1. Overview

Motion in a mechanical system is defined not only by the path an object follows, but also by when it moves, how long the movement continues, how often it repeats, and at what point it stops.

Classification by motion trajectory focuses on the spatial path of movement, such as linear, rotational, arc, helical, or curved motion. Classification by time characteristics focuses on questions such as:

• Does the motion continue without interruption?

• Does it repeat at regular intervals?

• Do movement and stopping occur alternately?

• Does the motion start and stop suddenly or gradually?

• Does the motion include a dwell period?

• Does the motion occur only when an external signal is received?

• Is it synchronized with another device?

• How do velocity and acceleration change over time?

Even when the spatial path is identical, continuous transfer, intermittent transfer, reciprocating transfer, and indexing transfer require different motors, reducers, sensors, controllers, and safety designs.

Time characteristics are therefore major design factors that determine cycle time, production capacity, positioning accuracy, vibration, impact, energy consumption, component life, and control complexity.

2. Difference Between Motion Trajectory and Time Characteristics

Motion trajectory refers to the path followed by an object through space.

Typical examples include:

• Linear path

• Circular path

• Arc path

• Helical path

• Curved path

• Three-dimensional spatial path

Time characteristics describe the time law according to which the object moves along that path.

Typical examples include:

• Continuous movement at a constant velocity

• Repeated movement and stopping at regular intervals

• Operation for only a short period

• Operation only when a specific signal is received

• Repeated acceleration and deceleration

• Synchronized operation with another device

A single motion therefore has both spatial characteristics and time characteristics.

For example, a conveyor can be described as follows:

• Spatial characteristic: Linear motion

• Time characteristic: Continuous motion

An indexing table can be described as follows:

• Spatial characteristic: Rotational motion

• Time characteristic: Intermittent or indexing motion

A sealing bar in a packaging machine can be described as follows:

• Spatial characteristic: Linear reciprocating motion

• Time characteristic: Periodic motion combined with a dwell period

3. Basic Classification System According to Time Characteristics

Time characteristics cannot always be classified using only one criterion, because several time-related characteristics may appear simultaneously in an actual machine.

It is therefore appropriate to analyze motion according to the following five criteria.

3.1 Classification by Continuity of Operation

• Continuous motion

• Intermittent motion

• Intermittent-duty motion

• Event-driven motion

3.2 Classification by Repeatability

• Periodic motion

• Aperiodic motion

• Repetitive-cycle motion

• One-time motion

3.3 Classification by State Change

• Transient motion

• Steady-state motion

• Starting motion

• Stopping motion

3.4 Classification by Velocity Change

• Constant-velocity motion

• Accelerating and decelerating motion

• Triangular-velocity motion

• Trapezoidal-velocity motion

• S-curve motion

• Pulse motion

3.5 Classification by Synchronization Method

• Time-based motion

• Position-based motion

• Event-based motion

• Synchronous motion

• Asynchronous motion

• Phase-controlled motion

Applying these classifications together makes it possible to describe the actual operating characteristics of a machine more accurately.

4. Continuous Motion

4.1 Definition

Continuous motion is a form of motion that continues without interruption while the machine is operating.

It is commonly used in devices that require continuous power transmission, such as rotating shafts, conveyors, pumps, fans, mixers, and screw feeders.

4.2 Main Characteristics

• There is no dwell period during operation.

• Velocity is constant or changes continuously.

• Steady-state operating time is long after startup.

• The number of repeated starts and stops is relatively low.

• A consistent production flow can be maintained.

• Rotational inertia and energy efficiency are important.

4.3 Typical Applications

• Belt conveyors

• Roller conveyors

• Agitators

• Mixers

• Centrifugal pumps

• Blowers

• Screw conveyors

• Continuous cutting devices

• Rotary filling machines

• Screw-transfer systems in meat-processing machinery

4.4 Time Characteristics

Continuous motion can generally be divided into three periods:

1. Starting period

2. Steady operating period

3. Stopping period

During the starting period, velocity increases from zero to the target velocity.

