# A Review on Methods and Systems for Remote Collaboration
## 3 Electronic Devices Used in Remote Assistance
Starting in 2010, we noticed that smart devices (mobile phones or tablets) were designed to facilitate remote visualization and collaboration between workers in factories and experts in different locations [14; 15]. The prototype proposed by [PERSON] in [32] is a mobile remote collaboration system used to assist a user in operating a mock-up airplane cockpit. The pilot was guided by the instructions of a remote helper. The local user was equipped with a tablet device with an integrated camera for sending environmental information remotely, and the display showed the virtual annotations placed by the remote expert. The remote user was presented with a view of the local user's environment and, besides controlling the annotations, the helper could also \"freeze\" his viewpoint at any time. Later, [PERSON] et al. [33] presented an improved solution for mobile remote collaboration. The solution enabled the helper to have an independent view of the local user's environment by controlling the remote video camera and the augmented reality (AR) annotations displayed on the local user's smart device (tablet). It was tested by a user repairing a car following the instructions of a remote helper. Teleadvisor [34], a novel design used to solve complex wiring tasks, comprises two devices, the Teleadvisor component and the controller display. A worker controls the position of the Teleadvisor, represented by a robotic arm with a camera and a pico projector mounted on the top. Teleadvisor's camera captures the visual information, and the data are transmitted to an off-site controller operated by an expert. With the help of the projector, the information sent from the controller back to the Teleadvisor is displayed as an overlay emphasizing objects in the worker's environment. Thanks to the mobile robotic arm, the helper can move the camera's viewpoint closer to the object and zoom in and out. All the aforementioned solutions [26; 27; 28; 29; 30; 31; 32; 33; 34] require a fixed setup for the cameras, either on the worker's or the helper's side. In contrast, HandsInAir [35] includes a new feature that allows mobility for both the remote helper and the worker. This novel approach is highly relevant for factories where workers need to walk around and inspect different machines. The solution requires that both users are wearing the same equipment, consisting of a camera mounted on a helmet and a custom-built near-eye display beneath the brim. The worker's camera is used to capture the worker's actions, and the remote user's camera captures the hand gestures of the helper, providing instructions for the local user. The MobileHelper presented in [36] proposes a similar approach as [35]. The worker has a helmet equipped with a video camera and a near-eye display, but the remote helper uses a tablet. The video transmitted from the worker's camera is displayed on the helper's device. The tablet's video camera captures the hand gestures of the helper and combines them with the video data, and the result is displayed on the helper's tablet screen and the worker's near-eye display. The study in [37] focused on how AR can be used to enhance remote space collaboration. The system used a Kinect depth sensor to capture a 3D model of the local user's surroundings, on which a remote user could overlay annotations. These labels appeared projected onto a screen with the help of a laser projector, which in turn could be manipulated by the remote expert. This solution also allowed the possibility for the off-site expert to manipulate the scene independently of the view of the local user. Domova [38] presented a system conceived for solving physical tasks in the manufacturing industry, allowing both the on-site worker and the off-site helper to annotate video feeds. The worker carried a mobile phone with video streaming capabilities to capture the details of the local environment, and the scene information was displayed on the remote user's PC.