UC2 - Car Teleoperation

Roboauto's main focus in VALU3S framework within the car teleoperation use case will be on safety of transmission line and on the routers. In cooperation with our partners we derived evaluation scenarios from these 2 areas, and plan to verify them on both simulator (our laboratory vehicle - Breach mobile robotic platform), and open environment vehicle (car or towing vehicle).
UC2
Automotive
Any vehicle equipped with sufficient sensors, and electronic actuators can be controlled remotely. Every teleoperated system consists of remotely controlled vehicle (car, towing tractor etc.), and a remote station operated by a human driver.The most important element for proper functionality of teleoperation system is a reliable transmission line.Transmission line can use different communication protocols; remote control of the vehicle is supported by the On Board Unit (OBU) as depicted in Figure 1.3.
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Figure 1.3: Car teleoperation model

Vehicle

A teleoperated vehicle must be equipped with sensors to cover the view of the driver, and actuators to control turning, acceleration and stopping. There are four or more cameras covering full field of view of the driver, GPS unit and optionally other sensors (sonars, radars, lidars). These peripherals are connected with the OBU -a box enclosing electronics essential for teleoperation.OBU includes:
  • Routers
    • Two routers for connection to two LTE network providers
    • Third router enabling connection to WiFi -both 2.4GHz and 5GHz
    • Routers are used to send camera streams and other data (e.g. car status, data from sensors or driver assistance systems) to the remote control station
  • Main communication hub (implemented by Jetson Nano) evaluates and distributes data from remote station, and controls camera nodes
  • Vehicle interface module which translates drive commands for the vehicle which are received from the Nano and sent to vehicle’s CAN BUS.

Gateway (GW)

Central server module serves for registration and authentication of all clients and connects the remote station with selected vehicle. Gateway ensures stability of connection so if the connection is lost, the gateway immediately initiates reconnection.

Remote station (RS)

Remote station allows the operator to control the vehicle. It is placed at a remote location. After the RS connects to the vehicle, operator is able to see the vehicle’s camera streams (and optionally other sensory data) on several displays, and, using the steering wheel and pedals, can operate the vehicle - see Figure 1.4.

Remote_Station.jpg

Figure 1.4: Remote station

Network

The primary way of data transfer for teleoperation are radio networks, more specifically WiFi and LTE technology.

WiFi is using both 2.4Ghz and 5Ghz band and was chosen for its low latency over local networks. WiFi also enables to transfer bigger volumes of data, which means a possibility of higher quality for streamed video.

LTE is data transfer over the public teleoperator mobile data and enables a connection also in places without WiFi coverage. The system utilises several routers in OBU for 2 reasons:

  1. Connection redundancy
  2. Possibility of data transfer using two independent mobile carriers. This makes the system more resistant to an outage.

Transmission line(s)

For the communication of GW with vehicle and RS the reliable TCP protocol is used. The following information is transferred over TCP: registration, status, connection request, connection checks.

Communication between the vehicle and RS is done via purpose-specific protocol based on UDP. This information goes over the protocol: car status, drive request, drive commands, drive release request. Camera streams are using SRTP protocol.All communication is encrypted using TLS/DTLS.
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