During steady operation, the target velocity is maintained or adjusted gradually according to process conditions.

During the stopping period, velocity decreases from the target velocity to zero.

4.5 Design Considerations

• Normal operating velocity

• Starting torque

• Braking torque

• Rotational inertia

• Continuous operating time

• Heat generation

• Bearing life

• Lubrication conditions

• Energy efficiency

• Stopping method during power failure

• Emergency-stop distance

Continuous-duty equipment has fewer start-stop cycles than intermittent equipment, but heat generation and wear during long-term operation are more important.

5. Intermittent Motion

5.1 Definition

Intermittent motion repeatedly alternates between a movement period and a dwell period.

The movement and stopping intervals are clearly separated in time.

Intermittent motion is widely used in machines that move a product from one processing position to another and then perform machining, assembly, inspection, filling, or packaging while the product is stationary.

5.2 Main Characteristics

• Movement and stopping are repeated.

• Processing is performed during the dwell period.

• Stopping-position accuracy is important.

• The ratio of movement time to dwell time determines productivity.

• Repeated acceleration and deceleration occur.

• Repeated inertial loads act on the drive system.

5.3 Typical Applications

• Indexing tables

• Product-transfer devices in packaging machines

• Automatic assembly machines

• Filling machines

• Labeling machines

• Tray-transfer devices

• Inspection equipment

• Pneumatic pushers

• Positioning devices before cutting

5.4 Cycle Time

The total cycle time of intermittent motion can be expressed as follows:

T_cycle = t_move + t_dwell

The terms represent:

• T_cycle: Total cycle time

• t_move: Movement time

• t_dwell: Dwell time

When acceleration and deceleration are considered separately:

T_cycle = t_acc + t_const + t_dec + t_dwell

• t_acc: Acceleration time

• t_const: Constant-velocity travel time

• t_dec: Deceleration time

• t_dwell: Dwell time

5.5 Design Considerations

• Travel distance

• Movement time

• Dwell time

• Stopping-position accuracy

• Repeatability

• Maximum allowable inertia

• Acceleration and deceleration impact

• Braking performance

• Rigidity during dwell

• Number of cycles per minute

In intermittent motion, stable acceleration and deceleration control may be more important than simply increasing maximum velocity.

6. Intermittent-Duty Motion

6.1 Definition

Intermittent-duty motion is motion in which the drive source is repeatedly switched on and off for short periods.

It is similar to intermittent motion. However, intermittent motion emphasizes a functional sequence of movement and dwell, whereas intermittent-duty motion focuses mainly on the ON and OFF states of the drive source.

6.2 Main Characteristics

• Short operating periods are repeated.

• Starting and stopping occur frequently.

• Thermal loading of the motor or actuator is important.

• High instantaneous torque may be required.

• Average load may be low while peak load is high.

6.3 Typical Applications

• Electromagnetic solenoids

• Clutches and brakes

• Short-stroke pneumatic cylinders

• Spot-welding devices

• Punching devices

• Instantaneous pressing devices

• Dosing valves

• Product-discharge flaps

6.4 Duty Cycle

In intermittent-duty motion, the ratio of operating time to the total cycle period is important.

D = t_on / T × 100%

The terms represent:

• D: Duty cycle

• t_on: Time during which the drive source is operating

• T: Total repetition period

For example, when the total period is 10 seconds and the actual operating time is 3 seconds:

D = 3 / 10 × 100% = 30%

6.5 Design Considerations

• Duty cycle

• Number of starts per hour

• Instantaneous current

• Instantaneous torque

• Winding temperature

• Cooling time

• Clutch and brake wear

• Solenoid heat generation

• Repetition life

7. Periodic Motion

7.1 Definition

Periodic motion is a form of motion in which the same or a similar movement repeats at regular time intervals.

