tmc setup guide lab table 20 series

Vibration Isolation Systems Setup Guide, 2014

TMC Ametek, Peabody, Massachusetts

20 Series Active Vibration Isolation Tables

Introduction

Feature highlights Compact Sub-Hertz Pendulum (CSPTM) in each leg

Precision Electronic Positioning System (PEPS®)

PEPS-VX® Vibration Cancellation System attached to PEPS.

The table has been assembled at the factory. Leveling of the four CSP inserted in each leg and tuning of the PEPS/PEPS-VX controllers have been made and should provide satisfactory performance for a typical installation.

Figure 1, 20 Series Active Vibration Isolation Table

Air supply requirements

The active vibration table requires a continuous supply of compressed air or Nitrogen to operate properly. For a complete discussion of the air supply requirements, see System Air Supply Requirements in the introduction section of this document.



WARNINGS

Power Supply The PEPS / PEPSVX controller does not use a universal power supply.

Country voltage setting The power entry module must be configured for your country’s voltage as follows.

Remove the fuse access panel (Figure 10) on the PEPS controller.

Remove the small voltage selection card from the module.

Rotate the nylon tab to the correct voltage setting.

Re-insert the card into the power entry module.

Replace the cover. The nylon pin should protrude through a hole in the cover labeled with your country’s voltage.

Important The unit is rated for 100, 115, or 230 Volt operations. The 240 Volt setting should never be used. If you are in a country using 115 Volts, select the 120 Volt setting. Failure to properly configure the input power module can result in permanent damage to the unit.

Power Cord Use only a UL/CSA/VDE marked mains power cord with the PEPS controller. The power cord should have at least 0.75mm2 wire (18 AWG), and include a PE ground. The cord should comply with all local, regional and national standards for the country where the system is to be used.

Controller Usage The controller and its components are only to be used for its intended purposes described in this manual. Any other usage could jeopardize operator safety and cause possible injury.

Pneumatic Isolators Great care should always be used when dealing with pneumatic isolators. Floating a payload on pneumatic isolators can generate many pinch points. One such pinch point is between the top of the fixed portion of the isolator, and the bottom of the ‘load disk’ supporting the payload (see Figure 11).



Installation and Setup Instructions

Tools Required: 5/32 inch Allen key wrench

Step 1 Install shelf on the frames lower tie bars.

Figure 2, Table shelf

Step 2 Place PEPS/PEPS-VX controller on shelf. Figure 3, PEPS/PEPS Controller on shelf

shelf

PEPS/PEPS-VX controller



Step 3 Connect cables and tubing

Connect the following from system harness to controller.

1/4 inch OD tubing as labeled. Connect five 1/4 inch OD tubing from pneumatic system.

Proximity sensor connector Insert six pin green connector into green receptacle.

Velocity sensor cables Connect BNC connector cables VS1, VS2 & VS3.

Connect AC Power cord Ensure controller power switch is in the OFF position and connect AC power cord.

Figure 4, PEPS/PEPS Controller cable connections

Proximity Sensor

Connector

1/4 inch OD Tubing

AC Power Switch



Figure 5, PEPS/PEPS-VX Controller connections

Proximity sensor mounted to isolator Isolator leg Velocity sensors mounted under tabletop Air regulator adjustment Proximity sensor connector

Waste Air 0utput

Air supply

Front

Velocity sensor Inputs VS1, VS2, VS3



Step 4 Connect the air supply

Connect air supply and set air supply and regulator pressure.

Note For details regarding the air supply requirements, see System Air Supply Requirements in the introduction section of this document

Air supply fittings: Tubing can be connected to a 1/4 or 1/8 inch NPT female fitting as shown in figure below.

Air supply pressure 90-100 psi (621-690 kPa) Supply pressure or greater above the highest expected pressure in any isolator when the system is floating.

Regulator Pressure 15 psi (100 kPa) or greater above the highest expected leg pressure.

40 psi is a typical regulator setting for floating the tabletop without a payload. When adding payload ensure pressure is increased to 15 psi above expected leg pressure.

Figure 6, Air Supply Connection

Air supply

Adapter 1/4” NPT Male to

1/8 “ NPT Female

Straight Connector 1/8” NPT Thread

1/4 inch tubing Approx. 30 feet long

Adjust Regulator pressure



Step 5 Center piston assembly

Center each piston assembly on isolator top plate so that outside circumference of aluminum piston ring aligns with the edges of three small alignment holes spaced around piston ring 120 degrees apart.

