ON CONCEPTUAL DESIGN OF
BY-WIRE SYSTEMS
Kristina Ahlström
Licentiatuppsats som presenteras vid seminarium i
Henry Wallmans rum, vån 6 S, Hörsalsvägen 11, Chalmers
Onsdagen den 6 december 2000, kl.15.15
Diskussionsledare är Dr Jonas Vasell från
CR&T, Göteborg
ABSTRACT
Future Control-By-Wire
systems are anticipated to face increased requirements of flexibility,
scalability, low weight, predictability, and testability. This at reduced
complexity and maintenance costs. These increased requirements are best
met with distributed control systems from a cost efficient point of
view.
To investigate how a future control-by-wire system could be designed, if
distributed control and smart actuators and sensors are used, a study of
a flight control system is carried out. This thesis presents a design
methodology and results in a proposed future distributed architecture.
Various issues regarding distributed architectures are investigated,
including system operation, control and computing allocation between
nodes, communication requirements, physical distribution, hardware
redundancy, communication scheduling and fault handling. Based on these
findings, a robust fault tolerant distributed architecture with minimum
hardware and low bandwidth is proposed.
The communication in a distributed system is the most vital component
with high reliable demands. An electrical bus system is the cheapest and
most reliable communication network available in the near future for fly-
and drive-by-wire systems. Theoretical and experimental investigations of
achievable bandwidth, including adequate EMC qualities, with an
electrical bus are also part of this thesis work.
Keywords: Distributed control, distributed systems, design
methodology, embedded systems, real-time communication, and safety
critical control systems.