## 1 Introduction
### State-of-the-Art Robotic Applications in Medication Adherence Activities  
To accurately classify a robot as personal service or a professional service robot, a precise overview of the task that the robot agent is designated to perform should be performed [7]. In the domain of personal service robots, which is of particular relevance in this work, the majority of the robots target domestic applications and can be classified as mobile servant, people carrier, physical assistant, personal care and healthcare assistant robots [8; 9]. A representative taxonomy in the domain of health care robots could differentiate them among those that provide physical assistance, those that provide companionship, and those that monitor health and safety. Remarkable assisting robots for the elderly have been developed so far under the scope of research projects, such as the HOBBIT project [1], which combined research from robotics, gerontology, and human-robot interaction in order to develop a healthcare robot capable of preventing falls, detecting emergencies, bringing of objects and offering reminders to the users. The ACCOMPANY project was built upon the Care-O-Bot(r)3 integrated in a smart-home environment aiming empathic and social human-robot interaction, robot learning and memory visualization as well as persons' monitoring at home [2]. Albeit the fact that these robots were mainly designed to provide healthcare assistance, the challenging task of assisting, with robotic manipulations intervention, in medication tasks was merely studied, and the provided solutions were focused solely on the provision of reminders and notifications. However, a plethora of laborious research has already been conducted in the respective domain covering feasibility studies of contemporary robots to provide assistance during medication tasks. The need of contemporary agents to assist in medication activities is a global preference for the healthcare robots [10]. The authors conducted a specific research in a retirement home which substantiates a claim that residents may expect robots to assist them in medication adherence activities. This is further reinforced by the study conducted in [11], where it is indicated that people, in a retirement village that utilizes healthcare robots, rate highly the reminders' provision in medication adherence activities. Moreover, apart from the user's preferences, it is important to assess the feasibility of robots to assist in medication sessions as well as the definition of the level and type of intervention. A touch screen and voice-based interface integrated on a robot, introduced in [12], proved it is an effective platform able to proactively support users with their healthcare delivery related to assistance provision to elderly individuals with mild cognitive and physical impairments, through human-robot interaction, people monitoring and probabilistic action planning for robot motion next to the user. Specifically, in this work, a robotic agent acted as a prompting mechanism, through the establishment of interactive communication, to stimulate the elderly to complete their medication adherence task. These findings are further emphasized when considering the feasibility study [13], where several years later, the same experimental topology had been applied on a sample of ten older users. This experiment exhibited remarkable results, based on which the concept of reminders provision through a robot was well received from all users that successfully completed the session, and most subjects found it easy to use, appropriately designed and felt confident using it. However, in accordance with a recent study [14], it is revealed that contemporary healthcare robots are mostly tailored to assist in medication adherence activities by providing reminders (regarding the medication adherence schedule) or monitoring the medication sessions while only few approaches also addressed the medication fetching task.