An Adaptive Nonsingular Fast Terminal Sliding Mode Controller for Dynamic Walking of a 5-Link Planar Biped Robot in Both Single and Double Support Phases

Le Anh Tuan,Ataollah Azarbani,Ahmad Fakharian,Mohammad Bagher Menhaj

doi:10.1155/2022/6462085

Le Anh Tuan, Ataollah Azarbani + Show 2 more

Open Access

https://doi.org/10.1155/2022/6462085

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Abstract

This paper aims to design an improved adaptive nonsingular fast terminal sliding mode controller for a fully actuated planar biped robot with five degrees of freedom in the single support (SSP) and double support (DSP) phases in the presence of external perturbation and uncertainties. A new sliding surface was proposed to avoid singularities and the chattering phenomenon. The proposed controller guarantees fast convergence of error signals in finite time. Unlike similar studies, the presented method considers a whole cycle of one step of walking, including SSP, double impact, and DSP phases. Also, the proposed approach does not require a predefined upper limit to estimate uncertainty using an adaptive law. Notably, dynamic walking was preferred over static walking to achieve more similarity to human walking. The designed trajectories were determined according to the position of the waist and swinging legs ankle, which could then be converted into the position of joints using inverse kinematics equations. The simulation results were used to approve the proposed controller's fast and robust tracking performance in the presence of external disturbances, mass, and inertia uncertainties without predefined knowledge of their upper bounds.

Highlights

Biped robot control has attracted considerable attention in the last two decades
Compared to mobile and manipulator robots, these robots are tough to control due to inherent instability and dependence on balance and motion control systems
Uncertainty in robot types and external perturbations, such as sudden forces applied to the robot or overweight and carrying cargo, have degraded the performance of such control systems. erefore, robust and adaptive controllers have been considered in this regard

Summary

Introduction

Biped robot control has attracted considerable attention in the last two decades. Compared to mobile and manipulator robots, these robots are tough to control due to inherent instability and dependence on balance and motion control systems. A fast nonsingular terminal sliding mode control was proposed in [18] to track reference trajectories in mobile robots in the presence of external perturbations and uncertainties. E adaptive nonsingular fast terminal sliding mode control was designed in [20] to track reference trajectories for a manipulator robot in the presence of uncertainty and external perturbations. In [21], the adaptive second-order fast nonsingular terminal sliding mode was introduced to control the manipulator robot in the presence of uncertainty and external perturbation. In [34], the sliding mode approach was adopted to control a biped robot with five degrees of freedom in the presence of uncertainty in both SSP and DSP states. E present paper has developed an adaptive nonsingular fast terminal sliding mode controller for a planar biped robot with five degrees of freedom. The vector of robot variables at final moment in the previous step, just after impact mapping [42, 43]

Motion Planning

Adaptive Nonsingular Fast Terminal Sliding Mode Controller Design

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