1. Development and Evolution of Intelligent Motion Control Solutions
Motion control has evolved over time, from simple grid-connected motors to complex multi-axis servo drive solutions suitable for machine tools and industrial robots. To achieve higher levels of productivity, flexibility, and automation in smart manufacturing, automation technologies are becoming increasingly complex, which in turn drives the development and evolution of related technologies (see Figure 1).
Figure 1. Development and Evolution of Smart Interconnected Motion Applications
Grid-connected motor
The most basic motion solutions are based on grid-connected or AC three-phase constant-speed motors, which use switching devices to provide switching control and protection circuits. These basic motion control solutions operate at a relatively constant speed, unaffected by load variations. Mechanical control devices are used to reduce output; these include throttle valves, dampers, gears or valves, pumps, and fans.
Inverter drives motor
Adding a rectifier, DC bus, and 3-phase inverter stage effectively generates a variable frequency and variable voltage source, now applied to motors for variable speed control. This inverter-driven motor allows it to operate at optimized speeds under load and application conditions, significantly reducing energy consumption. Examples include high-efficiency pumps and fans.
Variable speed drive
For higher-performance motion control applications, variable speed drives (VSDs) can facilitate precise torque, speed, and position control. To achieve this control, we add current and position measurements to a basic open-loop inverter drive. This allows for more accurate control of motor speed, position, and torque. Typical examples of such applications include conveyors, winding machines, printing and stamping machines.
Servo drive system
Synchronous multi-axis servo drive systems are used in more complex motion applications. Machine tools and CNC machine tools require synchronized operation of multiple axes, thus necessitating extremely accurate position feedback. While 5-axis coordination is common in CNC machining, some applications utilize up to 12 axes, where the tool and workpiece move relative to each other within a specific space.
Industrial robots / collaborative robots / mobile robots
Industrial robots require a combination of multi-axis servo drives, mechanical integration, and advanced machine control algorithms to achieve complex 3D spatial positioning. Robots typically have six axes, which must be coordinated and ordered; if the robot sometimes moves along a track, there may be seven axes. Collaborative robots are built upon industrial robot solutions but incorporate power and force limiting (PFL) to provide safe multi-axis machine control, allowing operators to work safely alongside them. Finally, mobile robots employ self-navigation-enabled safe machine control, supporting positioning sensing and collision avoidance.
2. Driving Factors Promoting the Development of Intelligent Motion Control
Intelligent motion control is accelerating its development, driven by four key growth drivers: reduced energy consumption, agile production, digital transformation, and a shift towards new service-based business models in smart manufacturing that focus on reducing downtime and increasing asset utilization. Let's take a closer look at these four key growth drivers.
Reduce energy consumption
Motor systems account for nearly 70% of the industry's total electricity consumption. Smart motion solutions are significantly reducing energy consumption, driven in part by energy efficiency regulations, by enabling more and more applications to shift from fixed-speed motors to high-efficiency motors and variable-speed drives. This energy reduction can contribute to more sustainable manufacturing. Gaining motion insights related to optimizing manufacturing processes will further help reduce energy consumption in smart manufacturing.
Agile production
As industries continue to adapt to consumer demands and evolving buyer behavior, there is a need for agile manufacturing based on reconfigurable production lines to deliver greater customization and faster turnaround times. Consumer demand is driving a shift from low-combination, high-volume manufacturing to high-combination, low-volume manufacturing, requiring greater flexibility on the factory floor. Complex, repetitive, and often hazardous tasks can now be performed by industrial robots for higher output and productivity. Agile manufacturing improves resilience in the face of disruptions, enabling faster responses to changing customer needs.
Digital Transformation
By 2023, global spending on digital transformation will reach $6.8 trillion. Variable speed drives and servo drives utilize data from voltage, current, position, temperature, power, and energy consumption, combined with external sensors to monitor vibration and other process variables. Leveraging Ethernet networks that integrate information technology/operational technology (IT/OT), motion applications are interconnected and transmit data and insights. Motion data and insights are now more readily accessible and can be analyzed by powerful cloud computing and AI (algorithms) to optimize manufacturing processes and monitor the current health of assets throughout the facility (see Figure 2).
