System For Transmitting Commands And A Video Stream Between A Remote Controlled Machine Such As A Drone And A Ground Station

Abstract

A system for transmitting commands and a video stream between a remote controlled machine such as a drone and a ground station comprises a two-way link between the machine and ground station, at least partially implementing a cellular communication network, said two-way link being provided by means of a cellular modem on the machine side and conveying a compressed video stream produced by a camera and a video encoding module, and information belonging to a group comprising movement control commands and flight data or operating characteristics of the remote controlled machine, the system further comprising means for managing the two-way link capable of ensuring said link is maintained, taking into account the variability in topology and performances of the link resulting from the implementation of the cellular communication network. Application to long-range drones.

1 . A system for transmitting commands and a video stream between a remote-controlled craft such as a drone and a ground station, characterized in that it comprises a bidirectional link between craft and ground station, at least partly implementing a cellular communication network, said bidirectional link being ensured by means of a cellular modem on the craft side and conveying, on the one hand, a compressed video stream generated by a camera and a video encoding module), and, on the other hand, information belonging to a group comprising movement control commands and flight data or piloting characteristics of the remote-controlled craft, the system further comprising means for managing the bidirectional link capable of ensuring that said link is maintained while taking account of the variability of topology and of performance levels of the link induced by the implementation of the cellular communication network. 
     
     
         2 . The method as claimed in  claim 1 , in which the craft and the ground station communicate over the bidirectional link via a packet-based protocol. 
     
     
         3 . The system of  claim 1 , in which the link management means are capable of performing an adaptation of the bit rate of the compressed video stream by adjusting the encoding parameters of the video stream as a function of a measurement of the bandwidth of the bidirectional link from the craft to the station. 
     
     
         4 . The system of  claim 3 , in which, in the absence of a reliable measurement of the bandwidth, said adaptation is performed by repeatedly varying the encoding parameters to progressively increase the bit rate of the compressed video stream and by adjusting the encoding parameters to obtain a bit rate slightly lower than a rate which would cause a congestion phenomenon. 
     
     
         5 . The system of  claim 3 , in which said adaptation is performed by reserving an incompressible portion of the bandwidth available for the routing of critical information. 
     
     
         6 . The system as claimed in  claim 5 , in which the critical information belong to a group comprising flight data, characteristics of the piloting of the remote-controlled craft and piloting or mission instructions. 
     
     
         7 . The system of  claim 1 , in which said link management means are capable of calculating a score of quality of the bidirectional link at least from the station to the craft, and neutralizing flight instructions received in the case where said score is below a threshold. 
     
     
         8 . The system of  claim 2  taken in combination, in which said score is established as a function of at least two measurements of characteristics of the link among the latency, the rate of packets received in disorder, the rate of packets not received and the rate of packets and the rate of packets received incomplete. 
     
     
         9 . The system of  claim 1 , in which said bidirectional link management means comprise the implementation of at least one session establishment protocol and of at least one NAT traversal or bypass protocol. 
     
     
         10 . The system as claimed in  claim 9 , in which the link management means are capable of including in the messages of the session establishment protocol information relating to the type of point connected, namely craft or ground station. 
     
     
         11 . The system as claimed in  claim 10 , in which the link management means are capable of including in the messages of the session establishment protocol information relating to rights of a ground station over a craft. 
     
     
         12 . The system as claimed in  claim 11 , in which said rights comprise rights to control the movement of the craft and rights to control the camera of the craft. 
     
     
         13 . A set of a remote-controlled craft such as a drone and a ground station, characterized in that it comprises a transmission system as claimed in  claim 1 . 
     
     
         14 . The set as claimed in  claim 13 , which further comprises at least one second ground station, one second bidirectional link between craft and ground station, at least partly implementing a cellular communication network, and second means for managing the second bidirectional link between the second ground station and the craft. 
     
     
         15 . The set as claimed in  claim 14 , in which the first and second bidirectional link management means are capable of conveying information on respective rights of the two ground stations with respect to said craft. 
     
     
         16 . The set as claimed in  claim 14 , in which the first and second bidirectional link management means are capable of routing critical instructions from the ground to the craft via the first bidirectional link or the second bidirectional link as a function of a type of criticality, namely temporal criticality or routing criticality.