System and method for determining relative vehicle mass

• US 5,482,359 A
• Filed: 04/22/1994
• Issued: 01/09/1996
• Est. Priority Date: 04/22/1994
• Status: Expired due to Fees

• Current Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Original Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Inventors: Breen, Michael T.
• Primary Examiner(s): Oberleitner, Robert J.
• Assistant Examiner(s): Poon, Peter M.
• Application Number:
  US08/232,716
• Time in Patent Office: 627 Days
• Field of Search: 303/9.69, 303/22.1, 303/7, 303/22.2, 303/22.8, 303/20, 303/DIG. 1-4, 188/3 R, 188/181 T
• US Class Current: 303/9.69
• CPC Class Codes: B60T 13/662 characterised by specified functions of the control system components
• CPC Class Codes: B60T 2250/02 Vehicle mass
• CPC Class Codes: B60T 7/20 specially for trailers, e.g. in case of uncoupling of or overrunning by trailer inertia-actuated overrun brakes B60T13/08
• CPC Class Codes: B60T 8/1708 for lorries or tractor-trailer combinations
• 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 8/18 responsive to vehicle weight or load, e.g. load distribution using electrical circuitry on regulation means B60T8/17; B60T8/30 takes precedence; responsive to weight and speed condition B60T8/58
• CPC Class Codes: B60T 8/58 responsive to speed and another condition or to plural speed conditions
• CPC Class Codes: G01G 19/035 using electrical weight-sensitive devices
• CPC Class Codes: Y10S 303/02 Brake control by pressure comparison

Abstract

A system and method for determining vehicle mass relative to a previous mass of the same vehicle utilizes a closed-loop control system to bring the vehicle to a controlled deceleration upon initiation of the procedure. The relative mass of the vehicle is determined by sensing the applied braking pressures at each of the vehicle axles and processing that information to generate the total braking force being applied to the wheels of the vehicle. Since a greater mass requires a greater braking force to achieve the same deceleration, the necessary braking force is indicative of the relative vehicle mass. An appropriate braking mode such as work balance, proportioning, or ABS, can then be determined based on the relative vehicle mass to better control subsequent braking maneuvers.

Claims

1. For use with a vehicle including an electronic control unit with memory and a plurality of axles, each axle with an associated plurality of braking sites controlled by the electronic control unit, a system for determining a relative vehicle mass during a controlled braking maneuver for the purpose of braking control during subsequent braking maneuvers, the system comprising:

means for decelerating the vehicle at a predetermined rate during the controlled braking maneuver, the means for decelerating delivering a braking pressure to each of the braking sites on at least one of the axles;

means for sampling the braking pressure delivered to the braking sites on the at least one of the axles to obtain at least one braking pressure signal;

means for determining the vehicle mass relative to a previously determined vehicle mass based on the at least one braking pressure signal; and

means for controlling vehicle braking during subsequent braking maneuvers based on the relative vehicle mass.

2. The system of claim 1 wherein the vehicle includes a plurality of wheels and wherein the means for decelerating the vehicle comprises:

a sensor in communication with the electronic control unit for sensing the rate of change in velocity of the vehicle; and

an air-pressure-actuated braking system for retarding rotation of at least two of the plurality of wheels in response to control signals from the electronic control unit.

3. The system of claim 2 wherein the means for sampling comprises at least one pressure transducer in communication with the electronic control unit, the at least one pressure transducer generating a signal having a value proportional to the braking pressure being delivered to each of the braking sites on the at least one axle.

4. The system of claim 1 wherein the means for determining the vehicle mass comprises:

means for determining an estimated vehicle deceleration based on the at least one braking pressure signal and the previously determined vehicle mass;

means for sensing vehicle deceleration to obtain an actual vehicle deceleration signal;

means for comparing the estimated vehicle deceleration to the actual vehicle deceleration signal so as to generate an error signal;

means for modifying at least one of the braking pressures so as to reduce the error signal;

means for repeating the above two steps until the error signal is less than a predetermined value so as to obtain a steady-state estimated vehicle deceleration; and

means for generating the vehicle mass based on the steady-state vehicle deceleration and the at least one braking pressure.

