Motor vehicle deceleration data acquisition and processing apparatus and methodology

• US 4,387,587 A
• Filed: 06/17/1981
• Issued: 06/14/1983
• Est. Priority Date: 06/17/1981
• Status: Expired due to Fees

• Current Assignee: Boyd M. Faulconer
• Original Assignee: Boyd M. Faulconer
• Inventors: Faulconer, Boyd M.
• Primary Examiner(s): Gill, James J.
• Application Number:
  US06/274,416
• Time in Patent Office: 727 Days
• Field of Search: 73/9, 73/121, 73/125, 73/128, 73/146, 73/129, 73/488, 73/489, 73/514, 73/517 R, 364/426
• US Class Current: 73/9
• CPC Class Codes: G01P 15/0907 of the compression mode type
• CPC Class Codes: G01P 15/121 by potentiometers

Abstract

The decelerating movement of a vehicle during a skid test is sensed by an accelerometer which provides an analog signal representative of the deceleration to a computer where the analog signal is periodically sampled and converted into a digital deceleration signal for storing in a computer memory. Alternatively, the decelerating movement of the vehicle may be sensed by a radar speed detector providing digital signals representative of the initial speed and final speed of a time increment to a computer processor which records and stores the digital speed signals in computer memory to be later recalled to produce a digital deceleration signal. The computer processor effects storing of the digital deceleration signals in the computer memory at the beginning of a skid test when the magnitude of the signals exceeds a predetermined threshold level as sensed by a threshold level detector or, alternatively, when a mercury position switch is operated by the deceleration force. Subsequently, the stored deceleration data is retrieved from the computer memory by the processor for performing selected mathematical operations on the data to derive information such as the coefficient of friction encountered by the skidding vehicle, the length of the skid, and the time duration of the skid. The results of the mathematical operations may be displayed on a digital display panel or printed on a tape to provide a permanent record.

Claims

1. Apparatus for providing a deceleration history of a vehicle during a skid test, comprising:

(a) sensing means for sensing the decelerating movement of a vehicle during a skid test and producing a signal representative of the decelerating movement of the vehicle;

(b) computer means receiving the signal from said sensing means and periodically sampling and processing the signal to periodically produce a digital deceleration signal indicative of the deceleration of the skidding vehicle;

(c) skid detecting means for detecting the beginning of a skid test and providing an actuating signal;

(d) said computer means having memory means for storing the digital deceleration signals; and

(e) said computer means being operable in response to the actuating signal for effecting storage of the digital deceleration signals in said memory means so as to provide a deceleration history of the skid test.

2. The apparatus according to claim 1 wherein:

(a) said sensing means is in the form of an accelerometer operable in response to the deceleration of the vehicle for providing an analog signal having a magnitude representative of the rate of deceleration of the vehicle;

(b) said computer means includes an analog to digital converter receiving the analog signal from said accelerometer and is operable in response to a control signal for converting the analog signal into a digital deceleration signal corresponding to the magnitude of the analog signal; and

(c) said computer means further includes processing means connected in controlling relation to said analog to digital converter and periodically supplying a control signal to said analog to digital converter.

3. The apparatus according to claim 1 wherein:

(a) said sensing means is in the form of a radar speed detector providing a digital speed signal representative of the decelerating speed of the vehicle; and

(b) said computer means includes processing means receiving the digital speed signal from said radar speed detector and periodically processing the digital speed signal to determine the deceleration in speed during a sampling period and produce a digital deceleration signal.

4. The apparatus according to claim 1, 2 or 3 wherein:

(a) said skid detecting means is an electrical position switch of a type containing mercury liquid movable to render the switch electrically conductive in one position and electrically non-conductive in another position; and

(b) said electrical position switch is supported in an electrically non-conductive position and is rendered electrically conductive by the movement of the mercury liquid in response to the deceleration of the vehicle so as to provide an actuating signal.

5. The apparatus according to claim 1, 2 or 3 wherein:

(a) said skid detecting means is a threshold level detector receiving said digital deceleration signals and being operable to provide an actuating signal in response to detecting a digital deceleration signal having a value greater than a predetermined threshold value.

6. The apparatus according to claim 2 or 3 wherein:

(a) said processing means is operable to process the stored deceleration signals according to any one of a plurality of predetermined mathematical operations and provide output signals indicative of the results of the mathematical operations in response to a signal corresponding to a selected one of the predetermined mathematical operations; and

(b) said computer means has switch means selectively operable to provide a signal to said processing means to effect processing of the stored deceleration signals according to a selected mathematical operation.

7. The apparatus according to claim 6 wherein said computer means further comprises:

(a) a display panel for displaying the results of the mathematical operations;

(b) a printer for printing the results of the mathematical operations; and

(c) output means receiving the output signals from said processing means and being connected in controlling relation with said display panel and said printer for effecting the display or printing of the results of the mathematical operations.

8. A method for determining coefficient of friction of a surface relative to tires of a vehicle and related information, including the steps of:

(a) operating the vehicle on the surface;

(b) braking the vehicle on the surface such that the wheels of the vehicle are locked and not free to rotate until the vehicle is substantially stopped;

(c) positioning a deceleration determining mechanism in the vehicle so as to determine deceleration rates of the vehicle during braking along a path of motion of the vehicle;

(d) at least periodically sampling deceleration data as determined by the deceleration determining mechanism during braking; and

(e) performing mathematical operations on said data for determining the coefficient of friction and related information.

9. The method according to claim 8 wherein:

(a) the deceleration determining mechanism is an accelerometer.

10. The method according to claim 8 wherein:

(a) the deceleration determining mechanism comprises a radar device; and

includes the steps of;

(b) taking velocity readings with the radar at pre-selected increments of time; and

(c) determining a deceleration for each increment of time based upon a change in velocity between each increment and a previous increment.

11. The method according to claim 8, 9 or 10 wherein:

(a) the mathematical steps are performed by a computer; and

including the steps of;

(b) taking the deceleration data on a continuous basis during braking;

(c) using an analog to digital converter to sample deceleration values at discreet time intervals during braking; and

(d) transferring the discreet time interval sampled deceleration values to the computer.

12. The method according to claim 11 including the step of:

(a) initiating the periodic sampling of deceleration data by detecting means for determining the substantial beginning and end of the braking of the vehicle.