METHOD FOR ESTIMATING THE HEIGHT OF THE GRAVITY CENTER OF A VEHICLE

• US 20120173133A1
• Filed: 09/25/2009
• Published: 07/05/2012
• Est. Priority Date: 09/25/2009
• Status: Active Grant

• Current Assignee: Volvo Truck Corporation (Volvo AB)
• Original Assignee: Renault Trucks (Volvo AB)
• Inventors: Doray, Jean-Baptiste, Ranc, Fabrice
• Granted Patent: US 8,751,141 B2
• Time in Patent Office: Days
• US Class Current: 701/124
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence
• CPC Class Codes: B60T 8/17551 determining control parameters related to vehicle stability used in the regulation, e.g. by calculations involving measured or detected parameters
• CPC Class Codes: G01M 1/122 Determining position of centre of gravity
• CPC Class Codes: G01M 17/007 Wheeled or endless-tracked vehicles G01M17/08 takes precedence

Abstract

A method is provided for estimating the height of the gravity center of a vehicle having at least a front axle and a rear axle each carrying at least two wheels. The method includes determining a first braking period and a second braking period occurring along road portions having substantially the same slope, but where the first and second braking periods result in different vehicle decelerations, and during both braking periods, estimating at least the following variables: vehicle acceleration; the wheel slippage rate for the front and rear axles; the braking forces or braking torque at each of the front and rear axles, or a ratio thereof; and the slope of the corresponding road portion. The method also includes estimating, using only the foregoing estimations made during both periods, the vehicle center of gravity height.

Claims

1. A method for estimating the height of the gravity center of a vehicle having at least a front axle and a rear axle each carrying at least two wheels, comprising:

a) determining a first braking period and a second braking period occurring along road portions having substantially the same slope, but where the first and second braking periods result in different vehicle decelerations, and during both braking periods, estimating at least the following variables;

vehicle acceleration (Acc);

the wheel slippage rate (WSR) for the front and rear axles;

the braking forces (Bkf) or braking torque at each of the front and rear axles, or a ratio thereof (K); and

the slope (Slp) of the corresponding road portion;

b) estimating, using only the estimations of step a) made during both periods, the vehicle center of gravity height (H).

2. Method according to claim 1 , wherein the determination that a first braking period and a second braking period result in different vehicle decelerations is achieved by taking into account, during the first braking period and second braking periods, the action of a driver on a brake command device and/or the pressure in a fluidic brake initiating circuit and/or the acceleration of a wheel.

3. Method according to claim 1, wherein the slope (Slp) determination involves the determination of the action of forces on the vehicle, of the vehicle mass (M);

of the vehicle acceleration (Acc) and the slope is determined using the following formula;

4. Method according to claim 3, wherein, during a braking period, external forces applied to the vehicle are considered to be limited to the braking forces and to the action of gravity.

5. Method according to claim 4, wherein the braking forces applied by the service brakes of the vehicle are estimated as a function of the pressure in fluidic brake initiating circuit(s).

6. Method according to claim 4, wherein the external forces applied to the vehicle may be considered to additionally comprise the aerodynamic drag of the vehicle.

7. Method according to claim 6, wherein the aerodynamic drag can be estimated as a linear or quadratic function of the vehicle speed.

8. Method according to claim 3, wherein the determination of the vehicle mass (M) comprises the step of comparing vehicle acceleration (Acc) when the vehicle is freewheeling and a vehicle acceleration when the vehicle is accelerating due to the provision of a known motoring torque or traction force from the vehicle powertrain.

9. Method according to claim 3, wherein the step of determining vehicle mass (M) is performed during a vehicle acceleration phase involving a gear shift.

10. Method according to claim 1, wherein the determination of vehicle acceleration (Acc) is, performed by derivation of a measured wheel rotation speed (W).

11. Method according to claim 1, wherein the height of the gravity center of the vehicle is estimated according to the following formula: