## CORRECTION article

Front. Robot. AI, 30 May 2023
Sec. Robotic Control Systems
Volume 10 - 2023 | https://doi.org/10.3389/frobt.2023.1204228

# Corrigendum: Terrain awareness using a tracked skid-steering vehicle with passive independent suspensions

• Department of Engineering for Innovation, University of Salento, Lecce, Italy

by Galati R and Reina G (2019). Front. Robot. AI 6:46. doi: 10.3389/frobt.2019.00046

In the published article, there was an error in section 2. Materials and Methods, 2.2 The Suspension System, paragraph two, regarding a term in Eq. 2 that was used to describe the simplified suspension system, as represented in Figure 6. This term was erroneously added to the equation because of an oversight, and in any case, it has not been used to elaborate the experimental data.

The paragraph previously stated:

“By considering a simplified suspension system as showed in Figure 6 where the presence of the sprung mass is neglected and the shock absorber has a spring constant of k = 37.27 N/mm, the linkage has mass M1 = 0.9 kg and length L = 0.1 m, the idle wheel has a radius of r = 0.04 m, mass m = 0.5 kg and stiffness kp, it is possible to write the equations to describe the subsystem behavior:

$IΘ″=−12gcosθM1L+mgL+r−kL02cosθ⁡sin⁡θ(1)$
$I=M13L2+m2r2+mL2(2)$

Where I is the inertia expression for the assembly composed by the suspension linkage and the idle wheel, θ is the angle related to the angular displacement of the linkage, $θ̈$ its second derivative, and O is the pivot point for the rotational motion of the linkage. By considering the small oscillations, it is possible to rewrite the expression in (Eq. 1) as:

$Iθ̈=−gLM12+m−kL0⁡cos⁡α2θ−L2kpθ(3)$
$fn=12π6kL0⁡cos⁡α2+kpL22M1L2+3mr2+6mL2(4)$

The last equation in (4) is used to express the natural frequency associated with the suspension system.”

The corrected paragraph appears as follows:

“By considering a simplified suspension system as shown in Figure 6, where the presence of the sprung mass is neglected and the shock absorber has a spring constant of k = 37.27 N/mm, the linkage has mass M1 = 0.9 kg and length L = 0.1 m, and the idle wheel has a radius of r = 0.04 m, mass m = 0.5 kg, and stiffness kp, it is possible to write the equations to describe the subsystem behavior:

$Iθ̈=−gLcosθM12+m−kL0⁡cos⁡α2⁡sin⁡θ−L2kp⁡sin⁡θ,(1)$
$I=M13L2+mL2,(2)$

where I is the inertia expression for the assembly composed by the suspension linkage and the idle wheel, θ is the angle related to the angular displacement of the linkage, $θ̈$ is its second derivative, and O is the pivot point for the rotational motion of the linkage. By considering the small oscillations, it is possible to rewrite the expression in (Eq. 1) as follows:

$Iθ̈=−gLM12+m−kL0⁡cos⁡α2θ−L2kpθ,(3)$
$fn=12π6kL0⁡cos⁡α2+kpL22M1L2+6mL2.(4)$

The last equation in (4) is used to express the natural frequency associated with the suspension system.”

The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated accordingly.

## Publisher’s note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors, and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Keywords: mobile robotics, terrain recognition, tracked vehicles, skid-steering, articulated suspension system

Citation: Galati R and Reina G (2023) Corrigendum: Terrain awareness using a tracked skid-steering vehicle with passive independent suspensions. Front. Robot. AI 10:1204228. doi: 10.3389/frobt.2023.1204228

Received: 11 April 2023; Accepted: 03 May 2023;
Published: 30 May 2023.

Edited and reviewed by

Kostas J. Kyriakopoulos, National Technical University of Athens, Greece

Copyright © 2023 Galati and Reina. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Rocco Galati, rocco.galati@unisalento.it