Educational Series – Four Types of Motion Control

As far as we know to date, our universe is made up of a small number of atoms, matter, and a vast amount of energy. All this energy is perhaps one reason why everything in our world seems naturally inclined to move or change its location and position. In order to move you need some form of motion. The four types of motion control that we know of and use in this world are:

• Translational (Linear)
• Rotational
• Oscillatory
• Irregular

As a bonus fifth form of motion control, we can combine any number of the above four types of motion control. Each type of movement provides a different mechanical means. Knowing these basic forms of motion helps us to understand the mechanics of linear motion and motion control as a whole.

Let’s discuss the four types of motion control (plus the fifth):

1. Translational Motion aka Linear Motion

Simply put, translational motion (or linear motion) is anything that moves in a straight line, such as linear actuators or anything that moves from one point to another. Translational motion can be divided into two other types:

• Rectilinear (the object moves in a straight line)
• Curvilinear motion (the object follows a curved path)

2. Rotational Motion

This type of movement was first studied and observed by humans in ancient times. An example of rotational motion that has captured the curiosity of humans for centuries is our own planet; Earth remains in one location, while spinning about an axis. Here we can identify two types of rotational motion:

• Rotation around an internal axis (ex. the spin of the earth)
• Rotation around an external axis (ex. the earth’s orbit around the sun)

Another important characteristic to note, is that rotational movement is periodical. Unlike curvilinear motion, which has a beginning and an end point, rotational motion always returns to the original point where the movement began. This forms a closed loop. A car’s engine works this way. Linear cylinders and rotary actuators are used throughout nearly every type of industry, from autos, agriculture, medical, robotics, even aerospace.

3. Oscillatory Motion

Oscillatory motion is something that moves back and forth, aka something that oscillates. Similar to rotational movement, oscillatory movement is repetitive and fluctuates between two locations, identified by the oscillatory motion from a side to side swinging, like a pendulum in a traditional grandfather clock.

This kind of motion is called “periodic”; the time for one complete oscillation (or one cycle) is considered a period. The cycle repeats and eventually comes to a stopover time, either through pre-determined programming, the force of another object or by the object’s own momentum. Periodic motion is important in the study of sound, light, and other waves.

4. Irregular Motion

This category of motion control can be seen as the most complex of all types as it has no fixed pattern or standard. A common example we are all familiar with, is the seemingly erratic flight of a swarm of bees. Another example, one you learned in science class, is the motion of an electron in an atom.

Of all the four types of motion control, irregular movement is the only one that does not follow a particular time sequence nor have a specified periodic motion.

5. Bonus: Combination of Motion

Now you know the four types of motion control. However, like many things in life, there is often an exception to the rule. In this case, it’s more of an exception by combination. By combining any two or more of the above four types of motion control, we find ourselves with a bonus: the fifth type of basic motion control.

This type is also one of the most common, which you will recognize in your everyday life. A great example of combined motion is a football in a football match. It spins (rotational), moves forward (linear) and can even be irregular sometimes. The introduction of quadcopters, multicopters and other types of flying robotic drones is another example of combination motion. The drones can move up, down, side to side, all made possible by rotary wings. When fitted with landing, blade or camera extensions, these drones can combine all of the four types of motion control.

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This concludes the first article in our Education Series.

To continue learning, go on to the second article: Brushed vs Brushless DC Motor (coming soon)

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