Dual closed-loop sliding mode control for a decoupled three-link wheeled mobile manipulator

Area of Science:

• Robotics
• Control Systems Engineering
• Mechatronics

Background:

• Wheeled mobile manipulators (WMPs) require advanced control for complex tasks.
• Conventional control methods can struggle with trajectory generation and precise joint control.
• Sliding mode control (SMC) offers robustness but can be enhanced for faster response.

Purpose of the Study:

• To develop a dual closed-loop sliding mode control strategy for a WMP with a three-link manipulator.
• To improve posture trajectory generation and joint trajectory tracking performance.
• To achieve faster settling times and enhanced robustness compared to conventional methods.

Main Methods:

• Derivation of the WMP's dynamic model using Euler-Lagrange and Newtonian methods.
• Design of a dual closed-loop control system with an outer loop for virtual velocity command and an inner loop for velocity compensation.
• Implementation of a finite-time sliding mode controller for manipulator joint control, incorporating finite-time control terms.
• Integration with DC and dynamixel motor systems via a microprocessor.

Main Results:

• The proposed dual closed-loop finite-time SMC scheme demonstrated effectiveness in simulations and experiments.
• Faster posture trajectory generation for the mobile platform was achieved.
• Improved joint trajectory tracking with faster settling times and superior robustness for the manipulator was observed.

Conclusions:

• The dual closed-loop finite-time sliding mode control strategy is effective for WMPs.
• This approach offers significant advantages in terms of speed and robustness for robotic manipulation tasks.
• The findings contribute to the advancement of control methodologies for complex robotic systems.