Closed-loop thrust control in a MEMS-based micro propulsion module for CubeSats

Transcription

1 Closed-loop thrust control in a MEMS-based micro propulsion module for CubeSats Pelle Rangsten, Kristoffer Palmer, Johan Bejhed, Ana Salaverri, Kerstin Jonsson, and Tor-Arne Grönland NanoSpace Uppsala Science Park pelle.rangsten@sscspace.com SE Uppsala http: SWEDEN

2 Work daily in our MEMS fab

3 then some MAIT to end up with Propellant tank Fluidic I/F Solenoid Valves MEMS Chip Side panels Sealings Electronics Brackets Bolts & Nuts Harness Top & Rear Plates

4 a CubeSat Propulsion Module!!! 0.3U comprising four thrusters!

5 To fly on the QB50-satellite ESTELLE MEMS, propulsion and CubeSats is a good match: Low mass, Low volume, Low power propulsion enables new missions ESTELLE will have a 0.3U module with: 4 thrusters and 50g propellant Key capability: 20 m/s dv (2+2 redundant thrusters) 2-axis control (pitch & yaw) Mission objectives: Orbit raising Precise attitude control Formation flying (TBC)

6 MEMS Micropropulsion Components First generation MEMS micropropulsion: Miniaturised, accurate and open-loop Next generation MEMS micropropulsion: Closed-loop control Xenon flow control module CubeSat propulsion module

7 Closed Loop Flow Control Filter ON/OFF Valve Integrated mass flow sensor provides control signal to the proportional flow control valve Closed-loop flow control MEMS Proportional Flow Control Valve Mass flow sensor Feed back loop to control FCV Including front end electronics Proportional flow control valve Schematic view of a complete closed -loop control thruster.

8 Thrust [µn] Key Capabilities Like any other 700 ON/OFF cycles, full thrust range Time [s] Test result of MEMS thruster operating in ON/OFF mode (open loop, using solenoid valve only) to show thrust range. Full thrust can be set in the range 50 micro-newton to 5 milli-newton

9 Thrust [µn] Key capabilities Unlike any other 25 Low thrust regime step response: 5µN steps 20 Commanded Thrust Delivered Thrust Time [s] Test result of a MEMS valve operating in closed-loop control mode showing the thrust response to commanded steps of 5 μn.

10 Thrust [µn] Unique Performance 5,3 Low thrust regime response: 0.1µN steps 5,2 5,1 Commanded Thrust Delivered Thrus 5 4,9 4,8 4,7 4,6 4,5 4,4 4, Time [s] Test result of a MEMS valve operating in closed loop control mode responding to the commanded steps of 0.1 μn.

11 Physics Problem Low flow rates (i.e. low thrust) in combination with the wish for fast response MEMS Proportional Flow Control Valve Feed line volumes Thrust chamber volume Mass flow sensor and feed back loop to control FCV Thruster case: Requirement: 250 ms in response time Flow rate: 5 µg/s Response time increases linearly with the internal dead volume Simplified estimate: V ~ 10 mm 3 Tubing Length Volume 1/8 5 mm (0.2 ) 9 mm 3 1/ mm (0.025 ) 10 mm 3

12 The Solution - MEMS

13 Record Shattering Resolution Capable to resolve extremely small changes: µn (nn-range!)

14 Summary CubeSat Propulsion Module Closed-loop thrust control demonstrated with unique performance (in terms of thrust and response time in the low thrust regime Key data Four 1mN thrusters with closed-loop thrust control Size: 10*10*3cm Thrust resolution: <10µN Propellant: Butane Total impulse: 40Ns Mass: 250g Operating pressure: 2-5 bar Power consumption: 2 W (average, operating) Mechanical interface: CubeSat payload I/F (Pumpkin) Electrical interface: 52 pins analog (0-12V) and digital (SPI) Note! Scalable tank size to increase total impulse

15 Back to the MEMS kitchen

16 SMÖRGÅSBORD [ˈsmœrɡɔsˌbuːɖ] MEMS Micropropulsion Components for Small Spacecraft Thrusters Flow Control Valves Filters MEMS Isolation Valve Pressure Sensors Presens (N) Pressure Relief Valve

17 Swedish lesson #3: Manager (informal: boss) Chef [sje:f] Welcome! SSC Universal Space Network s booth #35-36 Thank you!