Citation: Li, J.; Wang, C. Dynamics
Modeling and Adaptive Sliding
Mode Control of a Hybrid Condenser
Cleaning Robot. Actuators 2022, 11,
119. https://doi.org/10.3390/
act11050119
Academic Editor: André Preumont
Received: 11 March 2022
Accepted: 22 April 2022
Published: 24 April 2022
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Article
Dynamics Modeling and Adaptive Sliding Mode Control of a
Hybrid Condenser Cleaning Robot
Jiabao Li and Chengjun Wang *
College of Artificial Intelligence, Anhui University of Science and Technology, Huainan 232001, China;
2020201446@aust.edu.cn
* Correspondence: 2001055@aust.edu.cn
Abstract:
This study examines the pose control of the 4-RPU redundant parallel mechanism of
a hybrid condenser cleaning robot in response to the poor control accuracy of current cleaning
robots. The kinematics of the 4-RPU mechanism is analysed, and its dynamics model is constructed
using the virtual work principle. The theoretical calculation and virtual prototype simulation of
the constructed model are conducted in MATLAB and ADAMS, which yield basically consistent
results, demonstrating the precision of the model. Based on this model, an adaptive sliding mode
control method is proposed that can estimate and compensate for parameter uncertainties and load
perturbations simultaneously. The system stability is analysed using Lyapunov functions. The results
suggest that the adaptive sliding mode control method can significantly reduce the average tracking
error of each degree of freedom of the moving platform and exhibits higher control stability and
convergence accuracy than the conventional sliding mode control algorithm. This study provides a
reference and research basis for attitude control of the cleaning robots affected by uncertainties such
as water backlash during operation.
Keywords:
4-RPU parallel mechanism; dynamics model; adaptive sliding mode control; trajectory
tracking
1. Introduction
Condensers are essential heat-transfer equipment [
1
] in petrochemical and power
plant industries. The current cleaning methods for these are mostly tandem robotic arms
or manually operated high-pressure water-gun cleaning [
2
,
3
]. However, high-pressure
water backlash and other factors cause the existing methods to be less stable, accurate,
and efficient than is desired, and special cleaning robots must be developed for the use
of condensers.
Kinematic and dynamic analyses are the basis for parallel mechanism research [
4
–
6
].
Lei et al. [
7
] conducted kinematics calibration and error analysis for a 3-RRRU parallel
robot, while Jinzhu et al. [
8
] proposed a multi-branch coupled parallel drive mechanism
with five degrees of freedom and analysed the mechanism based on the azimuth feature set
method, degrees of freedom, and motion characteristics of the end of the mechanism. The
existing dynamic modeling methods mainly include: the Newton–Euler method
[9–11]
,
Lagrangian method [
12
,
13
], and virtual work principle method [
14
–
16
], in which the virtual
work principle omits calculation constraints force and moment, and the derivation process
is concise. Xinxue et al. [
17
] conducted a singular analysis of the 2-UPR-RPU parallel
mechanism, while Guangchun et al. [
18
] used the virtual work principle to carry out
dynamic and power analyses. The PD/PID control method is usually used to control
the trajectory and pose of the parallel mechanism [
19
–
21
], but control will be affected by
the parameter error or external load disturbance in the dynamic model of the parallel
mechanism. Xuemei et al. [
22
] used ASMC to suppress the load disturbance of the parallel
mechanism but did not consider the parameter uncertainty and the time-varying load.
Actuators 2022, 11, 119. https://doi.org/10.3390/act11050119 https://www.mdpi.com/journal/actuators
