1. Overview

In a mechanical system, motion does not simply mean that a component moves or rotates. In practice, a specific form of energy is supplied to a drive device, the drive device generates force or torque, and its output is converted into the required motion through mechanical elements.

Motion generation methods can therefore be analyzed through the following questions:

• What energy source generates the motion?

• What actuator produces the force or torque?

• Is the generated motion used directly?

• Is rotational motion converted into linear motion?

• Is fluid pressure or elastic force used?

• Is the motion generated in response to an external control signal?

• Is the motion generated actively or passively?

• Does one drive source generate multiple motions?

The motion generation method is a fundamental factor that determines the following characteristics of a motion system:

• Available force and torque

• Motion speed

• Positioning accuracy

• Repeatability

• Energy efficiency

• Structural complexity

• Maintainability

• Safety

• Noise and vibration

• Cleanliness and hygiene

• Installation cost

• Control complexity

2. Difference Between Motion Generation Method and Other Motion Classifications

2.1 Classification by Motion Trajectory

Motion trajectory describes the path followed by an object through space.

Typical examples include:

• Linear motion

• Rotational motion

• Arc motion

• Curved motion

• Helical motion

• Spatial motion

2.2 Classification by Time Characteristics

Time characteristics describe when motion begins, how long it continues, and how frequently it repeats.

Typical examples include:

• Continuous motion

• Intermittent motion

• Periodic motion

• Event-driven motion

• Synchronous motion

2.3 Classification by Speed and Position Characteristics

Speed and position characteristics describe how motion speed changes and how the target position is controlled.

Typical examples include:

• Constant-speed motion

• Variable-speed motion

• Point-to-point positioning

• Continuous-path control

• Position following

• Position holding

2.4 Classification by Motion Generation Method

Motion generation method describes the principle by which force and torque are produced and the mechanism through which they are converted into the required form of motion.

Typical examples include:

• Electric-motor drive

• Pneumatic drive

• Hydraulic drive

• Gravity drive

• Elastic-force drive

• Manual drive

• Electromagnetic drive

• Piezoelectric drive

• Mechanical motion-conversion drive

One motion may have several classification characteristics at the same time.

For example, a device that pushes a product with a pneumatic cylinder can be described as follows:

• Motion generation method: Pneumatic drive

• Motion trajectory: Linear motion

• Time characteristic: Event-driven or intermittent motion

• Position characteristic: Two-end positioning

3. Basic Classification of Motion Generation Methods

Motion generation methods can be classified according to the following criteria.

3.1 Classification by Energy-Supply Method

• Human-powered or manual drive

• Gravity drive

• Elastic-energy drive

• Electric drive

• Pneumatic drive

• Hydraulic drive

• Thermal-energy drive

• Combustion or engine drive

3.2 Classification by Actuator Principle

• Rotary electric motor

• Linear motor

• Solenoid

• Pneumatic cylinder

• Hydraulic cylinder

• Rotary actuator

• Piezoelectric actuator

• Shape-memory-alloy actuator

• Bimetal actuator

3.3 Classification by Motion-Conversion Method

• Direct drive

• Rotary-to-linear conversion

• Rotary-to-oscillating conversion

• Rotary-to-reciprocating conversion

• Continuous-to-intermittent conversion

• Speed and torque conversion

• Compound linkage conversion

3.4 Classification by Control Method

• Uncontrolled manual motion

• Mechanically controlled motion

• Valve-controlled motion

• Electrical ON/OFF control

• Speed control

• Position control

• Force control

• Closed-loop servo control

3.5 Classification by Motion Activeness

• Active motion

• Passive motion

• Semi-active motion

• Hybrid motion

4. Active Motion

4.1 Definition

Active motion is generated when an actuator converts externally supplied energy into force or torque.

4.2 Typical Energy Sources

• Electricity

• Compressed air

• Hydraulic pressure

• Heat

• Fuel

• Electromagnetic energy

4.3 Main Characteristics

• The start and stop of motion can be controlled.

• Speed and position can be adjusted.

• Force can be actively generated against an external load.

• It is suitable for automation systems.