Figure 2. Digital transformation enabled by seamless industrial Ethernet connectivity.
New business models suitable for deploying assets
Asset manufacturers are looking to sell more than just assets; they want to expand their business models to include after-sales service contracts based on productivity and asset utilization. For example, pump manufacturers want to sell new predictive maintenance service products based on the volume of liquid pumped (e.g., water or oil) and charge per cubic meter (m³) pumped, rather than just selling the pumps themselves. It is projected that 50% to 60% of pump OEM revenue will come from service-related activities over the next five years. System integrators want to charge based on the uptime of the manufactured assets they install, rather than just collecting an initial installation fee. New smart motion solutions integrate condition monitoring capabilities to monitor the health of assets in real time and schedule maintenance accordingly. This monitoring eliminates unplanned asset downtime, providing higher levels of productivity and asset utilization, forming the basis for new service-based contracts.
3. Requirements for Intelligent Motion Control
To improve the productivity and sustainability of smart manufacturing, new and advanced motion control solutions are needed to leverage the four driving forces mentioned above. The key requirements for intelligent motion control are shown in Figure 3.
Figure 3 Intelligent motion control requirements
Excellent motion control
Excellent motion control reduces the time required to complete manufacturing steps, thereby increasing output and manufacturing productivity while reducing energy consumption. For example, precise position and torque control enables higher quality and faster processing speeds, such as machining a complex part with fewer steps and less time. Key requirements for providing excellent motion control include: improved control loop performance, reliable solutions for demanding industrial deployments, and high levels of integration for highly reliable yet compact solutions. These are achieved through low latency, low drift, multiphase current, position detection, and signal chains with high transient reliability and highly integrated components.
Durable, safe and reliable
Durable and reliable solutions extend asset lifespan and are key to achieving more sustainable smart manufacturing. Extending asset lifespan significantly reduces the raw materials and energy consumed in manufacturing replacement assets. Power management solutions for power conditioning and protection are critical components in providing more durable and reliable assets. Power management requirements include: high-end power supplies for insulated-gate bipolar transistors (IGBTs), high power density solutions for FPGAs and processors, digital point-of-load (PoL) for power management telemetry, EMC robustness, operation at high ambient temperatures, and data and power isolation to protect users from high voltage. The reliable use of new wide-bandgap power switches (made of silicon carbide (SiC) and gallium nitride (GaN)) presents new challenges and requirements for providing fast overcurrent protection systems and reliable operation.
Real-time connection
In high-performance multi-axis synchronous motion applications, control timing requirements such as precision, determinism, and time priority must be met, and end-to-end latency must be minimized, especially as control cycle times shorten and control algorithm complexity increases. These high-performance applications demand real-time connectivity and sub-millisecond network cycle times to control complex motion applications. Smart manufacturing uses vision systems and motion applications to monitor manufacturing quality and improve production safety. Industrial Ethernet networks must support the coexistence of real-time deterministic motion control traffic and maximum vision traffic on the same network (bandwidth up to Gb). Devices and controllers connected to the network must be interoperable to provide seamless data flow throughout the manufacturing equipment and ensure data transparency to higher-level management systems, while making these networks more flexible and scalable by reducing commissioning time. Converged (IT/OT) Ethernet networks ensure seamless access to motion information from higher-level management software systems for analysis to optimize manufacturing processes and accelerate digital transformation.
Advanced testing
Advanced inspection solutions create motion information that can be used to optimize manufacturing processes and detect early signs of failure. Inspection modules include position, current, voltage, magnetic field, temperature, vibration, and shock. Currently, new business models are being created to deliver predictive maintenance service contracts (based on increasing asset uptime) by deploying real-time monitoring of asset health using advanced inspection. Advanced inspection requirements include: robustness in harsh industrial environments (e.g., dusty environments), accurate position detection, non-contact high-current detection, high-bandwidth current and vibration detection, reduced calibration to ensure solution accuracy, and compact solution size for encoder-type applications.