After one motion is completed, the system returns to the same state. The interval required for one complete repetition is called the period.

7.2 Period and Frequency

The relationship between period and frequency is expressed as follows:

f = 1 / T

The terms represent:

• f: Frequency

• T: Time required for one complete repetition

When the period is 0.5 seconds:

f = 1 / 0.5 = 2 Hz

This means that the motion repeats twice per second.

7.3 Main Characteristics

• Repetition time is constant.

• Motion is easy to predict.

• Production output is easy to calculate.

• Fatigue caused by repeated loading is important.

• The possibility of resonance must be evaluated.

• Synchronization between multiple devices is relatively easy.

7.4 Typical Applications

• Crank presses

• Piston pumps

• Reciprocating compressors

• Cam-driven devices

• Sealing devices in packaging machines

• Slicing devices

• Reciprocating cutting devices

• Vibratory feeders

• Rotary filling machines

7.5 Design Considerations

• Motion period

• Repetition frequency

• Maximum acceleration

• Repeated load

• Fatigue life

• Resonance range

• Phase difference

• Cycle-to-cycle variation

• Repeatability

8. Repetitive-Cycle Motion

8.1 Definition

Repetitive-cycle motion consists of several different operations arranged in one sequence, with the entire sequence repeated.

Simple periodic motion repeats one motion pattern. Repetitive-cycle motion sequentially repeats multiple steps, such as movement, stopping, clamping, processing, releasing, and returning.

8.2 Typical Cycle

One cycle of an automatic assembly machine may include:

1. Product detection

2. Forward movement of the transfer device

3. Positioning and stopping

4. Clamping

5. Assembly operation

6. Clamp release

7. Return of the transfer device

8.3 Main Characteristics

• Multiple motions are linked in a time sequence.

• Each step requires a completion condition.

• Some operations may be performed simultaneously.

• The bottleneck step determines the total cycle time.

• Sensors and interlocks are important.

• Sequence control is required.

8.4 Total Cycle Time

When all operations are performed sequentially:

T_cycle = t1 + t2 + t3 +... + tn

When some operations are performed simultaneously, the longest parallel operation determines the duration of that section.

8.5 Typical Applications

• Automatic assembly machines

• Packaging machines

• Filling and capping systems

• Food-cutting and packaging lines

• Inspection and sorting systems

• Robotic pick-and-place systems

• Press automation systems

• Tray-loading devices

9. Aperiodic Motion

9.1 Definition

Aperiodic motion does not repeat at fixed time intervals or according to an identical motion pattern.

Movement time, travel distance, velocity, direction, or stopping position may vary according to operating conditions.

9.2 Main Characteristics

• The repetition period is not constant.

• Motion changes according to external conditions.

• Program control is more suitable than a fixed mechanical cam.

• Sensor data and real-time decisions are important.

• Trajectory planning may change dynamically.

9.3 Typical Applications

• Industrial robots

• Vision-based sorting equipment

• Defective-product rejection devices

• Automated storage systems

• Variable-length cutting machines

• Make-to-order production systems

• Operator-controlled assistance devices

• Obstacle-avoidance systems

9.4 Design Considerations

• Maximum travel range

• Worst-case cycle time

• Variable load

• Sensor response time

• Controller processing capacity

• Position recalculation

• Collision prevention

• Exception handling

• Safe-stop conditions

10. Event-Driven Motion

10.1 Definition

Event-driven motion starts when a specific condition or signal occurs, rather than according to a fixed time schedule.

An event may be sensor detection, an operator command, product arrival, pressure reaching a set value, temperature reaching a set value, or a completion signal from the previous process.

10.2 Main Characteristics

• The motion start time may not be fixed.

• Motion is directly linked to sensor input.

• Waiting time may occur.

• Motion does not begin unless the required conditions are satisfied.

• Interlocks and safety conditions are important.