• An energy-supply system and control system are required.

4.4 Typical Applications

• Servo-motor transfer axes

• Pneumatic-cylinder pushers

• Hydraulic presses

• Linear-motor stages

• Robot joints

• Automatic clamps

5. Passive Motion

5.1 Definition

Passive motion is generated by an externally applied force or stored potential energy rather than by a dedicated drive source that directly produces force.

5.2 Typical Generation Principles

• Gravity

• Spring restoring force

• Inertia

• Contact force from another object

• Operator force

• Fluid flow

• Pressure difference

5.3 Main Characteristics

• The structure is simple.

• Little additional drive energy is required.

• The controllable motion range may be limited.

• Operation may vary according to the load and environmental conditions.

• Safety and return conditions must be evaluated separately.

5.4 Typical Applications

• Gravity chutes

• Spring-return levers

• Free rollers

• Flaps opened by product weight

• Counterweight systems

• One-way clutches

6. Human-Powered and Manual Drive

6.1 Definition

Human-powered drive is a method in which an operator directly applies force or torque to generate motion.

6.2 Typical Components

• Handles

• Levers

• Handwheels

• Pedals

• Cranks

• Grips

• Ratchets

• Manual screws

6.3 Main Characteristics

• The structure is simple.

• No separate power source is required.

• Fine adjustment is possible.

• Motion speed and force depend on the operator.

• Repetitive operation increases fatigue.

• Automation is limited.

6.4 Typical Applications

• Manual height-adjustment systems

• Manual clamps

• Valve-opening handles

• Mold-adjustment systems

• Maintenance jog mechanisms

• Manual lifts

6.5 Design Considerations

• Required operating force

• Handle size

• Lever length

• Operator posture

• Number of repeated operations

• Pinch hazards

• Reverse-rotation prevention

• Indication of operating direction

7. Gravity Drive

7.1 Definition

Gravity drive uses the weight or potential energy of an object to generate motion.

The force generated by gravity can be expressed as follows:

F_g = m × g

The symbols represent:

• F_g: Gravitational force

• m: Mass of the object

• g: Gravitational acceleration

7.2 Main Characteristics

• No separate drive source is required.

• The structure is simple and energy-efficient.

• The direction of movement is limited by gravity.

• Friction and inclination angle have a major effect.

• Speed control may be difficult.

7.3 Typical Applications

• Gravity roller conveyors

• Product-discharge chutes

• Drop-feeding systems

• Weight-return mechanisms

• Counterweights

• Inclined storage systems

7.4 Driving Force on an Inclined Plane

The gravitational component acting along an inclined plane can be expressed as follows:

F_slope = m × g × sinθ

The symbols represent:

• F_slope: Force acting along the slope

• m: Mass of the object

• g: Gravitational acceleration

• θ: Inclination angle

7.5 Design Considerations

• Inclination angle

• Product mass

• Coefficient of friction

• Travel speed

• Collision prevention

• Fall prevention

• Stopping device

• Product orientation

8. Elastic-Force Drive

8.1 Definition

Elastic-force drive uses energy stored in a spring, rubber component, leaf spring, or other elastic element to generate motion.

Spring force can be expressed as follows:

F = k × x

The symbols represent:

• F: Spring force

• k: Spring constant

• x: Deformation

8.2 Typical Elastic Elements

• Compression spring

• Extension spring

• Torsion spring

• Leaf spring

• Rubber elastomer

• Gas spring

• Belleville spring

8.3 Main Characteristics

• Energy can be stored and released.

• It is suitable for return motion.

• The structure is simple.

• Generated force changes with displacement.

• Fatigue and stress relaxation must be considered.

8.4 Typical Applications

• Spring-return valves

• Clamp return

• Safety-cover return

• Latch mechanisms

• Pusher return

• Shock-absorption devices

• Constant-pressure contact devices

8.5 Design Considerations

• Initial tension

• Maximum deformation

• Spring constant

• Fatigue life

• Buckling

• Corrosion

• Temperature effects

• Safety in the event of breakage

9. Rotary Electric-Motor Drive

9.1 Definition

Rotary electric-motor drive is the most common method of generating motion by converting electrical energy into rotational torque.

