Browse Prior Art Database

FLEXIBLE ANTI-LOCK BRAKING SYSTEM (ABS) HARDWARE WITH A SOFTWARE INTER-LOCKING MECHANISM

IP.com Disclosure Number: IPCOM000008755D
Original Publication Date: 1998-Jun-01
Included in the Prior Art Database: 2002-Jul-10
Document File: 3 page(s) / 153K

Publishing Venue

Motorola

Related People

Gary L. Miller: AUTHOR [+2]

Abstract

Inability of prior art in Anti-Lock Braking System (ABS) hardware to ensure that a service processor in a multi-processing system can, under all conditions, coherently access all data collected by the hardware.

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MOTOROLA Technical Developments

FLEXIBLE ANTI-LOCK BRAKING SYSTEM (ABS) HARDWARE WITH A SOFTWARE INTER-LOCKING MECHANISM

by Gary L. Miller and Marcella E. Meyer

PROBLEMS SOLVED

  Inability of prior art in Anti-Lock Braking System (ABS) hardware to ensure that a service processor in a multi-processing system can, under all conditions, coherently access all data collected by the hardware.

  ABS hardware has been primarily designed to operate in a distributed processor system, with a serial link from the ABS chip to the central engine controller MCU. With the trend in automotive power train control towards integration of external chips into the central engine controller MCU, it is necessary to ensure that the service processor can access ABS data coherently under all conditions which could occur in a multi-processing system. ABS hardware has been designed such that, if the sample period expires while the service processor is accessing the data collected by the hardware, the processor could access data which is not coherent
i.e. some data from the previous sample period and some data from the current sample period. And if the service processor performs the calculations for controlling the braking system with incoherent data, this could result in safety and liability problems for automakers. The mechanism provides the service processor with a software inter-lock with the ABS hardware, which ensures that, under all conditions, the service processor will access all ABS data coherently. Thus providing a more fault tolerant system.

Inability of prior art in ABS hardware to collect additional data which is required for future ABS

systems, such as steering angle from a quadrature encoder.

  ABS hardware has been primarily designed ~to collect two types of data to be used for controlling the braking system: the speed of each wheel during a sample period, and the "time tag" for the last input during the sample window for each wheel speed sensor. Another data type-the steering angle of the front wheels as input on a quadrature encoded signal-is anticipated for future ABS systems. The mechanism collects this type of data, if needed, and allows the service processor coherent access to all three types of ABS data. In addition, the ABS hard- ware has the flexibility to allow for other types of data to be collected (such as wheel position needed for slow-speed ABS) and accessed coherently by the service processor using the software inter- locking mechanism.

DESCRIPTION ABS HARDWARE SYSTEM

  The implementation of this system as shown in Hardware Description of Invention on the next page uses some of the same hardware as Motorola's Input Control Timer: counters which are incremented by the wheel speed sensor, capture registers which capture the "time tag" for the last input during the sample window for each wheel speed sensor, and holding registers to latch the counter value when the sample period expires. The essential differences, however, between this ABS...