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36 ADI | Engineering a More Sustainable Future For robots and cobots, motor encoders and joint encoders typically require 16-bit to 18-bit ADC performance, with the 22-bit ADCs required in some cases. High performance ADCs, with up to 24-bit resolution, are also required for some optical absolute position encoders. Future Trends for Motor Encoder Technologies Future encoder trends and technologies that will enable these trends are described in Figure 5. Research from Rockwell1 for servo drives, encoders, and encoder communication ports shows an annual growth of 20% in transceivers for feedback communication. Single-Pair Ethernet (SPE) transceivers that support 100 Mbps communications over two wires (IEEE 802.3dg standard 100BASE-T1L) 1 are currently under investigation, with future encoder drive interfaces benefitting from low latency, with ≤1.5 µs targeted. This low latency will support quicker feedback data acquisition and faster control loop response time. Condition-based monitoring (CbM) of robotics and rotating machines, such as turbines, fans, pumps, and motors, records real-time data related to the health and performance of the machine to enable targeted predictive maintenance, as well as optimized control. Targeted predictive maintenance, early in the machine life cycle, reduces the risk of production downtime resulting in increased reliability, significant cost savings, and increased productivity on the factory floor. Using MEMS accelerometers, placed in the encoder, provides vibration feedback for machines where quality control is critical. Adding a MEMS accelerometer to an encoder is convenient as the encoder already has existing cabling, communications, and power to provide vibration feedback to the controller. In some applications, such as CNC machines, the MEMS vibration data sent from the encoder to the servo can be used to optimize the performance of the system in real time. Extending the useful life of industrial assets using CbM can be complemented with robust longer life position sensors. Magnetic sensors, which produce analog outputs that indicate the angular position of the surrounding magnetic field, can be used instead of optical encoders. Magnetic encoders can be used in areas that have higher humidity, dirt, and dust. These harsh environments impair the performance and lifetime of optical solutions. For robotics and other applications, the position of the mechanical system must always be known, even in the event of a power loss. One of the major costs and inefficiencies associated with standard robots, cobots, and other automated assembly equipment is the resulting downtime required for rehoming and initializing power-up following a sudden loss of power while operating. The magnetic multiturn memory that has been developed by Analog Devices2 requires no external power to record the number of rotations of an external magnetic field. This leads to reduced system size and cost. Figure 5: Encoder trends and the technologies that will enable these trends. 5