THORLABS PWA090 User manual

PWA090
Benchtop, Electronic Self-levelling,
Vibration Isolation System
User Guide
Original Instructions

2
Contents
Chapter 1 Safety ..............................................................................................3
1.1 Safety Information ...................................................................................3
1.2 General Warnings ...................................................................................3
Chapter 2 Overview ........................................................................................4
2.1 Introduction .............................................................................................4
Chapter 3 Installation .....................................................................................5
3.1 Installation ...............................................................................................5
3.1.1 Siting .................................................................................................................. 5
3.1.2 Environmental Conditions .................................................................................. 5
3.1.3 Mounting ............................................................................................................ 6
3.1.4 Electrical Connections ........................................................................................ 7
3.1.5 Pneumatic Connections ..................................................................................... 8
3.2 Fitting/Removing The breadboard ........................................................10
3.2.1 Switching ON ................................................................................................... 11
Chapter 4 Set Up ...........................................................................................13
4.1 Front Panel Controls and Indicators .....................................................13
4.2 Menu System Overview ........................................................................13
4.2.1 Set Up Menu .................................................................................................... 14
4.3 Initial Set Up ..........................................................................................15
4.3.1 Units Selection ................................................................................................. 15
4.3.2 Weight/Pressure (Default PID) Selection ......................................................... 16
4.3.3 Switching ON Active Leveling .......................................................................... 17
4.4 Levelling the System .............................................................................18
4.4.1 Settle Position .................................................................................................. 18
4.4.2 Error Band ........................................................................................................ 19
4.5 Further Tuning and PID Parameter Adjustment ....................................20
4.6 Save Settings ........................................................................................25
4.7 Return ...................................................................................................25
Appendices
Appendix A Connector Pinout Detail ..........................................................26
Appendix A Load Position and Stability......................................................27
Appendix B Preventive Maintenance ..........................................................28
Appendix C Specifications............................................................................29
Appendix D Regulatory ................................................................................29
Appendix E Thorlabs Worldwide Contacts ................................................32

3
Chapter 1 Safety
1.1 Safety Information
For the continuing safety of the operators of this equipment, and the protection of the
equipment itself, the operator should take note of the Warnings, Cautions and Notes
throughout this handbook and, where visible, on the product itself.
The following safety symbols may be used throughout the ha ndbook and on the
equipment itself.
1.2 General Warnings
Shock Warning
Given when there is a risk of injury from electrical shock.
Warning
Given when there is a risk of injury to users.
Caution
Given when there is a risk of damage to the product.
Note
Clarification of an instruction or additional information.
Warnings
If this equipment is used in a manner not specified by the manufacturer, the
protection provided by the equipment may be impaired. In particular,
excessive moisture may impair operation.
Spillage of fluid, such as sample solutions, should be avoided. If spillage does
occur, clean up immediately using absorbant tissue. Do not allow spilled fluid
to enter the internal mechanism.

4
Chapter 2 Overview
2.1 Introduction
The PWA090 electronic, self-levelling, vibration isolation system, provides a portable,
lightweight, low-profile vibration-control solution for sen sitive benchtop equipment
and experiments.
The system comprises a set of four pneumatic isolators (which must be connected to
a compressed air supply) and an electronic control box.
The control box allows manual adjustment of the level via a keypad. Once set up, the
level is maintained and any further disturbances are corrected automatically.
Fig. 2.1 Benchtop, electronic self levelling vibration isolation system

