How to switch from motor control to motion control?

As more and more technologies are widely used in industrial automation, we have entered the era of Industry 4.0. New technologies are emerging to enable 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 are often mentioned together, which can be a bit confusing. What is the difference between these two concepts? In industrial automation, how do we apply the right solution to one or both concepts? Read on to learn the difference 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 and controls multiple motors to complete a series of movements. For example, a multi-axis robot requires multiple motors to work together seamlessly to make a specific movement. Motion control is mainly used for trajectory planning, velocity planning, interpolation algorithms, and kinematic transformations. Motion control systems are often found in printing, packaging, and assembly applications.

As shown below, a motion control system usually consists of the following main components:

 Motion controller, which generates the trajectory plan and then provides control commands to the motor drive.

 Motor drivers convert the motion controller's control commands (usually speed or torque signals) into higher power voltage or current signals to drive the motor

Several motors that can perform movements according to control commands

 Position sensor, which provides the position/speed data of the motor rotor to the position/speed controller to achieve precise position/speed control

Designing the next generation of smart, connected and safe industrial drives has never been easier. Read the latest blog post.

Motor Control and Motion Control

Motor control, on the other hand, is a system or technology that is more focused on controlling the rotation of a motor. A typical motor control system adjusts one or more parameters of torque, speed, and position of a single motor to achieve a target value. The requirements and technology for driving a motor can vary greatly depending on the type of motor. Motor controllers typically have no planning capabilities (advanced drives only have simple position and velocity planning capabilities). So, a simple way to explain the difference between motor control and motion control is:

 Motor control is a part of motion control system (usually current loop, working in torque control mode)

However , sometimes we may confuse them because the position loop/speed loop/torque loop of motor control can be used in both the motor controller and the motion controller

Now that we know the differences between the two systems, it is clear that their design requirements and resources are also very different.

Motor control is more focused on getting the motor to spin properly, 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 control often acts as a system supervisor and needs to communicate between multiple motor controllers, other sources such as data via Ethernet (EtherCAT and TSN.), CAN, RS485, and commands from human-machine interface (HMI) panels. As mentioned above, the motion controller can also participate in some motor control tasks, such as controlling the speed loop, position loop, and even the torque loop. Therefore, the real-time control loop of the motion controller can vary from 100 microseconds to hundreds of milliseconds, depending on the actual task the motion controller is involved in.

Design of motion control system

The design of a motion control system can be quite complex, covering many aspects such as motor control, industrial network, human-machine interface, codec, information security, and functional safety. Therefore, it requires multiple control units to coordinate with each other in the system.

This is where a full suite of devices is needed for motion control designers to choose from – and this is where NXP and its broad portfolio of microcontrollers (MCUs) and microprocessors (MPUs) come in.

In terms of motor controllers, NXP's Kinetis V MCU, Kinetis E MCU, LPC MCU and digital signal controller (DSC) offer a variety of options, from controlling simple motors using the ARM®Cortex®-M0+ core to running FOC algorithms on dual motors using the Cortex-M33 core or the efficient DSC core. More motors can be precisely controlled simultaneously using the popular flash-free i.MX RT crossover MCU. These MCUs not only have a wide range of processing power to choose from, but also integrate peripherals that are very suitable for motor control, such as high-speed, high-precision ADCs, high-speed comparators, flexible motor control timers and PWMs, and DSP acceleration sensors. Safety features such as fault detection and automatic shutdown can work seamlessly with the industrial safety compliance provided by these devices.

Which MCU is best for your motor control design? Explore our comprehensive motor control guide to learn about the latest solutions.

In terms of motion controllers, NXP offers i.MX RT crossover MCU and MPU product lines, including Layerscape and i.MX series processors. These devices support the integration of rich industrial communication interfaces, such as Ethernet/IP, Profinet, EtherCAT and TSN. The multi-core architecture provides sufficient power for communication protocols, motion trajectory planning and real-time loop control. They are also equipped with advanced timers to support multi-mode counting and flexible pulse train output.

As shown in the figure, the motion control system can use a large number of MCUs and MPUs to implement multiple motor drivers to promote the coordinated movement of each robot arm.

To accelerate time to market for motion control systems, a fast and easy way to do proof of concept and prototyping is urgently needed. Therefore, NXP has been developing reference design platforms that provide rich industrial motion control features and comply with industrial automation standards. We recently launched the i.MX RT Industrial Drive Development Platform, which is based on the i.MX RT crossover MCU and has a foundation for multi-motor control, deterministic communication, and compliance with the IEC 62443 safety standard. The Quad Motor Control Development Platform is now available and supports the full range of NXP products, including the i.MX RT crossover MCU and the EdgeLock® SE050 safety element. Working together, these devices demonstrate the features 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 introduces the definition of motion control, the difference between motor control and motion control, and the industry trends in motion control system design requirements. Continue to follow NXP to learn more about motor control solutions.

author:

Daniel Hou

Technical Marketing, Industrial Edge Processing Mass Market Team, NXP Semiconductors

Daniel Hou is a technical marketer in the Industrial Edge Processing Mass Market Team at NXP Semiconductors, supporting emerging microcontroller and microprocessor use cases in the industrial market segment. He previously worked in application engineering and marketing roles in the semiconductor industry and holds a Master's degree in electrical engineering from the Rose-Hulman Institute of Technology.