Tolomatic presentation understanding motion control technology

MOTION CONTROL TECHNOLOGY

Brushless Servo Systems Brushed DC SystemsMicrostepping Systems

ELECTROMATEToll Free Phone (877) SERVO98

Toll Free Fax (877) SERV099www.electromate.com

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ENCODER FEEDBACK

Open Loop System

– Gives a commanded position but has no feedback to ensure the actual position was reached.

• Controller commands a signal to the drive

• Drive converts and amplifies the signal to the motor

• Motor moves commanded number of steps



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ENCODER FEEDBACK

Command Dimmer Lamp

Supply

Open Loop Example



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ENCODER FEEDBACK

Closed Loop

– Monitors the commanded position versus the actual position and adjusts to insure the commanded position is reached

• Command signal responds to eliminate error based on feedback



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72o Command

65o Current Temp.

7o ErrorT Furnace

Closed Loop Example

ENCODER FEEDBACK



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PowerCOMMANDPosition 10”

ERRORMove 1”

FEEDBACK9” Machine Motion

Amplifier-

+ Motor

Servo Motor Control Example

ENCODER FEEDBACK



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FEEDBACK DEVICESTell the control system where the tool or work piece is located

– Analog(ex. tachometer)

• Directly represent some physical quantity

• Continually varied

– Digital (ex. encoder)

• Incremental

• AbsoluteELECTROMATE

Toll Free Phone (877) SERVO98Toll Free Fax (877) SERV099

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Incremental Encoder

– Counts the segments on a disc to determine position

– Uses a clock to determine velocity

– Has one single mark called an indexer to eliminate error and allow finer positioning on homing routine

– 1000 Counts

FEEDBACK DEVICES



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Quadrature Encoder

– Has two segment patterns that allow for finer positioning

– Reads 4x the physical line count

FEEDBACK DEVICES



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MOTION CONTROL SYSTEMS

Microstepping

Brushed DC

Brushless Servo



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Lowest cost for precision motion

Feedback device not needed

Low RPM applications

WHY A MICROSTEPPING SYSTEM?



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STEPPER MOTORS

Windings are on the stator and the magnets are on the rotor

Current switched electronically to windings Half Step Full Step



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STEPPER MOTORS

200 physical steps on the rotor assembly



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• Lowest cost for precision motion• High resolution and positioning precision• Easy angle and speed control• Large holding torque• Good for simple indexing• High torque at lower speeds

ADVANTAGES OF STEPPER MOTORS



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• Torque decreases as velocity increases• If the load torque exceeds the motor’s available

torque it can stall or lose position • Speeds typically limited to less than 2000 RPM• Motion is not as smooth as servos

LIMITATIONS OF STEPPER MOTORS



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STEPPER VS SERVO TORQUE CURVE

0

5

10

15

20

25

30

35

0

600

1200

1800

2400

3000

3600

4200

4800

5400

6000

RPM

Torq

ue (l

b-in

)

MRS31MRV31-ContinuousMRV31-Peak



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• Lowest cost for precision motion• High resolution• Large holding torque• Good for simple indexing• High torque at lower speeds• Torque decreases as velocity increases• Open loop system, no encoder feedback • Motion is not as smooth as servos

MICROSTEPPING SYSTEM SUMMARY



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Microstepping

Brushed DC

Brushless Servo



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• Low to medium cost

• Smooth and quiet operation• Simple control (switch to switch)

• Higher torque and speed than Stepper

WHY A BRUSHED DC SYSTEM?



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BRUSHED DC MOTORS

1. Magnets are on the stator and the windings are on rotor

2. Current is switched mechanically to the windings through the brushes



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Easily defined speed and torque output– Volts/RPM– Torque/Amp

Simple design keeps the cost down

Better torque roll off compared to steppers

ADVANTAGES OF BRUSHED MOTORS



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Current switched mechanically– Brush wear

Thermally inefficient– Heat has to dissipate through the magnets

• Can reduce performance and life• Larger size

Without encoder feedback limited in positioning capability

LIMITATIONS OF BRUSHED MOTORS



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BRUSHED DC SUMMARY• Low to medium cost • Smooth and quiet operation

• Typically switch to switch operation• Thermal inefficiencies can reduce performance and life

• Brush wear



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Microstepping

Brushed DC

Brushless Servo




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BRUSHLESS SERVO SYSTEM

Closed Loop

– Monitors the commanded position versus the actual position and adjusts to insure the commanded position is reached

• Command signal responds to eliminate error based on feedback



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• Extremely smooth and quiet operation• Torque, velocity, or position control

• Accurate position and high output torque at high speeds• Higher performance than Stepper and Brushed DC

• Maintenance free

WHY A BRUSHLESS SERVO SYSTEM?



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BRUSHLESS SERVO MOTORS

1. Windings are on the stator and the magnets are on the rotor

2. Current is switched electrically



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• High continuous and peak torque

• High speeds (up to 6,000 RPM)

• Motor thermal protection

• Metal shell plug and turn connectors

• IP65 options

ADVANTAGES OF BRUSHLESS MOTORS



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• Increased cost• Increased weight

• Higher control complexity due to encoder feedback

LIMITATIONS OF BRUSHLESS MOTORS



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• Accurate position and high output torque at high speeds• Excellent heat dissipation allows for higher continuous torque

• No mechanical brushes reduce speed torque ripple• Higher performance than Stepper and Brushed Servo

• Increased cost

BRUSHLESS SERVO SUMMARY



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Applying Motion Control Systems…..Use Micro-steppers when….– You identify low speed applications where cost outweighs feedback for

velocity or torque

Use Brushed DC when….– You run into low to midrange speed and torque applications that that need

simple point to point positioning without high accuracy

Use Brushless Servo when….– You see high speed and high torque applications that need accurate

feedback for position, velocity, or torque…or– You see applications that need high performance



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QUESTIONS???



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Tolomatic presentation understanding motion control technology

Technology

Transcript of Tolomatic presentation understanding motion control technology