Newport NPC DIG Series Instruction Manual Download Page 31

 

 

31

 

10  Controller Adjustment 

 

When any actuator made by 

Newport Corporation 

is connected to the 

NPCxxxDIG

, amplifier their specific 

values are read from the actuator’s ID-chip. The Digital Signal Processor (DSP) of the amplifier is set with 
these  values.  These  parameters  were  investigated  in  the 

Newport  Corporation 

laboratory  and  ensure  safe 

function of the actuator. 
 
There  are  no  kp-,  ki-,  and  kd-values  for  actuators  without  a  measurement  system  because  the  closed  loop 
mode is impossible in this configuration. Closed loop is automatically switched off. 
 

To adapt the controller properties to your special application please start with the default values. At 
first  please  switch  on  the  closed  loop  mode  by  pressing  the 

encoder  knob  “OFFSET”  or  by  the 

command 

cl,1

  via  RS232.  Change  one  parameter  step  by  step  and  check  the  result  with  the 

oscilloscope  on  the  ANALOG  9pin  SUB-D  socket  of  the  amplifier.  You  must  install  a  monitoring 
output to

 position value in open loop

 with the command 

monsrc,6

.

 

 
In general, change the parameters in small steps and, depending on the actuator's reaction, slightly increase 
the  step  width.  If  the  system  begins  to  oscillate,  switch  off  the  closed  loop  immediately  by  pressing  the 
encoder knob, then reset the last values entered! 
 
First of all, check the function of the notch filter. This has been factory adjusted so that the main resonant 
frequency is suppressed in an actuator with standard mass loading. If your application has a different mass, 
the resonant frequency changes (higher mass = lower frequency). 

The notch parameters  are adjustable 

with the commands 

notchon

notchf

 and 

notchb

.

 

 
The sweep function of the internal function generator can be used to determine the resonant frequency. Use 

function  generator 

in the 

menu 

of the actuator. Set the amplitude to 5%, the offset to 0%, and the sweep 

time to 1 (1sec/decade). Set the amplifier to open loop (“OL/CL” LED lights green). With the MOD/MON 
cable (MON plug) you can connect the oscilloscope to the ANALOG socket of the amplifier. The following 
adjustments  on  the  oscilloscope  are  required:  store  function,  time  base  =  0.5  sec/div  and  input  voltage  = 
0.1V/div. The display shows the response of the actuator measured by the integrated measurement system. 
Before the measured curve swings out, there is a position where the amplitude is 0 Volts. This is the adjusted 
notch frequency.  At  the  resonant  frequency,  the  measured  curve  goes  very  high.  At  this point  you  have  to 
adjust  the  notch  frequency  to  the  resonant  frequency  to  linearize  the  curve.  Using  the  notch  filter  might 
increase noise. 
 
The correct ki-value is determined as follows: 
In the 

function generator 

menu,

 

set rectangle to 1 Hz, amplitude to about 50%, and offset to 25%. Please set 

the monitoring output to 

Umes/CL 

in the 

analog  i/o 

menu. The following adjustments on the oscilloscope 

are 

required: 

store 

function, 

time 

base 

0.05sec/div 

and 

input  

voltage = 1V/div. Set the amplifier to closed loop (“OL/CL” LED lights yellow). The oscilloscope display 
shows the step response of the actuator measured by the integrated measurement system. If the slew rate is 
too  low,  please  increase  the  ki-value  in  the 

digital  controller 

menu.  The  over  swing  after  the  rise  time 

should be smaller than 1% of the total step. 

 
In  these  adjustments,  the  actuator  system  can  begin  to  oscillate in resonant frequency. Please  switch 
off the closed loop immediately by pressing the  encoder knob “OFFSET”.  Then reset the last values 
entered! Continuous use at resonance can damage the actuator! 

 
Now you can try to increase the slew rate in 

slew  rate/filter 

menu

as long as no oscillation or large over 

swing occurs. 

 

Summary of Contents for NPC DIG Series

Page 1: ...n Manual Digital Piezo Amplifier Series NPCxxxDIG Models NPC50DIG NPC300DIG Please read carefully before switching on the power Please see safety instructions for using piezoelectric actuators and pow...

Page 2: ...www newport com 2 English version last change 2017 02 16 by TP...

Page 3: ...3...

Page 4: ...for checking the function of the system quick start 11 8 How to operate the digital amplifier series NPCxxxDIG 12 8 1 Common Introduction 12 8 2 User Elements Connections 12 8 2 1 Front Panel 12 8 2...

Page 5: ...rporation You will also find additional information regarding piezoelectric products Definition All systems from Newport Corporation such as electronics actuators and optical systems are called units...

Page 6: ...uction and form put by us into circulation is in accordance with all relevant essential requirements of the EMC Directive 2014 30 EU This declaration is no longer valid if the device is modified witho...

