Hierarchical rule-base reduction fuzzy control for variable velocity path tracking

Dekhterman, Samuel Ryan

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https://hdl.handle.net/2142/121506 Copy

Description

Title

Hierarchical rule-base reduction fuzzy control for variable velocity path tracking

Author(s)

Dekhterman, Samuel Ryan

Issue Date

2023-07-21

Director of Research (if dissertation) or Advisor (if thesis)

Norris, William Robert

Department of Study

Industrial&Enterprise Sys Eng

Discipline

Systems & Entrepreneurial Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• differential steer vehicle
• fuzzy logic
• pure pursuit
• asymptotic stability
• waypoint navigation

Abstract

A novel waypoint navigation controller for a skid-steer vehicle, consisting of a multiple input-multiple output nonlinear angular velocity and linear speed controller, is presented. This controller, the Variable Linear Speed Fuzzy (VLSF) system, is a fuzzy controller which employs trapezoidal input membership functions with a completely symmetric rule-base. Notably, the controller utilizes Hierarchical Rule-Base Reduction (HRBR) in order to identify and select the rules most influential on state errors. This is achieved via a Fuzzy Relations Control Strategy (FRCS), which selects inputs/outputs, determines the most globally influential inputs, and generates a hierarchy of inputs. The entire operating environment was covered by the controller. However, a rule for every possible combination of variables, states, and outputs was no longer necessary. As a result, HRBR fuzzy controllers can increase the number of inputs and their associated fidelity without dramatically increasing the rule base. To contextualize the performance of the controller, a background on vehicle dynamic modeling methodologies and an in-depth explanation of the related simulation model are provided. An examination of the proposed controller is then conducted, consisting of stability analysis and testing on a set of courses. The test courses results enable an examination of the effects of steering disturbance, phase lag, and overshoot as expressed in Root Mean Square Error (RMSE), Max Error (ME), ect. Finally, simulation and real-world results of the controller's performance are compared with the results of several comparable navigation vehicle controllers: geometric pure pursuit, a simplified implementation with constant linear speed, and a Timed Elastic Band (TEB) controller. The VLSF was found to outperform the Pure Pursuit, Constant Linear Speed Fuzzy, and TEB controllers experimentally in most cases, validating the viability of the proposed controller.

Graduation Semester

2023-08

Type of Resource

Thesis

Copyright and License Information

Copyright 2023 Samuel Ryan Dekhterman

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