Abstract:
lt is the author's contention that a brake control
system incorporating the
following two features is suitable for high-performance, robust and adaptive
anti-skid control.
1.
Switching on wheel acceleration with hysteresis,
2. Fixed brake
pressure rate control.
Furthermore, the author contends that such a system can be developed in
the context of
large commercial aircraft development and with regard to;
Minimal
a-priori knowledge of system dynamics,
I No
requirement for on-line system identification.
This thesis documents a
programme of research conducted to examine this
hypothesis in the context of large commercial aircraft, and in conjunction with
Airbus UK at Filton in Bristol. The
physical basis for this method of control is
examined from first
principles, explored in detail through a simulation based
experimental process and is subsequently confirmed as a viable means of
control. This is further
developed into a prototype anti-skid braking control
algorithm which in turn is incorporated into a nominal brake control system
model. A detailed
analysis of the systems performance is then conducted and
reported upon. Finally, conclusions are drawn with respect to the aims and
objectives documented herein and recommendations for further research are
made.
The novel
aspects of this hypothesis and subsequent algorithm
development are as follows, and are to be considered with respect to the
current state-of-the-art in the field:
1. The use of a fixed brake
pressure rate control to isolate the friction
dependent aspects of the system dynamics,
2. The use of a
simple switching element which incorporates hysteresis
such that when combined with l, allows robust -slip gradient
control* to be effected, and
3. The use of brake
system response characteristics to drive an optimal
wheel acceleration demand
signal.
The author believes that these three
aspects of the anti-skid braking
algorithm documented within this thesis combine to provide an effective and
pragmatic solution to the problem, and represent a step forward in the state of-
the-art as is
befitting a research programme of EngD character.
'The
gradient of the -slip (friction coefficient vs. wheel slip ratio) curve is controlled.
