ADEPT User Manual
Contents
1. Frequency Response In this test a sine wave of 2 Volt peak to peak and 5Vrms of varying frequency is applied thru external input and the response of the top plate was interpreted on sensor out is observed and its amplitude is recorded This is used to determine what the maximum possible input frequency is Top plate is loaded with 600grams payload Page 7 a mo 5 f Oo Series1 Frequency in Hz Observation As the moves come more frequently the piezo top plate may not have sufficient time to finish its move and settle in and the move is left incomplete The above graph shows that over 10Hz or more that 10 commanded moves a second there are a lot of incomplete moves and at 40Hz the top plate only travels half the commanded distance Top plate Load capacity During testing we found the 150um can carry 2Kg load and the 300um and 500um can carry 1Kg load without any noticeable drop in performance The Top plates will continue to perform at high loads with some loss in performance like travel range accuracy and repeatability The maximum load we tested was 4Kg at which point the top plates lost 20 of their travels Caution Mass above 5Kgs may damage the top plate Always try to have the mass evenly distributed on the top plate Change log Last Updated Comments 8 16 2010 Rough Draft 4 25 2011 Updated the Performance section 4 26 2011 Performance section edited again 5 26 2011 Characteristic performance added 6 12. and a shorter self calibration is performed by MS2000 on startup So ideally users do not have to worry about calibrations offsets etc Here is a short description of what they involve Strain Gauge Offset ADEPT uses two semiconductor strain gauges installed in the piezo top plate in half bridge configuration for feedback One strain gauge flexes as the top plate moves while the other is installed in a non flexing position As the top plate moves up and down the flexing strain gauge s resistance relative to the unflexing strain gauge increases and decreases the sensor conditioning circuit interprets this as a voltage The strain gauge offset parameter is the setting for a digital potentiometer that adjusts the resistance of the unflexing strain gauge so that at a position of our choosing set by PZC F command it has the same resistance as the flexing strain gauge This setting can be viewed and adjusted with PZ X serial command It is automatically picked by the MS2000 controller during auto calibration routine and also during the shorter self calibration routine on startup When a PZINFO command is issued among one of the check it runs is for the strain gauge offset and it returnsaSG Offset OK or BAD Feedback Gain When the piezo top plate moves the strain gauge interprets this as the change in resistance The feedback gain is the parameter that helps the sensor conditioning circuit interprets this change in resistance as a voltage and
3. the calibration section for its usage e Y Argument sets the gain of the feedback stage Only values between 25 to 5100 are accepted The setting is stored in a non volatile memory on the ADEPT board This is one of the settings that is automatically picked during long auto calibration Please refer the calibration section for its usage e Z Argument sets the board in various modes Open Loop Closed loop MS2000 input and External input Z Argument sets the Mode of Operation of the ADEPT board PZZ Mode of Operation 0 MS2000 input Closed loop default It Page 2 1 External input Closed Loop 2 MS2000 input Open loop 3 External input open loop In Open Loop mode a set voltage is applied to the piezo and the feedback from strain gauge is ignored Useful during system calibration In Closed Loop mode the voltage applied to the piezo is adjusted according to the feedback coming from the strain gages This is the default mode of operation MS2000 input in this mode the MS2000 controller generates the positioning input for the piezo top plate This is the default mode of operation In External input mode the piezo top plate is positioned according to O to 10V analog signal provided by the user Every one volt change moves the piezo the range We recommend that frequency of the signal be kept less than 10Hz for long moves to give the piezo top plate sufficient time to settle and come to a complete stop The user ca
4. then into distance moved Performance Electrical Performance e Capable of Applying 24V to 150V to the Piezo actuators e Maximum continuous output current of 13mA e 1imsec Transient Response time 10 90 for moves below 30 travel range with 600grams load Characteristics Name PZ 2150 PZ 2300 PZ 2500 Piezo Travel Range 5 Piezo smallest 2 2nm 4 5nm 7 6nm travel in Kilogram Transient Response time External Analog input BNC 0 to 10 Volts Maximum Input Frequency This is with MS 2000 controller s 16Bit DAC User may improve this thru a high resolution signal generator and the system operating in external input mode Page 6 Time took to travel 10 90 for moves below 30 travel range and with 600 grams load Transient Response 10msec 15um Figure 3 the above graph shows the step transient response of ASIs piezo top plate for a 30um move The rise time is 11msec The above graph is the transient response of a 150um ASI piezo top plate Red waveform is the user commanded input or desired output Green waveform is the actual piezo top plate position interpreted from sensor out Here it shows the piezo top plate travel 30um with a rise time 10 to 90 of 11 msec The piezo top plate was loaded with 600grams payload We observed that the transient tends to increase for longer moves Travel Range 150um 300um_ 500um _ 30 50 70 All values listed above are with 600grams load
5. 7 2011 Load and transient response performance data added Page 8
