Method and apparatus for low speed estimation

• US 4,885,710 A
• Filed: 03/10/1989
• Issued: 12/05/1989
• Est. Priority Date: 06/25/1987
• Status: Expired due to Term

• Current Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Original Assignee: Delco Electronics Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Spadafora, Peter J., Hersberger, Jill G., Bell, Myron H., Harding, Robert L.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Mattson, Brian M.
• Application Number:
  US07/323,036
• Time in Patent Office: 270 Days
• Field of Search: 364/565, 364/484, 364/486, 364/487, 340/658, 340/670, 340/671, 340/672, 324/160, 324/166, 324/173, 377/15, 377/16, 377/19, 377/24, 361/236, 361/238, 361/239, 361/240
• US Class Current: 702/146
• 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: G01P 3/489 Digital circuits therefor

Abstract

A system and method determines the rotational speed of a rotating member by determining speed from signals having a frequency directly proportional to the rotational speed. The system provides for the estimation of rotational speed even if no speed signals are detected over a sampling interval.

Claims

1. A system for use with a rotating member having a rotational speed, the system comprising, in combination:

a speed sensor for generating a speed signal for each predetermined angular rotation of the rotating member, the generated speed signals having a time interval between speed signals that is a measure of the rotation speed and

means for (A) establishing successive sampling intervals, (B) measuring the rotational speed of the member following each sampling interval during which one or more speed signals are generated by determining an average time between speed signals generated in a calculation interval ending at the last speed signal generated in the sampling interval during which one or more speed signals were generated, the average time being a measurement of the rotational speed of the rotating member and (C) estimating the rotational speed of the member following each sampling interval during which no speed signals were generated by measuring a time interval extending from the last speed signal generated during a prior sampling interval to the end of the sampling interval during which no speed signals were generated, the measured time interval comprising an estimated time interval between speed signals and therefore an estimated of the rotational speed of the rotating member.

2. A system for use with a rotating member having a rotational speed, the system comprising, in combination:

a speed ring rotated by the rotating member and having teeth spaced therearound;

a sensor for sensing the teeth on the speed ring as the speed ring is rotated and generating a squarewave speed signal for each tooth sensed, the squarewave signals generated having a frequency directly proportional to the rotational speed of the member and each having a leading and a trailing edge; and

means for (1) establishing successive sampling intervals and (2) estimating the rotational speed of the rotating member following each sampling interval during which no edges of a squarewave signal occurred by (A) determining an estimated value of an average time T_av between squarewave speed signals in accord with an expression T-T₀ where T is the time of occurrence of the next-to-last edge of the squarewave speed signals that have been generated during prior sampling intervals and (B) estimating the rotational speed of the rotating member in accord with an expression K/T_av where K is a constant.

3. A system for use with a rotating member having a rotational speed, the system comprising, in combination:

a speed ring rotated by the rotating member and having teeth spaced therearound;

a sensor for sensing the teeth on the speed ring as the speed ring is rotated and generating a squarewave speed signal for each tooth sensed, the squarewave signals generated having a frequency directly proportional to the rotational speed of the member and each having a leading and trailing edge; and

means for (1) establishing successive sampling intervals, (2) measuring an actual value of the rotational speed of the rotating member following each sampling interval during which one or more edges of the generated squarewave speed signals occurred by (A) determining an actual value of an average time T_av between squarewave speed signals generated by the sensor and (B) determining an actual value of the rotational speed of the rotating member in accord with an expression K/T_av where K is a constant and (3) estimating the rotational speed of the rotating member following each sampling interval during which no edges of a squarewave speed signal occurred by (A) determining an estimated value of the average time T_av in accord with an expression T-T₀ where T is the time of occurrence of the sampling interval just ended and T₀ is the time of occurrence of the next-to-last edge of the squarewave speed signals that have been generated during prior sampling intervals and (B) determining an estimated value of the rotational speed of the rotating member in accord with the expression K/T_av.

4. A method for use with a rotating member having a rotational speed, the method comprising the steps of:

generating a speed signal for each predetermined angular rotation of the member, the generated speed signals having a time interval between speed signals that is a measure of the rotational speed;

generating periodic signals establishing successive sampling intervals;

determining an average time between speed signals following each sampling interval during which speed signals were generated, the average time determined being a measure of the rotational speed of the rotating member; and

estimating the rotational speed of the rotating member following each sampling interval during which no speed signals were generated by measuring a time interval from the last speed signal generated during a prior sampling interval to the end of the sampling interval during which no speed signals were generated, the measured time interval comprising an estimated time interval between speed signals and therefore an estimated rotational speed of the rotating member.