Motion Controllers Explained: How to Choose the Right Motion Controller

A motion controller is the core element of a motion control system: it calculates and generates output commands for each trajectory or motion path. Motion controllers vary in regards to sophistication, complexity, interpolator, and servo motor control loop. However, they are all designed to execute tasks at precise speeds, positioning and torque control. They rely on their calculated trajectories to determine the ideal torque command that should be sent to the motor amplifier and trigger motion. This explains why motion control systems are ideal for applications that require product positioning, separate elements synchronization, and prompt start and stop motion control.

Trajectory calculation

Motion trajectory defines the motion controller command signal output forwarded to the amplifier with the aim of triggering motion in line with the current profile. Motion controllers calculate trajectory segments based on the programmed parameter values. They evaluate the preferred target position acceleration values and maximum target velocity they receive to determine the time they should spend in the three core segments: acceleration, deceleration and constant velocity.

Under the acceleration segment, motion starts from the previous stop position and follows a predetermined acceleration ramp until it achieves the targeted velocity for each move. For a specified period, the motion continues at the preferred velocity until the controller triggers the deceleration segment to slow the motion to a stop at its desired position.

Choosing the right motion controller

There are three main motion controller categories: individual, PC-based and stand-alone controllers.

Stand-alone controllers represent complete systems that are mounted in a single physical enclosure that contains all the essential electronics, external connections, and power supply. Stand-alone controllers are dedicated to a single motion controller that can effectively control a single or multiple motion axes.

PC-based controllers are mounted on a PC’s motherboard because they are processing boards that create and implement motion profiles. They are common in industrial settings because they offer a ready-made and graphical user interface that simplifies tuning and programming.

Individual microcontrollers are designed on a printed circuit board with driver inputs and outputs that control a motor. They are inexpensive and offer chip-level access to systems. However, they require excellent programming skills to implement and configure correctly.

Choosing the ideal motion controller for your application starts with understanding the different motion controller types and your application-specific requirements. Of utmost importance is your application’s complexity. For example, a less complex application requires relatively slow speed and a single motion axis while a more complex application requires multiple motion axes that should be highly coordinated.

KINGSTAR offers economical, easy-to-install, reliable and easy-to-program motion control products that can be used in multi-axis, axis and a half, and single axis servo systems. The products are designed to operate in distributed, hybrid and centralized control architectures. As such, KINGSTAR motion control solutions allow users to optimize their controller system investment by choosing the precise functionality they require.

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.