**1. Introduction**

We are currently facing a societal problem: the world's population is growing older fast [1]. While this could be grea<sup>t</sup> news (and it is), there are intrinsic problems that come with fast shifting demographic changes, and being unprepared for growing health requirements that elderly people have is one of them.

Persons over the age of 65 are the fastest-growing age group, and it is expected that by 2050, 16% of the world population will be over 65 years, while in 2019, this value was already 9% [1]. This projection is global, meaning that regions such as Northern Africa and Western Asia, Central and Southern Asia, Eastern and South-Eastern Asia, and Latin America and the Caribbean are expected to double their elderly population [1]. Furthermore, by 2050, 25% of the population in Europe will be 65 years or over, being accompanied by an interesting fact: in 2018, children under five years of age were outnumbered by persons aged over 65 [1]. This rapid increase is mainly due to improved medical care, which diminishes the mortality rate. Although people live longer, this is not without its problems. In the Euro28 area, it is expected that people over 65 years only have 10 more years (on average) until serious health problems start to appear, as reported by the United Nations (UN) [1].

In their latest census, the UN has identified that there is an increasing shortage of employed people, thus causing high stress to social protection systems [1]. This is due to two factors: the decrease of working-age people and the social-economic problems of countries. For instance, in Japan, the ratio between people aged 25–64 to those over age 65 is 1.8, while in most of Europe, the value is starting to fall below of three. This means that there will be a high impact to countries' economies as the GDP will be affected by the decrease of the labor market, being overburdened by the increasing costs of healthcare systems, pensions, and social protection.

Apart from the economic distress, there is the healthcare distress. Studies, like the ones that were presented by Licher [2] and Jaul [3], show that maintaining high levels of quality of life while aging is complicated. There is no clear path towards a definitive medical solution, as most of the illnesses are non-curable and have very complex pathologies. A possible stand-in replacement to a medical treatment is backed by several research studies [4–6] that show that it is possible to refrain from the advances of these illnesses by keeping the elderly active both physically and cognitively through exercises. These exercises are often complex and require attention from a caregiver, either to help perform those exercises or to correct the posture/strategy. This requires a large amount of monitoring time by another person.

The caregivers are often overburdened by the care and assistance work, as evidenced by these works [7–9] (with the most severe cases being non-specialized trained caregivers combined with high-dependency elders). This means that often, the caregiver puts his/her health at risk, and the elder does not receive adequate care. In specialized facilities, like nursing homes, this is less accentuated; nonetheless, the lack of caregivers and the high number of residents may lead to a poorer experience in these facilities [10]. Furthermore, as previously stated, the elderly are not economically prepared for the high cost that these facilities charge [11].

In short, in the near future, a large number of older people will be left alone in their homes while suffering from limiting and life-threatening diseases because they cannot afford nursing homes or home care services or because they are not able to have assistance from an informal caregiver.

A possible solution to these issues may be the usage of technology to help elderly people perform Activities of Daily Living (ADL) or attenuate their loneliness, while actively monitoring their health status. There are already some projects in this domain, explained in depth in Section 2. These projects shed some light on what the current approaches are, and more importantly, what the needs of elderly people are and how technology can improve their quality of life.

Our project goal is to create a way so that elderly people can in stay their homes safely and under active supervision, while at the same time engaging them in personalized active exercises and exergames. The way that this goal is achieved by our platform is by using a low-cost, easy-to-deploy sensor system that is able to monitor said exercises and interact with the elders, sending reports to the informal/formal caregivers. The platform is constituted by two components: the sensors and the software (exercise evaluator, scheduler, information portal, and interactor). Our proposal covers a less traveled path, which is the usage of low-cost sensors (using in expensive commercial components and 3D printing) together with health-related software that gives personalized advice.

This paper is a continuation of the work presented in [12]. The main improvements in relation to it are the improved sensor systems and the learning models for information extraction. Additionally, the objective is that others are able to reproduce our platform with ease from the information presented in this paper.

The paper is structured as follows. Section 2 analyses the related work. Section 3 presents the proposed system, which describes the hardware (wristbands) and the emotion and activity detection. Finally, the conclusions are presented in Section 4.

## **2. Related Work**

This project touches on prolific domains: emotion detection, human activity recognition, and cognitive assistants. Therefore, in this section, we present related work that belongs to those domains or, like this project, touches on all or part of them.
