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Fail-safe system for multiple control systems having at least one common sensor for monitoring common control parameter

  • US 5,170,343 A
  • Filed: 05/10/1990
  • Issued: 12/08/1992
  • Est. Priority Date: 05/11/1989
  • Status: Expired due to Term
First Claim
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1. A fail-safe system for a multiple task control system for performing mutually different first and second control tasks, said multiple task control system performing said first control task on the basis of a first parameter monitored by first monitoring means and a second parameter monitored by second monitoring means and performing said second control task on the basis of said first parameter common to said first task and a third parameter monitored by third monitoring means, said fail-safe system comprising:

  • first malfunction detecting means for monitoring operation of said first monitoring means to detect a faulty condition of said first monitoring means and for producing a first failure detecting signal which is indicative of failure of both of said first and second control tasks;

    second malfunction detecting means for monitoring said second and third monitoring means to detect a faulty condition of one of said second and third monitoring means and for producing a second failure detecting signal which indicates failure of one of said second and third monitoring means for which said failure is detected; and

    controlling means for normally performing said first and second control tasks independent of each other on the basis of said first, second and third parameters, said controlling means being responsive to said first failure detecting signal to perform a first mode fail-safe operation in both of first and second control operations and for performing said first and second tasks, and to said second failure detecting signal to perform a second mode fail-safe operation in one of said first and second control operations utilizing a faulty one of said second and third monitoring means as indicated by said second failure indicative signal.

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