9.2 Typical Motors

• AC induction motor

• Synchronous motor

• DC motor

• Brushless DC motor

• Servo motor

• Stepper motor

• Torque motor

9.3 Main Characteristics

• High rotational speeds are easy to achieve.

• Speed control is possible.

• Torque can be increased using a reducer.

• Rotational motion can be converted into other forms of motion.

• It is suitable for automation and precision control.

9.4 Output Torque and Power

The mechanical power of a rotating shaft can be expressed as follows:

P = T × ω

The symbols represent:

• P: Power

• T: Torque

• ω: Angular velocity

9.5 Typical Applications

• Conveyor drives

• Mixers

• Pumps

• Screw feeders

• Ball-screw transfer axes

• Robot joints

• Rotary cutters

9.6 Design Considerations

• Rated torque

• Maximum torque

• Rated speed

• Starting torque

• Load inertia

• Reduction ratio

• Heat generation

• Cooling

• Brake

• Protection rating

10. Stepper-Motor Drive

10.1 Definition

A stepper motor is an electric actuator that rotates through a fixed angle in response to input pulses.

10.2 Main Characteristics

• Position can be controlled by the number of pulses.

• High torque can be generated at low speed.

• Open-loop control is possible.

• Holding torque is generated at standstill.

• Torque decreases at high speed.

• Step loss may occur under overload.

10.3 Typical Applications

• Small transfer axes

• Indexing systems

• Valve-position adjustment

• Printers

• Small automation systems

• Metering feeders

10.4 Design Considerations

• Step angle

• Microstepping

• Maximum pulse frequency

• Acceleration and deceleration

• Step-loss prevention

• Resonance

• Holding torque

• Motor heating

11. Servo-Motor Drive

11.1 Definition

Servo-motor drive uses encoder feedback to control position, speed, and torque in a closed loop.

11.2 Main Characteristics

• High positioning accuracy can be achieved.

• Rapid acceleration and deceleration are possible.

• Speed and torque can be controlled.

• The system can respond to load changes.

• Controller tuning is required.

• Cost and system complexity increase.

11.3 Typical Applications

• Precision transfer axes

• Robots

• CNC equipment

• Electronic cams

• Flying cutters

• Packaging machines

• Multi-axis synchronous control

11.4 Design Considerations

• Load-inertia ratio

• Encoder resolution

• Maximum torque

• Continuous torque

• Control gain

• Settling time

• Following error

• Regenerative energy

12. Linear-Motor Drive

12.1 Definition

A linear motor directly converts electrical energy into linear thrust.

It generates linear motion without using a rotary motor and a conversion mechanism such as a ball screw.

12.2 Main Characteristics

• Linear motion is generated directly.

• Backlash is almost eliminated.

• High speed and acceleration are possible.

• Mechanical contact and friction are reduced.

• It is suitable for precision positioning.

• Heat generation and magnetic effects must be considered.

12.3 Typical Applications

• Semiconductor equipment

• High-speed pick-and-place systems

• Precision-inspection equipment

• Linear stages

• High-speed cutting machines

• Electronic-assembly equipment

12.4 Thrust and Acceleration

The required thrust of a linear motor can be calculated as follows:

F = m × a + F_friction + F_external

The symbols represent:

• F: Required thrust

• m × a: Force required for acceleration

• F_friction: Friction force

• F_external: External load

13. Solenoid and Electromagnetic Drive

13.1 Definition

Solenoid drive uses the magnetic force generated by current flowing through a coil to move a plunger in a linear or rotational direction.

13.2 Main Characteristics

• Fast ON/OFF operation is possible.

• The structure is simple.

• It is suitable for short strokes.

• Heat is generated while power is applied.

• The position-control range is limited.

• Generated force varies according to stroke position.

13.3 Typical Applications

• Solenoid valves

• Locking devices

• Latches

• Product-discharge systems

• Electromagnetic brakes

• Small clutches

• Door interlocks

13.4 Design Considerations

• Stroke

• Pulling force

• Duty cycle

• Coil temperature

• Return spring

• Response time

• Residual magnetism

• Supply voltage

14. Pneumatic Drive

14.1 Definition

Pneumatic drive uses compressed-air pressure to generate linear or rotational motion.

