Power-Train Control Applications Th

Power-Train Control Applications
The design of a power-train control system
involves trade-offs among a number of attri-
butes. When viewed in a control theory con- text, the various attributes are categorized
quantitatively as follows:
Emissions: A set of terminal (final-time)
inequality constraints.
Fuel Consumption: A scalar quantity to be
minimized over a time interval; usually, it is the objective function to be mini- mized.
Drivability: One or more state-variable in-
equality constraints that must be satisfied
at every instant on the time interval.
Performance: Either part of the objective
function or an intermediate point con-
straint-for example, achieve a specified
0-60-mph acceleration time.
Reliability: As part of the emission control
system, the components in the computer control system (sensors, actuators, com- puters) have a 50,000-mile/5-year war-
ranty. In the design process, reliability usually enters as a sensitivity or robust- ness condition-for example, location of
roots in the Z-plane.
Cost: The effects of cost are problem-de-
pendent. Typical ways that costs enter the
problem quantitatively are increased weightings on control variables in qua-
dratic performance indexes (which implies
relatively lower cost actuators) and output



instead of state feedback (which implies fewer sensors but more software).
Packaging: Networking of computers and/
or smart sensors and actuators requires
distributed control theory and trade-offs among data rates, task partitioning, and
redundancy, among others.
Electromagnetic Interference: This is
mainly a hardware problem, which is not
treated explicitly in the analytic control
design process.
Tamperproof: This is one of the reasons
for computer control, and it leads to adap- tive/self-calibrating systems so that dealer
adjustments are not required as the power
train ages o r changes.
The flexibility of microprocessor-based
power-train control systems allows the de- signer to deal effectively with the relatively
large number of interacting attributes listed
earlier. However, this same flexibility re- quires a systems-oriented discipline to en- sure that the major attributes are considered continually as the total system design evolves. Control theory can play a major role
in such a discipline, and examples of its use
in idle speed control and electronic trans-
mission control will be presented below. Further details on these applications may be found in [1]-[8]. It should be noted that the
present paper focuses mainly on work at Ford
Motor Company; representative examples of work outside of Ford can be found in [9]-
~71.