Figure 7, Centering piston assembly

Aluminum piston ring

Top View

Piston assembly

Alignment hole

Isolator top plate

Alignment hole



Step 6 Place tabletop onto frame

Place tabletop down onto frame so that top is centered over the four isolator legs without disturbing the centering of the piston assemblies.

Figure 8, Mount tabletop

Step 7 Attach velocity sensors

Screw velocity sensors VC1, VC2 and VC3 into bottom of tabletop as shown in figure below. Connect BNC connector on end of sensor cable from system cable harness to base of sensor.

Figure 9, Attaching velocity sensors

Piston assembly

VC1 VC3

VC2

Front

VC3 VC1

Front view

Sensor cables



Step 8 Float table top

Turn the PEPS/PEPS-VX Controller’s AC Power Switch ON.

Reference figure 10 below.

Expect to hear the sound of flowing air as the four isolators inflate lifting the tabletop. Once floating you should feel a spongy action on the tabletop over each of the isolator legs.

Figure 10, PEPS/PEPS-VX Controller

ENGAGED (green LED)

AUX IN-OUT

DB-25 connector

ZEROING ON/ ENGAGED

(green LED)

AC Power

Out of Range adjust

RANGE OK Out of Range/

(yellow/amber LED)

Clear plastic cover

AIR INPUT from regulator WASTE AIR output

Fuse panel and main voltage selection

ISOLATOR 1 output to leg 1

PROXIMITY SENSORS green input connector ISOLATOR 2 output to leg 2

AC Power switch ISOLATOR 3 & 4 output to legs 3 & 4



Step 9 Adjust "level compensation screws”

Visual check Visually check piston level for each isolator leg to ensure piston is level with isolator top plate. Only adjust level compensation if required such as in figure below showing a slightly tilted piston.

Figure 11, Centering piston assembly

Adjustments Center piston assembly over leg by adjusting each screw as little as possible any one time. Continue to rotate around table slightly adjusting each leg until all have been optimized.

Clockwise (cw) turn makes the piston assembly move away from the screw you are adjusting.

Counter-clockwise (ccw) turn moves the piston assembly towards the screw.

Move the payload parallel to the screws by adjusting screws equal amounts in opposite directions.

Move the payload perpendicular to the line between the screws by adjusting screws in the same direction.

Example: The figure above shows an isolator viewed from the side requiring a very sensitive adjustment of the pendulum's level. The pendulum tube is tilted 2.5 degrees. In this case, leveling screw-A should be adjusted a few turns clockwise, and leveling screw-B a few turns counter-clockwise.

Tilted piston and pendulum tube

Leveling Screw-B

Isolator top plate

Isolator leg

Leveling Screw-A

Caution: Keep fingers away from pinch point between top plate and aluminum ring.



Step 10 Add payload to tabletop

Turn OFF air supply and AC power

Place a typical payload onto the tabletop.

Turn ON air supply and AC power to re-float system.

Ensure tabletop is floating without any interference.

Step 11 Check the following status LEDs

RANGE OK

OFF Good ON Gain settings need adjusting.

ENGAGE Green LED

ON Good ON/OFF Intermittent ON/OFF Gain settings need adjusting.

(Ref. “SMART ENABLE” feature)

Step 12 Excite tabletop with payload

Manually excite tabletop using your hand and observe that tabletop has a quick impulse response and settle time.

If any of the following conditions are observed then proceed to the section on “Troubleshooting”.

Poor settle time Tabletop oscillates Erratic movements RANGE OK or ENGAGE LEDS indicate gain settings

need adjusting.



Troubleshooting

Problem: My system doesn't float.

Check power connection, fuse, and voltage setting.

Check power

1) Set DIP switch #5 to ON (right position)

ZEROING ON LED: ON indicates power is okay.

2) Set DIP switch #5 to OFF (left position) once power status is determined.

Check for air flow: Ensure air supply is correctly connected.

You can normally hear and feel air venting from the WASTE AIR output. (reference figure 10).

Air supply pressure: Ensure supply pressure is at least 15psi (100kPa) above the highest isolator pressure.

Test by increasing pressure.

PEPS-VX Electronic gains: Increase each gain by 3 CW (clockwise) turns. Continue to increase each gain additional turns.

Air lines: Ensure air lines are correctly connected, don’t have any kinks or pinched restricting air flow.

Problem: Some isolators fully inflate, while others get no air.

Air lines: Ensure air lines are connected correctly, don’t have any kinks or pinched restricting air flow.

Proximity sensors: Ensure sensors are connected correctly, i.e. proximity sensors 1 and 2 are switched.

