Video Transmission with Adaptive Quality based on Network Feedback for Mobile Robot Teleoperation in Wireless Multi-hop Networks

A video stream is still one of the most important data sources for the user while remote-operating a mobile robot. Human operators have comprehensive capabilities to interpret the displayed image information, but therefore, some constraints must be fulfilled. Constant frame rates and delays below a certain threshold are a minimum requirement to use video for teleoperation. Modern multi-hop networks often use WLAN to set up ad-hoc networks of mobile nodes with each node acting as traffic source, sink, or router. Considering these networks, routes between sources and destinations might be established via several relay nodes. Thus, the utilization of intermediate nodes which are part of a route influences the overall route performance, whereas sender and receiver have no direct feedback of the overall route status. In case video is transmitted via wireless ad-hoc networks in a teleoperation scenario, the displayed video-stream for the operator might have variable frame rates, very high packet loss, and packet inter-arrival times which are not appropriate for mobile robot teleoperation. This work presents an approach using a feedback generated by the network to adapt the image quality to present communication constraints. Thus, according to the current network status, the best possible video image is provided to the operator while keeping constant frame rates and low packet loss.

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