1
$\begingroup$

I have a robotic system with many sensors that need to have very accurate localization associated with the data they gather. We have a geolocalization system that acquire localization at high speed (up to 100Hz) and we want to broadcast a synchronization signal that we can associate with this localization data.

We develop the electronics for the whole system and we hesitate between a clock signal or a signal that delivers event such that we can have ids broadcasted that will serve as timestamp. Our requirement is to be accurate with a drift of maximum 1ms.

The signal can have to traverse up to 4m of cables between the generator of the synchronization signal and the sensors.

If we can we would like to use CAN bus, but we have no experience with it as a synchronization bus.

We would like to ask the community what communication bus is used in state of the art systems to implement a synchronization signal ?

$\endgroup$
1
$\begingroup$

There are many possible routes you can take.

You mentioned CAN. CANOpen is built on CAN and is used in many automation and robotics related devices. CANOpen specifies a SYNC mechanism exactly for the purpose you mention. More about this here. As for cycle times, the bandwidth and exact message size of CAN packets is knows, so cycle times are easy to calculate. CANOpen is widely used in the automation industry for millisecond cycle time applications.

PTP is a time synchronisation mechanism for networked devices. It can be implemented on different communication protocols. Most commonly it is used in ethernet-based networks with UDP implementation. More about this here. This mechanism does not trigger a measurement but makes sure that internal clocks on the network are synched (and then measurements can be self-triggerd cyclically).

Depending on the application you are working on, low-latency industrial ethernet-based bu systems may be an option, as an alternative to CAN (or to be more precise, as an alternative to CANOpen), you could look into sercos, Ethernet-IP, Profinet, DeviceNet, EtherCAT. Some (most?) of this are proprietary and will require that you select equipment already compatible with the communication bus. These are designed to work as you intend, low jitter, low latency, high speed.

| improve this answer | |
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.