Wheel speed and acceleration detection immune to disturbance

• US 4,670,852 A
• Filed: 07/20/1984
• Issued: 06/02/1987
• Est. Priority Date: 07/20/1983
• Status: Expired due to Term

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation), Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation), Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Asami, Ken, Sakai, Kazunori, Tamura, Kimio, Nakashima, Noriyuki, Masaki, Shouichi, Wakao, Teruyoshi
• Primary Examiner(s): Chin, Gary
• Application Number:
  US06/632,657
• Time in Patent Office: 1,047 Days
• Field of Search: 364/426, 364/565, 364/566, 364/575, 324/160-162, 324/166, 303/93, 303/95, 303/108, 361/238
• US Class Current: 702/146
• CPC Class Codes: B60T 2210/14 Rough roads, bad roads, gravel roads
• CPC Class Codes: B60T 8/173 Eliminating or reducing the effect of unwanted signals, e.g. due to vibrations or electrical noise
• CPC Class Codes: G01P 3/489 Digital circuits therefor

Abstract

A pulse signal is generated by a wheel speed sensor with a frequency proportional to the speed of rotation of a vehicle wheel, the pulse signal comprising a plurality of frames each having a series of a predetermined number of pulses which are tended to be affected by noise and pulse mutilation. Pulses in each frame are counted and from the count is derived an instantaneous wheel speed value. The difference between the successively derived instantaneous speed values is taken and compared with a predetermined threshold. A first or a second indication is given in response to the difference being lower or higher than the threshold, respectively. If the first indication is given, output signals representing the average wheel speed and average wheel acceleration of the wheel are derived from the instantaneous speed values of successive frames. If the second indication is given, the instantaneous speed value of the previous frame is used instead of the instantaneous value of the subsequent frame which is disturbed by noise or pulse mutilation to derive the output signals.

Claims

1. Apparatus for detecting the average speed and average acceleration of a vehicle wheel, comprising:

pulse generating means for generating a pulse signal with a frequency proportional to the speed of rotation of the vehicle wheel, said pulse signal comprising a plurality of frames each having a series of a predetermined number of pulses which are affected by disturbance;

counter means for counting the pulses of said pulse signal and successively generating wheel speed signals each being indicative of an instantaneous value of said speed;

memory means having first and second storage locations for respectively storing therein preceding and following ones of said wheel speed signals, and third and fourth storage locations for respectively storing therein preceding and following ones of wheel acceleration signals;

means for successively deriving said wheel acceleration signals from the wheel speed signals stored in said first and second storage locations;

differential means for detecting a difference between the signals stored in said first and second storage locations;

comparator means for comparing said difference with a predetermined threshold and generating a comparator output when said difference is greater than said threshold;

means responsive to said comparator output for disabling the following wheel speed signal and rewriting into said second storage location the preceding wheel speed signal stored in said first storage location and further disabling said following wheel acceleration signal and rewriting said fourth storage location with the preceding wheel acceleration signal stored in said third storage location; and

means for deriving said average wheel speed from the wheel speed signals stored in said first and second storage locations of said memory means, and for deriving said average wheel acceleration from the wheel acceleration signals stored in said third and fourth storage locations.

2. Apparatus for detecting the average speeds and average acceleration of a vehicle wheel, comprising:

pulse generating means for generating a pulse signal with a frequency proportional to the speed of rotation of the vehicle wheel, said pulse signal comprising a plurality of frames each having a series of a predetermined number of pulses which are affected by disturbance;

memory means having first, second, third and fourth storage locations; and

data processing means responsive to the pulses in each frame of said pulse signal for successively generating wheel speed signals each being indicative of an instantaneous value of said speed, storing a preceding one of said wheel speed signals into the first storage location of said memory means and storing a following one of said wheel speed signals into said second location of said memory means, successively deriving wheel acceleration signals from the wheel speed signals stored in said first and second storage locations, storing preceding and following ones of the successively derived wheel acceleration signals into said third and fourth storage locations, respectively, detecting a difference between the successively generated wheel speed signals, detecting when said difference is greater than a predetermined threshold, rewriting the following wheel speed signal with the preceding wheel speed signal when said difference is detected as being greater than said threshold, and deriving said average wheel speed from the signals stored in said first and second storage locations and deriving said average wheel acceleration from the signals stored in said third and fourth storage locations.

3. Apparatus for detecting the average speed and average acceleration of a vehicle wheel, comprising:

pulse generating means for generating a pulse signal with a frequency proportional to the speed of rotation of a vehicle wheel, said pulse signal comprising a plurality of frames of variable length, each frame having a series of a predetermined number of pulses which are affected by disturbance;

a memory having first, second, third and fourth storage locations; and

data processing means which is programmed to execute the following steps;

(a) detecting the length of each of said frames;

(b) counting the pulses in each of said frames to provide a count value;

(c) successively deriving instantaneous speed values from said count value and the detected lengths of successive ones of said frames and storing preceding and following ones of the instantaneous values respectively into said first and second storage locations of said memory;

(d) detecting a difference between the instantaneous values stored in said first and second storage locations;

(e) comparing said difference with a predetermined threshold and generating a comparator output when said difference is greater than said threshold

(f) successively deriving wheel acceleration signals from the signals stored in said first and second storage locations and storing preceding and following ones of said successively derived wheel acceleration signals into said third and fourth storage locations, respectively;

(g) deriving said average wheel speed from the instantaneous value stored in said first and second storage locations, and deriving said average wheel acceleration from the signals stored in said third and fourth storage locations;

(h) replacing the instantaneous value stored in said second storage location with the instantaneous value stored in said first storage location in response to said comparator output; and

(i) replacing the signal stored in said fourth storage location with the signal stored in said third storage location in response to said comparator output;

(j) repeating the steps (a) to (i).

4. A method for detecting the average speed and average acceleration of a vehicle wheel, comprising:

(a) generating a pulse signal with a frequency proportional to the speed of rotation of a vehicle wheel, said pulse signal comprising a plurality of frames of variable length, each frame having a series of a predetermined number of pulses which are affected by disturbance;

(b) detecting the length of each of said frames;

(c) counting the pulses in each of said frames to provide a count value;

(d) successively deriving instantaneous speed values from said count value and the detected lengths of successive ones of said frames and storing preceding and following ones of the instantaneous values respectively into first and second memory locations;

(e) detecting a difference between the instantaneous values stored in said first and second memory locations;

(f) comparing said difference with a predetermined threshold and generating an output when said difference is greater than said threshold;

(g) successively deriving wheel acceleration signals from the signals stored in said first and second memory locations and storing preceding and following ones of said successively derived wheel acceleration signals into third and fourth memory locations, respectively;

(h) deriving said average wheel speed from the instantaneous values stored in said first and second memory locations and deriving said average wheel acceleration from the signals stored in said third and fourth memory locations;

(i) replacing the instantaneous value stored in said second memory location with the instantaneous value stored in said first memory location in response to the output of the step (f); and

(j) replacing the signal stored in said fourth memory location with the signal stored in said third memory location in response to the output of the step (f).