14.2 Typical Pneumatic Actuators

• Single-acting cylinder

• Double-acting cylinder

• Rodless cylinder

• Guided cylinder

• Rotary actuator

• Pneumatic gripper

• Pneumatic muscle

14.3 Cylinder Thrust

The theoretical thrust of a pneumatic cylinder can be calculated as follows:

F = P × A

The symbols represent:

• F: Cylinder thrust

• P: Supply pressure

• A: Effective piston area

Actual thrust is lower than theoretical thrust because of friction and pressure loss.

F_actual = P × A × η

The symbol represents:

• η: Efficiency coefficient

14.4 Main Characteristics

• It is suitable for fast reciprocating motion.

• The structure is simple.

• A high level of cleanliness can be achieved.

• It is relatively resistant to overload.

• Precise position control is difficult because air is compressible.

• Producing compressed air requires significant energy.

14.5 Typical Applications

• Product pushers

• Clamps

• Discharge devices

• Door-opening systems

• Grippers

• Stoppers

• Sealing devices in packaging machines

14.6 Design Considerations

• Cylinder bore

• Stroke

• Supply pressure

• Required speed

• Air consumption

• Cushioning

• Side load

• Rod buckling

• Exhaust noise

• Moisture and contamination

15. Hydraulic Drive

15.1 Definition

Hydraulic drive uses pressurized fluid to generate large force or torque.

15.2 Typical Hydraulic Actuators

• Hydraulic cylinder

• Hydraulic motor

• Rotary actuator

• Hydraulic press

• Hydraulic clamp

15.3 Cylinder Thrust

The theoretical thrust of a hydraulic cylinder can be calculated as follows:

F = P × A

Hydraulic systems use much higher pressure than pneumatic systems, allowing a small cylinder to generate a large force.

15.4 Main Characteristics

• Very large forces can be generated.

• Stable low-speed motion is possible.

• High rigidity and load-holding capability are available.

• The system is resistant to impact loading.

• Leakage and contamination must be controlled.

• Auxiliary equipment such as pumps, tanks, and valves is required.

15.5 Typical Applications

• Presses

• Forming equipment

• Large clamps

• Lifts

• Heavy equipment

• Cutting devices

• Compression systems

15.6 Design Considerations

• Operating pressure

• Flow rate

• Cylinder bore

• Rod diameter

• Fluid temperature

• Leakage

• Seal life

• Fluid cleanliness

• Pressure shock

• Safety valve

16. Rotary-to-Linear Motion Conversion

16.1 Definition

Rotary-to-linear conversion changes the rotational motion of a motor into linear motion.

16.2 Typical Mechanisms

• Ball screw

• Lead screw

• Rack and pinion

• Belt and pulley

• Chain and sprocket

• Slider-crank mechanism

• Cam and follower

16.3 Ball-Screw Drive

A ball screw converts rotational motion into precise linear motion.

Travel distance can be calculated as follows:

x = n × L

The symbols represent:

• x: Travel distance

• n: Number of screw revolutions

• L: Screw lead

16.4 Main Characteristics

• High positioning accuracy

• High transmission efficiency

• High axial-load capacity

• Adjustable backlash

• Critical speed and buckling must be considered for long screws

16.5 Typical Applications

• CNC feed axes

• Servo actuators

• Presses

• Precision-positioning devices

• Lifting axes

17. Rotary-to-Reciprocating Motion Conversion

17.1 Definition

Rotary-to-reciprocating conversion changes continuous rotational input into repeated linear reciprocating motion.

17.2 Typical Mechanisms

• Slider-crank mechanism

• Eccentric cam

• Scotch-yoke mechanism

• Cam and follower

• Eccentric shaft

• Linkage mechanism

17.3 Main Characteristics

• Repetitive motion can be generated from one rotary drive source.

• High repetition speed can be achieved.

• Stroke and velocity profile are determined geometrically.

