Motion Control or Mechatronics, What’s in a Name?

Are we talking about Motion Control? or are we talking about Mechatronics?

Words are important in describing reality and communicating with others.  The term Mechatronics was coined a few years ago, possibly from the frustration that the term Motion Control does not adequately cover the subject.  It is, however, a made up word. And as a result, its real meaning is somewhat controversial.

The complexity is in the “mecha” part.  The idea is that the we are trying to include all things mechanical.  And that’s where it opens the door to everything and anything.  Mechanical engineering can include hydraulics, pneumatics, bearings, cams, gears, springs, shafts, materials, you name it.  The fact that an almost endless list of technologies makes up the field of “mechatronics” dilutes the meaning of the term.

So I would like to assert my original definition based on the old term ” Motion Control”.  And, by the way, I am OK with the use of Mechatronics interchangeably with Motion Control, but I will also suggest that the two should be identical.  What we need is more clarity about the subject.

Motion Control is the combination of three core subjects, mechanics, electronics and electrical, and control.  And while the topic incorporates all disciplines, the relationships between the three are extremely important to keep in mind.  The mechanism that is to be controlled is exclusively mechanical in nature, regardless of the means of motive power. And the goal is exert control over the mechanism.  The means of that control is usually electronic and electrical in nature.

The mechanical system sets the boundary conditions for what is possible from the perspective that the physics of mass and inertia (F=ma) cannot be manipulated by the control system.  There is, however, a separate relationship between time, torque and inertia in which various tradeoffs can be explored to improve a given system.  More on this in another post.

John Eidson is attributed with an insight regarding the nature of real time control, although it was in the context of communications.  Everything you need to know about the system you are trying to control is contained in the description of the system to be controlled.  To this I will add, that in order to control something, it is necessary to describe it sufficiently well that the control system can achieve its objectives.  The “magic” in the control system is in how well or poorly the mechanism is represented. If you can’t describe it, you can’t control it.

In the case of motion control or mechatronics, the ultimate goal is performance or behavior.  This means that the control system will be the ultimate determinant of how the system will operate.  But it also means that when control system strategy is developed, an in-depth understanding of the desired behavior is required.  All of the behavior being modeled is based on mechanical equipment, gears, cams, common power takeoff shafts, rotary indexing features, are all based on real world mechanisms.  And with a better understanding of the mechanical context of mechatronics, better solutions are will result. And better solutions benefit everyone.