# Predefined-Time Super-Twisting Sliding Mode Control for Construction Robot with Arbitrary Initial Values

## TL;DR

This paper introduces a new control method for construction robots to track reference trajectories accurately and efficiently.

## Contribution

A novel super-twisting sliding mode controller with predefined-time convergence is developed for construction robots.

## Key findings

- The controller ensures accurate tracking of reference trajectories with an angular error of 3 × 10−6 rad.
- A nonsingular sliding surface and RBF neural network are used to handle disturbances in the system.
- The proposed method is validated through numerical simulations.

## Abstract

To tackle the practical engineering challenge that construction robots are required to track the reference trajectory completely and precisely, this study puts forward a control scheme based on the extended reference trajectory and develops a novel super-twisting sliding mode controller with predefined-time convergence capability. First, the influence mechanism of fluid materials on construction robots and their trajectory tracking control features are explored, and the design approach for the extended reference trajectory is elaborated. Subsequently, a nonsingular sliding surface with predefined-time convergence is constructed, and a RBF neural network with convergent weight vectors is established to approximate the composite disturbances existing in the robot system. On the basis of the proposed predefined-time convergent super-twisting control theory, a super-twisting sliding mode controller tailored for construction robots is devised, and the predefined-time convergence performance of the closed-loop system is theoretically validated. Numerical simulation results indicate that the proposed algorithm can guarantee that the construction robot’s angles move accurately along the actual reference trajectory, with the angular tracking error achieving a precision of 3 × 10−6 rad, thereby confirming the feasibility and effectiveness of the proposed method.