Method and apparatus for controlling synchronization of camera shutters in in-vehicle Ethernet communication network
The present invention relates to a method and apparatus for controlling synchronization of camera shutters in an in-vehicle Ethernet communication network. A method for controlling synchronization of a camera shutter by a camera controller cooperating with a grandmaster through Ethernet communication may include performing a time synchronization procedure with the grandmaster, reducing a preset pulses per second (PPS) down counter if the time synchronization procedure is successfully completed, and operating the camera shutter when the PPS down counter reaches 0. Accordingly, the present invention may provide accurate image frames of a desired time through synchronization of shutters of cameras connected to an in-vehicle Ethernet network.
1. A method for controlling synchronization of camera shutters of a plurality of cameras by a camera controller communicatively connected to the plurality of cameras and cooperating with a grandmaster through Ethernet communication, the method comprising steps of:
performing a time synchronization procedure with the grandmaster between the camera shutters, each included in the plurality of cameras mounted in a vehicle;
reducing a preset pulses per second (PPS) down counter if the time synchronization procedure is completed;
operating each of the camera shutters when the PPS down counter reaches 0; and
switching each of the camera shutters to a continuous shot mode when the time synchronization procedure is not completed within a pre-specified time,
wherein the step of operating each of the camera shutters comprises operating a camera shutter in a single shot mode to generate an image frame for each of the plurality of cameras when the time synchronization procedure is completed, and
wherein the step of reducing the PPS down counter is restarted when the image frame is generated.
2. The method according to claim 1 , wherein the generated image frame is transmitted to a predetermined controller using an audio/video bridging (AVB) protocol over Ethernet.
3. The method according to claim 1 , wherein the time synchronization procedure is defined in IEEE 802.1AS.
4. The method according to claim 1 , further comprising setting a value of the PPS down counter when the camera controller is powered on,
wherein a number of image frames to be captured per second is determined based on the value of the PPS down counter.
5. An apparatus for controlling synchronization of camera shutters of a plurality of cameras, the apparatus cooperating with a grandmaster through Ethernet communication and comprising a controller communicatively connected to the plurality of cameras and configured to:
perform a time synchronization procedure for setting an internal reference time using reference time information received from the grandmaster between the camera shutters, each included in the plurality of cameras mounted in a vehicle;
reduce a preset pulses per second (PPS) down counter when the time synchronization procedure is completed;
operate each of the camera shutters when the PPS down counter reaches 0; and
switch each of the camera shutters to a continuous shot mode when the time synchronization procedure is not completed within a pre-specified time,
wherein each of the camera shutters operates in a single shot mode to generate an image frame when the time synchronization procedure is completed, and
wherein the PPS down counter restarts when the image frame is generated.
6. The apparatus according to claim 5 , wherein the generated image frame is transmitted to a predetermined controller using an audio/video bridging (AVB) protocol over Ethernet.
7. The apparatus according to claim 5 , wherein the time synchronization procedure is defined in IEEE 802.1AS.
8. The apparatus according to claim 5 , wherein a value of the PPS down counter is set when the apparatus is powered on, and
wherein a number of image frames to be captured per second is determined based on the set value of the PPS down counter.