5
Chapter 3 Installation
3.1 Installation
3.1.1 Siting
The system is designed to be mounted on a benchtop or similar surface. The isolators
can be used free stand ing to p rovide a temporary isolation solution. For more
permenant applications, the isolators can be bolted to an imperial or metric tapped
work surface - see Section 3.1.3. for more details
3.1.2 Environmental Conditions
Location Indoor use only
Maximum altitude 2000 m
Temperature range 5oC to 40oC
Maximum Humidity Less than 80% RH (non-condensing) at 31°C
To ensure reliable operation the system should not be exposed to corrosive agents or
excessive moisture, heat or dust.
If the system has been stored at a low tem perature or in an environment of high
humidity, it must be allowed to reach ambient conditions before being powered up.
3.1.3 Mounting
1) Position the isolators at least 400 mm (16”) apart and inside the footprint of the
breadboard (a typical set up is shown in Fig. 3.1 on the next page). Ensure that
the leg AIR IN and FEEDBACK connections are facing outwards and easily
accessible.
Caution
When positioning the isolators, ensure that the benchtop or mounting
surface is level. The legs have an adjustment range of ± 2.5 mm only.
Warning
Operation outside the following environmental limits may adversely affect
system performance and could endanger operator safety.
Caution
Heavy loads may require the isolators to be positioned further apart to
ensure good stability - see Table 3.1 for more details.

6 HA0260T Rev B Mar 2014
Chapter 3
Fig. 3.1 Positioning the isolators
2) The base plate of each leg is fitted with four slotted holes to enable secure fixing
to the work surface. T he orientation of the legs, when mounting to imperial and
metric tapped surfaces is shown below.
Fig. 3.2 Leg orientation for imperial and metric surfaces
3) If required, bolt the legs to the worksurface.
Note
The mounts can also be used to upgrade the PFR series rigid support frames.
4” (100 mm) 4” (100 mm)
4”
(100 mm)
4”
(100 mm)
ImperialMetric

7
Benchtop, Self Levelling Vibration Isolation System
3.1.4 Electrical Connections
1) Using the leads supplied, connect the Feedback terminals on the master legs, to
the corresponding LEG 1, LEG 2 and LEG 3 FEEDBACK INPUT connections on
the control box - see Fig. 3.3 and Fig. 3.4. The slave leg has no feedback terminal.
2) Connect the control box to the power supply shipped with the unit but DO NOT
apply power.
Fig. 3.3 Rear panel FEEDBACK connection
Fig. 3.4 Leg FEEDBACK connection
Shock Warning
The unit must be connected only to the power supply unit supplied.
DC 15V 1A
AIR IN
FEEDBACK INPUT
LEG 1 LEG 2 LEG 3
_
+
DC 15V 1A
AIR IN
FEEDBACK INPUT
LEG 1 LEG 2 LEG 3
_
+

8 HA0260T Rev B Mar 2014
Chapter 3
3.1.5 Pneumatic Connections
1) Using the 6mm outside diameter nylon tubing, connect the pneumatic connectors
on each master leg, to the LEG 1, LEG 2 and LEG 3 PNEUMATIC OUT PUT
connections on the control box - see Fig. 3.6 and Fig. 3.7. Note that the slave leg
is driven by a master leg - see item (2).
Fig. 3.5 T piece connections
Fig. 3.6 Front panel PNEUMATIC OUTPUT connections
Caution
When cutting the tubing to the required length, ensure that all cuts are made
at 90° to allow the tube to fit flush against the end stop – see Fig. 3.5.
The push-in connectors on the T-pieces and bulkhead fittings accept the nylon
tube in two steps.
LEG 1
PNEUMATIC OUTPUT
LEG 2 LEG 3

9
Benchtop, Self Levelling Vibration Isolation System
Fig. 3.7 Pneumatic connections
2) Using the 6mm outside diameter nylon tubing and the T-piece supplied, connect
the slave leg to one of the master legs as shown below.
Fig. 3.8 Slave Leg connections
3) Ensure that the air supply is turned OFF, then connect the AIR IN terminal on the
Control Box (see Fig. 3.3) to the compressed air supply.
Warning
The air supply may come from an air line, a compressed gas bottle, or a small
compressor dedicated to this installation. In all cases the supply to the
isolators must be delivered through a pressure regulator.
LEG 1
PNEUMATIC OUTPUT
LEG 2 LEG 3
To LEG connector
on Control Box

