Synchronization of Multi-Axis Motion Control Over Real-Time Networks

Real-time deterministic Ethernet protocols, such as EtherCAT, have enabled synchronized operation of multi-axis motion control systems [Ref1]. There are two aspects to this synchronization. First, the delivery of command and references between the various control nodes must be synchronized to a common clock and second, the execution of the control algorithms and feedback functions must be synchronized to the same clock. The first kind of synchronization is well understood and an inherent part of the Network Controller. However, the second kind of synchronization has up to this point been neglected and is now a bottleneck when it comes to motion control performance. This paper presents novel concepts to synchronize motor drives all the way from a Network Controller and down the motor terminals and sensors. The presented technologies enable much improved synchronization leading to significantly increased control performance.