# A Review on Methods and Systems for Remote Collaboration
## 3 Electronic Devices Used in Remote Assistance
The study's main interest was to see how quickly the job was completed when the worker was using an HMD with head-tracking and mono camera systems, while the helper was using a fixed 2D monitor to see the worker's space. The video feed, captured at the local site by a camera mounted on the robot pan/tilt servo system, was seen by the remote user on his HMD. Using a head-tracking module, the helper could control the robot and the camera's orientation so that he could see the remote environment from various angles. Most of the previously described prototypes concentrate on the remote user's awareness rather than the local user's reactions. In contrast, Empathy Glasses [49; 50], proposed by [PERSON] et al., focus on acquiring the local user's heart rate and facial expression as well as his gaze and viewpoint. To accomplish this, the system combines a see-through display with a head-mounted camera, an eye tracker, a facial expression tracker, and a heart rate monitor. The helper sees all the information acquired from those modules on a remote desktop interface. Traditional remote collaboration solutions have examined what a single user sees in his local space, but JackInSpace [51] utilizes a new approach that allows a remote user to switch between the view of different local users (body users). In the prototype, the local user's side includes a head-mounted fisheye camera and depth sensors that capture the data and recreate a virtual 3D environment for the ghost (remote user). The remote user can enter the first local user's view to analyze the environment and, afterwards, can switch to another local user's view to see the scene from a different angle. The ghost wears 3D glasses to see the virtual perspective of the body user, displayed on three screens with the help of three projectors, an HDMI splitter, and a motion capture system. MirrorTablet [52] is a low-cost system used for capturing hand gestures and is proposed for situations where both the helper and the worker are equipped with a mobile device (tablet). The hardware setup on the helper's side is composed of a mobile tablet on top of which is positioned a mirror within the field of view of the tablet's video camera. The mirror reflects the tablet's screen and the image of the hand gestures to make them visible to the camera. The video data captured from the worker are transmitted to the helper, and the instructions from the helper are overlaid on the worker's screen. Unlike traditional remote collaboration systems, where the communication is done face to face, Gutsy-Avatar [53] allows the remote user to have the same view as the local one in an unusual way. This is performed using an electronically controlled t-shirt. The system architecture is presented in Figure 5. A local user wears a t-shirt embedded with a smart device/tablet with an attached camera. The device captures the local user's surroundings and displays them to the remote user. Behind the tablet, there are four servo motors commanded by a microcontroller, which receives commands from the expert's PC via the user's tablet. For the remote user, a PC with a video camera is needed to capture the user's face and send instructions related to the direction of the local camera view. The remote user changes the camera's view by sending commands to the server. Microsoft Remote Assist [17; 18; 19] is based on a HoloLens app that enables the remote collaborator to see everything that the local user is seeing (including holograms and the real environment) and to add annotations that can be seen by the local user. The host wears a Microsoft HoloLens device equipped with a video camera and depth sensors capable of tracking hand gestures and eye and head movements. Remote Manipulator (ReMa) [54] focuses on reproducing the local object's manipulation of the remote site using a proxy object. At the tracking site, the object's manipulations are captured by infrared cameras and are transmitted to the manipulator's site, where they are displayed on a similar object, called a proxy object.