Citation: Riabtsev, M.; Petuya, V.;
Urízar, M.; Altuzarra, O. Design and
Testing of Two Haptic Devices Based
on Reconfigurable 2R Joints. Appl.
Sci. 2022, 12, 339. https://doi.org/
10.3390/app12010339
Academic Editor: Jose Machado
Received: 1 December 2021
Accepted: 27 December 2021
Published: 30 December 2021
Publisher’s Note: MDPI stays neutral
with regard to jurisdictional claims in
published maps and institutional affil-
iations.
Copyright: © 2021 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
Article
Design and Testing of Two Haptic Devices Based on
Reconfigurable 2R Joints
Mykhailo Riabtsev *, Victor Petuya , Mónica Urízar and Oscar Altuzarra
Department of Mechanical Engineering, University of the Basque Country UPV/EHU, Plaza Torres Quevedo 1,
48013 Bilbao, Spain; victor.petuya@ehu.es (V.P.); monica.urizar@ehu.es (M.U.); oscar.altuzarra@ehu.es (O.A.)
* Correspondence: mriabtsev001@ikasle.ehu.eus
Abstract:
This paper presents the design and testing of two haptic devices, based on reconfigurable
2R joints: an active 2R spherical mechanism-based joint and a differential gear-based joint. Based
on our previous works, in which the design and kinematic analysis of both reconfigurable joints
were developed, the experimental setup and the various tasks intended to test the reconfigurability,
precision, force feedback system and general performance, are presented herein. Two control modes
for the haptic device operation are proposed and studied. The statistical analysis tools and their
selection principles are described. The mechanical design of two experimental setups and the main
elements are considered in detail. The Robot Operating System nodes and the topics that are used in
the software component of the experimental setup are presented and explained. The experimental
testing was carried out with a number of participants and the corresponding results were analyzed
with the selected statistical tools. A detailed interpretation and discussion on of the results is provided.
Keywords: haptic device; reconfigurable joint; statistical analysis; force feedback; control mode
1. Introduction
A haptic device is an instrument that is used to perform different kinds of manipula-
tions with objects, providing the operator with feedback, i.e., tactile feedback, vibrational
feedback, force feedback, etc. The application of haptic devices varies from handling
virtual three-dimensional (3D) bodies [
1
,
2
] to device remote control [
3
–
5
] and surgery [
6
,
7
].
Different types of feedback can be used to indicate the interaction with the controlled object.
Some devices provide vibrational feedback [
8
–
10
] and others can implement torque [
6
]
or force feedback [
2
,
11
–
13
]. The most widely used architectures of haptic devices are
serial [2,7] parallel [6,13,14] or cable drive-based architectures [15].
Regarding the most common type of joints that are implemented in commercial robots
and manipulators, universal and spherical joints are among the most widely used in parallel
manipulators. They are utilized in Delta robots and Stewart–Gough platforms and in haptic
devices that share a similar architecture [
6
,
14
]. Spherical joints and mechanisms have been
applied in commercially available serial haptic devices. The 3D SYSTEMS Company has
proposed three models of serial haptic devices [
2
,
11
]. Examples of applications of spherical
mechanisms in haptic devices can be found in [
16
,
17
]. A spherical joint was applied in a
haptic device with magnetorheological-based feedback in [7].
However, typically a haptic device design does not provide any reconfiguration
ability that can extend the device’s capacity. This functionality can be provided by using
reconfigurable or active spherical joints that could be adapted for reconfiguration. A
reconfigurable joint is a joint that can change its performance according to the necessary
task. It can lock a degree of freedom (DOF) [
18
], changing the direction of an axis of one of
the DOFs [
19
], or combining the functions of several different joint types [
20
]. The joints
can have different working principles. They can be based on a gear-like drive [
21
–
24
], have
a direct connection with the actuators [
25
], form a spherical 2DOF [
26
] or 3DOF mechanism,
or be electromagnetically driven [27].
Appl. Sci. 2022, 12, 339. https://doi.org/10.3390/app12010339 https://www.mdpi.com/journal/applsci
