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robotics system with limited access to internal components. SPE-based network can minimise downtime to diagnose and troubleshoot network issues and cable faults with Ethernet PHY’s built-in cable diagnostic capabilities, such as signal quality indicator (SQI) and time domain reflectometry (TDR), accessible though serial management interface (SMI). SQI monitors link quality by evaluating signal strength, noise levels, and transmission errors to provide real-time status of connection heath. In a closed system like humanoid robot, SQI can detect signal degradation or instability early to allow for proactive maintenance or identify which part of the network is experiencing problems. SQI value at any given time is stored in a register and can be correlated to a signal-to-noise ratio (SNR) with a simple calculation. Figure 6 shows an example of SQI value increasing with more noise. TDR identifies faults along the cable length, such as shorts or opens, and the distance from the PHY. Figure 7 (Buntz & Daimler AG, 2017) shows different types of faults that can be detected with TDR capability. This diagnostic method can be highly useful to pinpoint exact location of a fault within the cable. As Figure 8 shows, TDR works by injecting high energy pulses into the cable and measuring the reflected signal (in phase, out
Figure 5. Galvanic coupling concept
Robustness and reliability Overcoming EMI and EMC challenges Humanoid robots present a space-con- strained system with multiple electronic components, motors, actuators, and power electronics, all of which can create interference. As such, managing electromagnetic compatibility (EMC) is critical, as electromagnetic interference (EMI) can disrupt sensor readings and control signals within the robot. TI’s 100BASE-T1 and 1000BASE-T1 Ethernet PHYs are designed to meet OPEN Alliance EMI/EMC standards, offering proven robustness from the automotive market that is now essential in robotics. Robust architecture for noise using galvanic isolation, as shown in Figure 5, allows for TI parts to be compliant with industrial IEC and CISPR standards for EMI/EMC. For more details please refer to EMC/EMI Compliant Design for Single Pair Ethernet application note. Cable diagnostics Troubleshooting network issues can prove to be a challenging task in a closed
Figure 6. SQI example
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