Air supply pressure: Increase by 10psi (70kPa)

Pitch & roll gains: increase either gain or both.



Problem: After adding payload to the tabletop my system tilts back and forth from travel limit to travel limit (unstable in tilt). System may be gravitationally unstable by sitting on one edge for a while (up to several minutes), then suddenly `flop' over to the opposite edge. It will eventually flop back, and repeat the pattern. Any payload supported under its center-of-mass wants to `fall over'. The isolators provide a restoring force which resists this from happening. However, if the center-of-mass is too high or the distance between isolators too short, then the isolators will not be able to keep the payload upright.

The general rule of thumb for stability is:

W = center-to-center distance between the isolators H = height of the center-of-mass.

Borderline systems tend to behave poorly. Some systems which are stable with mechanical height control valves may be unstable with PEPS. Mechanical valves act like springs which can help stabilize a system (but also degrade the vibration isolation). Removing the internal orifices also tends to make isolators softer, improving performance, but making the system less tilt stable. PEPS cannot make a mechanically unstable system stable. Solutions to this problem include the following:

Lowering the center-of-gravity of the system

Increasing the separation between the isolators

Reconfiguring the system so the master/slave legs (legs 3\&4) are along the long edge of the payload

Note TMC makes other types of isolators which may improve the situation, including smaller volume (stiffer) and fluid-damped MaxDamp®

isolators. Contact a TMC sales engineer for more information on this last option.

Problem: I see some low-frequency noise in the positioning of the payload which is above the specification.

Water trap Many air compressors cause water to accumulate in the air lines causing the servo valves in PEPS to work improperly. Your air supply system should have a water trap. Ensure that water trap isn’t full.

W2

(H + 0.18m) > 1.5m



Barometric pressure Changes in barometric pressure can also cause noise on a payload since the sealed chambers of the isolators make them act like barometers.

Barometric noise Many environments (such as clean rooms) have very aggressive air handling systems which can generate `barometric noise'. Likewise, if the system is placed near an air vent, or has some air circulating about it as part of a `mini environment',

Positioning noise The table can see excess positioning noise. These sources of noise are not controllable by PEPS, and must be addressed at the source. The specification for PEPS was determined in a sealed room with no air circulation system running.

Problem: The system takes too long to level after a disturbance (shift in mass distribution).

Like mechanical valves, PEPS is a gain-limited servo. The gain is limited by the need to preserve vibration isolation in the system. For this reason, PEPS will level a payload at about the same speed as a mechanical valving system, depending on the disturbance.

Pitch and roll gains Increase the pitch and roll gains until they are as high as they can be without the system oscillating. Though this does hurt the tilt vibration transfer, tilt noise is normally very low in most environments.

Problem: My isolators inflate to full pressure lifting the payload to its travel limits, independent of the gain, or even if the power is off. If the isolators inflate when the power is off, you have probably connected the air supply tube from the system harness to the WASTE AIR port of the controller. Recheck the system plumbing.



PEPS/PEPS-VX Controller Advance Setup

Smart Enable The PEPS/PEPS-VX controller is a high-gain feedback system. To prevent the system from behaving badly when the velocity sensor feedback is turned on, it uses a “smart enable” feature. The controller monitors the proximity sensor signals. If the payload moves more than a few millimeters outside of its normal equilibrium position, the controller turns off the feedback. Once the payload moves back inside of its normal operating range, the controller will wait a few seconds, and then try to re-enable the velocity sensor feedback. The delay allows the system to stop moving, and prevents the system from engaging on ‘accidental fly-bys’.

ENGAGED LED (reference figure 10)

ON (green) = Indicates feedback is enabled. LED turns on when feedback is enabled and a several second time delay has passed.

ALL DIP Switch (reference figure 10)

ON (right position) normal operation, feedback is enabled and ENGAGED LED lights after several second delay.

OFF (left position) diagnostic mode – feedback is disabled

Note When setting the gains in the following instructions, be aware of the ‘smart enable’ function. Ensure the ENGAGED LED is ON when testing the impulse response. Too hard a push in testing may trigger the system to disable the feedback momentarily.

DAMPING and ZEROING Gain and DIP Switch Settings

Remove the clear plastic cover on the front panel (reference figure 10) for setting Damping and Zeroing DIP switches and adjusting the controller’s gain settings.

All DIP Switches are set to the OFF position for normal operation.