• Velocity becomes zero at both ends of the stroke.

• Repeated loads act on links and pins.

17.4 Typical Applications

• Presses

• Slicers

• Reciprocating pumps

• Sealing bars

• Cutting devices

• Packaging machines

18. Rotary-to-Oscillating Motion Conversion

18.1 Definition

Rotary-to-oscillating conversion changes continuous rotary motion into repeated angular motion within a limited range.

18.2 Typical Mechanisms

• Crank-rocker mechanism

• Four-bar linkage

• Cam rocker

• Eccentric linkage

• Worm and sector gear

18.3 Main Characteristics

• Limited-angle motion can be generated repeatedly.

• Mechanical synchronization is easy.

• Output angle and velocity are determined by link length.

• Joint clearance and fatigue must be considered.

18.4 Typical Applications

• Wipers

• Swing nozzles

• Flaps

• Product-orientation devices

• Oscillating washing systems

19. Continuous-to-Intermittent Motion Conversion

19.1 Definition

Continuous-to-intermittent conversion changes continuously rotating input into repeated movement and dwell.

19.2 Typical Mechanisms

• Geneva mechanism

• Cam indexer

• Barrel cam

• Ratchet and pawl

• Escapement

• Clutch and brake

19.3 Main Characteristics

• Movement and dwell are generated mechanically.

• It is suitable for synchronizing multiple processes.

• High rigidity can be achieved during dwell.

• Impact and vibration must be considered at high speed.

19.4 Typical Applications

• Indexing tables

• Automatic assembly machines

• Filling machines

• Packaging machines

• Turret systems

• Multi-process machine tools

20. Gear and Reducer Drive

20.1 Definition

Gear and reducer drive converts rotational speed and torque according to the required ratio.

20.2 Basic Relationships

In an ideal reducer, speed and torque relationships can be expressed as follows:

ω_out = ω_in / i

T_out = T_in × i × η

The symbols represent:

• ω_in: Input speed

• ω_out: Output speed

• T_in: Input torque

• T_out: Output torque

• i: Reduction ratio

• η: Reducer efficiency

20.3 Typical Reducers

• Spur-gear reducer

• Helical reducer

• Worm reducer

• Planetary reducer

• Cycloidal reducer

• Harmonic reducer

• Bevel reducer

20.4 Main Characteristics

• Speed can be reduced and torque increased.

• Rotational direction can be changed.

• Shaft arrangement can be changed.

• Backlash and efficiency losses occur.

• Accuracy and rigidity vary according to reducer type.

21. Belt and Chain Drive

21.1 Definition

Belt and chain drive transmits rotational motion and power between two separated shafts.

21.2 Typical Methods

• Flat belt

• V-belt

• Timing belt

• Roller chain

• Toothed chain

21.3 Main Characteristics

• Power can be transmitted over a relatively long center distance.

• The structure is simple.

• Timing belts and chains can provide synchronous transmission.

• Belts can absorb impact and vibration.

• Tension adjustment and wear management are required.

21.4 Typical Applications

• Conveyors

• Transfer axes

• Multi-axis synchronous drives

• Packaging machines

• Roller drives

• Lifting systems

22. Cam Drive

22.1 Definition

Cam drive mechanically determines follower displacement, velocity, and acceleration according to the cam profile.

22.2 Main Characteristics

• Complex motion laws can be implemented mechanically.

• High repeatability can be achieved.

• Multiple motions can be synchronized to one shaft.

• Changing the motion requires changing the cam profile.

• Contact stress and wear occur.

22.3 Typical Applications

• Packaging machines

• Filling machines

• Valve drives

• Product transfer

• Clamping devices

• High-speed assembly machines

22.4 Design Considerations

• Cam profile

• Pressure angle

• Follower size

• Contact stress

• Lubrication

• Follower separation

• Spring preload

• Vibration and noise

23. Linkage Drive

23.1 Definition

Linkage drive combines several rigid links and rotary or linear joints to generate the required motion.

23.2 Typical Linkage Mechanisms

• Four-bar linkage

• Crank-rocker mechanism

• Slider-crank mechanism

• Pantograph

• Toggle linkage

• Parallel linkage

23.3 Main Characteristics

• Complex output motion can be produced from one input.

