Motion Control Classified: 3 Common Types of Motion Controllers

A motion controller is the center of a motion control system that works with the central logic control unit as its core, the motor as its controlled object, and the sensor as the feedback signal sensitive component. However, its main task is to perform required mathematical and logic operations as per sensor signals and control task requirements. It also provides appropriate driving device control signals.

Motion controllers can be classified into three types:

Computer standard bus-based motion controller

A computer standard bus-based motion controller is independent from computers and features an open architecture. It utilizes different busses like PCI interface, ISA interface, USB interface, RS232 interface and VME interface to combine with computers. A wide range of these motion controllers also use microprocessor chips or DSP as CPU and can perform different functions such as servo filter control, motion planning, real-time and high speed interpolation, servo drive and standardized general interface to external I/O. They also feature powerful motion control software libraries like the C language motion function library and Windows DLL dynamic link library. Therefore, users can develop application software on Windows or DOS in order to create different control systems as per their requirements.

The motion controller and PC form a master-slave control structure. The PC monitors the control system’s operations in real-time and manages the human computer interface while the motion controllers complete all the motion control task details, like calculating the trace, detecting limit and home signals, producing direction and pulse signals. Such a structure is highly beneficial because it combines a PC’s ability to process information and the ability to control motion traces by motion controllers. As such, CNC systems that have open architectures that are based on motion controllers are widely used in manufacturing industries for equipment automation.

Embedded motion controller

This is a motion controller in which a computer is embedded and operates independently. Embedded motion controllers communicate with computers via a computer bus; as such, it is a bus-based motion controller variation. In its application, it is connected to superior computers or control panels via a field communication interface such as profibus, industrial Ethernet, SERCOS and RS485. Embedded motion controllers can be offered with hard disk and floppy drivers and receive remote diagnosis via the cloud.

Software-based open motion controller

Software-based open motion controllers provide unmatched flexibility. All its motion control software is installed on a computer and the hardware is only tasked to provide standardized general interfaces to servo drivers, the computer and external I/O, since the computer can be installed using different sound cards, corresponding drivers and CDROM. Additionally, with support from Windows and other operating systems, users can get their desired motion control functions as well as develop different highly performing motion control systems. Due to these capabilities, software-based open motion controllers offer more flexibility and choice for their users.

In summary, regardless of their type, motion controllers are the brains behind motion control system operations. They create trajectories that are used by motors to meet the required commands, powering many of today’s most important industrial automation applications.

Jerry has over 25 years of experience developing high performance motion control and vision systems, as well as developing real time software to control automation equipment. Prior to joining IntervalZero, Jerry was the Software Development Manager at Pitney Bowes, where he helped develop very large scale mailing and sorting machines. He was brought there in 1999 to help develop a purely software based motion control system. These systems used custom ethernet based servo amplifiers and could have over eighty servo motors on one machine.