Title:
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Design of an analog fuzzy robot navigator
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One of the greatest challenges facing the control research community is to
extend ,the domains of application of autonomous robot navigation to the
general class of unstructured environments, that is, environments that are
generally dynamic, not fully known a priori, and typically unpredictable. The
paramount complexity of the sensor-based navigation problem in unstructured
environments arises mainly from the uncertainties. Humans can cope very
well with uncertain and unpredictable environments, often relying on
approximate or qualitative data and. reasoning to make decisions and to
accomplish their objectives.
In this thesis a novel design of a fuzzy logic controller for real time
navigation of a nonholonomic car-like robot in a dynamic environment and its
amilog circuit implementation are investigated. A real time navigator for a
nonholonomic car-like robot in a dynamic environment IS proposed. The
system consists of a Sugeno-type fuzzy motion planner and a modified
proportional navigation based fuzzy controller. The system philosophy is
inspired by human routing when moving between obstacles based on visual
information including the right and left views and he makes already the next
step to the goal in the free space. A Sugeno-type fuzzy motion planner of four
inputs one output is used to give a free direction to the robot controller. A modified proportional navigation based fuzzy logic controller for real time
navigation of a nonholonomic car-like robot in a dynamic environment is
proposed. It has intelligent combination of two behaviours to cope with
obstacle avoidance as well as approaching a goal using a proportional
navigation path accounting for car-like robot kinematics. Other behaviours can
be integrated to perform more co.mplex tasks.
In order to ensure stability for the proposed navigator, a new practical
approach to stabilize fuzzy systems based on adaptive nonlinear feedback is
introduced. This new approach can also be used to stabilize a non-linear
cqntrol system using a fuzzy' stabilizer in the feedback loop. The fuzzy
stabilizer is tuned such that its nonlinearity lies in a bounded sector results
using the circle criterion theory. The new approach has been used to ensure
stability' of a car-like robot controller. In addition, the idea has been extended
to stabilize MIMO systems based on the additively decomposition technique.
A new fully CMOS voltage mode analog circuit. design of two-layer fuzzy
navigator and the simulation results are presented. The design also includes a
new high precision MAX and MIN circuits for fuzzy inference engine block.
The analog design of the main blocks of the fuzzy system (fuzzification block,
rule evaluation block, and defuzzification block) is introduced. The circuit
design and simulation results of the proposed fuzzy motion planner are
presented.
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