Fluid-pressure and analogous brake systems – Speed-controlled – Wheel generated pulse signal control
Patent
1994-02-28
1996-01-30
Oberleiter, Robert J.
Fluid-pressure and analogous brake systems
Speed-controlled
Wheel generated pulse signal control
30312205, 324166, 36442601, B60T 860, G01P 3489
Patent
active
054875951
ABSTRACT:
A system for anti-lock brake and traction control has a control circuit comprising a microprocessor on a silicon die. Inputs from several variable reluctance wheel speed sensors are multiplexed to a single channel on the same die for signal processing including diagnostics, A/D conversion, square wave generation for each sensor by a state machine, end wheel speed determination from the square waves. The state machine algorithm tracks signal peaks and valleys and uses a dual hysteresis method of generating output transitions to capture all cycles of a signal having single cycle anomalies while rejecting noise. A single rear wheel sensor having twice the frequency of front wheel sensors for equal wheel speeds is processed twice as often as each front sensor. The diagnostics include detecting sensor and harness short and open circuits by comparison of signals to programmable thresholds and fault timing and latching by gauging open and short signals against programmable time limits. Common mode noise rejection is accomplished by detecting common mode aberration and disabling an A/D converter during the aberrations. Other diagnostics include inputting known artificial signals at sensor inputs or wheel speed circuit inputs and checking for expected outputs, or by calculating wheel speed in parallel paths having the same square wave inputs and using different algorithms.
REFERENCES:
patent: 4125295 (1978-11-01), Ruhnau et al.
patent: 4270176 (1981-05-01), Skarvada
patent: 4626763 (1986-12-01), Edwards
patent: 4700304 (1987-10-01), Byrne et al.
De Wever Marc L.
Kumke Dale J.
Lumpkin Everett R.
Sale Matthew D.
Schousek Brian W.
Delco Electronics Corporation
Muratori Alfred
Navarre Mark A.
Oberleiter Robert J.
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