4 Key Technologies for Accelerating the Realization of Higher-Value Motion Control Solutions
To realize next-generation intelligent motion control solutions for smart manufacturing, a combination of technologies is required. When used together, these technologies can provide reliable and precise motion control for demanding industrial deployments, while also providing access to system information from advanced sensing (see Figure 4).
Figure 4. Key technologies for accelerating the realization of higher-value motion control solutions, with access to system information.
Precise measurement
Complex motion control requires precise converter technology to provide high-quality current feedback, leveraging both isolated and non-isolated solutions to deliver control loop performance that is both highly accurate and has a fast transient response. Current feedback is a fundamental building block for improving drive performance, determining overall control bandwidth and response time. Key requirements for current feedback include: synchronous measurement of the PWM cycle, isolated or high common-mode measurement, low offset drift to minimize torque ripple, and low-latency synchronous sampling with 14 to 18-bit resolution to measure phase current. Precise converter technology is also needed to provide accurate position measurement in encoder and linear tracking applications, leading to higher output and increased productivity.
Isolation and Interfaces
Next-generation drives and motors supporting complex motion control require digital isolation to provide isolated data and communication interfaces such as RS-485, USB, and LVDS. Insulated-gate drivers (IGBTs) are also needed to drive high-side and low-side power semiconductors, providing reliable, secure, and highly dependable assets. IGBTs translate logic-level PWM signals into high-side reference signals that control power transistors. High-voltage inverter applications typically use IGBTs, but future trends favor SiC and GaN to increase switching frequency and/or reduce switching losses. Low-voltage applications generally use MOSFET-based switches. Key requirements for IGBTs include high speed, low propagation delay, low delay skew, robustness and common-mode transient rejection, switching protection features (DESAT, Miller clamp, soft turn-off, UVLO), and controllable switching (switches with variable switching speeds). Standard digital isolators play a crucial role in many drives for transmitting signals between high-voltage power electronics and safety extra-low voltage (SELV) areas (PWM and other signals). Examples include isolated signals in integrated power modules (IPMs). Fully integrated isolated power supply solutions can also be used in combination with digital isolators or other isolation functions to significantly reduce the size of the solution (compared to discrete transformer solutions).
Industrial Ethernet
Deterministic real-time communication in motion control applications (servers and drives) requires industrial Ethernet connectivity and sub-millisecond cycle time network performance. Reliable physical layer devices (100 Mb and Gb speeds) combined with Layer 2 industrial Ethernet protocols (such as EtherCAT, PROFINET, EtherNET/IP, and IEEE Time-Sensitive Networking (TSN)) ensure deterministic Ethernet connectivity. Next-generation designs are moving towards Gb TSNs on converged networks, employing multiple traffic types, using cyclic communication for control and acyclic communication for maximum throughput (e.g., vision and monitoring traffic). Low-latency industrial Ethernet solutions are needed to reduce cycle times in multi-axis applications. These deterministic motion control solutions enable more complex motion control applications, driving higher levels of manufacturing productivity and flexibility.
Magnetic sensing
Magnetic sensing, based on anisotropic magnetoresistive (AMR) position sensor solutions, provides reliable and accurate position detection for encoder applications. Position feedback is used to perform direct position control or to infer the rotational speed of servo drives and perform machine speed control. Compared to optical encoders, magnetic sensing offers a lower cost solution and greater reliability in industrial environments susceptible to dust and vibration.
Power Management
Intelligent motion applications are typically deployed in harsh industrial environments that require operation at high ambient temperatures and resilience to conducted noise and high-voltage transients. In some distributed applications, the driver is positioned closer to the motor in a smaller package; in others, the driver is integrated with the motor. Higher power density power management solutions capable of operating at high ambient temperatures are needed to support these compact intelligent motion control applications.
