A composite fixed-time sliding mode control scheme for Unmanned Ground Vehicles affected by external disturbances

Area of Science:

• Robotics
• Control Systems Engineering
• Autonomous Navigation

Background:

• Accurate path-following control is essential for Unmanned Ground Vehicles (UGVs), but external disturbances cause performance issues like overshoot and chattering.
• Existing sliding mode control (SMC) methods with disturbance observers (DOB) struggle to fully eliminate the chattering phenomenon.

Purpose of the Study:

• To develop a novel control strategy for UGVs that achieves fast chattering reduction and accurate path-following.
• To enhance the robustness and stability of UGV systems against external disturbances.

Main Methods:

• A composite fixed-time sliding mode (CFTSM) control scheme was designed for improved convergence and tracking near the origin.
• A fixed-time disturbance observer (FTDO) was developed to estimate and eliminate external disturbances within a fixed time.
• A composite control strategy integrated the FTDO with the CFTSM to stabilize the UGV and suppress chattering.

Main Results:

• Simulations and experiments confirmed the proposed CFTSM-FTDO strategy offers superior robustness and stability.
• Real-world experiments showed RMSE reductions of 26.8% (lateral) and 8.9% (heading) compared to CFTSM-FFE.
• Further improvements included 19.1% (lateral) and 3.9% (heading) RMSE reductions compared to FTSMC-AESO.

Conclusions:

• The CFTSM-FTDO control strategy significantly enhances UGV path-following accuracy and stability.
• The method effectively suppresses chattering and mitigates the impact of external disturbances.
• This advancement contributes to more precise and reliable autonomous navigation for UGVs.