10 HA0260T Rev B Mar 2014
Chapter 3
3.2 Fitting/Removing The breadboard
A Installation
1) Perform the installation procedures as detailed in Section 3.1.
2) Fit the lifting handles supplied to the breadboard as shown in below.
Fig. 3.9 Fitting the breadboard
3) Observing the warnings listed above, lift the breadboard into position - see
Fig. 3.9.
Warning
During item (3):
Breadboards should be manipulated using the lifting handles supplied. If
these are not available, use appropriate lifting equipment.
Breadboards must be lifted by two people and standard lifting safety
precautions must be observed.
Breadboards should be lifted only in an unpopulated condition.
When lowering the breadboard into position, take care not to trap fingers or
clothing.

11
Benchtop, Self Levelling Vibration Isolation System
4) Populate the bre adboard. Wherever possible, the lo ad should be distributed
evenly. Unevens or tall loads may adversely effect the settling time and stability.
See Appendix B for more information.
B Removal
To remove the breadboard:
1) Switch off the power supply to the compressor and vent the pressure.
2) Remove the air inlet pipe from the isolation system and allow any pressure in the
system to vent.
3) Reverse the installation procedure.
3.2.1 Switching ON
1) Set the outlet pressure regulator to the required pressure - see Table 3.1.
Table 3.1 Typical pressure versus weight
Caution
During item (4), the total load including the breadboard must not exceed 210kg
(462 lb).
Warning
Breadboards should be manipulated only using appropriate lifting equipment.
Breadboards should be lifted only in an unpopulated condition.
Caution
Before removing the breadboard, switch off the compressor or air supply and
vent SLOWLY all pressure from the system. Failure to vent the pressure may
cause the diaphragms to rupture when the load is removed.
Warning
The air supply may come from an air line, a compressed gas bottle, or a small
compressor dedicated to this installation. In all cases the supply to the
isolators must be delivered through a pressure regulator.
DO NOT EXCEED 80 psi.
Weight Pressure (psi) Min Isolator Separation
<47 kg 20 400 mm
>47 kg to <98 kg 40 400 mm
>98 kg to <152 kg 60 600 mm
>152 kg to <210 kg 80 900 mm

12 HA0260T Rev B Mar 2014
Chapter 3
2) Turn the regulator outlet valve ON.
3) Connect the control box power supply to mains power and switch ON.
4) Proceed to Section 4.3. to perform the initial set up and tune the system for your
specific load and pressure.
Note
If the weight of the load is unknown, consult www.thorlabs.com to find
the weight of the breadboard (weights are listed by part number and by
size), then estimate the weight of the experiment. Further tuning can be
performed once the system is ‘floated’.
Note
The system will not ‘float’ until the ‘Initial Set Up procedure has been performed

13
Chapter 4 Set Up
4.1 Front Panel Controls and Indicators
Fig. 4.1 Control Panel
Digital Display – 2-line, 16-digit liquid crystal display. In normal operation, the top line
(I) shows the nominal position of each leg in 10 µm steps, (-250 to 250 which relates
to ±2.5 mm), and the bottom line (O) shows the output voltage applied to each valve
(in encoder counts, 0 to 1000 which relates to 0 to 12 V). In Set Up mode, the display
shows the various parameters being set.
MENU – Toggles access into and out of the set up level - see Chapter 4
ENTER – Used in navigation and saves parameter settings in the set up l evel. To
save the settings so they are available after the system has been powered down, click
and hold for about 3 seconds.
UP and DOWN ARROWS – Adjusts the value of the parameters when in the set up
level.
LEG LEDs - These LEDs indicate that the associated leg is settled within the Error
Band - see Section 4.4.2.
4.2 Menu System Overview
The set up menu consists of several levels which allow the various parameters to be
adjusted for a particular application. These are described in detail in the following
sections.
Active Levelling Controller
ENTERMENU
321
LEG
I 60 0 40
O 200 450 700

