Fault-Tolerant Dynamic Control of a Four-Wheel Redundantly-Actuated Mobile Robot

Xiaolong Zhang,Yuanlong Xie,Yu Huang,Jie Meng,Liquan Jiang,Gen Li

doi:10.1109/access.2019.2949746

Xiaolong Zhang, Yuanlong Xie + Show 4 more

Open Access

https://doi.org/10.1109/access.2019.2949746

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Journal: IEEE Access	Publication Date: Jan 1, 2019
Citations: 50	License type: CC BY 4.0

Affiliation: Huazhong University of Science and Technology

Abstract

Four-wheel redundantly-actuated mobile robot (FRMR) offers high controllability and maneuverability for automation applications. However, the robot dynamics and actuator failures are normally omitted in existing kinematic control schemes, which may lead to steering vibration and degraded robustness. To deal with these problems, a fault-tolerant dynamic control method is developed for precise trajectory tracking of the FRMR, which utilizes a two-level structure to cover the wheel-ground interactions and possible actuator failures. In the high level, with a novel fractional-order sliding mode control, this method offers an effective way to regulate the steering angle and eliminate the rotation chattering simultaneously. For the redundantly-actuated issue, a robust allocation solution is presented in the lower level to straightly determine optimal driving torques with full considerations of actuator failures and optimization efficiency. The convergence and stability of the achieved FRMR system are guaranteed theoretically. The experimental comparative results verify that higher tracking precision and enhanced robustness can be obtained using our proposed method.

Highlights

Due to the remarkable maneuverability, flexibility and dexterity, mobile robots have received a growing interest in broad applications, such as manufacturing, agriculture and outdoor exploration [1]–[3]
Precise trajectory tracking of an four-wheel redundantly-actuated mobile robot (FRMR) performs as the basic foundation that is worthy of effective investigation, especially when the excessive slip, force disturbances and actuator failures at the four wheels cannot be ignored in dynamic environments
Many efforts have been devoted to the control design of mobile robots, which can be classified into two categories, i.e., kinematic control and dynamic control [5]–[7]

Summary

INTRODUCTION

Due to the remarkable maneuverability, flexibility and dexterity, mobile robots have received a growing interest in broad applications, such as manufacturing, agriculture and outdoor exploration [1]–[3]. The main contributions of this paper are fourfold: (1) Compared with conventional kinematic control designs, the FTDC keeps the steering control relatively independent of velocity control, and directly generate the desired driving torques for each wheel to achieve control satisfaction and over-actuated feasibility for the FRMR, despite the actuator failures; (2) Instead of exploiting integer calculus, a novel FOSMC with fractional-integral sliding surface is presented for accurate steering control with enhanced abilities of mitigating the chattering phenomenon; (3) An enhanced artificial bee colony (ABC) is incorporated into the developed FTDC scheme, which is beneficial for guarantying the driving torque optimization efficiency; (4) Implemented on a developed real-time FRMR, comprehensive experiments substantiate the efficacy and superiority of the proposed FTDC trajectory tracking method. Where t > 0, 0 < β < 1, α1, α2, α3, a and b are arbitrary positive constants, x(t) is global Mittag-Leffler stable

PROBLEM STATEMENT

25: Replaces xi with a newly produced individual v

Findings

CONCLUSION