system of claim 84, wherein the power source comprises:

a self-powering device;

wherein the self-powering device is adapted to generate electrical power as a result of mechanical stresses undergone by the sensor device during the running of the vehicle.

87. The system of claim 86, wherein the self-powering device comprises a piezoelectric element.

88. The system of claim 86, wherein the self-powering device comprises an electrical storage circuit.

89. The system of claim 88, wherein the electrical storage circuit comprises:

a resistor; and

a capacitor.

90. The system of claim 77, wherein the sensor device comprises the at least one processing unit.

91. The system of claim 77, further comprising:

a fixed unit located on the vehicle;

wherein the fixed unit comprises a receiving device for receiving data from the sensor device.

92. The system of claim 91, wherein the sensor device further comprises:

a transmitting device;

wherein the transmitting device is operatively connected to a first antenna, and

wherein the receiving device comprises a second antenna.

93. The system of claim 92, wherein the first and second antennas are adapted for data transmission at a frequency greater than or equal to 400 MHz and less than or equal to 450 MHz.

94. The system of claim 67, wherein the device for estimating the rotation speed of the tyre is the at least one processing unit.