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Melting Probe 2008-06-24 1IWF-EXP/ÖAW GRAZ Size: 40 x 40 x 195 mm Mass w/o electronics Calculated: 450g Measured: 350g, 3m tether Main Components Cable.

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Presentation on theme: "Melting Probe 2008-06-24 1IWF-EXP/ÖAW GRAZ Size: 40 x 40 x 195 mm Mass w/o electronics Calculated: 450g Measured: 350g, 3m tether Main Components Cable."— Presentation transcript:

1 Melting Probe IWF-EXP/ÖAW GRAZ Size: 40 x 40 x 195 mm Mass w/o electronics Calculated: 450g Measured: 350g, 3m tether Main Components Cable cartridge Contains the tether and the slip-ring mechanism Body Contains the MP electronics and provides space for the payload Tip Contains front heater and provides space for optional vibration system Melting Probe V2.0 Mechanics

2 Melting Probe IWF-EXP/ÖAW GRAZ The Tip

3 Melting Probe IWF-EXP/ÖAW GRAZ Small mass, but rigid structure Space for MP electronics and payload Relatively large openings for installation of MP electronics and payload (18 x 31mm) Water tight interface to the tip and the cable cartridge The Main Body

4 Melting Probe IWF-EXP/ÖAW GRAZ Enough space to contain more than 10m of tether Slip-ring mechanism with water tight cover System to measure the vertical position of the probe Water tight interface to the main body The Cable Cartridge

5 Melting Probe IWF-EXP/ÖAW GRAZ All mechanical parts available Manufacturing quality is good, price was reasonable All parts have been pre-assembled Minor changes have been applied during the assembly process Additional openings for heater and sensor harness Cut-outs in the tip for Pt1000 and harness Adjustment of slip-ring contacts Tests with cable cartridge Slip-ring test Cable pull-out test Summary and Tests

6 Melting Probe IWF-EXP/ÖAW GRAZ Assembly of slip-ring is critical: balance between friction for cable pull-out and spring load to electrical contacts Test: Slip-ring assembled without tether Applied current 3A per signal line Contact voltage measured Slip-ring failed after ~4500 turns Slip-ring Test (1/2)

7 Melting Probe IWF-EXP/ÖAW GRAZ Test was performed in steps: 1000, 1000, 1000, 7000 After each stip slip-ring was dismantled and images were taken Slip-ring Test (2/2)

8 Melting Probe IWF-EXP/ÖAW GRAZ Too high pull-out forces could cause the probe to get stuck Test set-up Cartridge fully assembled with slip-ring and tether Cartridge fixed at the bottom; actuator was used to pull out the cable (0.5 mm/sec, 1.3 mm/sec) Load cell was used to measure the force applied to the tether Necessary force is low and results repeatable Cable Pull-out Test

9 Melting Probe IWF-EXP/ÖAW GRAZ Status More changes than foreseen for this phase Circuit diagrams ready Layout of prototyping board started Functionality of prototyping board Electrically identical with final MP electronics (MPE V3) For cost reasons standard PCB technology used All heaters, sensor, mechanisms and communication will be checked before final PCB in rigid-flex technology is ordered Reference model for the update of the interface unit and the control software Electronics Design (1/2)

10 Melting Probe IWF-EXP/ÖAW GRAZ Electronics Design (2/2) Placement and Layout All passive SMD components changed to 0805 size Both sides of the board will be populated Available space is still critical Power module shall be separated from measurement and communication module Connector type OMNETICS mounted directly onto flex board Largest component is the DC/DC converter

11 Melting Probe IWF-EXP/ÖAW GRAZ Power and Grounding Concept Power electronics galvanically disconnected from control electronics All power devices, heater and motor, at primary ground Control and measurement devices at secondary ground Communication channel connected to +28V lines only Interference from DC/DC converter to communication is minimised DC/DC converter with dual supply output

12 Melting Probe IWF-EXP/ÖAW GRAZ Same processor type, but latest version with 12bit ADC will be used Thirteen analogue channels used In total seven heater control units ( ) Accelerometer with three axis (analogue output) Temperature reference with AD590 (1µA/K) Voltage reference for corrections Monitoring of 28V supply Additional signal lines In- and output for position measurement PWM output with opto-coupled 28V for motor control Processor

13 Melting Probe IWF-EXP/ÖAW GRAZ Heater control line is galvanically isolated Opto-coupler for isolation FET with +5V control input, current limiter and thermal control Temperature measurement Change to Pt1000 Current source with 1mA Two wire interface Instrumentation amplifier with dual supply Heater Control

14 Melting Probe IWF-EXP/ÖAW GRAZ Three axis accelerometer ADXL330 Range ±3g Analogue output typically 300mV/g Additional amplifier to increase sensitivity Change from two axis to three axis sensor to support direct mounting at the PCB Probe Orientation

15 Melting Probe IWF-EXP/ÖAW GRAZ Infrared LED activated by processor Opto-transistor as sensor Cut-out in track is not sufficient, since absorption of Kapton foil is too high Next version of tether shall provide cut outs through all layers LED only activated when signal from opto-transistor is sensed Position Measurement

16 Melting Probe IWF-EXP/ÖAW GRAZ Serial, full duplex, carrier frequency based communication, similar as used for MPE V2.0 Signal is now transmitted as differential signal, via +28V-Nominal and +28V-Redundant line Noise of DC/DC converter is not seen by communication signal Improved filter designs All OpAmps with dual supply Input filter identical with MPE V2.0, but improved design for signal reconstruction Simulation showed larger separation Coding for new version is inverted, logic 1 activates carrier Communication

17 Melting Probe IWF-EXP/ÖAW GRAZ Transmitter

18 Melting Probe IWF-EXP/ÖAW GRAZ Receiver

19 Melting Probe IWF-EXP/ÖAW GRAZ Simulation Results

20 Melting Probe IWF-EXP/ÖAW GRAZ MP Mechanics Installation of heater, Pt1000 and harness MP Electronics Layout, assembly and board level test of prototype Layout and assembly of final MPE MPE Software Adoption of MPE software and communication protocol to new sensor configuration Additional control routine for motor PWM Interface/Surface Unit Population of another board (differential signals) Adoption of interface module software EGSE Software Adoption to new sensor configuration Update of data correction routines Tasks still to be Finished


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