• Mechanical synchronization is possible.

• A predetermined path can be repeated without external control.

• Link length and joint position determine motion.

• Clearances and assembly tolerances affect performance.

23.4 Typical Applications

• Door-opening systems

• Clamps

• Product-transfer arms

• Folding mechanisms

• Packaging machines

• Presses

24. Piezoelectric Drive

24.1 Definition

Piezoelectric drive uses the small deformation of piezoelectric material when voltage is applied.

24.2 Main Characteristics

• Very small displacement can be controlled precisely.

• Response speed is very high.

• High resolution can be achieved.

• Stroke is short.

• High-voltage drive may be required.

• Hysteresis and creep may occur.

24.3 Typical Applications

• Precision-positioning stages

• Optical-lens adjustment

• Semiconductor equipment

• Ultrasonic transducers

• Precision valves

• Micro-flow control

25. Thermal and Shape-Memory Drive

25.1 Definition

Thermal drive uses expansion, contraction, or phase transformation caused by temperature change to generate motion.

25.2 Typical Methods

• Bimetal

• Shape-memory alloy

• Wax actuator

• Thermal-expansion actuator

• Thermopneumatic actuator

25.3 Main Characteristics

• The structure can be simple.

• Sensor and actuator functions can be combined.

• Response speed is relatively slow.

• Temperature and environmental conditions have a major effect.

• Repetition life and cooling time are important.

25.4 Typical Applications

• Temperature-control valves

• Thermal relays

• Automatic ventilation devices

• Small locking devices

• Overheat-protection devices

26. Vibration-Generating Drive

26.1 Definition

Vibration-generating drive uses rotational eccentricity, electromagnetic force, piezoelectric effects, or pneumatic force to generate repetitive vibration.

26.2 Typical Methods

• Eccentric motor

• Electromagnetic vibrator

• Piezoelectric vibrator

• Pneumatic vibrator

• Cam vibrator

26.3 Main Characteristics

• Repetitive small displacements are generated.

• It is effective for feeding, alignment, and separation.

• Resonance can be used intentionally.

• Vibration may be transmitted to the frame.

• Noise and fastener loosening must be considered.

26.4 Typical Applications

• Vibratory feeders

• Screening machines

• Product-alignment systems

• Vibratory chutes

• Compaction systems

• Cleaning systems

27. Direct Drive and Indirect Drive

27.1 Direct Drive

Direct drive transmits actuator output directly to the load without a reducer or motion-conversion mechanism.

Typical examples include:

• Direct-drive motor

• Linear motor

• Torque motor

• Motorized roller

Advantages

• Low backlash

• High transmission efficiency

• Simple structure

• High response

• Fewer maintenance components

Limitations

• A larger motor may be required.

• Cost may be higher.

• Load inertia acts directly on the motor.

• Thermal management is important.

27.2 Indirect Drive

Indirect drive transmits or converts motion through a reducer, belt, chain, screw, or linkage.

Advantages

• Speed and torque can be changed easily.

• Motor location can be arranged freely.

• Motion can be converted into various forms.

• Large loads can be driven more easily.

Limitations

• Backlash may occur.

• Transmission efficiency decreases.

• The number of wear components increases.

• The structure becomes more complex.

28. Single Drive and Multiple Drive

28.1 Single Drive

A single actuator drives one axis or one mechanism.

Characteristics

• Mechanical and control structures are simple.

• Individual-axis adjustment is easy.

• Fault location is easy to identify.

• The number of actuators may increase.

28.2 Multi-Output Drive

One drive source operates several axes or mechanisms simultaneously.

Typical Methods

• Gear distribution

• Timing-belt distribution

• Chain distribution

• Camshaft

• Line shaft

• Linkage distribution

Characteristics

• Mechanical synchronization is possible.

• The number of motors can be reduced.

• The overall structure may become complex.

• Individual-axis adjustment is difficult.

• Failure in one section may affect the entire system.

28.3 Independent Multi-Axis Drive

Each axis uses a separate actuator and is synchronized electronically.