14 HA0260T Rev B Mar 2014
Chapter 4
4.2.1 Set Up Menu
Press the MENU button to enter the Set Up Menu.
Press the Up and Down keys to move between levels.
This level allows preset PID parameters for a specific load
and pressure to be applied - see Section 4.3.
This level allows the demanded height (settle position) to be
set for each leg, in order to level the system - see Section
4.4.
This level allows the error ban d to be set - se e Section
4.4.2.
This level allows the PID parameters for ea ch leg to be
tuned individually - see Section 4.5.
This level switches active le veling ON an d OFF - see
Section 4.3.3.
This level switches allows the units to be set, lb s/PSI or
Kgs/Kpa- see Section 4.3.1.
This level allows the settings to be saved to memory such
that they are available next time the unit is powered up - see
Section 4.6.
Press the Up and Do wn keys to return to the PID Params
level or press ENTER to go back to the normal display
mode.
MENU
PID Parameters
170 25 150
Weight Selection
66lbs/20 PSI
Error Band
+/- 100
Settle Position
60 0 40
Active Leveling
OFF
Units
lbs/PSI
Save Settings
Return

15
Benchtop, Self Levelling Vibration Isolation System
4.3 Initial Set Up
Before the system can be used, it must be configured to operate with the specific load
and pressure with which it is being used. Perform the installation procedure detailed
at Chapter 3 then proceed as follows:
Ensure that the air pressure and system power are switched ON (see Section 3.2.1.).
then proceed as follows:
4.3.1 Units Selection
Press the MENU key to enter the set up level.
Press the UP/Down ke ys to scroll to the Un its
Selection panel.
Press the ENTER key to access the level.
The units flash to show that edit mode is active.
Press the Up/Down keys to set either lbs/PSI or
Kg/Kpa.
Press ENTER to set the units.
Press the UP/Down keys to scroll to the Weight
Selection Panel.
Continued on next page...
MENU
Units
Kg/Kpa
Units
Kg/Kpa
Units
lbs/PSI
Weight Selection
66lbs/20 PSI
ENTER
Units
lbs/PSI
ENTER

16 HA0260T Rev B Mar 2014
Chapter 4
4.3.2 Weight/Pressure (Default PID) Selection
...Continued from previous page
Before the system can be ‘floated’, the PID parameters must be set for the associated
load and air pressure. These are applied automatically when the weight is selected.
Press the UP/Down keys to scroll to the Weight
Selection panel, which contains default PID values
for a range of typical loads.
Press the ENTER key to access the level.
A series of pre-defined PID setti ngs for typical
weights/pressures is displayed as follows:
66 lbs/20 PSI (30Kg/138Kpa) - 170 25 150
99 lbs/20 PSI (45Kg/138Kpa) - 155 25 150
132 lbs/40 PSI (60Kg/276Kpa) - 110 25 150
210 lbs/40 PSI (95Kg/276Kpa) - 80 25 150
220 lbs/60 PSI (100Kg/414Kpa) - 70 25 150
330 lbs/60 PSI (150Kg/414Kpa) - 60 25 150
353 lbs/80 PSI (160Kg/552Kpa) - 55 25 150
463 lbs/80 PSI (210Kg/552Kpa) - 45 25 150
Press the Up/Down keys to scroll to the weight/
pressure combination closest to the needs of your
application then press ENT ER to make the
selection. If the weight is unknown, select the
weight closest to that chosen in Section 3.2.1.
The setting is d isplayed on the Weight Selection
panel.
Note. If the PID parameters are manually adjusted
later (see Section 4.5.) the display will change to
‘CUSTOM PID’ instead of the weight/pressure
setting shown here.
Press the UP/Down keys to scroll through to the
Active Leveling panel.
Continued on next page...
MENU
Weight Selection
66lbs/20PSI
Weight Selection
463lbs/80PSI
66lbs/20PSI
99lbs/20PSI
132lbs/40PSI
210lbs/40PSI
220lbs/60PSI
330lbs/60PSI
353lbs/80PSI
10 10 10
463lbs/80PSI
45 25 150
463lbs/80PSI
45 25 150
ENTER
ENTER
MENU
Weight Selection
66lbs/20PSI
Weight Selection
463lbs/80PSI
66lbs/20PSI
99lbs/20PSI
132lbs/40PSI
210lbs/40PSI
220lbs/60PSI
330lbs/60PSI
353lbs/80PSI
10 10 10
463lbs/80PSI
45 25 150
463lbs/80PSI
45 25 150
ENTER
ENTER
Active Leveling
OFF
MENU
Weight Selection
66lbs/20PSI
Weight Selection
463lbs/80PSI
66lbs/20PSI
99lbs/20PSI
132lbs/40PSI
210lbs/40PSI
220lbs/60PSI
330lbs/60PSI
353lbs/80PSI
10 10 10
463lbs/80PSI
45 25 150
463lbs/80PSI
45 25 150
ENTER
ENTER
Active Leveling
OFF

