## 3 The Human Role in Teleoperation
### Human Factors, Tasks, and Telepresence  
Human beings have a remarkable ability to adapt to unexpected constraints and still carry on with their actions [30]. Skilled people can perform tasks, including teleoperation, even when there are momentary failures in certain feedback channels, such as visual feedback. This means that the person has memorized all the operations and can predict the output of his/her actions under certain ranges of disturbances in the visual feedback. In the absence of the typical feedback modality, other senses are used to get the necessary feedback; memories are triggered, and adjustments can be made (e.g., haptic feedback, touch). Even in cases where the sequence of actions is to be memorized and the person is expected to be able to execute the sequence of actions without any kind of external stimuli, he or she uses various sensorial cues (e.g., proprioception and time notion) to adjust the performance and correct any motor action deviations. With teleoperation, a user aims to transfer his/her abilities to a remote agent to perform tasks like navigation, perception, and manipulation. If during this process, he/she may have the impression of being at the remote site, these actions will benefit from first person perception and cognitive mechanisms, and therefore improve the achieved performance. This sense of being at the remote site may be defined as telepresence [13]. [PERSON] [31] and [PERSON] [32] mentioned that there is a close link between self-experience, selfhood, and the first-person perspective. [PERSON] also referred to \"The Consciously Experienced First-Person Perspective\" to support more complex forms of phenomenal content, such a conscious representation of the _relation_ between the person and varying objects in his/her environments. _Issues affecting telepresence_: A user can perceive a remote environment and navigate or manipulate objects through a teleoperated robotic system; however, several issues can affect such tasks, degrading the sense of telepresence [8; 19]:  
_Field of view (FoV)_: Observing the remote environment through a camera's video stream reduces the peripheral vision of the user, and it can negatively affect the spatial perception, compromising manipulation and navigation abilities. _Knowledge of the robot's orientation_: Users need to know the position and orientation of the robotic agent in the remote place, as well as the robot's topology (e.g., arm position, body size, and pitch and roll angles). _Camera's view point_ and _frame of reference_: The placement of the cameras may affect visual perception by providing unnatural views to the user (i.e., compromising pose and position estimation). The egocentric (first-person) perspective comes up as the view for someone present in a space, enhancing, therefore, the sense of telepresence. However, sometimes, an exocentric camera view (third person) may present advantages in the execution of a specific task. _Depth perception_: Viewing the remote scenario through a monocular camera can limit the acquisition of significant depth information. The projection of 3D depth information onto a 2D display surface foreshortens or compresses depth cues (e.g., distance underestimation). _Video image quality_: Factors like low image resolution, reduced frame rate, or reduced number of colors can make user's remote spatial awareness, target localization, and consequently, response time difficult. _Latency_: The time lag verified between the operator's input control action and the observed system response determines his/her control behavior. The aim is a continuous and smooth control operation; however, when the latency increases, the operator adopts the \"move and wait\" control strategy. _Motion effect_: Performing manual tasks on top of a moving platform can be quite challenging and ultimately can induce the operator's motion sickness. Vibrations and disturbances of the visual feedback can make the operator's input controls challenging.