Characteristics

• Motion of each axis can be changed easily.

• Electronic cams and position compensation can be used.

• Wiring and control become more complex.

• Synchronization-control performance is important.

29. Combined and Hybrid Drive

29.1 Definition

Combined drive integrates two or more motion generation methods to use the advantages of each.

29.2 Typical Combinations

• Servo motor and pneumatic cylinder

• Electric axis and mechanical cam

• Hydraulic cylinder and electric positioning axis

• Motor drive and spring return

• Pneumatic drive and mechanical lock

• Gravity transfer and electric stopper

29.3 Main Characteristics

• Drive characteristics can be combined according to the required function.

• Precision positioning and large force can be implemented separately.

• Energy efficiency may be improved.

• Structure and control may become more complex.

• Response differences between drive sources must be considered.

29.4 Typical Applications

• Pneumatic clamp and servo transfer axis

• Electric lifting axis with mechanical fall prevention

• Servo press with spring cushioning

• Pneumatic pusher and electric conveyor

• Hydraulic press with servo positioning

30. Comparison of Typical Applications by Motion Generation Method

31. Criteria for Selecting a Motion Generation Method

31.1 Required Motion

• Is linear motion required?

• Is rotational motion required?

• Is reciprocating motion required?

• Is limited-angle motion required?

• Is intermittent motion required?

• Is micro-motion required?

31.2 Load Conditions

• Required force

• Required torque

• Moving mass

• Rotational inertia

• Impact load

• Eccentric load

• Vertical load

31.3 Performance Conditions

• Maximum speed

• Acceleration

• Positioning accuracy

• Repeatability

• Settling time

• Cycle time

• Duty cycle

31.4 Control Conditions

• Simple ON/OFF control

• Speed control

• Position control

• Torque control

• Force control

• Multi-axis synchronous control

• Sensor feedback

31.5 Environmental Conditions

• Water and cleaning agents

• High and low temperatures

• Dust

• Corrosion

• Explosion risk

• Clean environment

• Food contact

• Water and dust protection

31.6 Maintenance Conditions

• Lubrication requirements

• Seal replacement

• Belt-tension adjustment

• Chain elongation

• Brake wear

• Air leakage

• Hydraulic leakage

• Motor replaceability

31.7 Economic Conditions

• Initial installation cost

• Energy cost

• Maintenance cost

• Consumable cost

• Control-system cost

• Expected service life

• Downtime cost

32. Comparison from an Energy-Efficiency Perspective

32.1 Electric Drive

Electric drive generally provides easy speed and position control and can consume energy only when needed.

Servo motors can return regenerative energy to the power supply during deceleration or dissipate it through a braking resistor.

32.2 Pneumatic Drive

Pneumatic actuators have a simple structure, but significant energy loss occurs during compressed-air generation.

Additional losses occur through leakage, pressure reduction, and exhaust.

32.3 Hydraulic Drive

Hydraulic systems provide high force density, but energy loss and heat generation may increase when the pump operates continuously.

Efficiency can be improved using variable-displacement pumps and accumulators.

32.4 Gravity and Elastic Drive

Gravity and spring systems are effective for reducing energy consumption.

However, potential energy or elastic energy must be stored again before the motion can be repeated.