5. The system of claim 4 wherein the means for sensing vehicle deceleration comprises an accelerometer.

6. The system of claim 4 wherein the means for determining an estimated vehicle deceleration comprises:

means for determining braking torques exerted by the plurality of braking sites located at each of the plurality of vehicle axles;

means for summing the braking torques exerted on each vehicle axle to generate a total vehicle braking torque;

means for processing the total vehicle braking torque to determine a vehicle braking force; and

means for multiplying the vehicle braking force by the reciprocal of the vehicle reference mass.

7. The system of claim 1 wherein the means for controlling vehicle braking comprises means for modifying the delivered braking pressure based on the relative vehicle mass.

8. For use with a vehicle including an electronic control unit with memory and a plurality of axles, each axle with an associated plurality of braking sites controlled by the electronic control unit, a method for determining a relative vehicle mass during a controlled braking maneuver for the purpose of braking control during subsequent braking maneuvers, the method comprising:

decelerating the vehicle at a predetermined rate during the controlled braking maneuver by delivering a braking pressure to each of the braking sites on at least one of the axles;

sampling the braking pressure delivered to the braking sites on the at least one of the axles to obtain at least one braking pressure signal;

determining the vehicle mass relative to a previously determined vehicle mass based on the at least one braking pressure signal; and

controlling vehicle braking during subsequent braking maneuvers based on the relative vehicle mass.

9. The method of claim 8 wherein determining the vehicle mass comprises:

determining an estimated vehicle deceleration based on the at least one braking pressure signal and the previously determined vehicle mass;

sensing vehicle deceleration to obtain an actual vehicle deceleration signal;

comparing the estimated vehicle deceleration to the actual vehicle deceleration signal so as to generate an error signal;

modifying at least one of the braking pressures so as to reduce the error signal;

repeating the above two steps until the error signal is less than a predetermined value so as to obtain a steady-state estimated vehicle deceleration; and

generating the vehicle mass based on the steady-state vehicle deceleration and the at least one braking pressure.

10. The method of claim 9 wherein determining an estimated vehicle deceleration comprises:

determining braking torques exerted by the plurality of braking sites located at each of the plurality of vehicle axles;

summing the braking torques exerted on each vehicle axle to generate a total vehicle braking torque;

processing the total vehicle braking torque to determine a vehicle braking force; and

multiplying the vehicle braking force by the reciprocal of the vehicle reference mass.

11. For use with a tractor semi-trailer including an electronic control unit with memory and a plurality of axles, each axle with an associated plurality of braking sites controlled by the electronic control unit, a method for determining a relative tractor semi-trailer mass during a controlled braking maneuver for the purpose of braking control during subsequent braking maneuvers, the method comprising:

decelerating the tractor semi-trailer at a predetermined rate during the controlled braking maneuver by delivering a braking pressure to each of the braking sites on at least one of the axles;

sampling the braking pressure delivered to the braking sites on the at least one of the axles to obtain at least one braking pressure signal;

determining an estimated vehicle deceleration based on the at least one braking pressure signal and a previously determined tractor semi-trailer reference mass;

sensing tractor semi-trailer deceleration to obtain an actual tractor semi-trailer deceleration signal;

comparing the estimated tractor semi-trailer deceleration to the actual tractor semi-trailer deceleration signal so as to generate an error signal;

modifying at least one of the braking pressures so as to reduce the error signal;

repeating the above two steps until the error signal is less than a predetermined value so as to obtain a steady-state estimated tractor semi-trailer deceleration;

determining a tractor semi-trailer mass relative to the previously determined tractor semi-trailer mass based on the at least one braking pressure signal; and

controlling tractor semi-trailer braking during subsequent braking maneuvers based on the relative tractor semi-trailer mass.