Open Systems Based Emissions Test Benches Come to the Automotive Industry 981375
For decades the Automotive Industry has purchased emission test equipment to meet EPA requirements. Existing systems utilize gas analyzers that provide analog outputs to computers or programmable controllers that, in turn, digitize the signals and communicate them to the cell computer. These systems use complex computer hardware and software systems to collect more than 25 channels of analog signals, convert them to digital, and report them. This architecture is very difficult to maintain and requires excessive effort to modify. The systems do not have any provisions for self-diagnostics or control charting. In 1996 Quantum Controls, Inc. and Chrysler Corporation, Chelsea Proving Grounds began work on the next generation emission test cell. The design goals were:
Speed of response to be maximized. The time to digitize the signal and communicate it to the cell computer for all analyzers in a bench must be at least 20Hz with a goal of 30Hz.
System accuracy to be improved by eliminating the bench computer A/D conversion.
System life cycle costs be decreased.
System modularity, an important consideration, to allow the addition of analyzers in the future.
The bench computer user interface must be flexible and graphical. In addition, it must use an industry standard development tool.
The first Open Systems Based Emissions Test Benches were delivered in early 1997. Reactions from the operators and maintenance personnel are that the system goals are being met. Engineering personnel responsible for the design also believe the goals are being met.