17
Benchtop, Self Levelling Vibration Isolation System
4.3.3 Switching ON Active Leveling
...Continued from previous page
Before the system can be ‘floated’, the ‘Active Leveling’ system must be switched ON.
Press the DOWN key to step through to the Active
Leveling panel.
Press the ENTER key to en able parameter editing.
The display flashes to show tha t editing mode is
active.
Press the UP and DOWN keys to select ON.
To configure the system to float automatically when
power is applied, press and hold ENTER to save the
setting.
The valves will turn ON and the system wil l try to
level. Allow the system to settle before proceeding.
Press MENU to return to the operating display.
Note
If the system will not settle or becomes unstable, the load may be incorrectly
positioned on the breadboard - see Appendix B for more details
If the system is not level this can also lead to instability. If hunting or instability
is apparent, level the system as detailed in Section 4.4.
MENU
MENU
Active Leveling
OFF
Active Leveling
OFF
Active Leveling
ON
ENTER
ENTER
I 60 0 40
O 200 450 700

18 HA0260T Rev B Mar 2014
Chapter 4
4.4 Levelling the System
4.4.1 Settle Position
The Settle Position parameters are the demanded positions of each leg and are used
to level the system. On initial set up, these parameters are typically set to ‘0’ which is
an arbitrary mid position (it is normal for each leg to have a different ‘0’ position). The
display shows the settle position in ADC c ounts, in the ran ge -250 to 2 50, which
relates to a ±2.5 mm range (non-linear) about the mid point.
Using a bubble level, check that the work surface is
level, if not, proceed as follows:
Press the MENU button to enter the set up level then
press the DOWN ke y to step throu gh to the Se ttle
Position panel.
Press ENTER to access the level. The valves will turn
ON.
The present setting for each leg is displayed. The
Leg1 setting flashes to show edit mode is active.
Watch the bubble level, and use the UP and DOWN
keys adjust the height.
P ress ENTER to save the setting and advance to Leg2
or MENU to discard the changes.
Watch the bubble level, and use the UP and DOWN
keys adjust the height.
Press ENTER to save the setting and advance to Leg3
or MENU to discard the changes.
Watch the bubble level, and use the UP and DOWN
keys adjust the height.
Press ENTER to save the se tting and return to the
Settle Position panel
or MENU to discard the changes.
Using a bubble level, check that the work surface is
level and repeat the above procedure as necessary.
Press the DOWN key to advance to the Error Band
parameter.
MENU
Leg1 Leg2 Leg3
0 0 0
ENTER
Leg1 Leg2 Leg3
60 0 0
Leg1 Leg2 Leg3
60 100 0
ENTER
ENTER
Settle Position
60 100 60
ENTER
Error Band
+/-100
Settle Position
0 0 0