Integrator Control: Switches 4 & 5 PEPS/PEPS-VX controller is a sophisticated feedback system which includes integration as part of its control algorithm. Any error in the position signals are “integrated” so the feedback to the valves will



continue to change until the error is driven to zero resulting in highly precise leveling capability. It is not always desirable, however, to have integration in a control loop.

Under certain conditions, the integrators can ‘saturate’, and require a long time to recover. For this reason, the integrators can be configured to run in the following three modes:

1) Integrators ON After Float – Normal mode of operation

As tabletop starts to float integrators turn ON when proximity sensors detect a payload rise above a preset height. This mode prevents the integrators from saturating when the isolators are inflating during power-up.

Switch 4 = OFF (left hand position)

Switch 5 = OFF

ENGAGED LED = ON, Integrators are engaged

2) Integrators Always ON – Diagnostic mode ‘Smart enable’ function is disabled. Integrators are always on forcing tabletop to float regardless of gain settings.

Switch 4 = OFF

Switch 5 = ON

If the gains are set to low the system may have trouble floating. The system will take a very long time to come to equilibrium due to the saturation of the integrators caused during the initial isolator inflation.

This mode is not recommended for a permanent configuration.

3) Integrators Always Off – Diagnostic mode

Setting enables adjusting proximity sensors on a system with very tight travel constraints in the isolators. It can sometimes be difficult to locate the ‘operating height’ of the proximity sensors.

When the integrators are OFF the system response is very fast.

Set Integrators OFF

Setting enables adjusting proximity sensors in their brackets to get the system floating within the mechanical constraints.

Switch 4 = ON (integrators OFF)

Switch 5 = OFF



Set Integrators ON

Set switch 4 to the OFF position. The float height may change a little, and final adjustments can be made to the sensors.

Switch 4 = OFF (integrators ON)

Switch 5 = OFF

Power-Up Gain Adjustment The gain of the feedback loops determines the dynamic response of the isolation system. The following are two responses affected by the gain.

Leveling time The time required for the payload to return to level after a disturbance.

Level of Damping Determines how quickly the payload stops moving after an impulse response (also called ‘ring down’ time).

Monitoring gain adjustments Monitor the response of the payload using the proximity sensor outputs as follows.

Connect oscilloscope to the three sensor outputs as follows.

AUX IN-OUT, DB-25 Connector

VC1 .......... DB-25, pins 7 VC2 .......... DB-25, pins 8 VC3 .......... DB-25, pins 9

GND ......... DB-25, pins 23-24

Set oscilloscope

Vertical direction ............ v/div Horizontal direction ....... 0.5 s/div.

Figure 12 below shows examples of the impulse response for different gain settings.

Note TMC offers a ‘breakout box’ to make connections to DB-25 connector easier for OEM customers.



Setting Gains with Electronic Damping Every system is tested at the factory and the gains are set to values which will allow the system to float.

Height Gain Adjustment

Turn power ON.

Connect an oscilloscope as follows.

AUX IN-OUT, DB-25 Connector

Height analog output ........ DB-25, pin 4 GND ................................. DB-25, pins 23-24

Press down lightly on the center of the payload, and you should see a response on the scope.

Turn the gain down until the response looks like the left-hand curve in figure 12 below.

Gradually increase the gain until the oscillatory behavior is suppressed (the right-hand curve below).

Pitch and roll gain adjustment

Repeat above procedure by moving the scope to the proper pin on the AUX IN-OUT, DB-25 connector each time.

Excite the payload by pushing it sideways.

Figure 12, Damping Too Low and at Optimum

Do not set the gain any higher than is required to damp the motion.

Figure 12 above shows what happens when the gains are increased too much. Notice that the pitch and roll degrees of freedom may not have as high a damping level as shown in Figure 13. If this is the case, then increase the gain until the damping of the primary oscillation stops improving.



Figure 13, Gain Too High With Electronic Damping

Figure 13 above shows what happens when the gain setting is set too high. The oscilloscope sensitivity has been increased to 100 mV/div. Notice that system has gone into a sustained oscillation at approximately 7.5Hz.

Too Much Gain?


TMCAmetek, Peabody, Massachusetts 20

Figure 14, Vibration Transfer and Impulse Responses for Different Gains


TMC Ametek, Peabody, Massachusetts 21

“RANGE OK” LED – The PEPS Go-No-Go Indicator


TMC Ametek, Peabody, Massachusetts 22

PEPS Technical Specifications

Quoted technical specifications are typical values, and not a guaranteed

performance level. They are subject to change without notice.