33. Safety Design

33.1 Electric Drive

• Overcurrent protection

• Overspeed protection

• Brake

• Safe torque off

• Emergency stop

• Encoder-fault monitoring

33.2 Pneumatic Drive

• Residual-pressure release

• Fall prevention

• Pilot-operated check valve

• Speed-control valve

• Pressure limitation

• Prevention of unintended cylinder extension

33.3 Hydraulic Drive

• Relief valve

• Hose-rupture valve

• Check valve

• Pressure monitoring

• Cylinder fall prevention

• Leakage detection

33.4 Gravity and Spring Drive

• Prevention of unexpected return

• Spring-breakage protection

• Fall prevention

• Mechanical stopper

• Locking device

• Stored-energy release procedure

34. Design Verification Items

34.1 Driving-Force Verification

• Required force

• Required torque

• Starting load

• Acceleration load

• Friction load

• Maximum external load

• Safety factor

34.2 Speed Verification

• Maximum speed

• Minimum speed

• Response time

• Acceleration time

• Deceleration time

• Cycle time

34.3 Position Verification

• Travel distance

• Positioning accuracy

• Repeatability

• Backlash

• Settling time

• Homing repeatability

34.4 Thermal Verification

• Motor temperature

• Solenoid temperature

• Hydraulic-fluid temperature

• Pneumatic-exhaust temperature

• Reducer temperature

• Allowable continuous operating time

34.5 Structural Verification

• Shaft strength

• Buckling

• Torsion

• Link stress

• Bearing life

• Frame deformation

• Vibration and resonance

34.6 Service-Life Verification

• Motor-bearing life

• Cylinder-seal life

• Spring fatigue

• Belt fatigue

• Chain wear

• Cam-contact fatigue

• Link-pin wear

35. Main Related Equations

Gravitational Force

F_g = m × g

Gravitational force is the product of mass and gravitational acceleration.

Force Along an Inclined Plane

F_slope = m × g × sinθ

Force along the slope is the product of mass, gravitational acceleration, and the sine of the inclination angle.

Spring Force

F = k × x

Spring force is the product of the spring constant and deformation.

Linear Acceleration Force

F = m × a

The force required for acceleration is the product of mass and acceleration.

Rotational Acceleration Torque

T = J × α

Rotational acceleration torque is the product of moment of inertia and angular acceleration.

Rotational Power

P = T × ω

Rotational power is the product of torque and angular velocity.

Cylinder Thrust

F = P × A

Cylinder thrust is the product of fluid pressure and effective piston area.

Actual Cylinder Thrust

F_actual = P × A × η

Actual thrust is calculated by multiplying theoretical thrust by efficiency.

Reducer Output Speed

ω_out = ω_in / i

Output speed is the input speed divided by the reduction ratio.

Reducer Output Torque

T_out = T_in × i × η

Output torque is the product of input torque, reduction ratio, and efficiency.

Screw Travel Distance

x = n × L

Screw travel distance is the product of the number of revolutions and the screw lead.

36. Conclusion

Classification of motion according to motion generation method does not describe the path followed by a machine. It analyzes how the force and torque required for motion are generated, how they are transmitted, and how they are converted into the required form of movement.

Manual, gravity, and elastic-force drives have simple structures and low energy consumption, but their controllable range and available force may be limited.

Electric-motor drive efficiently generates rotational motion and can be converted into various motion forms through reducers, belts, screws, and linkages. Servo motors are particularly suitable for automation equipment requiring precise control of position, speed, and torque.

Pneumatic drive is suitable for fast and simple reciprocating motion and is widely used in product pushers, clamps, and discharge devices. However, the compressibility of air limits precise position and speed control.

Hydraulic drive can generate large force from a compact actuator, making it suitable for presses, forming equipment, and heavy machinery. Leakage, contamination, heat generation, and maintenance must nevertheless be considered.

Linear motors, piezoelectric actuators, and shape-memory alloys are respectively suited to high-speed linear motion, ultra-precise micro-motion, and compact thermal-actuation systems.

Direct drive can reduce backlash and transmission loss but may require a larger actuator. Indirect drive allows flexible speed and torque conversion but may increase clearance and wear.

The following factors should therefore be considered together when selecting a motion generation method:

• Required motion type

• Required force and torque

• Speed and acceleration

• Travel distance and rotational angle

• Positioning accuracy

• Repeatability

• Cycle time

• Energy efficiency

• Safety

• Noise and vibration

• Cleanliness and hygiene

• Maintainability

• Installation cost

• Operating cost

• Expected service life

Good motion design is not simply the selection of a powerful drive source. It means generating the required motion with the most suitable energy source and actuator, transmitting it to the load with minimum loss and clearance, and ensuring safe, stable, and repeatable operation at the required speed and position.

The motion generation method is a fundamental motion-design criterion that determines the mechanical structure, control system, energy consumption, maintenance requirements, and overall service life of the equipment.