Machine Health
Machine health utilizes vibration and shock sensors to perform real-time status monitoring of machine health, eliminating unplanned downtime, extending asset lifespan, and reducing maintenance costs. By integrating machine health monitoring into motion applications, new revenue streams can be generated through digital strategies that create new service-based business models based on ensured uptime, enabling higher levels of manufacturing productivity. Asset health data based on vibration, shock, and temperature is transformed into asset health insights by edge AI and then transmitted to management control software via wired or wireless solutions, providing real-time health status of critical assets.
5. Conclusion
To rapidly respond to evolving consumer demands and support efficient production (batch sizes as low as 1), agile manufacturing is essential. Agile manufacturing is enabled by rapidly reconfigurable, intelligently connected assets. These interconnected assets share data in real time; this data can be used to identify production bottlenecks and improve operational efficiency by eliminating unplanned downtime through monitoring asset health. Smart manufacturing, built on intelligent motion control solutions, consumes less energy and supports more complex movements, driving greater flexibility, productivity, and sustainability.
Intelligent motion control solutions
Analog Devices (ADI) technologies and system-level solutions for intelligent motion control applications enable higher levels of performance while reducing energy consumption and downtime. Figure 5 provides a summary of a typical motor driver signal chain, consisting of six main modules, each representing an ADI solution.
Figure 5. ADI's solutions for intelligent motion control applications.
Power electronic devices
Power electronics provide power conversion in motor drive systems. High-voltage systems (>100 V) use insulated-gate drivers to drive power semiconductors. The ADuM4122 is a single-gate insulated-gate driver that provides 3 A short-circuit (<3 Ω), supports functional or enhanced insulation (up to ~800 V DC bus), provides slew rate control for EMI/power loss optimization, and also supports high common-mode transient rejection (CMTI) and low propagation delay for use with SiC and GaN power semiconductors. The ADuM160N multi-channel digital isolator can be used to isolate PWM signals and works with integrated power modules (IPMs) that integrate gate drivers and power semiconductors. The ADuM6028 isolated power device can be used with digital isolators, isolated transceivers, and isolated data converters, providing a very small, fully safety-certified, ready-to-use solution.
For low-voltage systems (<100 V), the 100 V half-bridge driver LTC7060, which offers floating ground and programmable dead time, or the 150 V protected high-side NMOS static switch driver LTC 7000, featuring PassThru™ technology and adaptive breakdown protection, can be used to drive low-voltage semiconductors. The LTC 7000 also supports programmable dead time (for optimized efficiency), enhanced current control, and slew rate control (for reduced EMI).
Current detection
The ADuM7701 is a high-performance, second-order Σ-Δ modulator with on-chip digital isolation using Analog Devices' iCoupler® technology, converting analog input signals into a high-speed single-data stream for isolated current sensing measurements. The ADuM7703 offers low offset drift (0.6 μV/°C max), reduced torque ripple, and a compact 8-pin package with an integrated LDO for simplified power supply design and reduced board area. It provides 150 V/ns CMTI (minimum rating) and is compatible with GaN and SiC power electronics.
The AD8410 high-voltage current sense amplifier offers high gain (20 V/V, 50 V/V, 100 V/V), low offset drift (~1 μV/°C), and high bandwidth (2 MHz) for optimized current control. The AD8410 also includes bidirectional current measurement inputs (up to 100 V common-mode input). The LTC6102 precision zero-drift current sense amplifier ensures accuracy over a wide range of operating conditions and can be powered from the high-side voltage (up to 100 V) in current shunt sensing applications.