10.3 Typical Events

• Product-detection sensor ON

• Confirmation that a door is closed

• Clamp pressure reached

• Motor homing completed

• Previous process completion signal

• Operator start-button input

• Vision inspection completed

• Confirmation that no abnormality exists in the safety zone

10.4 Typical Applications

• Pushers activated after product detection

• Defective-product rejection cylinders

• Automatic doors

• Sensor-based alignment devices

• Robotic pickup systems

• Safety-interlock devices

• Sealing devices activated after packaging-material detection

10.5 Design Considerations

• Sensor response time

• Input-signal noise

• Debouncing

• Delay time

• Prevention of unintended operation

• Signal-loss handling

• Duplicate-signal handling

• Timeout

• Emergency-stop priority

11. One-Time Motion

11.1 Definition

One-time motion is performed only once or at a very low frequency during normal operation, such as during adjustment, installation, replacement, or emergency operation.

11.2 Typical Applications

• Initial homing

• Movement to a mold-change position

• Movement to a cleaning position

• Movement to a maintenance position

• Opening a safety cover

• Emergency return

• Initial machine setup

• Manual adjustment

11.3 Main Characteristics

• Repetition frequency is low.

• Safety and operability are more important than speed.

• Manual operation may be included.

• Operating conditions may differ from normal automatic operation.

• Maintenance accessibility is important.

11.4 Design Considerations

• Low-speed operating mode

• Jog operation

• Manual-operation authorization

• Safe-speed limitation

• Operator visibility

• Dead-man switch

• Lockout and indication procedures

• Interlock with automatic operation

12. Transient Motion

12.1 Definition

Transient motion occurs temporarily while the system changes from one state to another.

Typical examples include acceleration from rest to operating velocity and deceleration from operating velocity to rest.

12.2 Main Characteristics

• Velocity and acceleration change over time.

• Large inertial forces may occur.

• Vibration and impact are likely to occur.

• Higher torque may be required than during steady-state operation.

• Controller response characteristics are important.

12.3 Typical Transient States

• Motor startup

• Rapid acceleration

• Rapid deceleration

• Direction reversal

• Load application

• Clutch engagement

• Brake operation

• Emergency stopping

12.4 Design Considerations

• Starting torque

• Acceleration time

• Deceleration time

• Braking distance

• Maximum current

• Temporary structural deformation

• Impact on fastened joints

• Product movement

• Control overshoot

• Settling time

Although transient motion lasts only briefly, it may be the period in which the greatest load acts on the machine.

13. Steady-State Motion

13.1 Definition

Steady-state motion is motion in which velocity, load, and output remain constant or maintain a stable repetitive pattern after the starting process has ended.

13.2 Main Characteristics

• Velocity variation is small.

• Load is relatively stable.

• Long-term operating characteristics are easy to evaluate.

• Temperature rise and frictional loss are important.

• Average power and efficiency are easy to calculate.

13.3 Typical Applications

• Conveyors operating at constant velocity

• Pumps under normal operation

• Mixers operating at constant rotational speed

• Continuously rotating cutters

• Screw feeders under steady operation

13.4 Design Considerations

• Rated velocity

• Rated torque

• Continuous allowable output

• Thermal equilibrium

• Vibration level

• Noise

• Lubrication condition

• Long-term operating life

14. Motion Including a Dwell Period

14.1 Definition

Motion including a dwell period is a form of motion in which the object remains stationary for a specified time after completing its movement.

This stationary period is called dwell time.

14.2 Purpose of the Dwell Period

• Securing machining time

• Securing filling time

• Securing sealing time

• Securing cooling or heating time

• Securing inspection time

• Product stabilization

• Clamping

• Safety confirmation by the operator

14.3 Main Characteristics

• Dwell stability is as important as positioning accuracy.

• The position must not change under external force during dwell.

• A brake or mechanical lock may be required.

• Dwell time has a major effect on total productivity.

