Tuning ASDA Series Servo Systems

The Encoder Resolution
Three Scales of Encoder Resolution • The 2500 ppr encoder, which is an AB-phase encoder, will send out 10000 pulses per revolution.
Abundant Operation Modes
The Table Beside is for ASDA-A2 • Most of the operation modes are shared by all series. • Please reference to user manuals for details.
Mode 00 01 02 03 04 05 Dual Mode 06 07 08 09 0A CANopen Mode 0D Multiple Mode 0E 0F Pt Pr S T Sz Tz Single Mode
The Control Skeleton
Multiple Cascaded Loops • Position loop, Speed loop, and Current loop.
20 bits => 1,280,000 p/r (> 220=1,048,576)
The Advantage of High Resolution
Several Advantages • The position of a rotor cannot be known until it is at the division point. • The higher resolution, the more positing accuracy. • The higher resolution, the better low speed stability. • The higher resolution, the smaller acoustical noise.
ASDA-AB 10000 p/rev 450 Hz 100 w ~ 2 kw
ASDA-B 10000 p/源自ev 250 Hz 100 w ~ 2 kw
ECMA Servo Motor
The Power Range 0.1kW ~ 7.5kW
• • • •
Rated Torque: 0.32 N-m ~ 47.74 N-m Max. Torque: 0.96 N-m ~ 119.36 N-m Rotation Speed: 1000 rpm ~ 5000 rpm Encoder Resolution: 2500 ppr,17 bits, 20 bits
The Rigidity
Connected to the Response of a System • The more rigid a system, the higher bandwidth it is . • The resonance frequency of a rigid system is always higher. • It must be taken into account during the developing phase of a machine.
The Control Skeleton
Three Cascaded Loops, Position Control Loop, Speed Control Loop, and Torque Control Loop
Scope Skill
How to Measure Resonance, Performance Monitoring, and Inertia Evaluation
Position Command and Source Selection • Pulse Type Selection, Control Mode, Electronic Gear Ratio, Moving Filter, and Position Control Unit.
The Position and Speed (1)
Presentation Revision
Revision: 1/24/2010 Revision: Rev. 1/21/2010 is abandoned.
Table of Contents
The Background Knowledge
A Glance of ASDA Series Servo System, Resolution of Encoder, Response, Bandwidth, Stiffness, and Rigidity
TUNING ASDA SERIES SERVO SYSTEMS
About This Presentation
Intended Audience
Basic level, for the users who knows how to operate ASDA series servo systems.
The Whole ASDA Series
ASDA-A2 1280000 p/rev (20 bits) 1000 Hz 100 w ~ 5.5 kw ASDA-B2 160000 p/rev (17 bits) 550 Hz 100 w ~ 3 kw ASDA-A 10000 p/rev 450 Hz 100 w ~ 3 kw ASDA-A+ 1280000 p/rev (20 bits) 550 Hz 4.5 kw ~ 7.5 kw
• The notation of a 20-bits encoder represents for its level instead of the number of divisions per revolution, because it communicates with servo motor via communication protocol not pulse signal. • 17 bits => 160,000 p/r (> 217=131,072)
A Stable System
Industry V.S. Academic • The stability is defined to a system before it turns to self-oscillating in academic. • It is unreal for industry even it is not self-oscillating. • The stability is asked to fit the requirements of operation of a machine; excellent smooth speed and accurately positioning performance in CNC world, for example.
Position Control Loop
Position Control Path • Position Command Unit, Position Control Unit, Speed Loop, Current Loop, and Vibration Suppression Unit.
Position Command Unit
Acceleration Zone Stop Zone Constant Speed Zone Position Curve Deceleration Zone Stop Zone Acceleration Zone Stop Zone Constant Speed Zone Position Curve Deceleration Zone Stop Zone
The Position-Speed-Torque
From the View of Real World • The Impulse function does not exist in physical world; that is another perspective to see why we need S-Curve. • If the acceleration or deceleration zone is short, the system should be with the ability to offer tremendous power in a short time or the drive will operate in saturation and cannot follow the command well.
The Position Curve Defines Speed • The longer the distance moved per unit time, the higher the speed will be.
The Position and Speed (2)
Why the S-Curve needed • To generate an acceleration zone and a deceleration zone is necessary for a smooth movement.
The Stiffness
To Evaluate the Ability of a System to Resist Disturbance • Disturbance exists everywhere. • All movements lead to load change can be attributed to disturbance. • Higher gain means faster response which can adjust the system to get rid of load change effect fast.