# A Review on Methods and Systems for Remote Collaboration
## 3 Electronic Devices Used in Remote Assistance  
When developing a remote collaboration system, particular devices with different form factors are adapted for various purposes and scenarios. For example, video cameras can be head-mounted or worn on the shoulder; information can be displayed on a PC screen, projected, or seen through a head-mounted device (HMD). The system proposed by [PERSON] et al. [1] was intended for remote surgery. A 2 DOF (degree of freedom) robotic arm was controlled distantly by electromyographic signals captured from the remote user's muscles, corresponding to the human arm's natural movements. Another system for remote surgery is presented in [2]; the doctor performing the surgery uses an HMD and controls a surgical robot remotely. The article's title is \"The rise of robots in surgical environments during COVID-19\", which underlines the favorable context for the proliferation of remote systems during the COVID-19 pandemic. A more complex system used in remote surgery that employs a robotic arm is presented by [PERSON] et al. in [4]. The system has an expert station that allows the surgeon to control the surgical robots located at the remote intervention site through a 3D force-feedback haptic robot. [PERSON] [26] was among the first researchers who proposed a system to be used by two remote users for educational purposes, the aim being to set up a wired circuit. The prototype developed for the worker's side was composed of a video camera attached to a head-mounted device (HMD). The camera sensor was pointing away from the user in the approximate direction of the local user's gaze and tried to capture images of the task area. On the remote side, the expert analyzed the images and instructed the user on what steps to follow via a telepointer. [PERSON]'s [27] study showed that in a remote bike repairing context, in addition to a head-mounted camera worn by the repairer, a scene camera provided valuable visual information for remote collaboration on physical tasks and augmented the feeling of co-presence for the remote helper. The wearable active camera laser (WACL) described in [28] incepted the idea of placing the camera on the shoulder of the local user. A laser pointer was attached to the video camera, and the remote user controlled the laser beam intended for spatial guidance. The expert and the worker had headsets with microphones used to convey instructions and explanations from the working site. The system was tested in the context of an assembly task (Lego assembly). The results from [28] showed that, compared with a head-mounted camera, the WACL was more comfortable and caused less fatigue, although, if the wearer moved the laser pointer slightly, the pointer position changed; hence, guidance became difficult. [PERSON] [29; 30] proposed a 2 DOF robot on wheels, situated on a worksite and controlled by a remote expert. A video camera was fixed to the top of the robot, allowing it to capture the local environment, while a projector was used to project the expert's instructions to the remote worker. The solution was targeted to the manufacturing industry for tasks involving maintenance operations. [PERSON] and [PERSON] [31] presented a remote guidance system that enabled a remote expert to instruct a mobile worker using sticky annotations. The worker wore a helmet equipped with a small camera and a laser pico projector placed on top of the helmet. These devices were connected to a laptop in the local user's backpack. The remote helper received the video stream on a tablet that also communicated with the worker's PC. The tablet allowed the expert to sketch the instructions, which were transmitted, with the help of the pico projector, as a 3D line into the local user's environment. This system was aimed to be deployed in the domains of industrial manufacturing for maintenance and healthcare for medical consultations.