Citation: Yang, J.; Sun, T. Finite-Time
Interactive Control of Robots with
Multiple Interaction Modes. Sensors
2022, 22, 3668. https://doi.org/
10.3390/s22103668
Academic Editors: Enrico Vezzetti,
Andrea Luigi Guerra, Gabriele
Baronio, Domenico Speranza and
Luca Ulrich
Received: 14 April 2022
Accepted: 10 May 2022
Published: 11 May 2022
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Article
Finite-Time Interactive Control of Robots with Multiple
Interaction Modes
Jiantao Yang and Tairen Sun *
The School of Health Science and Engineering, University of Shanghai for Science and Technology,
Shanghai 200093, China; jty@usst.edu.cn
* Correspondence: suntren@gmail.com
Abstract:
This paper proposes a finite-time multi-modal robotic control strategy for physical human–
robot interaction. The proposed multi-modal controller consists of a modified super-twisting-based
finite-time control term that is designed in each interaction mode and a continuity-guaranteed control
term. The finite-time control term guarantees finite-time achievement of the desired impedance
dynamics in active interaction mode (AIM), makes the tracking error of the reference trajectory
converge to zero in finite time in passive interaction mode (PIM), and also guarantees robotic motion
stop in finite time in safety-stop mode (SSM). Meanwhile, the continuity-guaranteed control term
guarantees control input continuity and steady interaction modes transition. The finite-time closed-
loop control stability and the control effectiveness is validated by Lyapunov-based theoretical analysis
and simulations on a robot manipulator.
Keywords:
multiple interaction modes; finite-time control; human–robot interaction; impedance
control; trajectory tracking
1. Introduction
With the development of modern robots, human robot co-existent scenario are proven
to be a clear trend, which gives rise to the emerging field of research named human robot in-
teraction (HRI). Human collaborated with robots will enhance their strength and efficiency.
When maximizing the performance, efficiency, and applicability of coupled human–robot
systems, robots are used for assisting users toward realizing their planed action makes
up of half of the solution, and the other half is ensuring the reliability and safety of the
system [
1
]. Today, robot technology can be seen everywhere, including industrial robot,
social robot, medical robot. It seems that robot technology can do anything. However, a
serious problem also arises that robots’ reliability may be overtrusted [
2
]. For example, it is
reported that people may copy Artificial Intelligence (AI)’ action without evaluations [
3
].
Thus, reliability and safety in human–robot interaction should be investigated widely.
In active interaction mode (AIM) of physical human–robot interaction, the human
initiates a motion and the robot plays as a follower. In this mode, interaction compliance is
important to guarantee the human’s comfort and safety. As a powerful active compliance
control approach, impedance control proposed in 1980s by Hogan can regulate robot
impedance in certain ranges through the desired impedance dynamics which describes
a dynamical relationship between robot position and interaction force [
4
]. Since its first
development, it has received large much research attention and applied in service robots
and industrial robots [
5
–
7
]. Robot modeling uncertainties are the main factor that affects
impedance control stability and robustness. To improve control robustness, categories
of impedance control strategies were proposed based on adaptive control [
8
–
11
], neural
networks [
12
–
16
], sliding mode technique [
17
,
18
], and iterative learning [
19
,
20
]. However,
these impedance controllers obtain infinite-time control stability and the desired impedance
dynamics in these results were achieved in infinite time. Compared with infinite-time
control, finite-time control of robot has better control robustness and can make robot track
Sensors 2022, 22, 3668. https://doi.org/10.3390/s22103668 https://www.mdpi.com/journal/sensors
