What Are The Different Types Of Motion System?

In classical physics, four basic types of motion are defined as linear, rotary, reciprocating and oscillating. When these are applied to mechanical devices, this natural physical behaviour transforms motion into force. This force or power is then used to create some form of output motion, which drives the equipment or machinery. In industrial automation, we use a wide variety of equipment that employs these different types of motion systems, usually either rotary or linear, but sometimes a combination of both.

Linear Motion

Linear motion is the simplest and most fundamental form of movement, characterised by altering one’s position in a single direction. Picture it as a person walking, swimming or running in a straight line, or a mechanical object like a vehicle travelling on a straight track. A linear motion system is based on some form of mechanism that moves a load along a single axis. In pneumatics, loads are driven in a straight line by devices such as linear motors, slides or actuators, or ball screw assemblies. You’ll find this type of motion system most commonly in applications like material handling, CNC machining, packaging, palletising, and robotics.

Types Of Linear Drive 

Various drive technologies employ linear motion, each with its own advantages

• Linear motors create direct linear motion. They can accelerate rapidly to high speeds and require no mechanical conversion. They’re very well suited to pick-and-place applications.

• Linear guides such as roller or rail guides provide low-friction, smooth linear motion. They’re frequently used in automation and machine tools to support heavy loads.

• Ball screws convert rotary movements to linear motion. They’re extremely precise and efficient and used a lot in robotics and applications like CNC machines.

• Rack and pinion systems provide high force capacity and long travel distances, using toothed gears to convert rotary motion into linear movement. You’ll find this type of drive in gantry systems and large machinery.

Rotary Motion

The most basic form of rotary motion is the wheel, where something spins or revolves in either direction around a central axis or pivot point. The motion can be self-generating, like a tornado or the rotation of the earth, but in automation systems, it’s created by rotational actuators, gear-driven systems or rotary tables.

A rotary actuator generates power in a radius that can be a partial angle of a circle or a complete, continuous revolution. Applications that use rotary motion systems include turbines to generate energy from wind, water or steam, machine tool spindles, drilling or grinding tools, robot joints and indexing tables. 

Types Of Rotary Drive 

Rotary devices are categorised by their source of power or energy, including manual, electric, or fluid-based (either hydraulic or pneumatic).

• Manual drives create rotary motion with a gear system, typically a hand-operated wheel that transmits rotational energy via the gearing to the actuating element. The mechanical torque reduces the amount of effort required to move a large load.

• Electric rotary drives usually run on a motor controlling a system of gears. They’re generally reversible and can generate angular rotation or oscillation. An electric controller regulates the input current to the motor, so it can vary acceleration and velocity.

• Fluid-based rotary drives use pressurised air or fluid to generate motion. There are many ways to do this, including those using rack and pinion gearing, pressure on a vane or diaphragm, or a piston and rotating coupling system called a scotch yoke.

Combination Motion Systems

More complex tasks create a system from a combination of motion types, most commonly linear and rotary. You’ll find these in applications like pick-and-place operations and robotics, where they’re used for different types of robots and some robotic arms. You’ll also see technological advances in solutions for multi-axis motion control and complex electronic programming.

Combined Motion Drives

To achieve accurate movement with combined motion drives, the main solutions are gears, belt drives and lead screws. Each solution has its own strengths and weaknesses, including repeatability, positioning speed, precision and cost. 

• Gears are mechanical devices that transmit torque by connecting teeth. The teeth in the gear mechanism mesh with compatibly toothed parts in another gear or drive to create rotational force. Gears are usually circular, with a toothed circumference, but it’s also possible to put teeth on the internal diameter of a gear wheel. Such designs are usually used in space and weight-critical applications and offer a high degree of torque and speed control. Two or more intermeshing gears can also work in sequence as a gear train to transmit rotational motion, typically powered by a motor or engine.

• Belt drives usually consist of a flexible, circular band or belt that connects a pair of pulleys. They’re driven by a motor, and their cyclical motion transmits rotational power from one place to another. They’re very useful for applications that need to travel long distances, being lighter, quieter, cheaper and more efficient to operate than gears. The most common application for belt drives is in conveyor systems and cam belts for engines.

• Like a ball screw, lead screws or power screws convert the rotary movement of a screw or nut into linear motion. Lead screws and nuts use a helical thread design to translate the motion, so they’re also often called translation screws. They come in a wide variety of sizes and values, so you can determine how much motion will be provided in one revolution of the screw. That makes them viable either for drives demanding high precision and speed, like a disc reader head or for those requiring low speed and high torque, like a bench vice. Lead screws are also good for applications requiring high load transference or accurate motion and are commonly used in hobby machinery and robotics. 

Which Type Of Motion Should You Choose?

What type of motion system you use depends largely on your application and its working environment. How much space do you have, or what distance to cross? Other factors to consider include how much precision and velocity you require and how much force you need to carry out a task. Choosing linear, rotary or combination motion systems may require some complex calculations. If you’re in any doubt or need assistance, don’t hesitate to contact our experts here at Rowse Automation.