EMBEDDED TECHNOLOGY
Transmission tradeoffs in robot control
By Simone Medardoni, technical marketing manager, GigaDevice Semiconductor
R
obots are becoming ever more agile and able to take on an expanding range of tasks. AI is advancing this, requiring a level of precise motion control that coordinates the movement of each limb.
multiple MCUs distributed throughout the machine, each controlling a few motors that move each actuator and communicating with its peers to ensure carefully synchronised movements.
To handle the large amounts of sensor data and synchronisation signals, the network needs to operate at high speed and which calls for communications with variability in packet delivery, or jitter, of less than 1ms… and ideally, less than 1μs. operate over distances of a meter or more
Protocol tradeoffs
Several standards exist that meet at least some of the needs presented in robotics. PCIe notably delivers the high data rates needed, and PCIe signals can proprietary nature of these solutions and their expense mean PCIe is mainly used to support daughterboard expansion to add capabilities like improved AI performance. CAN FD has been presented as a viable capabilities, its ability to support necessary In comparison to standard CAN, CAN FD demonstrates several key advantages. The following characteristics set it apart: • During the arbitration phase, the speed is limited to 1 Mbps to ensure compatibility with standard CAN
• The data phase is the theoretical maximum speed, which is 8–10 Mbps. In
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GigaDevice GD32 range of high-performance MCUs combines high-performance Arm Cortex-M7 cores with a dual-PHY EtherCAT controller, plus Ethernet and CAN FD interfaces
industrial and automotive practice, the speed usually hovers around 2–5 Mbps
• Extended Payload: In addition to its higher speed, CAN FD supports up to 64 bytes of data per frame (compared to 8 bytes for standard CAN), which increases the total throughput It can thus be concluded that CAN FD can be employed for secondary communication within the robot control system, whilst required for the main channel. such as CAN XL, but even here the maximum bandwidth is still only 20Mbps.
distance, provides a strong alternative to CAN. Additionally, it has the ability to use weight and compatibility with traditional drawbacks still limit its use for robotic motion, notably it lacks deterministic delivery
APRIL 2026 | ELECTRONICS FOR ENGINEERS
colliding and unacceptable latencies when they do.
While, techniques to solve this (based on randomness) can reduce this, they prevent a guarantee that delivery jitter will remain below the hundreds of nanoseconds needed by today’s robots. Finally, its use of support for guaranteeing maximum latency of delivery.
still suffers a risk of high jitter in periods of this, its use of switched Ethernet hardware for core network functions adds other unacceptable delays.
Although standard Ethernet is ideal for transmitting large volumes of data, it is guarantee of the exact arrival time of a set of standards that evolved to address this
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