6. ASIs Drive Electronics for Piezo Top Plate ADEPT s Features e Closed loop operation with strain gauge feedback e Auto strain gauge calibration on startup e Accepts inputs from MS2000 digital or external analog sources e Nanometer precision with low noise and drift Figure 1 ADEPT Card Introduction ADEPT is an add on module that extends the MS2000 controller s capability to control piezo top plate The user can position the piezo top plate through MS2000s serial commands or manual inputs like the knob or through an external signal source It can also be used also with other MS2000 modules like AUTOFOCUS CRIFF and SEQUENCER etc ADEPT can operate either in open loop or closed loop mode In closed loop mode it uses high sensitivity semiconductor strain gauge as sensors to position the piezo top plate with nanometer precision and transient time less than 25ms MS2000 performs calibration on ADEPT card on startup so the system maintains calibration Connectors 1 Piezo Top plate Connector 2 Sensor Out 3 External Input Figure 2 MS2000 Connections External Input and Output Apart from using the ADEPT card to position the piezo top plate through MS2000 this card can also get positioning information through 0 10V analog signal Page 1 When the controller is set to external input mode using the PZ Z command or holding the button down for 6 sec ADEPT positions the piezo top plate based on the voltag
7. djusting the strain gauge offset Accepts values between 1 to 100 units are default is 50 i e middle of the piezo range SS z command is applicable settings will be saved between controller restarts Please use HALT command to stop a running calibration routine else the routine will leave incorrect settings on the ADEPT card Command PZINFO Format PZINFO Rely Voltages Posl gt HV 147 V Sout 4 V PZout 65 V I2C Check gt DAC OK SWITCH OK DigPot OK DigPot gt SGoffset 110 Gain 96 Closed Loop MS2000 IN SG Offset OK Function When issued MS2000 replies with all relevant ADEPT card settings to aid in trouble shooting Please refer to the Troubleshooting section for explanation of the message Button Format long press i e 6 sec Function Toggle between external input mode and MS2000 input mode Page 4 Troubleshooting e On startup if the axis with piezo top plate comes up as disabled with either a COD error of 140 or 141 it indicates one of the startup self test for the ADEPT card has failed Use the PZINFO command to further investigate e If you re noticing any odd behavior the PZINFO command is a good way to debug the error When this serial command is issued MS2000 controller performs a series of test and returns the result that looks like this Voltages Posl gt HV 147 V Sout 4 V PZout 65 V I2C Check gt DAC OK SWITCH OK DigPot OK DigPot gt SGoffset 110 Ga
8. e applied to EXT IN or external input The analog signal should be between O to 10 volts where 10 represents lower limit and O volts represents higher limit For every 1 volt change the piezo top plate changes the piezo range Example if it s a 150um piezo top plate 1 volt represents 15um 0 1 volt represents 1 5um We recommend that frequency of the signal be kept less than 10Hz for long moves so as to give the piezo top plate time to settle down and come to a complete stop In external input mode the letters XT are display next to the axis position on LCD and the position displayed is extracted from the strain gauge feedback This position is accurate to lum Sensor Out is a O to 10 volt analog signal that corresponds to position of the piezo top plate is a buffered output of the strain gauge sensors Command Set Apart from the regular axis commands like MOVE MOVREL ZERO INFO refer to MS2000 Programming section here are some ADEPT specific commands Most users do not need to use these commands unless configuration are changed or problems are encountered Command PZ Format PZ X 1 to 255 Y 25 to 5101 Z 0 to 3 Function e X argument sets the zero adjust potentiometer of the ADEPT card Only values between 1 to 255 are accepted The setting is stored in a non volatile memory on the ADEPT board This is one of the settings that are automatically picked during both long and short auto calibration Please refer
9. in 96 Closed Loop MS2000 IN SG Offset OK o Voltage Pos1 indicates the Voltage on High Voltage Rail as HV Voltage on Sensor Out as Sout and Voltage being applied to the piezo top plate as PZout at the current position High Voltage rail should always be in high 140s and more if not it indicates a problem on the board o 12C Check pings the various digital ICs on the ADEPT board and returns OK or BAD OK indicates that the IC is powered and is communicating with MS2000 BAD indicates a problem o DigPot returns the current calibration settings strain gauge offset and feedback gain o Next it indicates whether the card is in open loop or closed Loop mode o Then it displays the current source of piezo top plate position MS2000 IN or EXT IN o SG Offset is a quick routine to checks the validity of the strain gauge offset setting and returns OK or BAD This routine will only check the strain gauge offset and will not try to correct it Issue a PZC command to run calibration routine it will automatically pick the correct value Calibration Note All ADEPT boards are calibrated in the factory and undergo thorough testing Users do not have to perform any calibration This section is for your understanding of the piezo top plate s working Page 5 For optimal closed loop operation when a strain gauged piezo top plate and ADEPT board are paired together calibration is performed Every piezo system is calibrated in factory
10. n toggle between external input mode and MS2000 input mode by holding the button down for 6 sec The modes will revert back to default state i e MS2000 input with Closed Loop PZ Z 0 when system is powered off Use the ss z command to save your preference Command PZC Format PZC X O or 1 Y 0 1 2 3 Z i to 100 F 1 to 100 yor PZC Function PZC when entered alone runs the auto calibration routine that sets various internal parameters for optimal operation of the piezo top plate A is returned on completion N 5 is returned if the routine failed e X argument sets the auto calibration type to perform O is for short calibration default i e only strain gauges offset is adjusted While 1 is long calibration routine with adjusts both strain gauge offset and the feedback gain You will need a length gauge to run the full calibration routine ss z command is not applicable settings will revert back to default when controller restarts e Y argument sets the axis index to which the length gauge is assigned Default is O i e X index in a 4 axis build SS z command not applicable settings will revert back to default on controller restart e Z argument sets the delay between routine runs default is 35 i e 35ms Units are in milliseconds SS Z command not applicable settings will revert back to default on controller restart Page 3 e F argument sets the position where controller moves the piezo top plate before a
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