Public Safety
Sensor Validation Software
Call it "reasoning with uncertainty." That is the raison d'etre
of Expert Microsystems, Inc. of Orangevale, California.
The company developed SureSense™, real-time sensor data validation
software. The work was a direct result of a Small Business Innovation Research
(SBIR) contract with Lewis Research Center. This ultra-reliable control
and sensing system product was produced and distributed through a partnership
in 1994 between Expert Microsystems and Intelligent Software Associates,
Inc. (ISAI).
SureSense was created in response to a NASA need for verifying the reliability
of sensor input that operates advanced automation and control systems.
The SureSense software had an immediate assignment: improve safety and
reliability of Space Shuttle Main Engine (SSME) operations. Along with
its unprecedented number of successful flights, Space Shuttle history also
illustrates the potential value of sensor validation. The program has suffered
test aborts, launch delays and postponements as a result of sensor failures.
Dangerous conditions may result when the sensors used to prevent catastrophic
system malfunction fail themselves.
SureSense was designed to detect failures in sensors that must function
in a trustworthy manner. Erroneous engine shutdowns due to sensor failures
are costly, with any test abort or launch delay forcing an expensive and
time-consuming anomaly investigation.
| Expert Microsystems, Inc.'s validation
software was developed for verifying sensor operations in Space Shuttle
Main Engines (SSMEs). The user interface screen shows normal operation
of the SSME during testing at Marshall Space Flight Center's avionics simulation
facility. |
In one dramatic instance, sensor failure caused the premature in-flight
shut down of an SSME roaring toward orbit. Space Shuttle mission 51-F in
July 1985 had the number one SSME shut down early. Luckily, the Shuttle
was over five minutes into its ascent and was capable of an "abort
to orbit." On the second engine, sensors also indicated that shutdown
was necessary. A mission operations engineer noticed an incongruency in
the sensor readouts and advised against it.
Expert Microsystems's SureSense real-time sensor validation software
reduces the workload, schedule and uncertainty associated with sensor failure
identification and recovery. Furthermore, data integrity also improves
safety, dependability and economics for any mission critical aerospace
or industrial control application.
| In real-time, SureSense software can depict
failure of several mission critical sensors on the Space Shuttle Main Engine
and highlight the sensor value display in red. |
Sensor validation is advantageous for several reasons. Among them:
- averts safety system false alarms that leads to unwarranted shutdown
or maintenance,
- lengthens hardware life and assures mission success,
- provides reliable "red-line" safety protection for personnel
and equipment, and
- strengthens system automation by ensuring that automated checkout and
diagnostic systems "reason" with valid data.
The NASA work led to recognizing the wide-spread commercial potential
of sensor data validation software, says Randy Bickford, President of Expert
Microsystems. The company has structured the software to enable application
to virtually any process control environment, such as computer integrated
manufacturing, power plants, and hazardous gas sensing and control systems.
It is estimated that the nationwide market for special purpose industrial
controls is in the billions of dollars, indicating the size and diversity
of the process controls market.
™ SureSense is a trademark of Expert Microsystems, Inc.
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