DESIGN FOR SIX SIGMA (DFSS) TEAM AND TEAM SOFTWARE PROCESS (TSP) - Software Design for Six-Sigma: A Roadmap for Excellence - page 254

Efficiency of power supply
EMC compliance
Module operational temperature range
Cold-crank operation
Wake-up
Sleep current
DFSS Conceptualize Phase— Understanding the requirements in detail for a “Pro-
gram Plan” consisting of a time line, the deliverables at each milestone, and the
final buy-off plan were prepared. Before the requirements discussions, roughly eight
personnel were chosen to handle a different task to finish the system in eight weeks
based on the engineering judgment, as no past data were available. During the initial
stage, it was decided to reduce the head count to six, which included three software
engineers, two hardware engineers, and one integration and test engineer because the
design was based heavily on the previously exercised concept.
DFSS Optimize Phase— With the detailed requirements, understanding the design
was based on a previous concept that required adopting the proven architecture to
the new vehicle with minimal changes at the architecture level. The addition to the
previous architecture was adding the Measurement Validity Algorithm to ensure the
sensor measurement. The Spiral Model was used for this embedded controls example
project. Figure 10.8 shows the Electrical Steering Control Unit Design Architecture.
Encoder 1, Encoder 2, Resolver, Motor Temperature, and Inverter Temperature were
interfaced with the “sensor measurement” block in Figure 10.8. The sensor diagnos-
tics block was designed to perform a power-on sensor health and a periodic sensor
health check and to report sensor errors upon detection. If sensors were determined
to be good, and no hybrid and motor safety interlock fault or ECU health check faults
were set, then a “NO FAULT” flag was SET. The measurement validity algorithm
block was designed to determine the validity of the sensor measurement. Vehicle
parameters such as torque, RPM, speed, acceleration, deceleration, motor phase R, S,
and T voltage, and current were fed to the motor control algorithm block in addition to
the measurements from the sensor measurement block. Finally this block determined
the required amount of steering angle by determining the required motor voltage and
current for the R, S, and T phases of the motor.
DFSS Verify and Validate Phase— Here the scope is not to discuss the software
implementation because the intention is to evaluate the software process and its
effectiveness on the software product quality and reliability. After going through
the requirements and suitability of previous software architecture, new functional
requirements were discussed with the internal project team and the external teams.
Together it was decided that the previous architecture could be used with some
modification for a new functionality with a portability of available code. This was
done to ensure that only necessary changes were made in order to reduce errors
during various phases to provide maximum quality with the highest reliability with
minimal effort and cost. Also, in this particular software development, no operating
system or lower layer software development was carried out. The changes in the