14.4 Typical Applications

• Indexing tables

• Sealing devices

• Presses

• Labeling devices

• Filling machines

• Inspection equipment

• Robotic assembly systems

14.5 Design Considerations

• Dwell time

• Stopping-position error

• Vibration during dwell

• Holding torque

• Use of a brake

• Use of a mechanical lock

• Thermal deformation

• Settling time after stopping

15. Constant-Velocity Motion

15.1 Definition

Constant-velocity motion is motion in which velocity remains constant over time.

In ideal constant-velocity motion, acceleration is zero.

a = 0

15.2 Main Characteristics

• Product flow remains constant.

• Process time is easy to predict.

• Variation in drive torque is small.

• Vibration is relatively low.

• It is suitable for continuous processes.

15.3 Typical Applications

• Conveyors

• Roller transfer systems

• Continuous cutting

• Constant-speed mixing

• Pumps

• Screw-transfer systems

15.4 Design Considerations

• Velocity variation caused by load changes

• Velocity-control accuracy

• Reducer efficiency

• Slip

• Long-term velocity stability

• Feedback sensors

16. Trapezoidal-Velocity Motion

16.1 Definition

Trapezoidal-velocity motion consists of acceleration, constant velocity, and deceleration.

It is called a trapezoidal-velocity profile because the velocity-time graph forms a trapezoidal shape.

16.2 Motion Periods

1. Velocity increases at a constant acceleration.

2. Target velocity is maintained.

3. Velocity decreases at a constant deceleration.

16.3 Main Characteristics

• It is relatively simple to implement.

• Travel time is easy to calculate.

• It is widely used for servo-motor and stepper-motor control.

• Acceleration may change suddenly.

• Vibration and impact may occur in high-speed equipment.

16.4 Typical Applications

• XY tables

• Ball-screw transfer axes

• Belt-driven transfer axes

• Pick-and-place devices

• Automatic positioning devices

• CNC feed axes

16.5 Design Considerations

• Maximum velocity

• Acceleration

• Deceleration

• Travel distance

• Motor torque

• Load inertia

• Structural rigidity

• Stopping error

17. Triangular-Velocity Motion

17.1 Definition

Triangular-velocity motion occurs when the travel distance is too short to reach a constant-velocity period, causing the motion to change directly from acceleration to deceleration.

The velocity-time graph forms a triangular shape.

17.2 Main Characteristics

• It is suitable for short travel distances.

• Time to reach maximum velocity is short.

• There is no constant-velocity period.

• Acceleration performance determines the total travel time.

• It is widely used in repeated short-stroke operations.

17.3 Typical Applications

• Short-distance pick-and-place systems

• Small pushers

• Short-stroke sealing devices

• Small robotic transfer systems

• High-speed sorting systems

18. S-Curve Motion

18.1 Definition

S-curve motion smoothly increases and decreases velocity by limiting jerk, which is the rate of change in acceleration.

Jerk is expressed as follows:

j = da / dt

The terms represent:

• j: Jerk

• a: Acceleration

• t: Time

18.2 Main Characteristics

• Impact is reduced.

• Vibration is reduced.

• Product movement is minimized.

• Structural fatigue can be reduced.

• It is suitable for precision positioning.

• Control is more complex than with a trapezoidal profile.

18.3 Typical Applications

• Transfer of containers containing liquids

• Food-tray transfer

• Semiconductor equipment

• Precision-assembly equipment

• High-speed robots

• Transfer of glass and brittle materials

• Large transfer axes

18.4 Design Considerations

• Allowable jerk

• Maximum acceleration

• Travel time

• Product movement

• Natural frequency of the structure

• Motor torque

• Controller performance

19. Pulse and Impact Motion

19.1 Definition

Pulse motion is motion in which a large force or velocity change occurs over a very short period.

Impact motion involves a large change in momentum over a short period and applies a high instantaneous load to the structure.

