# Telepresence Social Robotics towards Co-Presence: A Review
## 1 Introduction
The system consisted of a simple controllable mobile platform with a video conference set-up (microphone, speaker, and a video camera with 16x zoom and a 30-cm screen on the top of a plastic pole). Additionally, the robot enabled simple gesturing through a two-DoF pointer. They introduced the concept of _tele-embodiment_ in the robotics context to describe the sensation of embodiment of a human in a real distant location [21]. _Tele-embodiment_ was defined as _telepresence with a personified perceptible body_[22]. However, they did not address key conditions such as body ownership [23] or agency [24]. [PERSON] [25] surveyed and compared 33 experimental works involving people's interactions with virtual agents, telepresence robots, and co-present robots, concluding that robots are more persuasive and positively perceived when they are physically present in the user's environment. Figure 1: Interaction scenario with telepresence and co-presence. [PERSON] [12] introduced the concept of _social presence_, defining it as the degree of salience of the participants involved in an interaction and their interpersonal relationship. He mentioned that _social presence_ relied on two concepts: _inttimacy_ and _immediacy_. _Intimacy_ senses the degree of connectedness between the interactants, and _immediacy_ refers to the psychological sense of togetherness between the communicators. Taking face to face (Ftf) as the reference, both concepts are determined by a set of verbal and nonverbal cues such as vocal cues, gestures, facial expressions, and physical appearance. The capability to deliver such cues differs from communication means, so [PERSON] considered social presence as the _quality of the medium itself_. Later, [PERSON] [13] referred to _social presence_ as the effect on one person's behavior caused by the presence of another or caused by knowing that he or she could be observed. _Co-presence_, defined as the \"psychological connection to and with another person\" [17; 26], has been explored in several works [27; 28; 29; 30]. Cognitive robotics aims to provide robots with intelligent behavior through a processing architecture that involves perception, long- and short-term memory, learning, and reasoning. These approaches try to deal with people's behavior unpredictability and with real-world complexity. Cognitive technologies are a form of hyper-automation that may combine areas such as symbolic representation, automation, prediction, user-adaptive systems, computer vision (CV), machine learning (ML), deep learning (DL), or artificial intelligence (AI) [2; 9; 31]. Nevertheless, the use of AI methodologies to emulate or interpret human subjective experiences, such as emotions, should be inspired by neurophysiologic-psychological foundations [32]. An inner issue related to teleoperated telepresence robots is the time delay issue (mainly due to the communication channel and less due to the hardware performance). This can affect synchronicity (rate of message exchange between operator and bystander), compromising the social presence [33] (e.g., degradations in audio and video streams, control streams, and haptic feedback). Problems regarding latency, bandwidth limitations, and channel corruptions should be mitigated, and while early solutions involved user interface design and control theory-based models (e.g., supervisory control or passivity-based teleoperation), the approaches evolved to predictive displays and control. Advanced solutions for time delay issues are using time series prediction methods to predict the time delay, a robot's movements, and user intentions. These new adaptive-based control methods make use of nonlinear statistical models and neural network (NN) or machine learning (ML) techniques (e.g., recurrent neural networks, sequence to sequence, long short-term memory, or generative adversarial networks) [31].