19
Benchtop, Self Levelling Vibration Isolation System
4.4.2 Error Band
The Error Band setting is provided to improve the repeatability and/or settling time of
the system and is defined as the allowable error between the actual and demanded
position on a particular leg. A large error band results in a fast settling time whereas
a small error band results in improved repeatability When the difference between the
actual and demanded position is within the band, the associated LEG LED on the key
pad is lit. When all 3 LEDs are lit continuously for longer than 2 seconds, the pressure
system is locked and the system floats. If a disturbance occurs and the error band on
a leg is excee ded, the pressure is reapp lied to level the system. The error band is
measured in ADC counts either side of the Settle Position (see previous section).
Press the MENU button to enter the set up level then
press the DOWN key to step through to the Error
Band panel.
Press ENTER to access the level.
The present setting for the Error Band is shown and
the display flashes to i ndicate that e dit mode is
active.
Use the UP an d DOWN keys to set th e required
value. The value is adjusted in steps of 2 in the range
±24 to ±250 ADC counts (i.e. 0.2 to ±2.5 mm in real
world units).
Press ENTER to save the se tting and return to the
Error Band panel.
Press the DOWN key to advance to the PID
parameters panel.
System stability depends on both the error band and the PID settings, and some trial
and error may be req uired before the ideal settings for a specific application are
achieved. See the next section for details on adjusting the PID parameters.
MENU
Error Band
+/- 100
Error Band
+/- 150
Error Band
+/- 100
ENTER
Error Band
+/- 150
ENTER
PID Parameters
45 25 150

20 HA0260T Rev B Mar 2014
Chapter 4
4.5 Further Tuning and PID Parameter Adjustment
The control box contains a number of hall effect sensors which use a position control
loop to determine the command output. The purpose of the position loop is to match
the actual leg position and the demanded position. This is achieved by comparing the
demanded position with the actual leg position to create a position error, which is then
passed through a dig ital PID-type filter. The filtered value is the valve command
output.
Proportional term - Incre asing the proportional term will increase the amount of
effective pressure used to correct a given position error. Typically this is used to
minimise the amount of position error when an impulse event or disturbance affects
the current targe t position. If the proportional term is too high this ca n lead to
overshoot and general instability. If this is too low it can result in a sloppy response.
It accepts values in the range 0 to 327.
Integral term - Increasing the integral term minimises following error and final position
error. If Integral is too h igh this will typically lead to o vershoot of the demanded
position. If the integral term is too low final position may take a long time to reach, if
at all. It accepts values in the range 0 to 100.
Derivative term - Increasing the derivative term decreases the rate of change of
controller output. Typically this is used to reduce the overshoot from a given motion.
If derivative is too high it can become sensitive to noise from the measured position
error. If derivative is too low, fluctuations may arise during motion. It accepts values
in the range 0 to 327.
If the PID parameters loaded in the Weight Selection panel do not provide satisfactory
performance, the values can b e tuned to your particular application. The cautions
above must be read and understood before changing PID parameters.
Caution
The PID parameters must be set according to the load being supported. Default
values for specific loads have already been optimized and stored within the
controller. These are loaded in the ‘Weight Selection’ set up screen (see
Section 4.3.) and should not need adjustment under normal operating
conditions.
If problems are encountered (e.g. instability/hunting of the system, or
incomplete positional adjustments) these PID parameters should be adjusted
further to tune the system for the given application. If instability is experienced,
the proportional parameter in particular should be reduced in conjunction with
the error band (see previous section). Normally, only minor adjustment of the
Proportional parameter should be necessary, though some trial and error will
be required before the ideal settings for a specific application are achieved.
USE EXTREME CAUTION WHEN CHANGING PID PARAMETER VALUES.
PERFORM ONLY SMALL CHANGES. INCORRECT PID SETTINGS CAN CAUSE
MAJOR INSTABILITY WHICH COULD RESULT IN DAMAGE TO DELICATE
EXPERIMENTS OR APPLICATIONS.