19.2 Typical Applications

• Presses

• Punching devices

• Hammers

• Striking devices

• Instantaneous cutting devices

• Product-discharge knockers

• Vibration-generating devices

• Impact-testing equipment

19.3 Main Characteristics

• Operating time is short.

• Instantaneous maximum load is high.

• Peak power is more important than average power.

• Structural impact-absorption capability is important.

• Fatigue and noise can occur easily.

19.4 Design Considerations

• Impact energy

• Maximum contact force

• Impact duration

• Cushioning device

• Frame rigidity

• Fastener loosening

• Fatigue life

• Noise and vibration

• Operator safety

20. Synchronous Motion

20.1 Definition

Synchronous motion is motion in which two or more axes or devices maintain a specified relationship according to the same time reference or position reference.

20.2 Typical Synchronization Methods

• Velocity synchronization

• Position synchronization

• Phase synchronization

• Electronic gearing

• Electronic cam

• Master-slave control

• Mechanical gear synchronization

• Timing-belt synchronization

20.3 Main Characteristics

• The velocity ratio between axes remains constant.

• The positional relationship between axes can be maintained.

• Product flow can be matched with a processing device.

• Phase error directly affects product quality.

• Encoders and high-speed control may be required.

20.4 Typical Applications

• Synchronization of packaging film and product transfer

• Rotary cutters

• Flying cutters

• Printing rollers

• Multi-axis robots

• Filling machines

• Conveyor-tracking devices

• Electronic-cam systems

20.5 Design Considerations

• Selection of the master axis

• Velocity ratio

• Position ratio

• Phase difference

• Encoder resolution

• Control cycle

• Communication delay

• Synchronization error

• Axis relationship during emergency stopping

21. Asynchronous Motion

21.1 Definition

Asynchronous motion is motion in which multiple devices operate independently without maintaining a direct time or position relationship.

Each device operates according to its own operating conditions and control criteria.

21.2 Typical Applications

• Independently driven conveyors

• Individual pumps

• Independent ventilation fans

• Multiple independent workstations

• Production lines with buffers

21.3 Main Characteristics

• Mechanical structure and control are relatively simple.

• Individual devices can operate independently.

• Buffers may be required between devices.

• An imbalance in production flow may occur.

• Product accumulation or process waiting may occur.

22. Phase-Controlled Motion

22.1 Definition

Phase-controlled motion maintains a specified time-position difference between two or more motions that repeat at the same period.

Phase difference indicates how far one motion leads or lags behind another.

22.2 Typical Applications

• Multi-piston pumps

• Multi-cylinder systems

• Cutting and sealing in packaging machines

• Multi-axis cam systems

• Multiple vibration generators

• Multi-gripper rotary systems

22.3 Main Characteristics

• Motion interference can be prevented.

• Load can be distributed over time.

• Vibration can be reduced or amplified.

• The sequence of production processes can be adjusted precisely.

22.4 Design Considerations

• Phase angle

• Period

• Phase error

• Encoder origin

• Mechanical backlash

• Control delay

• Phase alignment during startup

• Phase recovery after power failure

23. Comparison of Typical Applications by Time Characteristic

24. Criteria for Selecting Motion According to Time Characteristics

24.1 Production Method

• Is production continuous?

• Is it batch production?

• Is each product processed individually?

• Is it make-to-order production?

• Must processing be performed while the product is stationary?

24.2 Cycle Conditions

• Target cycle time

• Production quantity per minute

• Movement time

• Dwell time

• Processing time

• Waiting time

24.3 Load Conditions

• Continuous load

• Repeated load

• Impact load

• Variable load

• Instantaneous maximum load

• Rotational inertia

24.4 Accuracy Conditions

• Positioning accuracy

• Repeatability

• Velocity accuracy

• Phase accuracy

• Settling time after stopping

• Synchronization error

24.5 Product Characteristics

• Product mass

• Product center of gravity

• Presence of liquid

• Possibility of deformation

• Possibility of slipping

• Sensitivity to impact

24.6 Mechanical Structure Conditions

• Frame rigidity

• Guide structure

• Backlash

• Reducer clearance

• Vibration characteristics

• Braking device

• Position-holding device

24.7 Control Conditions

• PLC sequence control

• Motion controller

• Servo control

• Encoder feedback

• Sensor input

• Network synchronization

• Electronic-cam function

25. Design Verification According to Time Characteristics

25.1 Cycle-Time Verification

• Does the system satisfy the target production quantity?

