[Paper Review] An Improved Active Disturbance Rejection Control for a Differential Drive Mobile Robot with Mismatched Disturbances and Uncertainties

Ibraheem Kasim Ibraheem, Wameedh Riyadh Abdul Adeem|arXiv (Cornell University)|May 25, 2018

Control and Dynamics of Mobile Robots17 references10 citations

TL;DR

This paper proposes an Improved Active Disturbance Rejection Control (IADRC) for differential drive mobile robots to handle mismatched disturbances and model uncertainties. By transforming the total disturbance into a matched form and using extended state observers, the method effectively estimates and cancels disturbances, significantly reducing chattering and enhancing robustness against torque disturbances in simulations.

ABSTRACT

In this paper a new strategy based on disturbance and uncertainty (DU) estimation and attenuation technique is proposed and tested on the nonlinear kinematic model of the differential drive mobile robot (DDMR). The proposed technique is an improved version of the Active Disturbance Rejection Control (ADRC) strategy suggested by J. Han. The ADRC is used to actively reject disturbances caused by the unknown exogenous signals and the matched uncertainties of the system model, which are lumped all together and attributed as a total disturbance. In this work, the considered system is assumed to be affine and the total disturbance and the input are considered to be on different channels. To deal with the mismatched disturbances and uncertainties, the total disturbance has been converted into a matched one. Then, based on the improved ADRC (IADRC), the dynamic performance of the DDMR has been enhanced by estimating the total disturbance and canceling it from the system. Through digital simulations, different performance measures are applied, and they all indicate the effectiveness of the proposed IADRC by almost removing the chattering phenomenon and providing a high immunity in the closed-loop system against torque disturbance.

Motivation & Objective

• To address the challenge of mismatched disturbances and model uncertainties in differential drive mobile robots (DDMRs).
• To enhance the dynamic performance of DDMR systems under external disturbances and parametric uncertainties.
• To improve the robustness and stability of active disturbance rejection control (ADRC) in the presence of mismatched disturbances.
• To develop a control strategy that effectively estimates and cancels total disturbances without requiring precise system models.

Proposed method

• The total disturbance, including both exogenous disturbances and model uncertainties, is lumped into a single disturbance term.
• A coordinate transformation is applied to convert the mismatched disturbance into a matched disturbance for easier estimation.
• An extended state observer (ESO) is designed to estimate the total disturbance in real time.
• The estimated disturbance is then actively canceled in the control law, improving system robustness.
• The control structure is applied to the nonlinear kinematic model of a differential drive mobile robot.
• Digital simulations are conducted to validate the performance under various disturbance conditions.

Experimental results

Research questions

• RQ1 How can mismatched disturbances in a differential drive mobile robot be effectively handled using active disturbance rejection control?
• RQ2 What transformation technique enables the conversion of mismatched disturbances into matched forms for improved estimation?
• RQ3 To what extent does the proposed IADRC reduce chattering compared to conventional ADRC?
• RQ4 How does the IADRC perform in terms of disturbance rejection and system stability under uncertain conditions?

Key findings

• The proposed IADRC significantly reduces chattering in the control input compared to standard ADRC.
• The system demonstrates high immunity to torque disturbances due to effective disturbance estimation and cancellation.
• The extended state observer successfully estimates the total disturbance in real time, even under model uncertainties.
• Simulation results show improved transient response and steady-state accuracy in trajectory tracking.
• The method maintains robust performance without requiring exact knowledge of system parameters or disturbance models.
• All performance metrics evaluated confirm the effectiveness of the IADRC in enhancing closed-loop system stability and disturbance rejection.