Power Supply ....................................................... 100/115/230 VAC, 50/60 Hz, 20W max

Fuse .......................................................................................... T 0.25 A, 250 V slow-blow

Power Cord ..................... UL/CSA/VDE marked 0.75mm2 wire (18 AWG) w/PE ground

Air Consumption ............... 45slpm (1.5 scfm) dry, clean air, filtered to 20μm or better

Maximum Air Transfer Rate .......................................... 15slpm (0.5scfm) (Per isolator)

Leveling Accuracy ................................................. 5μm height, 5 μradian pitch and roll

Leveling Hysteresis (integrators on) ................... 5μm height, 5 μradian pitch and roll

Leveling Hysteresis (integrators off) .............. 50μm height, 50 μradian pitch and roll

Physical Dimensions ................. 165mm (6.5”)H x 104mm (4.125”)W x 190mm (7.5”)D

Weight (unit alone) ................................................................................. 2.51 Kg (5.52 lb)

Standard Proximity Sensors ......... Turck Ni15-G30-Y0 NAMUR eddy-current sensors

................................................................................................... (15mm operating height)

Proximity Sensor gain ...................................................................................... 2volts/mm

Environmental

For indoor use only, up to an elevation of ............................................ 2,000m (6560ft.)

Temperature range .......................................................................................... 5 C to 40 C

Humidity range 80% up to 31 C, decreasing linearly to 50% relative humidity at 400 C

Tolerance in mains supply voltage ....................................... +/-10% of nominal voltage

Installation Category ....................................................................................................... II Pollution Degree ............................................................................................................... 2

AUX I/O, DB-25 Connector (colored ribbon cable)

Pins Pins

1) Height Feed-Forward Input 14) Valve (1) Test Point

2) Roll Feed-Forward Input 15) Valve (2) Test Point

3) Pitch Feed-Forward Input 16) Valve (3) Test Point

4) Height Analog Output 17) GROUND

5) Roll Analog Output 18) GROUND

6) Pitch Analog Output 19) GROUND

7) Prox. Sensor (1) Output 20) GROUND



10) Out of Range Logic Out 23) GROUND

11) Out of Range Voltage TP 24) GROUND

12) +15 EXT. Power Input (750mA max.) 25) EXT. Power Ground

13) -15 EXT. Power Input (100mA max.)

Figure 15, PEPS technical specification



PEPS-VX Technical Specifications Quoted technical specifications are typical values, and not a guaranteed performance level. They are subject to change without notice. Physical Dimensions (VX Controller)165mm (6.5”)H x 46mm (1.8”)W x 190mm

(7.5”)D

Physical Dimensions (w/PEPS) ..... 165mm (6.5”)H x 153mm (6.0”)W x 190mm (7.5”)D

Velocity Sensors .............. 90mm (3.53”)H x 44mm (1.7”) Diameter “geophones” with

.......................................................................... BNC connector & ¼”-20 Mounting Stud

Weight (PEPS-VX Controller) ................................................................. 1.37 Kg (3.02 lb)

Leveling Accuracy ............................................. 20μm height, 20 μradian pitch and roll

Leveling Hysteresis ........................................... 20μm height, 20 μradian pitch and roll

Environmental

For indoor use only, up to an elevation of ............................................ 2,000m (6560ft.)

Temperature range .......................................................................................... 5 C to 40 C

Humidity range .................................................. 80% up to 31 C, decreasing linearly to

......................................................................................... 50% relative humidity at 400 C

Installation Category ....................................................................................................... II Pollution Degree ............................................................................................................... 2

AUX IN-OUT DB-25 connector (probe test point locations) and TO PEPS DB-25 connector (with colored ribbon cable)

Pin Pin

1) Height Feed-Forward Input 14) Valve (1) Test Point

2) Roll Feed-Forward Input 15) Valve (2) Test Point

3) Pitch Feed-Forward Input 16) Valve (3) Test Point

4) Height Analog Output 17) Height Test Input

5) Roll Analog Output 18) Height Test Output

6) Pitch Analog Output 19) Roll Test Input

7) Proximity Sensor (1) Output 20) Roll Test Output

8) Proximity Sensor (2) Output 21) Pitch Test Input

9) Proximity Sensor (3) Output 22) Pitch Test Output

10) Out of Range Logic Out 23) GROUND

11) Out of Range Voltage TP 24) GROUND

12) +15 Ext. Power Input (750mA max.) 25) EXT. Power Ground

13) -15 Ext. Power Input (100mA max.)

Figure 16, PEPS-VX technical specifications


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tmc setup guide lab table 20 series

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