• Is movement time excessive?

• Is dwell time sufficient?

• Is there a bottleneck process?

• Can parallel operation be applied?

25.2 Drive-Performance Verification

• Maximum velocity

• Maximum acceleration

• Maximum torque

• Starting current

• Braking torque

• Allowable number of repeated operations

25.3 Vibration and Impact Verification

• Impact during direction reversal

• Change in acceleration

• Jerk

• Structural resonance

• Product movement

• Fastener loosening

25.4 Thermal Verification

• Motor temperature

• Reducer temperature

• Brake heat generation

• Clutch heat generation

• Solenoid duty cycle

• Cooling time

25.5 Control Verification

• Sensor response time

• Control cycle

• Communication delay

• Timer error

• Synchronization error

• Sequence conflict

• Emergency-stop response

25.6 Service-Life Verification

• Repeated fatigue

• Bearing life

• Guide life

• Belt fatigue

• Clutch and brake life

• Cylinder-seal life

• Cable repeated-bending life

26. Main Time-Related Equations

Cycle Time

T_cycle = t_acc + t_const + t_dec + t_dwell

The total cycle time is the sum of acceleration time, constant-velocity time, deceleration time, and dwell time.

Frequency

f = 1 / T

Frequency is the number of repetitions per unit time.

Duty Cycle

D = t_on / T × 100%

Duty cycle is the percentage of the total cycle during which the drive source is operating.

Average Velocity

v_avg = Travel distance / Total travel time

Average velocity is calculated by dividing total travel distance by the time required for movement.

Acceleration

a = dv / dt

Acceleration is the rate of change in velocity with respect to time.

Jerk

j = da / dt

Jerk is the rate of change in acceleration with respect to time.

Production Quantity per Minute

Production quantity = 60 / T_cycle

When T_cycle is expressed in seconds, the production quantity per minute can be calculated.

For example, when the cycle time is 3 seconds:

Production quantity = 60 / 3 = 20 units per minute

27. Conclusion

Classification of motion according to time characteristics analyzes not where a machine moves, but when the movement starts, how long it continues, how often it repeats, and how long it remains stationary.

Continuous motion is suitable for stable production flow and long-term operation. Intermittent motion repeatedly alternates between movement and dwell to provide fixed processing positions. Periodic motion is suitable for regular repetitive production, while event-driven motion responds flexibly to sensors and external conditions.

Transient motion occurs during startup, deceleration, and direction reversal. Although brief, it can generate large inertial forces and impact loads. Steady-state motion determines long-term velocity stability, heat generation, and service life.

Trapezoidal, triangular, and S-curve velocity profiles produce different levels of impact, vibration, and cycle time even when the travel distance is identical. In machines where multiple axes operate together, synchronization, phase, and control delay directly affect product quality and machine performance.

Motion design according to time characteristics should therefore consider the following factors together:

• Motion duration

• Cycle time

• Movement time

• Dwell time

• Repetition frequency

• Duty cycle

• Velocity profile

• Acceleration and jerk

• Synchronization and phase

• Sensor response time

• Repeated load

• Thermal characteristics of motors and drive components

• Emergency-stop time

Good motion design does not simply create a fast-moving system. It ensures that motion begins at the required moment, reaches the target position within the required time, remains stable during the necessary process period, and repeats the next cycle without excessive impact or vibration.

Time characteristics do not determine production speed alone. They are fundamental design factors that also determine precision, stability, safety, energy efficiency, and service life.