With the widespread application of more and more technologies in industrial automation, we have entered the era of Industry 4.0. New technologies are constantly emerging, empowering artificial intelligence and machine learning, data analytics, industrial networks, cybersecurity, and functional safety. However, most industrial automation, as the core of all other technologies, still relies on robotics and motion control.
Motion control and motor control often appear together, which can be confusing. What are the differences between these two concepts? In industrial automation, how do we apply the appropriate solutions to one of these concepts, or to both simultaneously? Read on to learn about the differences between motion control and motor control, and how to make them work together.
What is motion control?
Motion control is a subsystem of industrial automation systems. It synchronizes the control of multiple motors to complete a series of movements. For example, a multi-axis robotic arm requires multiple motors to work seamlessly together to perform specific actions. Motion control is mainly used for trajectory planning, velocity planning, interpolation algorithms, and kinematic transformation. Motion control systems are frequently found in printing, packaging, and assembly applications.
As shown below, a motion control system typically consists of the following main components:
The motion controller generates trajectory plans and then provides control commands to the motor driver.
A motor driver converts control commands (usually speed or torque signals) from a motion controller into higher power voltage or current signals to drive the motor.
Several motors can execute motion according to control commands.
Position sensors provide the position/speed data of the motor rotor to the position/speed controller, enabling precise position/speed control.
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Motor control and motion control
On the other hand, motor control focuses more on systems or technologies that control the rotation of a motor. A typical motor control system adjusts one or more parameters of a single motor, such as torque, speed, and position, to achieve a target value. Different types of motors may have significantly different requirements and technologies for driving them. Motor controllers typically lack planning capabilities (advanced drives only have simple position and speed planning capabilities). Therefore, a simple way to explain the difference between motor control and motion control is:
Motor control is a component of a motion control system (usually a current loop, operating in torque control mode).
However, we may sometimes confuse them because the position loop/speed loop/torque loop of motor control can be used in both motor controllers and motion controllers.
Now that we know the differences between these two systems, it is obvious that their design requirements and resources are also very different.
Motor control focuses more on making the motor rotate normally, or more precisely, commutate. To do this, the motor controller needs to interface with various sensors, process analog and digital signals, and generate waveforms to drive the motor. All of this happens within a very short time loop, ranging from 50 microseconds to 300 microseconds.
However, motion controllers typically act as system monitors, requiring communication between multiple motor controllers, via data from other sources such as Ethernet (EtherCAT and TSN), CAN, and RS485, and between commands from human-machine interface (HMI) panels. As mentioned above, motion controllers can also participate in some motor control tasks, such as controlling speed loops, position loops, and even torque loops. Therefore, the real-time control loop of a motion controller can range from 100 microseconds to hundreds of milliseconds, depending on the specific task the motion controller is involved in.
Design of motion control system
The design of motion control systems can be quite complex, encompassing many aspects such as motor control, industrial networks, human-machine interfaces, codecs, information security, and functional safety. Therefore, it requires multiple control units to coordinate with each other within the system.
This is where a complete set of components is needed to facilitate selection by motion control designers—and this is where NXP and its extensive portfolio of microcontrollers (MCUs) and microprocessors (MPUs) come in.
In the motor controller segment, NXP offers a wide range of options with its KineTIs V MCUs, KineTIs E MCUs, LPC MCUs, and Digital Signal Controllers (DSCs), from controlling simple motors using an ARM Cortex-M0+ core to running FOC algorithms on dual motors using a Cortex-M33 core or a high-efficiency DSC core. More motors can be precisely controlled simultaneously using the popular flashless i.MX RT crossover MCU. These MCUs not only offer a wide range of processing capabilities but also integrate peripherals ideally suited for motor control, such as high-speed, high-precision ADCs, high-speed comparators, flexible motor control timers and PWM, and DSP accelerometers. Safety features such as fault detection and automatic shutdown work seamlessly with the industrial safety compliance offered by these devices.
Which MCU is best suited for your motor control design? Explore our comprehensive motor control guide to learn about the latest solutions.
In the motion controller sector, NXP offers the i.MX RT crossover MCU and MPU product line, including Layerscape and i.MX series processors. These devices support a rich set of integrated industrial communication interfaces, such as Ethernet/IP, Profinet, EtherCAT, and TSN. The multi-core architecture provides ample power for communication protocols, motion trajectory planning, and real-time loop control. They also feature advanced timers to support multi-mode counting and flexible pulse train outputs.
As shown in the figure, the motion control system can use a large number of MCUs and MPUs to implement multiple motor drivers, thereby promoting the coordinated movement of various robotic arms.
To accelerate the time-to-market for motion control systems, we urgently needed a rapid and easy method for proof-of-concept and prototyping. Therefore, NXP has been developing reference design platforms to provide rich industrial motion control capabilities and comply with industrial automation standards. We recently launched the i.MX RT Industrial Drive Development Platform, based on the i.MX RT crossover MCU, featuring multi-motor control, deterministic communication, and IEC 62443 safety compliance. The four-motor control development platform is now available, supporting the full suite of NXP products, including the i.MX RT crossover MCU and the EdgeLock SE050 safety element. These devices work together to demonstrate the functionality required for industrial motor control systems, such as power management, driving four motors, industrial communication interfaces, HMI touch panel interfaces, and safety integration.
In summary, this article has introduced the definition of motion control, the differences between motor control and motion control, and industry trends in the design requirements of motion control systems.