Page 7: ...l occur After excitation of the actuators by a voltage in the upper control range the ceramic will move and generate an opposite high voltage after disconnection Heating of the ceramic material will o...

Page 8: ...regular waste Instead it is the user responsibility to dispose of waste equipment according to the local laws The separate collection and recycling of the waste equipment at the time of disposal will...

Page 9: ...rs Only work with the units in a clean and dry environment Only specially prepared units e g actuators can work under other conditions Please only use original parts from Newport Corporation Newport C...

Page 10: ...cables e g power cords sensor cables actuator cables optical cables Do not block ventilated openings or place the units near a radiator oven or other heat sources Plug in the power cord completely so...

Page 11: ...r shape should be parallel each to each other and not have any scratches If there is any damage to the system please contact our local representative immediately If the packaging material is damaged p...

Page 12: ...high speed positioning with the highest accuracy available It includes rise time optimization and an active oscillation damping for every special application The NPCxxxDIG comes with an auto calibrati...

Page 13: ...13 8 2 2 Back Panel...

Page 14: ...www newport com 14 8 3 Function The following sketch shows the function groups of the amplifier sketch 1 function groups of the amplifier...

Page 15: ...akes for the output to get a certain value For a step input it is the time taken for the output to equal the input yi yi ki err Ts Ts 1 sample frequency 50 kHz 1 ki time constant yi output of i term I...

Page 16: ...er of magnitude While using open loop you can also switch on the notch filter to reduce stimulation of the resonant frequency Using the notch filter might increase noise The PID specific parameters kp...

Page 17: ...500Hz Actuator measurement connector PIEZO 15pin D Sub plug Monitor output 0 10V programmable signal source Monitor output impedance 1k Modulation input 0 10V disconnectable Modulation input impedanc...

Page 18: ...ription value monsrc value monitor output default 0 0 position value in closed loop 1 reference input 2 PID command voltage 3 closed loop deviation incl sign 4 closed loop deviation absolute 5 actuato...

Page 19: ...n loop position voltage back from the measured monitor voltage use the following formula Umes OL Umon 2 5V 2 The default setting is the position value in closed loop see No 0 sketch 3 monitor output 8...

Page 20: ...is connected to this plug The actuator voltage goes to the piezo the position signal from the measurement system goes to the DSP and the integrated actuator information is stored on an ID chip which g...

Page 21: ...ohm operation time of actuator since shipping minutes rgver version number of loop controller request table 6 commands without values commands with values command value Enter command description value...

Page 22: ...amplitude sine 0 to 100 gosin amplitude offset sine 0 to 100 gfsin generator frequency sine 0 1 to 9999 9 Hz gatri generator amplitude triangle 0 to 100 gotri amplitude offset triangle 0 to 100 gftri...

Page 23: ...rface every 500 milliseconds This value can then be read out via the interface Subsequent increasing of the query sequence for this value does not increase the refreshing rate If the piezoelectric act...

Page 24: ...11 10 9 211 210 29 0 0 0 generator off 0 0 1 sine on 0 1 0 triangle on 0 1 1 rectangle on 1 0 0 noise on 1 0 1 sweep on 0 512 1024 1536 2048 2560 12 212 0 notch filter off 1 notch filter on 0 4096 13...

Page 25: ...of the impulses trglen 1 or decrease the movement speed of the actuator Furthermore you must be sure that the trigger range between trgss and trgse passes through plus 0 2 of the total stroke otherwis...

Page 26: ...xt Trigger position is set to 10 m the trigger impulse will be generated when the 10 m position is reached from a lower position than 10 m rising edge Extended trigger functions trgedge 4 5 7 The func...

Page 27: ...ed This principle depends on whether or not trgss and trgse are bordered by a working area that crosses at least 0 2 of total stroke out of the borders trgss lower trigger position this is the lowest...

Page 28: ...triangle This will require that the relevant functional parameters be set frequency amplitude offset or symmetry The function generator does not need to be activated gfkt 0 To select a scan set the sc...

Page 29: ...combined use of trigger generation and scan function permits a highly exact scan of a probe Acceleration forces and with it oscillations are minimized by using a sine function and actions can be initi...

Page 30: ...OD input the actuator is in the most negative position pos 1 of its deviation pos 1 to pos 4 see sketch 2 By pressing the knob in the operation mode changes to closed loop and the OL CL LED changes to...

Page 31: ...onant frequency Use function generator in the menu of the actuator Set the amplitude to 5 the offset to 0 and the sweep time to 1 1sec decade Set the amplifier to open loop OL CL LED lights green With...

Page 32: ...justments reduce the ki value Reduce the kd value Check whether the function generator is still working read back parameters always deviate at the same level from the digital target value Please switc...

Page 33: ...ng in nm resolution you must warm up the amplifier 2 hours before use A constant temperature is beneficial Consider that a variation of 5 Kelvin results in elongation by 13 m in steel with a length of...

Page 34: ...www newport com 34 12 Your Notes...

Reviews: