machines Article On the Suspension Design of Paquitop, a Novel Service Robot for Home Assistance Applications Luigi Tagliavini, Andrea Botta , Paride Cavallone , Luca Carbonari and Giuseppe Quaglia *   Citation: Tagliavini, L.; Botta, A.; Cavallone, P.; Carbonari, L.; Quaglia, G. On the Suspension Design of Paquitop, a Novel Service Robot for Home Assistance Applications. Machines 2021, 9, 52. https:// doi.org/10.3390/machines9030052 Academic Editor: Dan Zhang Received: 27 January 2021 Accepted: 24 February 2021 Published: 2 March 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/). Department of Mechanical and Aerospace Engineering, Politecnico di Torino, 10129 Torino, Italy; luigi.tagliavini@polito.it (L.T.); andrea.botta@polito.it (A.B.); paride.cavallone@polito.it (P.C.); luca.carbonari@polito.it (L.C.) * Correspondence: giuseppe.quaglia@polito.it Abstract: The general and constant ageing of the world population that has been observed in the last decade has led robotics researchers community to focus its aims to answer the ever-growing demand for health care, housing, care-giving, and social security. Among others, the researchers at Politecnico di Torino are developing a novel platform to enhance the performance offered by present- day issues, and to assess many others which were not even taken into consideration before they have been highlighted by the pandemic emergency currently in progress. This situation, in fact, made dramatically clear how important it is to have reliable non-human operators whom one can trust when the life of elderly or weak patients is endangered by the simple presence of other people. The platform, named Paquitop, features an innovative architecture conceived for omni-directional planar motion. The machine is designed for domestic, unstructured, and variously populated environments. Therefore, the mobile robot should be able to avoid or pass over small obstacles, passing through the capability to achieve specific person tracking tasks, and arriving to the need of operating with an high dynamic performance. Given its purpose, this work addresses the design of the suspension system which enables the platform to ensure a steady floor contact and adequate stability in every using condition. Different configurations of such system are then presented and compared through use-case simulations. Keywords: mobile robot; service robotics; modular robot; suspensions design 1. Introduction The ageing of the population and the increasing attention to automatized caregiving are pushing research towards the development of autonomous machines, tailored to meet the need of assisting weak or non-self-sufficient subjects [1]. The current pandemic emergency caused by the Covid-19, has highlighted the need of freeing many activities from the presence of human operators, especially in hospital environments or geriatric wards and hospices, where patients are endangered by their closeness to other people [2]. Although human staff cannot be replaced entirely (e.g., for complex operations and companionship), properly conceived and instrumented robots can be entrusted with other duties. Blood pressure, temperature, and oxygen saturation measurements, patient monitoring, triage activities, delivery of lightweight medical products and documents or simply remote presence are some examples of tasks that could be easily assessed without the presence of humans. Moreover, autonomous machines can accomplish these easy tasks enabling a better redistribution of the precious human resource on those fundamental duties where operators cannot be replaced by robots. Pursuing this objective automatically implies a variety of technical challenges that go far beyond a careful motion planning and smart control of the robotic system, even if significant advances were made in this sense [3]: on-line path planning [4], innovative use of sensors [5], and development of localization strategies [6] are examples of the fields that caught the attention of the research community. Alongside with such aspects, Machines 2021, 9, 52. https://doi.org/10.3390/machines9030052 https://www.mdpi.com/journal/machines