Modeling and automatic control of a wheeled robot for agricultural operations

Abstract: This diploma thesis focuses on the development and analysis of a dynamic model for a wheeled vehicle equipped with four independently steerable wheels. The research includes the application of automatic control techniques to regulate the vehicle’s orientation as it follows a predetermined route. By leveraging advanced mathematical and control theory methods, this study aims to provide insights into the control mechanisms necessary for precise trajectory tracking in vehicles with nonholonomic constraints.

Introduction: Wheeled vehicles with independent steering capabilities for each wheel offer significant advantages in terms of maneuverability and control, particularly in environments that demand complex navigation. This thesis addresses the challenges associated with modeling such vehicles and implementing automatic control techniques to achieve accurate orientation and trajectory tracking. The focus is on creating a dynamic model that captures the intricacies of vehicle motion and applying control algorithms to ensure the vehicle follows a specified path.

Prerequisite knowledge: Mathematical Analysis, Knowledge of Matlab, Non-Linear Differential Equations, Nonlinear Dynamical Systems, Partial Differential Equations, Lagrange equations, Hamilton equations, Nonholonomic system, trajectory tracking

Objectives:

• Develop a dynamic model for a wheeled vehicle with four independent steerable wheels, incorporating nonholonomic constraints.
• Investigate automatic control techniques for vehicle orientation and trajectory tracking along a predetermined route.
• Apply mathematical analysis and control theory, including Lagrange and Hamilton equations, to formulate and solve the model.
• Simulate the vehicle’s behavior and control strategies using Matlab, demonstrating the effectiveness of the proposed model and control techniques.

Methodology: The methodology comprises several stages:

• Modeling: Formulate the dynamic model of the vehicle using nonholonomic systems theory, incorporating Lagrange and Hamilton equations to describe the motion of the vehicle with independent wheel steering.
• Control Strategy Development: Explore various automatic control techniques for orientation and trajectory tracking, ensuring that the vehicle adheres to the predefined path while maintaining stability and accuracy.
• Matlab Simulations: Implement the developed models and control strategies in Matlab to simulate the vehicle’s behavior, evaluating the performance of the control techniques in different scenarios.
• Validation and Analysis: Analyze the results of the simulations to validate the model’s accuracy and the control strategies’ effectiveness in maintaining the desired trajectory.

Expected Contributions:

• A comprehensive dynamic model of a wheeled vehicle with four independently steerable wheels, accounting for nonholonomic constraints.
• Insights into the application of advanced control techniques for vehicle orientation and trajectory tracking, offering solutions for navigating complex environments.
• Practical Matlab simulations demonstrating the functionality of the dynamic model and the effectiveness of the control methods in real-world scenarios.
• Contributions to the field of vehicle dynamics and control systems, providing a foundation for further research in autonomous and semi-autonomous vehicle navigation.

Conclusion: This thesis seeks to advance the study of dynamic modeling and control in wheeled vehicles with independently steerable wheels. Through the development of a detailed mathematical model and the application of automatic control techniques, the work provides valuable insights into vehicle orientation and trajectory tracking. The use of Matlab simulations further illustrates the practical implications of the research, contributing to the broader field of control systems and autonomous vehicle technology.