Location detection
Position feedback is used to perform direct position control, or to infer rotational speed and perform machine speed control. The ADA4570 and ADA4571 integrate an ARM angle sensor and an integrated signal conditioner to provide higher accuracy absolute position detection (error < 0.1°, lifetime/temperature < 0.5°) for motor drives and servo applications. They operate reliably in harsh magnetic environments, support wide air gap tolerances without compromising angular error accuracy (unlike Hall/GMR/TMR), and simplify system design considerations. Compared to optical sensors in industrial applications, the ADA4570 and ADA4571 are unaffected by dust or dirt and have very low latency compared to digital output solutions with built-in calibration engines on the market. The ADA4571 generates two single-ended analog outputs (sine and cosine) to represent the angular position of the surrounding magnetic field, while the ADA4570 generates two differential analog output pairs. A dual version of the ADA4571 (ADA4571-2) can also be used in safety-critical applications where full redundancy is required.
The AD7380 is a 4 MSPS dual-channel synchronous sampling 16-bit SAR ADC that offers accuracy, throughput, and a minimal size, making it suitable for encoder applications. The AD7380's small package (3 mm × 3 mm) enables encoder miniaturization, providing 4 MSPS throughput for minimal latency and fast transient response in the control loop. The AD7380's oversampling engine can achieve higher accuracy under slower operating conditions.
Machine Health
Vibration and shock sensors are being integrated into encoders or motors to provide asset health information. The ADXL1002, an ultra-low noise (25 μg/√Hz over ±50 g) high-frequency ±50 g MEMS accelerometer, offers vibration detection with a high data bandwidth of up to 11 kHz (3 dB point) and a resonant frequency of 21 kHz. The ADXL1002 is a low-cost, low-power alternative to piezoelectric sensors. Compared to piezoelectric sensors, the ADXL1002 can monitor low-speed devices down to DC while reducing calibration requirements. The ADXL354 is a low-noise, low-power 3-axis MEMS accelerometer in a small package (3 mm × 5 mm) with digital interfaces, SPI (3-wire and 4-wire), and I2C, providing a compact vibration detection integration solution for encoders.
ADI OtoSense™ Smart Motor Sensors are AI-based hardware and software solutions that combine best-in-class detection technology with leading data analytics to monitor motor condition. Regardless of motor type, ADI OtoSense SMS provides critical diagnostics, transforming data into actionable information to help users predict maintenance cycles and avoid unplanned downtime.
Network interface
Smart manufacturing is based on intelligent motion application networks that share data between assets and higher-level control and management networks. ADI offers reliable, low-power, and low-latency PHYs, including the ADIN1200 (10/100) PHY and ADIN1300 (10/100/1000) PHY. Both of these industrial Ethernet PHYs were developed for industrial applications requiring operating temperatures up to 105°C and have been extensively tested to meet EMC and reliability standards for operation in harsh industrial environments. The low-latency PHYs support shorter cycle times, allowing more devices to be connected to the network and meeting the timing requirements of complex, high-performance deterministic motion applications. For deterministic industrial Ethernet connectivity, ADI's Layer 2 industrial Ethernet incorporates a 2-port switch. The fido5100 and fido5200 support PROFINET, Ethernet/IP, EtherCAT, Modbus TCP, and Ethernet POWERLINK industrial Ethernet protocols, as well as any processor, protocol, and stack.
motion controller
The motion controller provides the processing engine, generating PWM signals to drive power semiconductors and receiving current and position feedback signals to control the motor's speed and torque. A reliable, high-ambient-temperature, high-power-density power management solution is required to power the controller, typically an FPGA or processor, offering selectable power-up sequence and power telemetry capabilities. Analog Devices' Power by Linear™ power management ICs and power modules provide the foundation for today's and future intelligent motion control applications. Motion controllers are typically located in a central rack and require long-distance communication with encoders. In this case, Analog Devices' isolated and non-isolated RS-485 transceivers can be used to transmit encoder position feedback information to the motion controller via serial communication. The ADM3066E is a ±12 kV IEC ESD-protected full-duplex 50 Mbps RS-485 transceiver that provides a high-bandwidth, high-ambient-temperature (125°C), reliable communication solution in a small 3 mm × 3 mm package, suitable for encoder applications.
